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1 /*
2 ** 2001 September 15
3 **
4 ** The author disclaims copyright to this source code. In place of
5 ** a legal notice, here is a blessing:
6 **
7 ** May you do good and not evil.
8 ** May you find forgiveness for yourself and forgive others.
9 ** May you share freely, never taking more than you give.
10 **
11 *************************************************************************
12 ** This header file defines the interface that the SQLite library
13 ** presents to client programs. If a C-function, structure, datatype,
14 ** or constant definition does not appear in this file, then it is
15 ** not a published API of SQLite, is subject to change without
16 ** notice, and should not be referenced by programs that use SQLite.
17 **
18 ** Some of the definitions that are in this file are marked as
19 ** "experimental". Experimental interfaces are normally new
20 ** features recently added to SQLite. We do not anticipate changes
21 ** to experimental interfaces but reserve the right to make minor changes
22 ** if experience from use "in the wild" suggest such changes are prudent.
23 **
24 ** The official C-language API documentation for SQLite is derived
25 ** from comments in this file. This file is the authoritative source
26 ** on how SQLite interfaces are suppose to operate.
27 **
28 ** The name of this file under configuration management is "sqlite.h.in".
29 ** The makefile makes some minor changes to this file (such as inserting
30 ** the version number) and changes its name to "sqlite3.h" as
31 ** part of the build process.
32 */
33 #ifndef _SQLITE3_H_
34 #define _SQLITE3_H_
37 /*
38 ** Make sure we can call this stuff from C++.
39 */
40 #ifdef __cplusplus
42 #endif
45 /*
46 ** Add the ability to override 'extern'
47 */
48 #ifndef SQLITE_EXTERN
49 # define SQLITE_EXTERN extern
50 #endif
52 #ifndef SQLITE_API
53 # define SQLITE_API
54 #endif
57 /*
58 ** These no-op macros are used in front of interfaces to mark those
59 ** interfaces as either deprecated or experimental. New applications
60 ** should not use deprecated interfaces - they are support for backwards
61 ** compatibility only. Application writers should be aware that
62 ** experimental interfaces are subject to change in point releases.
63 **
64 ** These macros used to resolve to various kinds of compiler magic that
65 ** would generate warning messages when they were used. But that
66 ** compiler magic ended up generating such a flurry of bug reports
67 ** that we have taken it all out and gone back to using simple
68 ** noop macros.
69 */
70 #define SQLITE_DEPRECATED
71 #define SQLITE_EXPERIMENTAL
73 /*
74 ** Ensure these symbols were not defined by some previous header file.
75 */
76 #ifdef SQLITE_VERSION
77 # undef SQLITE_VERSION
78 #endif
79 #ifdef SQLITE_VERSION_NUMBER
80 # undef SQLITE_VERSION_NUMBER
81 #endif
83 /*
84 ** CAPI3REF: Compile-Time Library Version Numbers
85 **
86 ** ^(The [SQLITE_VERSION] C preprocessor macro in the sqlite3.h header
87 ** evaluates to a string literal that is the SQLite version in the
88 ** format "X.Y.Z" where X is the major version number (always 3 for
89 ** SQLite3) and Y is the minor version number and Z is the release number.)^
90 ** ^(The [SQLITE_VERSION_NUMBER] C preprocessor macro resolves to an integer
91 ** with the value (X*1000000 + Y*1000 + Z) where X, Y, and Z are the same
92 ** numbers used in [SQLITE_VERSION].)^
93 ** The SQLITE_VERSION_NUMBER for any given release of SQLite will also
94 ** be larger than the release from which it is derived. Either Y will
95 ** be held constant and Z will be incremented or else Y will be incremented
96 ** and Z will be reset to zero.
97 **
98 ** Since version 3.6.18, SQLite source code has been stored in the
99 ** <a href="http://www.fossil-scm.org/">Fossil configuration management
100 ** system</a>. ^The SQLITE_SOURCE_ID macro evaluates to
101 ** a string which identifies a particular check-in of SQLite
102 ** within its configuration management system. ^The SQLITE_SOURCE_ID
103 ** string contains the date and time of the check-in (UTC) and an SHA1
104 ** hash of the entire source tree.
105 **
106 ** See also: [sqlite3_libversion()],
107 ** [sqlite3_libversion_number()], [sqlite3_sourceid()],
108 ** [sqlite_version()] and [sqlite_source_id()].
109 */
111 #define SQLITE_VERSION_NUMBER 3007010
114 /*
115 ** CAPI3REF: Run-Time Library Version Numbers
116 ** KEYWORDS: sqlite3_version, sqlite3_sourceid
117 **
118 ** These interfaces provide the same information as the [SQLITE_VERSION],
119 ** [SQLITE_VERSION_NUMBER], and [SQLITE_SOURCE_ID] C preprocessor macros
120 ** but are associated with the library instead of the header file. ^(Cautious
121 ** programmers might include assert() statements in their application to
122 ** verify that values returned by these interfaces match the macros in
123 ** the header, and thus insure that the application is
124 ** compiled with matching library and header files.
125 **
126 ** <blockquote><pre>
127 ** assert( sqlite3_libversion_number()==SQLITE_VERSION_NUMBER );
128 ** assert( strcmp(sqlite3_sourceid(),SQLITE_SOURCE_ID)==0 );
129 ** assert( strcmp(sqlite3_libversion(),SQLITE_VERSION)==0 );
130 ** </pre></blockquote>)^
131 **
132 ** ^The sqlite3_version[] string constant contains the text of [SQLITE_VERSION]
133 ** macro. ^The sqlite3_libversion() function returns a pointer to the
134 ** to the sqlite3_version[] string constant. The sqlite3_libversion()
135 ** function is provided for use in DLLs since DLL users usually do not have
136 ** direct access to string constants within the DLL. ^The
137 ** sqlite3_libversion_number() function returns an integer equal to
138 ** [SQLITE_VERSION_NUMBER]. ^The sqlite3_sourceid() function returns
139 ** a pointer to a string constant whose value is the same as the
140 ** [SQLITE_SOURCE_ID] C preprocessor macro.
141 **
142 ** See also: [sqlite_version()] and [sqlite_source_id()].
143 */
149 /*
150 ** CAPI3REF: Run-Time Library Compilation Options Diagnostics
151 **
152 ** ^The sqlite3_compileoption_used() function returns 0 or 1
153 ** indicating whether the specified option was defined at
154 ** compile time. ^The SQLITE_ prefix may be omitted from the
155 ** option name passed to sqlite3_compileoption_used().
156 **
157 ** ^The sqlite3_compileoption_get() function allows iterating
158 ** over the list of options that were defined at compile time by
159 ** returning the N-th compile time option string. ^If N is out of range,
160 ** sqlite3_compileoption_get() returns a NULL pointer. ^The SQLITE_
161 ** prefix is omitted from any strings returned by
162 ** sqlite3_compileoption_get().
163 **
164 ** ^Support for the diagnostic functions sqlite3_compileoption_used()
165 ** and sqlite3_compileoption_get() may be omitted by specifying the
166 ** [SQLITE_OMIT_COMPILEOPTION_DIAGS] option at compile time.
167 **
168 ** See also: SQL functions [sqlite_compileoption_used()] and
169 ** [sqlite_compileoption_get()] and the [compile_options pragma].
170 */
171 #ifndef SQLITE_OMIT_COMPILEOPTION_DIAGS
174 #endif
176 /*
177 ** CAPI3REF: Test To See If The Library Is Threadsafe
178 **
179 ** ^The sqlite3_threadsafe() function returns zero if and only if
180 ** SQLite was compiled with mutexing code omitted due to the
181 ** [SQLITE_THREADSAFE] compile-time option being set to 0.
182 **
183 ** SQLite can be compiled with or without mutexes. When
184 ** the [SQLITE_THREADSAFE] C preprocessor macro is 1 or 2, mutexes
185 ** are enabled and SQLite is threadsafe. When the
186 ** [SQLITE_THREADSAFE] macro is 0,
187 ** the mutexes are omitted. Without the mutexes, it is not safe
188 ** to use SQLite concurrently from more than one thread.
189 **
190 ** Enabling mutexes incurs a measurable performance penalty.
191 ** So if speed is of utmost importance, it makes sense to disable
192 ** the mutexes. But for maximum safety, mutexes should be enabled.
193 ** ^The default behavior is for mutexes to be enabled.
194 **
195 ** This interface can be used by an application to make sure that the
196 ** version of SQLite that it is linking against was compiled with
197 ** the desired setting of the [SQLITE_THREADSAFE] macro.
198 **
199 ** This interface only reports on the compile-time mutex setting
200 ** of the [SQLITE_THREADSAFE] flag. If SQLite is compiled with
201 ** SQLITE_THREADSAFE=1 or =2 then mutexes are enabled by default but
202 ** can be fully or partially disabled using a call to [sqlite3_config()]
203 ** with the verbs [SQLITE_CONFIG_SINGLETHREAD], [SQLITE_CONFIG_MULTITHREAD],
204 ** or [SQLITE_CONFIG_MUTEX]. ^(The return value of the
205 ** sqlite3_threadsafe() function shows only the compile-time setting of
206 ** thread safety, not any run-time changes to that setting made by
207 ** sqlite3_config(). In other words, the return value from sqlite3_threadsafe()
208 ** is unchanged by calls to sqlite3_config().)^
209 **
210 ** See the [threading mode] documentation for additional information.
211 */
214 /*
215 ** CAPI3REF: Database Connection Handle
216 ** KEYWORDS: {database connection} {database connections}
217 **
218 ** Each open SQLite database is represented by a pointer to an instance of
219 ** the opaque structure named "sqlite3". It is useful to think of an sqlite3
220 ** pointer as an object. The [sqlite3_open()], [sqlite3_open16()], and
221 ** [sqlite3_open_v2()] interfaces are its constructors, and [sqlite3_close()]
222 ** is its destructor. There are many other interfaces (such as
223 ** [sqlite3_prepare_v2()], [sqlite3_create_function()], and
224 ** [sqlite3_busy_timeout()] to name but three) that are methods on an
225 ** sqlite3 object.
226 */
229 /*
230 ** CAPI3REF: 64-Bit Integer Types
231 ** KEYWORDS: sqlite_int64 sqlite_uint64
232 **
233 ** Because there is no cross-platform way to specify 64-bit integer types
234 ** SQLite includes typedefs for 64-bit signed and unsigned integers.
235 **
236 ** The sqlite3_int64 and sqlite3_uint64 are the preferred type definitions.
237 ** The sqlite_int64 and sqlite_uint64 types are supported for backwards
238 ** compatibility only.
239 **
240 ** ^The sqlite3_int64 and sqlite_int64 types can store integer values
241 ** between -9223372036854775808 and +9223372036854775807 inclusive. ^The
242 ** sqlite3_uint64 and sqlite_uint64 types can store integer values
243 ** between 0 and +18446744073709551615 inclusive.
244 */
245 #ifdef SQLITE_INT64_TYPE
248 #elif defined(_MSC_VER) || defined(__BORLANDC__)
251 #else
254 #endif
258 /*
259 ** If compiling for a processor that lacks floating point support,
260 ** substitute integer for floating-point.
261 */
262 #ifdef SQLITE_OMIT_FLOATING_POINT
263 # define double sqlite3_int64
264 #endif
266 /*
267 ** CAPI3REF: Closing A Database Connection
268 **
269 ** ^The sqlite3_close() routine is the destructor for the [sqlite3] object.
270 ** ^Calls to sqlite3_close() return SQLITE_OK if the [sqlite3] object is
271 ** successfully destroyed and all associated resources are deallocated.
272 **
273 ** Applications must [sqlite3_finalize | finalize] all [prepared statements]
274 ** and [sqlite3_blob_close | close] all [BLOB handles] associated with
275 ** the [sqlite3] object prior to attempting to close the object. ^If
276 ** sqlite3_close() is called on a [database connection] that still has
277 ** outstanding [prepared statements] or [BLOB handles], then it returns
278 ** SQLITE_BUSY.
279 **
280 ** ^If [sqlite3_close()] is invoked while a transaction is open,
281 ** the transaction is automatically rolled back.
282 **
283 ** The C parameter to [sqlite3_close(C)] must be either a NULL
284 ** pointer or an [sqlite3] object pointer obtained
285 ** from [sqlite3_open()], [sqlite3_open16()], or
286 ** [sqlite3_open_v2()], and not previously closed.
287 ** ^Calling sqlite3_close() with a NULL pointer argument is a
288 ** harmless no-op.
289 */
292 /*
293 ** The type for a callback function.
294 ** This is legacy and deprecated. It is included for historical
295 ** compatibility and is not documented.
296 */
299 /*
300 ** CAPI3REF: One-Step Query Execution Interface
301 **
302 ** The sqlite3_exec() interface is a convenience wrapper around
303 ** [sqlite3_prepare_v2()], [sqlite3_step()], and [sqlite3_finalize()],
304 ** that allows an application to run multiple statements of SQL
305 ** without having to use a lot of C code.
306 **
307 ** ^The sqlite3_exec() interface runs zero or more UTF-8 encoded,
308 ** semicolon-separate SQL statements passed into its 2nd argument,
309 ** in the context of the [database connection] passed in as its 1st
310 ** argument. ^If the callback function of the 3rd argument to
311 ** sqlite3_exec() is not NULL, then it is invoked for each result row
312 ** coming out of the evaluated SQL statements. ^The 4th argument to
313 ** sqlite3_exec() is relayed through to the 1st argument of each
314 ** callback invocation. ^If the callback pointer to sqlite3_exec()
315 ** is NULL, then no callback is ever invoked and result rows are
316 ** ignored.
317 **
318 ** ^If an error occurs while evaluating the SQL statements passed into
319 ** sqlite3_exec(), then execution of the current statement stops and
320 ** subsequent statements are skipped. ^If the 5th parameter to sqlite3_exec()
321 ** is not NULL then any error message is written into memory obtained
322 ** from [sqlite3_malloc()] and passed back through the 5th parameter.
323 ** To avoid memory leaks, the application should invoke [sqlite3_free()]
324 ** on error message strings returned through the 5th parameter of
325 ** of sqlite3_exec() after the error message string is no longer needed.
326 ** ^If the 5th parameter to sqlite3_exec() is not NULL and no errors
327 ** occur, then sqlite3_exec() sets the pointer in its 5th parameter to
328 ** NULL before returning.
329 **
330 ** ^If an sqlite3_exec() callback returns non-zero, the sqlite3_exec()
331 ** routine returns SQLITE_ABORT without invoking the callback again and
332 ** without running any subsequent SQL statements.
333 **
334 ** ^The 2nd argument to the sqlite3_exec() callback function is the
335 ** number of columns in the result. ^The 3rd argument to the sqlite3_exec()
336 ** callback is an array of pointers to strings obtained as if from
337 ** [sqlite3_column_text()], one for each column. ^If an element of a
338 ** result row is NULL then the corresponding string pointer for the
339 ** sqlite3_exec() callback is a NULL pointer. ^The 4th argument to the
340 ** sqlite3_exec() callback is an array of pointers to strings where each
341 ** entry represents the name of corresponding result column as obtained
342 ** from [sqlite3_column_name()].
343 **
344 ** ^If the 2nd parameter to sqlite3_exec() is a NULL pointer, a pointer
345 ** to an empty string, or a pointer that contains only whitespace and/or
346 ** SQL comments, then no SQL statements are evaluated and the database
347 ** is not changed.
348 **
349 ** Restrictions:
350 **
351 ** <ul>
352 ** <li> The application must insure that the 1st parameter to sqlite3_exec()
353 ** is a valid and open [database connection].
354 ** <li> The application must not close [database connection] specified by
355 ** the 1st parameter to sqlite3_exec() while sqlite3_exec() is running.
356 ** <li> The application must not modify the SQL statement text passed into
357 ** the 2nd parameter of sqlite3_exec() while sqlite3_exec() is running.
358 ** </ul>
359 */
366 );
368 /*
369 ** CAPI3REF: Result Codes
370 ** KEYWORDS: SQLITE_OK {error code} {error codes}
371 ** KEYWORDS: {result code} {result codes}
372 **
373 ** Many SQLite functions return an integer result code from the set shown
374 ** here in order to indicate success or failure.
375 **
376 ** New error codes may be added in future versions of SQLite.
377 **
378 ** See also: [SQLITE_IOERR_READ | extended result codes],
379 ** [sqlite3_vtab_on_conflict()] [SQLITE_ROLLBACK | result codes].
380 */
382 /* beginning-of-error-codes */
411 /* end-of-error-codes */
413 /*
414 ** CAPI3REF: Extended Result Codes
415 ** KEYWORDS: {extended error code} {extended error codes}
416 ** KEYWORDS: {extended result code} {extended result codes}
417 **
418 ** In its default configuration, SQLite API routines return one of 26 integer
419 ** [SQLITE_OK | result codes]. However, experience has shown that many of
420 ** these result codes are too coarse-grained. They do not provide as
421 ** much information about problems as programmers might like. In an effort to
422 ** address this, newer versions of SQLite (version 3.3.8 and later) include
423 ** support for additional result codes that provide more detailed information
424 ** about errors. The extended result codes are enabled or disabled
425 ** on a per database connection basis using the
426 ** [sqlite3_extended_result_codes()] API.
427 **
428 ** Some of the available extended result codes are listed here.
429 ** One may expect the number of extended result codes will be expand
430 ** over time. Software that uses extended result codes should expect
431 ** to see new result codes in future releases of SQLite.
432 **
433 ** The SQLITE_OK result code will never be extended. It will always
434 ** be exactly zero.
435 */
436 #define SQLITE_IOERR_READ (SQLITE_IOERR | (1<<8))
437 #define SQLITE_IOERR_SHORT_READ (SQLITE_IOERR | (2<<8))
438 #define SQLITE_IOERR_WRITE (SQLITE_IOERR | (3<<8))
439 #define SQLITE_IOERR_FSYNC (SQLITE_IOERR | (4<<8))
440 #define SQLITE_IOERR_DIR_FSYNC (SQLITE_IOERR | (5<<8))
441 #define SQLITE_IOERR_TRUNCATE (SQLITE_IOERR | (6<<8))
442 #define SQLITE_IOERR_FSTAT (SQLITE_IOERR | (7<<8))
443 #define SQLITE_IOERR_UNLOCK (SQLITE_IOERR | (8<<8))
444 #define SQLITE_IOERR_RDLOCK (SQLITE_IOERR | (9<<8))
445 #define SQLITE_IOERR_DELETE (SQLITE_IOERR | (10<<8))
446 #define SQLITE_IOERR_BLOCKED (SQLITE_IOERR | (11<<8))
447 #define SQLITE_IOERR_NOMEM (SQLITE_IOERR | (12<<8))
448 #define SQLITE_IOERR_ACCESS (SQLITE_IOERR | (13<<8))
449 #define SQLITE_IOERR_CHECKRESERVEDLOCK (SQLITE_IOERR | (14<<8))
450 #define SQLITE_IOERR_LOCK (SQLITE_IOERR | (15<<8))
451 #define SQLITE_IOERR_CLOSE (SQLITE_IOERR | (16<<8))
452 #define SQLITE_IOERR_DIR_CLOSE (SQLITE_IOERR | (17<<8))
453 #define SQLITE_IOERR_SHMOPEN (SQLITE_IOERR | (18<<8))
454 #define SQLITE_IOERR_SHMSIZE (SQLITE_IOERR | (19<<8))
455 #define SQLITE_IOERR_SHMLOCK (SQLITE_IOERR | (20<<8))
456 #define SQLITE_IOERR_SHMMAP (SQLITE_IOERR | (21<<8))
457 #define SQLITE_IOERR_SEEK (SQLITE_IOERR | (22<<8))
458 #define SQLITE_LOCKED_SHAREDCACHE (SQLITE_LOCKED | (1<<8))
459 #define SQLITE_BUSY_RECOVERY (SQLITE_BUSY | (1<<8))
460 #define SQLITE_CANTOPEN_NOTEMPDIR (SQLITE_CANTOPEN | (1<<8))
461 #define SQLITE_CORRUPT_VTAB (SQLITE_CORRUPT | (1<<8))
462 #define SQLITE_READONLY_RECOVERY (SQLITE_READONLY | (1<<8))
463 #define SQLITE_READONLY_CANTLOCK (SQLITE_READONLY | (2<<8))
465 /*
466 ** CAPI3REF: Flags For File Open Operations
467 **
468 ** These bit values are intended for use in the
469 ** 3rd parameter to the [sqlite3_open_v2()] interface and
470 ** in the 4th parameter to the [sqlite3_vfs.xOpen] method.
471 */
492 /* Reserved: 0x00F00000 */
494 /*
495 ** CAPI3REF: Device Characteristics
496 **
497 ** The xDeviceCharacteristics method of the [sqlite3_io_methods]
498 ** object returns an integer which is a vector of the these
499 ** bit values expressing I/O characteristics of the mass storage
500 ** device that holds the file that the [sqlite3_io_methods]
501 ** refers to.
502 **
503 ** The SQLITE_IOCAP_ATOMIC property means that all writes of
504 ** any size are atomic. The SQLITE_IOCAP_ATOMICnnn values
505 ** mean that writes of blocks that are nnn bytes in size and
506 ** are aligned to an address which is an integer multiple of
507 ** nnn are atomic. The SQLITE_IOCAP_SAFE_APPEND value means
508 ** that when data is appended to a file, the data is appended
509 ** first then the size of the file is extended, never the other
510 ** way around. The SQLITE_IOCAP_SEQUENTIAL property means that
511 ** information is written to disk in the same order as calls
512 ** to xWrite(). The SQLITE_IOCAP_POWERSAFE_OVERWRITE property means that
513 ** after reboot following a crash or power loss, the only bytes in a
514 ** file that were written at the application level might have changed
515 ** and that adjacent bytes, even bytes within the same sector are
516 ** guaranteed to be unchanged.
517 */
518 #define SQLITE_IOCAP_ATOMIC 0x00000001
519 #define SQLITE_IOCAP_ATOMIC512 0x00000002
520 #define SQLITE_IOCAP_ATOMIC1K 0x00000004
521 #define SQLITE_IOCAP_ATOMIC2K 0x00000008
522 #define SQLITE_IOCAP_ATOMIC4K 0x00000010
523 #define SQLITE_IOCAP_ATOMIC8K 0x00000020
524 #define SQLITE_IOCAP_ATOMIC16K 0x00000040
525 #define SQLITE_IOCAP_ATOMIC32K 0x00000080
526 #define SQLITE_IOCAP_ATOMIC64K 0x00000100
527 #define SQLITE_IOCAP_SAFE_APPEND 0x00000200
528 #define SQLITE_IOCAP_SEQUENTIAL 0x00000400
529 #define SQLITE_IOCAP_UNDELETABLE_WHEN_OPEN 0x00000800
530 #define SQLITE_IOCAP_POWERSAFE_OVERWRITE 0x00001000
532 /*
533 ** CAPI3REF: File Locking Levels
534 **
535 ** SQLite uses one of these integer values as the second
536 ** argument to calls it makes to the xLock() and xUnlock() methods
537 ** of an [sqlite3_io_methods] object.
538 */
539 #define SQLITE_LOCK_NONE 0
540 #define SQLITE_LOCK_SHARED 1
541 #define SQLITE_LOCK_RESERVED 2
542 #define SQLITE_LOCK_PENDING 3
543 #define SQLITE_LOCK_EXCLUSIVE 4
545 /*
546 ** CAPI3REF: Synchronization Type Flags
547 **
548 ** When SQLite invokes the xSync() method of an
549 ** [sqlite3_io_methods] object it uses a combination of
550 ** these integer values as the second argument.
551 **
552 ** When the SQLITE_SYNC_DATAONLY flag is used, it means that the
553 ** sync operation only needs to flush data to mass storage. Inode
554 ** information need not be flushed. If the lower four bits of the flag
555 ** equal SQLITE_SYNC_NORMAL, that means to use normal fsync() semantics.
556 ** If the lower four bits equal SQLITE_SYNC_FULL, that means
557 ** to use Mac OS X style fullsync instead of fsync().
558 **
559 ** Do not confuse the SQLITE_SYNC_NORMAL and SQLITE_SYNC_FULL flags
560 ** with the [PRAGMA synchronous]=NORMAL and [PRAGMA synchronous]=FULL
561 ** settings. The [synchronous pragma] determines when calls to the
562 ** xSync VFS method occur and applies uniformly across all platforms.
563 ** The SQLITE_SYNC_NORMAL and SQLITE_SYNC_FULL flags determine how
564 ** energetic or rigorous or forceful the sync operations are and
565 ** only make a difference on Mac OSX for the default SQLite code.
566 ** (Third-party VFS implementations might also make the distinction
567 ** between SQLITE_SYNC_NORMAL and SQLITE_SYNC_FULL, but among the
568 ** operating systems natively supported by SQLite, only Mac OSX
569 ** cares about the difference.)
570 */
571 #define SQLITE_SYNC_NORMAL 0x00002
572 #define SQLITE_SYNC_FULL 0x00003
573 #define SQLITE_SYNC_DATAONLY 0x00010
575 /*
576 ** CAPI3REF: OS Interface Open File Handle
577 **
578 ** An [sqlite3_file] object represents an open file in the
579 ** [sqlite3_vfs | OS interface layer]. Individual OS interface
580 ** implementations will
581 ** want to subclass this object by appending additional fields
582 ** for their own use. The pMethods entry is a pointer to an
583 ** [sqlite3_io_methods] object that defines methods for performing
584 ** I/O operations on the open file.
585 */
589 };
591 /*
592 ** CAPI3REF: OS Interface File Virtual Methods Object
593 **
594 ** Every file opened by the [sqlite3_vfs.xOpen] method populates an
595 ** [sqlite3_file] object (or, more commonly, a subclass of the
596 ** [sqlite3_file] object) with a pointer to an instance of this object.
597 ** This object defines the methods used to perform various operations
598 ** against the open file represented by the [sqlite3_file] object.
599 **
600 ** If the [sqlite3_vfs.xOpen] method sets the sqlite3_file.pMethods element
601 ** to a non-NULL pointer, then the sqlite3_io_methods.xClose method
602 ** may be invoked even if the [sqlite3_vfs.xOpen] reported that it failed. The
603 ** only way to prevent a call to xClose following a failed [sqlite3_vfs.xOpen]
604 ** is for the [sqlite3_vfs.xOpen] to set the sqlite3_file.pMethods element
605 ** to NULL.
606 **
607 ** The flags argument to xSync may be one of [SQLITE_SYNC_NORMAL] or
608 ** [SQLITE_SYNC_FULL]. The first choice is the normal fsync().
609 ** The second choice is a Mac OS X style fullsync. The [SQLITE_SYNC_DATAONLY]
610 ** flag may be ORed in to indicate that only the data of the file
611 ** and not its inode needs to be synced.
612 **
613 ** The integer values to xLock() and xUnlock() are one of
614 ** <ul>
615 ** <li> [SQLITE_LOCK_NONE],
616 ** <li> [SQLITE_LOCK_SHARED],
617 ** <li> [SQLITE_LOCK_RESERVED],
618 ** <li> [SQLITE_LOCK_PENDING], or
619 ** <li> [SQLITE_LOCK_EXCLUSIVE].
620 ** </ul>
621 ** xLock() increases the lock. xUnlock() decreases the lock.
622 ** The xCheckReservedLock() method checks whether any database connection,
623 ** either in this process or in some other process, is holding a RESERVED,
624 ** PENDING, or EXCLUSIVE lock on the file. It returns true
625 ** if such a lock exists and false otherwise.
626 **
627 ** The xFileControl() method is a generic interface that allows custom
628 ** VFS implementations to directly control an open file using the
629 ** [sqlite3_file_control()] interface. The second "op" argument is an
630 ** integer opcode. The third argument is a generic pointer intended to
631 ** point to a structure that may contain arguments or space in which to
632 ** write return values. Potential uses for xFileControl() might be
633 ** functions to enable blocking locks with timeouts, to change the
634 ** locking strategy (for example to use dot-file locks), to inquire
635 ** about the status of a lock, or to break stale locks. The SQLite
636 ** core reserves all opcodes less than 100 for its own use.
637 ** A [SQLITE_FCNTL_LOCKSTATE | list of opcodes] less than 100 is available.
638 ** Applications that define a custom xFileControl method should use opcodes
639 ** greater than 100 to avoid conflicts. VFS implementations should
640 ** return [SQLITE_NOTFOUND] for file control opcodes that they do not
641 ** recognize.
642 **
643 ** The xSectorSize() method returns the sector size of the
644 ** device that underlies the file. The sector size is the
645 ** minimum write that can be performed without disturbing
646 ** other bytes in the file. The xDeviceCharacteristics()
647 ** method returns a bit vector describing behaviors of the
648 ** underlying device:
649 **
650 ** <ul>
651 ** <li> [SQLITE_IOCAP_ATOMIC]
652 ** <li> [SQLITE_IOCAP_ATOMIC512]
653 ** <li> [SQLITE_IOCAP_ATOMIC1K]
654 ** <li> [SQLITE_IOCAP_ATOMIC2K]
655 ** <li> [SQLITE_IOCAP_ATOMIC4K]
656 ** <li> [SQLITE_IOCAP_ATOMIC8K]
657 ** <li> [SQLITE_IOCAP_ATOMIC16K]
658 ** <li> [SQLITE_IOCAP_ATOMIC32K]
659 ** <li> [SQLITE_IOCAP_ATOMIC64K]
660 ** <li> [SQLITE_IOCAP_SAFE_APPEND]
661 ** <li> [SQLITE_IOCAP_SEQUENTIAL]
662 ** </ul>
663 **
664 ** The SQLITE_IOCAP_ATOMIC property means that all writes of
665 ** any size are atomic. The SQLITE_IOCAP_ATOMICnnn values
666 ** mean that writes of blocks that are nnn bytes in size and
667 ** are aligned to an address which is an integer multiple of
668 ** nnn are atomic. The SQLITE_IOCAP_SAFE_APPEND value means
669 ** that when data is appended to a file, the data is appended
670 ** first then the size of the file is extended, never the other
671 ** way around. The SQLITE_IOCAP_SEQUENTIAL property means that
672 ** information is written to disk in the same order as calls
673 ** to xWrite().
674 **
675 ** If xRead() returns SQLITE_IOERR_SHORT_READ it must also fill
676 ** in the unread portions of the buffer with zeros. A VFS that
677 ** fails to zero-fill short reads might seem to work. However,
678 ** failure to zero-fill short reads will eventually lead to
679 ** database corruption.
680 */
696 /* Methods above are valid for version 1 */
701 /* Methods above are valid for version 2 */
702 /* Additional methods may be added in future releases */
703 };
705 /*
706 ** CAPI3REF: Standard File Control Opcodes
707 **
708 ** These integer constants are opcodes for the xFileControl method
709 ** of the [sqlite3_io_methods] object and for the [sqlite3_file_control()]
710 ** interface.
711 **
712 ** The [SQLITE_FCNTL_LOCKSTATE] opcode is used for debugging. This
713 ** opcode causes the xFileControl method to write the current state of
714 ** the lock (one of [SQLITE_LOCK_NONE], [SQLITE_LOCK_SHARED],
715 ** [SQLITE_LOCK_RESERVED], [SQLITE_LOCK_PENDING], or [SQLITE_LOCK_EXCLUSIVE])
716 ** into an integer that the pArg argument points to. This capability
717 ** is used during testing and only needs to be supported when SQLITE_TEST
718 ** is defined.
719 **
720 ** The [SQLITE_FCNTL_SIZE_HINT] opcode is used by SQLite to give the VFS
721 ** layer a hint of how large the database file will grow to be during the
722 ** current transaction. This hint is not guaranteed to be accurate but it
723 ** is often close. The underlying VFS might choose to preallocate database
724 ** file space based on this hint in order to help writes to the database
725 ** file run faster.
726 **
727 ** The [SQLITE_FCNTL_CHUNK_SIZE] opcode is used to request that the VFS
728 ** extends and truncates the database file in chunks of a size specified
729 ** by the user. The fourth argument to [sqlite3_file_control()] should
730 ** point to an integer (type int) containing the new chunk-size to use
731 ** for the nominated database. Allocating database file space in large
732 ** chunks (say 1MB at a time), may reduce file-system fragmentation and
733 ** improve performance on some systems.
734 **
735 ** The [SQLITE_FCNTL_FILE_POINTER] opcode is used to obtain a pointer
736 ** to the [sqlite3_file] object associated with a particular database
737 ** connection. See the [sqlite3_file_control()] documentation for
738 ** additional information.
739 **
740 ** ^(The [SQLITE_FCNTL_SYNC_OMITTED] opcode is generated internally by
741 ** SQLite and sent to all VFSes in place of a call to the xSync method
742 ** when the database connection has [PRAGMA synchronous] set to OFF.)^
743 ** Some specialized VFSes need this signal in order to operate correctly
744 ** when [PRAGMA synchronous | PRAGMA synchronous=OFF] is set, but most
745 ** VFSes do not need this signal and should silently ignore this opcode.
746 ** Applications should not call [sqlite3_file_control()] with this
747 ** opcode as doing so may disrupt the operation of the specialized VFSes
748 ** that do require it.
749 **
750 ** ^The [SQLITE_FCNTL_WIN32_AV_RETRY] opcode is used to configure automatic
751 ** retry counts and intervals for certain disk I/O operations for the
752 ** windows [VFS] in order to provide robustness in the presence of
753 ** anti-virus programs. By default, the windows VFS will retry file read,
754 ** file write, and file delete operations up to 10 times, with a delay
755 ** of 25 milliseconds before the first retry and with the delay increasing
756 ** by an additional 25 milliseconds with each subsequent retry. This
757 ** opcode allows these two values (10 retries and 25 milliseconds of delay)
758 ** to be adjusted. The values are changed for all database connections
759 ** within the same process. The argument is a pointer to an array of two
760 ** integers where the first integer i the new retry count and the second
761 ** integer is the delay. If either integer is negative, then the setting
762 ** is not changed but instead the prior value of that setting is written
763 ** into the array entry, allowing the current retry settings to be
764 ** interrogated. The zDbName parameter is ignored.
765 **
766 ** ^The [SQLITE_FCNTL_PERSIST_WAL] opcode is used to set or query the
767 ** persistent [WAL | Write AHead Log] setting. By default, the auxiliary
768 ** write ahead log and shared memory files used for transaction control
769 ** are automatically deleted when the latest connection to the database
770 ** closes. Setting persistent WAL mode causes those files to persist after
771 ** close. Persisting the files is useful when other processes that do not
772 ** have write permission on the directory containing the database file want
773 ** to read the database file, as the WAL and shared memory files must exist
774 ** in order for the database to be readable. The fourth parameter to
775 ** [sqlite3_file_control()] for this opcode should be a pointer to an integer.
776 ** That integer is 0 to disable persistent WAL mode or 1 to enable persistent
777 ** WAL mode. If the integer is -1, then it is overwritten with the current
778 ** WAL persistence setting.
779 **
780 ** ^The [SQLITE_FCNTL_POWERSAFE_OVERWRITE] opcode is used to set or query the
781 ** persistent "powersafe-overwrite" or "PSOW" setting. The PSOW setting
782 ** determines the [SQLITE_IOCAP_POWERSAFE_OVERWRITE] bit of the
783 ** xDeviceCharacteristics methods. The fourth parameter to
784 ** [sqlite3_file_control()] for this opcode should be a pointer to an integer.
785 ** That integer is 0 to disable zero-damage mode or 1 to enable zero-damage
786 ** mode. If the integer is -1, then it is overwritten with the current
787 ** zero-damage mode setting.
788 **
789 ** ^The [SQLITE_FCNTL_OVERWRITE] opcode is invoked by SQLite after opening
790 ** a write transaction to indicate that, unless it is rolled back for some
791 ** reason, the entire database file will be overwritten by the current
792 ** transaction. This is used by VACUUM operations.
793 **
794 ** ^The [SQLITE_FCNTL_VFSNAME] opcode can be used to obtain the names of
795 ** all [VFSes] in the VFS stack. The names are of all VFS shims and the
796 ** final bottom-level VFS are written into memory obtained from
797 ** [sqlite3_malloc()] and the result is stored in the char* variable
798 ** that the fourth parameter of [sqlite3_file_control()] points to.
799 ** The caller is responsible for freeing the memory when done. As with
800 ** all file-control actions, there is no guarantee that this will actually
801 ** do anything. Callers should initialize the char* variable to a NULL
802 ** pointer in case this file-control is not implemented. This file-control
803 ** is intended for diagnostic use only.
804 */
805 #define SQLITE_FCNTL_LOCKSTATE 1
806 #define SQLITE_GET_LOCKPROXYFILE 2
807 #define SQLITE_SET_LOCKPROXYFILE 3
808 #define SQLITE_LAST_ERRNO 4
809 #define SQLITE_FCNTL_SIZE_HINT 5
810 #define SQLITE_FCNTL_CHUNK_SIZE 6
811 #define SQLITE_FCNTL_FILE_POINTER 7
812 #define SQLITE_FCNTL_SYNC_OMITTED 8
813 #define SQLITE_FCNTL_WIN32_AV_RETRY 9
814 #define SQLITE_FCNTL_PERSIST_WAL 10
815 #define SQLITE_FCNTL_OVERWRITE 11
816 #define SQLITE_FCNTL_VFSNAME 12
817 #define SQLITE_FCNTL_POWERSAFE_OVERWRITE 13
819 /*
820 ** CAPI3REF: Mutex Handle
821 **
822 ** The mutex module within SQLite defines [sqlite3_mutex] to be an
823 ** abstract type for a mutex object. The SQLite core never looks
824 ** at the internal representation of an [sqlite3_mutex]. It only
825 ** deals with pointers to the [sqlite3_mutex] object.
826 **
827 ** Mutexes are created using [sqlite3_mutex_alloc()].
828 */
831 /*
832 ** CAPI3REF: OS Interface Object
833 **
834 ** An instance of the sqlite3_vfs object defines the interface between
835 ** the SQLite core and the underlying operating system. The "vfs"
836 ** in the name of the object stands for "virtual file system". See
837 ** the [VFS | VFS documentation] for further information.
838 **
839 ** The value of the iVersion field is initially 1 but may be larger in
840 ** future versions of SQLite. Additional fields may be appended to this
841 ** object when the iVersion value is increased. Note that the structure
842 ** of the sqlite3_vfs object changes in the transaction between
843 ** SQLite version 3.5.9 and 3.6.0 and yet the iVersion field was not
844 ** modified.
845 **
846 ** The szOsFile field is the size of the subclassed [sqlite3_file]
847 ** structure used by this VFS. mxPathname is the maximum length of
848 ** a pathname in this VFS.
849 **
850 ** Registered sqlite3_vfs objects are kept on a linked list formed by
851 ** the pNext pointer. The [sqlite3_vfs_register()]
852 ** and [sqlite3_vfs_unregister()] interfaces manage this list
853 ** in a thread-safe way. The [sqlite3_vfs_find()] interface
854 ** searches the list. Neither the application code nor the VFS
855 ** implementation should use the pNext pointer.
856 **
857 ** The pNext field is the only field in the sqlite3_vfs
858 ** structure that SQLite will ever modify. SQLite will only access
859 ** or modify this field while holding a particular static mutex.
860 ** The application should never modify anything within the sqlite3_vfs
861 ** object once the object has been registered.
862 **
863 ** The zName field holds the name of the VFS module. The name must
864 ** be unique across all VFS modules.
865 **
866 ** [[sqlite3_vfs.xOpen]]
867 ** ^SQLite guarantees that the zFilename parameter to xOpen
868 ** is either a NULL pointer or string obtained
869 ** from xFullPathname() with an optional suffix added.
870 ** ^If a suffix is added to the zFilename parameter, it will
871 ** consist of a single "-" character followed by no more than
872 ** 11 alphanumeric and/or "-" characters.
873 ** ^SQLite further guarantees that
874 ** the string will be valid and unchanged until xClose() is
875 ** called. Because of the previous sentence,
876 ** the [sqlite3_file] can safely store a pointer to the
877 ** filename if it needs to remember the filename for some reason.
878 ** If the zFilename parameter to xOpen is a NULL pointer then xOpen
879 ** must invent its own temporary name for the file. ^Whenever the
880 ** xFilename parameter is NULL it will also be the case that the
881 ** flags parameter will include [SQLITE_OPEN_DELETEONCLOSE].
882 **
883 ** The flags argument to xOpen() includes all bits set in
884 ** the flags argument to [sqlite3_open_v2()]. Or if [sqlite3_open()]
885 ** or [sqlite3_open16()] is used, then flags includes at least
886 ** [SQLITE_OPEN_READWRITE] | [SQLITE_OPEN_CREATE].
887 ** If xOpen() opens a file read-only then it sets *pOutFlags to
888 ** include [SQLITE_OPEN_READONLY]. Other bits in *pOutFlags may be set.
889 **
890 ** ^(SQLite will also add one of the following flags to the xOpen()
891 ** call, depending on the object being opened:
892 **
893 ** <ul>
894 ** <li> [SQLITE_OPEN_MAIN_DB]
895 ** <li> [SQLITE_OPEN_MAIN_JOURNAL]
896 ** <li> [SQLITE_OPEN_TEMP_DB]
897 ** <li> [SQLITE_OPEN_TEMP_JOURNAL]
898 ** <li> [SQLITE_OPEN_TRANSIENT_DB]
899 ** <li> [SQLITE_OPEN_SUBJOURNAL]
900 ** <li> [SQLITE_OPEN_MASTER_JOURNAL]
901 ** <li> [SQLITE_OPEN_WAL]
902 ** </ul>)^
903 **
904 ** The file I/O implementation can use the object type flags to
905 ** change the way it deals with files. For example, an application
906 ** that does not care about crash recovery or rollback might make
907 ** the open of a journal file a no-op. Writes to this journal would
908 ** also be no-ops, and any attempt to read the journal would return
909 ** SQLITE_IOERR. Or the implementation might recognize that a database
910 ** file will be doing page-aligned sector reads and writes in a random
911 ** order and set up its I/O subsystem accordingly.
912 **
913 ** SQLite might also add one of the following flags to the xOpen method:
914 **
915 ** <ul>
916 ** <li> [SQLITE_OPEN_DELETEONCLOSE]
917 ** <li> [SQLITE_OPEN_EXCLUSIVE]
918 ** </ul>
919 **
920 ** The [SQLITE_OPEN_DELETEONCLOSE] flag means the file should be
921 ** deleted when it is closed. ^The [SQLITE_OPEN_DELETEONCLOSE]
922 ** will be set for TEMP databases and their journals, transient
923 ** databases, and subjournals.
924 **
925 ** ^The [SQLITE_OPEN_EXCLUSIVE] flag is always used in conjunction
926 ** with the [SQLITE_OPEN_CREATE] flag, which are both directly
927 ** analogous to the O_EXCL and O_CREAT flags of the POSIX open()
928 ** API. The SQLITE_OPEN_EXCLUSIVE flag, when paired with the
929 ** SQLITE_OPEN_CREATE, is used to indicate that file should always
930 ** be created, and that it is an error if it already exists.
931 ** It is <i>not</i> used to indicate the file should be opened
932 ** for exclusive access.
933 **
934 ** ^At least szOsFile bytes of memory are allocated by SQLite
935 ** to hold the [sqlite3_file] structure passed as the third
936 ** argument to xOpen. The xOpen method does not have to
937 ** allocate the structure; it should just fill it in. Note that
938 ** the xOpen method must set the sqlite3_file.pMethods to either
939 ** a valid [sqlite3_io_methods] object or to NULL. xOpen must do
940 ** this even if the open fails. SQLite expects that the sqlite3_file.pMethods
941 ** element will be valid after xOpen returns regardless of the success
942 ** or failure of the xOpen call.
943 **
944 ** [[sqlite3_vfs.xAccess]]
945 ** ^The flags argument to xAccess() may be [SQLITE_ACCESS_EXISTS]
946 ** to test for the existence of a file, or [SQLITE_ACCESS_READWRITE] to
947 ** test whether a file is readable and writable, or [SQLITE_ACCESS_READ]
948 ** to test whether a file is at least readable. The file can be a
949 ** directory.
950 **
951 ** ^SQLite will always allocate at least mxPathname+1 bytes for the
952 ** output buffer xFullPathname. The exact size of the output buffer
953 ** is also passed as a parameter to both methods. If the output buffer
954 ** is not large enough, [SQLITE_CANTOPEN] should be returned. Since this is
955 ** handled as a fatal error by SQLite, vfs implementations should endeavor
956 ** to prevent this by setting mxPathname to a sufficiently large value.
957 **
958 ** The xRandomness(), xSleep(), xCurrentTime(), and xCurrentTimeInt64()
959 ** interfaces are not strictly a part of the filesystem, but they are
960 ** included in the VFS structure for completeness.
961 ** The xRandomness() function attempts to return nBytes bytes
962 ** of good-quality randomness into zOut. The return value is
963 ** the actual number of bytes of randomness obtained.
964 ** The xSleep() method causes the calling thread to sleep for at
965 ** least the number of microseconds given. ^The xCurrentTime()
966 ** method returns a Julian Day Number for the current date and time as
967 ** a floating point value.
968 ** ^The xCurrentTimeInt64() method returns, as an integer, the Julian
969 ** Day Number multiplied by 86400000 (the number of milliseconds in
970 ** a 24-hour day).
971 ** ^SQLite will use the xCurrentTimeInt64() method to get the current
972 ** date and time if that method is available (if iVersion is 2 or
973 ** greater and the function pointer is not NULL) and will fall back
974 ** to xCurrentTime() if xCurrentTimeInt64() is unavailable.
975 **
976 ** ^The xSetSystemCall(), xGetSystemCall(), and xNestSystemCall() interfaces
977 ** are not used by the SQLite core. These optional interfaces are provided
978 ** by some VFSes to facilitate testing of the VFS code. By overriding
979 ** system calls with functions under its control, a test program can
980 ** simulate faults and error conditions that would otherwise be difficult
981 ** or impossible to induce. The set of system calls that can be overridden
982 ** varies from one VFS to another, and from one version of the same VFS to the
983 ** next. Applications that use these interfaces must be prepared for any
984 ** or all of these interfaces to be NULL or for their behavior to change
985 ** from one release to the next. Applications must not attempt to access
986 ** any of these methods if the iVersion of the VFS is less than 3.
987 */
1010 /*
1011 ** The methods above are in version 1 of the sqlite_vfs object
1012 ** definition. Those that follow are added in version 2 or later
1013 */
1015 /*
1016 ** The methods above are in versions 1 and 2 of the sqlite_vfs object.
1017 ** Those below are for version 3 and greater.
1018 */
1022 /*
1023 ** The methods above are in versions 1 through 3 of the sqlite_vfs object.
1024 ** New fields may be appended in figure versions. The iVersion
1025 ** value will increment whenever this happens.
1026 */
1027 };
1029 /*
1030 ** CAPI3REF: Flags for the xAccess VFS method
1031 **
1032 ** These integer constants can be used as the third parameter to
1033 ** the xAccess method of an [sqlite3_vfs] object. They determine
1034 ** what kind of permissions the xAccess method is looking for.
1035 ** With SQLITE_ACCESS_EXISTS, the xAccess method
1036 ** simply checks whether the file exists.
1037 ** With SQLITE_ACCESS_READWRITE, the xAccess method
1038 ** checks whether the named directory is both readable and writable
1039 ** (in other words, if files can be added, removed, and renamed within
1040 ** the directory).
1041 ** The SQLITE_ACCESS_READWRITE constant is currently used only by the
1042 ** [temp_store_directory pragma], though this could change in a future
1043 ** release of SQLite.
1044 ** With SQLITE_ACCESS_READ, the xAccess method
1045 ** checks whether the file is readable. The SQLITE_ACCESS_READ constant is
1046 ** currently unused, though it might be used in a future release of
1047 ** SQLite.
1048 */
1049 #define SQLITE_ACCESS_EXISTS 0
1053 /*
1054 ** CAPI3REF: Flags for the xShmLock VFS method
1055 **
1056 ** These integer constants define the various locking operations
1057 ** allowed by the xShmLock method of [sqlite3_io_methods]. The
1058 ** following are the only legal combinations of flags to the
1059 ** xShmLock method:
1060 **
1061 ** <ul>
1062 ** <li> SQLITE_SHM_LOCK | SQLITE_SHM_SHARED
1063 ** <li> SQLITE_SHM_LOCK | SQLITE_SHM_EXCLUSIVE
1064 ** <li> SQLITE_SHM_UNLOCK | SQLITE_SHM_SHARED
1065 ** <li> SQLITE_SHM_UNLOCK | SQLITE_SHM_EXCLUSIVE
1066 ** </ul>
1067 **
1068 ** When unlocking, the same SHARED or EXCLUSIVE flag must be supplied as
1069 ** was given no the corresponding lock.
1070 **
1071 ** The xShmLock method can transition between unlocked and SHARED or
1072 ** between unlocked and EXCLUSIVE. It cannot transition between SHARED
1073 ** and EXCLUSIVE.
1074 */
1075 #define SQLITE_SHM_UNLOCK 1
1076 #define SQLITE_SHM_LOCK 2
1077 #define SQLITE_SHM_SHARED 4
1078 #define SQLITE_SHM_EXCLUSIVE 8
1080 /*
1081 ** CAPI3REF: Maximum xShmLock index
1082 **
1083 ** The xShmLock method on [sqlite3_io_methods] may use values
1084 ** between 0 and this upper bound as its "offset" argument.
1085 ** The SQLite core will never attempt to acquire or release a
1086 ** lock outside of this range
1087 */
1088 #define SQLITE_SHM_NLOCK 8
1091 /*
1092 ** CAPI3REF: Initialize The SQLite Library
1093 **
1094 ** ^The sqlite3_initialize() routine initializes the
1095 ** SQLite library. ^The sqlite3_shutdown() routine
1096 ** deallocates any resources that were allocated by sqlite3_initialize().
1097 ** These routines are designed to aid in process initialization and
1098 ** shutdown on embedded systems. Workstation applications using
1099 ** SQLite normally do not need to invoke either of these routines.
1100 **
1101 ** A call to sqlite3_initialize() is an "effective" call if it is
1102 ** the first time sqlite3_initialize() is invoked during the lifetime of
1103 ** the process, or if it is the first time sqlite3_initialize() is invoked
1104 ** following a call to sqlite3_shutdown(). ^(Only an effective call
1105 ** of sqlite3_initialize() does any initialization. All other calls
1106 ** are harmless no-ops.)^
1107 **
1108 ** A call to sqlite3_shutdown() is an "effective" call if it is the first
1109 ** call to sqlite3_shutdown() since the last sqlite3_initialize(). ^(Only
1110 ** an effective call to sqlite3_shutdown() does any deinitialization.
1111 ** All other valid calls to sqlite3_shutdown() are harmless no-ops.)^
1112 **
1113 ** The sqlite3_initialize() interface is threadsafe, but sqlite3_shutdown()
1114 ** is not. The sqlite3_shutdown() interface must only be called from a
1115 ** single thread. All open [database connections] must be closed and all
1116 ** other SQLite resources must be deallocated prior to invoking
1117 ** sqlite3_shutdown().
1118 **
1119 ** Among other things, ^sqlite3_initialize() will invoke
1120 ** sqlite3_os_init(). Similarly, ^sqlite3_shutdown()
1121 ** will invoke sqlite3_os_end().
1122 **
1123 ** ^The sqlite3_initialize() routine returns [SQLITE_OK] on success.
1124 ** ^If for some reason, sqlite3_initialize() is unable to initialize
1125 ** the library (perhaps it is unable to allocate a needed resource such
1126 ** as a mutex) it returns an [error code] other than [SQLITE_OK].
1127 **
1128 ** ^The sqlite3_initialize() routine is called internally by many other
1129 ** SQLite interfaces so that an application usually does not need to
1130 ** invoke sqlite3_initialize() directly. For example, [sqlite3_open()]
1131 ** calls sqlite3_initialize() so the SQLite library will be automatically
1132 ** initialized when [sqlite3_open()] is called if it has not be initialized
1133 ** already. ^However, if SQLite is compiled with the [SQLITE_OMIT_AUTOINIT]
1134 ** compile-time option, then the automatic calls to sqlite3_initialize()
1135 ** are omitted and the application must call sqlite3_initialize() directly
1136 ** prior to using any other SQLite interface. For maximum portability,
1137 ** it is recommended that applications always invoke sqlite3_initialize()
1138 ** directly prior to using any other SQLite interface. Future releases
1139 ** of SQLite may require this. In other words, the behavior exhibited
1140 ** when SQLite is compiled with [SQLITE_OMIT_AUTOINIT] might become the
1141 ** default behavior in some future release of SQLite.
1142 **
1143 ** The sqlite3_os_init() routine does operating-system specific
1144 ** initialization of the SQLite library. The sqlite3_os_end()
1145 ** routine undoes the effect of sqlite3_os_init(). Typical tasks
1146 ** performed by these routines include allocation or deallocation
1147 ** of static resources, initialization of global variables,
1148 ** setting up a default [sqlite3_vfs] module, or setting up
1149 ** a default configuration using [sqlite3_config()].
1150 **
1151 ** The application should never invoke either sqlite3_os_init()
1152 ** or sqlite3_os_end() directly. The application should only invoke
1153 ** sqlite3_initialize() and sqlite3_shutdown(). The sqlite3_os_init()
1154 ** interface is called automatically by sqlite3_initialize() and
1155 ** sqlite3_os_end() is called by sqlite3_shutdown(). Appropriate
1156 ** implementations for sqlite3_os_init() and sqlite3_os_end()
1157 ** are built into SQLite when it is compiled for Unix, Windows, or OS/2.
1158 ** When [custom builds | built for other platforms]
1159 ** (using the [SQLITE_OS_OTHER=1] compile-time
1160 ** option) the application must supply a suitable implementation for
1161 ** sqlite3_os_init() and sqlite3_os_end(). An application-supplied
1162 ** implementation of sqlite3_os_init() or sqlite3_os_end()
1163 ** must return [SQLITE_OK] on success and some other [error code] upon
1164 ** failure.
1165 */
1171 /*
1172 ** CAPI3REF: Configuring The SQLite Library
1173 **
1174 ** The sqlite3_config() interface is used to make global configuration
1175 ** changes to SQLite in order to tune SQLite to the specific needs of
1176 ** the application. The default configuration is recommended for most
1177 ** applications and so this routine is usually not necessary. It is
1178 ** provided to support rare applications with unusual needs.
1179 **
1180 ** The sqlite3_config() interface is not threadsafe. The application
1181 ** must insure that no other SQLite interfaces are invoked by other
1182 ** threads while sqlite3_config() is running. Furthermore, sqlite3_config()
1183 ** may only be invoked prior to library initialization using
1184 ** [sqlite3_initialize()] or after shutdown by [sqlite3_shutdown()].
1185 ** ^If sqlite3_config() is called after [sqlite3_initialize()] and before
1186 ** [sqlite3_shutdown()] then it will return SQLITE_MISUSE.
1187 ** Note, however, that ^sqlite3_config() can be called as part of the
1188 ** implementation of an application-defined [sqlite3_os_init()].
1189 **
1190 ** The first argument to sqlite3_config() is an integer
1191 ** [configuration option] that determines
1192 ** what property of SQLite is to be configured. Subsequent arguments
1193 ** vary depending on the [configuration option]
1194 ** in the first argument.
1195 **
1196 ** ^When a configuration option is set, sqlite3_config() returns [SQLITE_OK].
1197 ** ^If the option is unknown or SQLite is unable to set the option
1198 ** then this routine returns a non-zero [error code].
1199 */
1202 /*
1203 ** CAPI3REF: Configure database connections
1204 **
1205 ** The sqlite3_db_config() interface is used to make configuration
1206 ** changes to a [database connection]. The interface is similar to
1207 ** [sqlite3_config()] except that the changes apply to a single
1208 ** [database connection] (specified in the first argument).
1209 **
1210 ** The second argument to sqlite3_db_config(D,V,...) is the
1211 ** [SQLITE_DBCONFIG_LOOKASIDE | configuration verb] - an integer code
1212 ** that indicates what aspect of the [database connection] is being configured.
1213 ** Subsequent arguments vary depending on the configuration verb.
1214 **
1215 ** ^Calls to sqlite3_db_config() return SQLITE_OK if and only if
1216 ** the call is considered successful.
1217 */
1220 /*
1221 ** CAPI3REF: Memory Allocation Routines
1222 **
1223 ** An instance of this object defines the interface between SQLite
1224 ** and low-level memory allocation routines.
1225 **
1226 ** This object is used in only one place in the SQLite interface.
1227 ** A pointer to an instance of this object is the argument to
1228 ** [sqlite3_config()] when the configuration option is
1229 ** [SQLITE_CONFIG_MALLOC] or [SQLITE_CONFIG_GETMALLOC].
1230 ** By creating an instance of this object
1231 ** and passing it to [sqlite3_config]([SQLITE_CONFIG_MALLOC])
1232 ** during configuration, an application can specify an alternative
1233 ** memory allocation subsystem for SQLite to use for all of its
1234 ** dynamic memory needs.
1235 **
1236 ** Note that SQLite comes with several [built-in memory allocators]
1237 ** that are perfectly adequate for the overwhelming majority of applications
1238 ** and that this object is only useful to a tiny minority of applications
1239 ** with specialized memory allocation requirements. This object is
1240 ** also used during testing of SQLite in order to specify an alternative
1241 ** memory allocator that simulates memory out-of-memory conditions in
1242 ** order to verify that SQLite recovers gracefully from such
1243 ** conditions.
1244 **
1245 ** The xMalloc, xRealloc, and xFree methods must work like the
1246 ** malloc(), realloc() and free() functions from the standard C library.
1247 ** ^SQLite guarantees that the second argument to
1248 ** xRealloc is always a value returned by a prior call to xRoundup.
1249 **
1250 ** xSize should return the allocated size of a memory allocation
1251 ** previously obtained from xMalloc or xRealloc. The allocated size
1252 ** is always at least as big as the requested size but may be larger.
1253 **
1254 ** The xRoundup method returns what would be the allocated size of
1255 ** a memory allocation given a particular requested size. Most memory
1256 ** allocators round up memory allocations at least to the next multiple
1257 ** of 8. Some allocators round up to a larger multiple or to a power of 2.
1258 ** Every memory allocation request coming in through [sqlite3_malloc()]
1259 ** or [sqlite3_realloc()] first calls xRoundup. If xRoundup returns 0,
1260 ** that causes the corresponding memory allocation to fail.
1261 **
1262 ** The xInit method initializes the memory allocator. (For example,
1263 ** it might allocate any require mutexes or initialize internal data
1264 ** structures. The xShutdown method is invoked (indirectly) by
1265 ** [sqlite3_shutdown()] and should deallocate any resources acquired
1266 ** by xInit. The pAppData pointer is used as the only parameter to
1267 ** xInit and xShutdown.
1268 **
1269 ** SQLite holds the [SQLITE_MUTEX_STATIC_MASTER] mutex when it invokes
1270 ** the xInit method, so the xInit method need not be threadsafe. The
1271 ** xShutdown method is only called from [sqlite3_shutdown()] so it does
1272 ** not need to be threadsafe either. For all other methods, SQLite
1273 ** holds the [SQLITE_MUTEX_STATIC_MEM] mutex as long as the
1274 ** [SQLITE_CONFIG_MEMSTATUS] configuration option is turned on (which
1275 ** it is by default) and so the methods are automatically serialized.
1276 ** However, if [SQLITE_CONFIG_MEMSTATUS] is disabled, then the other
1277 ** methods must be threadsafe or else make their own arrangements for
1278 ** serialization.
1279 **
1280 ** SQLite will never invoke xInit() more than once without an intervening
1281 ** call to xShutdown().
1282 */
1293 };
1295 /*
1296 ** CAPI3REF: Configuration Options
1297 ** KEYWORDS: {configuration option}
1298 **
1299 ** These constants are the available integer configuration options that
1300 ** can be passed as the first argument to the [sqlite3_config()] interface.
1301 **
1302 ** New configuration options may be added in future releases of SQLite.
1303 ** Existing configuration options might be discontinued. Applications
1304 ** should check the return code from [sqlite3_config()] to make sure that
1305 ** the call worked. The [sqlite3_config()] interface will return a
1306 ** non-zero [error code] if a discontinued or unsupported configuration option
1307 ** is invoked.
1308 **
1309 ** <dl>
1310 ** [[SQLITE_CONFIG_SINGLETHREAD]] <dt>SQLITE_CONFIG_SINGLETHREAD</dt>
1311 ** <dd>There are no arguments to this option. ^This option sets the
1312 ** [threading mode] to Single-thread. In other words, it disables
1313 ** all mutexing and puts SQLite into a mode where it can only be used
1314 ** by a single thread. ^If SQLite is compiled with
1315 ** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
1316 ** it is not possible to change the [threading mode] from its default
1317 ** value of Single-thread and so [sqlite3_config()] will return
1318 ** [SQLITE_ERROR] if called with the SQLITE_CONFIG_SINGLETHREAD
1319 ** configuration option.</dd>
1320 **
1321 ** [[SQLITE_CONFIG_MULTITHREAD]] <dt>SQLITE_CONFIG_MULTITHREAD</dt>
1322 ** <dd>There are no arguments to this option. ^This option sets the
1323 ** [threading mode] to Multi-thread. In other words, it disables
1324 ** mutexing on [database connection] and [prepared statement] objects.
1325 ** The application is responsible for serializing access to
1326 ** [database connections] and [prepared statements]. But other mutexes
1327 ** are enabled so that SQLite will be safe to use in a multi-threaded
1328 ** environment as long as no two threads attempt to use the same
1329 ** [database connection] at the same time. ^If SQLite is compiled with
1330 ** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
1331 ** it is not possible to set the Multi-thread [threading mode] and
1332 ** [sqlite3_config()] will return [SQLITE_ERROR] if called with the
1333 ** SQLITE_CONFIG_MULTITHREAD configuration option.</dd>
1334 **
1335 ** [[SQLITE_CONFIG_SERIALIZED]] <dt>SQLITE_CONFIG_SERIALIZED</dt>
1336 ** <dd>There are no arguments to this option. ^This option sets the
1337 ** [threading mode] to Serialized. In other words, this option enables
1338 ** all mutexes including the recursive
1339 ** mutexes on [database connection] and [prepared statement] objects.
1340 ** In this mode (which is the default when SQLite is compiled with
1341 ** [SQLITE_THREADSAFE=1]) the SQLite library will itself serialize access
1342 ** to [database connections] and [prepared statements] so that the
1343 ** application is free to use the same [database connection] or the
1344 ** same [prepared statement] in different threads at the same time.
1345 ** ^If SQLite is compiled with
1346 ** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
1347 ** it is not possible to set the Serialized [threading mode] and
1348 ** [sqlite3_config()] will return [SQLITE_ERROR] if called with the
1349 ** SQLITE_CONFIG_SERIALIZED configuration option.</dd>
1350 **
1351 ** [[SQLITE_CONFIG_MALLOC]] <dt>SQLITE_CONFIG_MALLOC</dt>
1352 ** <dd> ^(This option takes a single argument which is a pointer to an
1353 ** instance of the [sqlite3_mem_methods] structure. The argument specifies
1354 ** alternative low-level memory allocation routines to be used in place of
1355 ** the memory allocation routines built into SQLite.)^ ^SQLite makes
1356 ** its own private copy of the content of the [sqlite3_mem_methods] structure
1357 ** before the [sqlite3_config()] call returns.</dd>
1358 **
1359 ** [[SQLITE_CONFIG_GETMALLOC]] <dt>SQLITE_CONFIG_GETMALLOC</dt>
1360 ** <dd> ^(This option takes a single argument which is a pointer to an
1361 ** instance of the [sqlite3_mem_methods] structure. The [sqlite3_mem_methods]
1362 ** structure is filled with the currently defined memory allocation routines.)^
1363 ** This option can be used to overload the default memory allocation
1364 ** routines with a wrapper that simulations memory allocation failure or
1365 ** tracks memory usage, for example. </dd>
1366 **
1367 ** [[SQLITE_CONFIG_MEMSTATUS]] <dt>SQLITE_CONFIG_MEMSTATUS</dt>
1368 ** <dd> ^This option takes single argument of type int, interpreted as a
1369 ** boolean, which enables or disables the collection of memory allocation
1370 ** statistics. ^(When memory allocation statistics are disabled, the
1371 ** following SQLite interfaces become non-operational:
1372 ** <ul>
1373 ** <li> [sqlite3_memory_used()]
1374 ** <li> [sqlite3_memory_highwater()]
1375 ** <li> [sqlite3_soft_heap_limit64()]
1376 ** <li> [sqlite3_status()]
1377 ** </ul>)^
1378 ** ^Memory allocation statistics are enabled by default unless SQLite is
1379 ** compiled with [SQLITE_DEFAULT_MEMSTATUS]=0 in which case memory
1380 ** allocation statistics are disabled by default.
1381 ** </dd>
1382 **
1383 ** [[SQLITE_CONFIG_SCRATCH]] <dt>SQLITE_CONFIG_SCRATCH</dt>
1384 ** <dd> ^This option specifies a static memory buffer that SQLite can use for
1385 ** scratch memory. There are three arguments: A pointer an 8-byte
1386 ** aligned memory buffer from which the scratch allocations will be
1387 ** drawn, the size of each scratch allocation (sz),
1388 ** and the maximum number of scratch allocations (N). The sz
1389 ** argument must be a multiple of 16.
1390 ** The first argument must be a pointer to an 8-byte aligned buffer
1391 ** of at least sz*N bytes of memory.
1392 ** ^SQLite will use no more than two scratch buffers per thread. So
1393 ** N should be set to twice the expected maximum number of threads.
1394 ** ^SQLite will never require a scratch buffer that is more than 6
1395 ** times the database page size. ^If SQLite needs needs additional
1396 ** scratch memory beyond what is provided by this configuration option, then
1397 ** [sqlite3_malloc()] will be used to obtain the memory needed.</dd>
1398 **
1399 ** [[SQLITE_CONFIG_PAGECACHE]] <dt>SQLITE_CONFIG_PAGECACHE</dt>
1400 ** <dd> ^This option specifies a static memory buffer that SQLite can use for
1401 ** the database page cache with the default page cache implementation.
1402 ** This configuration should not be used if an application-define page
1403 ** cache implementation is loaded using the SQLITE_CONFIG_PCACHE2 option.
1404 ** There are three arguments to this option: A pointer to 8-byte aligned
1405 ** memory, the size of each page buffer (sz), and the number of pages (N).
1406 ** The sz argument should be the size of the largest database page
1407 ** (a power of two between 512 and 32768) plus a little extra for each
1408 ** page header. ^The page header size is 20 to 40 bytes depending on
1409 ** the host architecture. ^It is harmless, apart from the wasted memory,
1410 ** to make sz a little too large. The first
1411 ** argument should point to an allocation of at least sz*N bytes of memory.
1412 ** ^SQLite will use the memory provided by the first argument to satisfy its
1413 ** memory needs for the first N pages that it adds to cache. ^If additional
1414 ** page cache memory is needed beyond what is provided by this option, then
1415 ** SQLite goes to [sqlite3_malloc()] for the additional storage space.
1416 ** The pointer in the first argument must
1417 ** be aligned to an 8-byte boundary or subsequent behavior of SQLite
1418 ** will be undefined.</dd>
1419 **
1420 ** [[SQLITE_CONFIG_HEAP]] <dt>SQLITE_CONFIG_HEAP</dt>
1421 ** <dd> ^This option specifies a static memory buffer that SQLite will use
1422 ** for all of its dynamic memory allocation needs beyond those provided
1423 ** for by [SQLITE_CONFIG_SCRATCH] and [SQLITE_CONFIG_PAGECACHE].
1424 ** There are three arguments: An 8-byte aligned pointer to the memory,
1425 ** the number of bytes in the memory buffer, and the minimum allocation size.
1426 ** ^If the first pointer (the memory pointer) is NULL, then SQLite reverts
1427 ** to using its default memory allocator (the system malloc() implementation),
1428 ** undoing any prior invocation of [SQLITE_CONFIG_MALLOC]. ^If the
1429 ** memory pointer is not NULL and either [SQLITE_ENABLE_MEMSYS3] or
1430 ** [SQLITE_ENABLE_MEMSYS5] are defined, then the alternative memory
1431 ** allocator is engaged to handle all of SQLites memory allocation needs.
1432 ** The first pointer (the memory pointer) must be aligned to an 8-byte
1433 ** boundary or subsequent behavior of SQLite will be undefined.
1434 ** The minimum allocation size is capped at 2**12. Reasonable values
1435 ** for the minimum allocation size are 2**5 through 2**8.</dd>
1436 **
1437 ** [[SQLITE_CONFIG_MUTEX]] <dt>SQLITE_CONFIG_MUTEX</dt>
1438 ** <dd> ^(This option takes a single argument which is a pointer to an
1439 ** instance of the [sqlite3_mutex_methods] structure. The argument specifies
1440 ** alternative low-level mutex routines to be used in place
1441 ** the mutex routines built into SQLite.)^ ^SQLite makes a copy of the
1442 ** content of the [sqlite3_mutex_methods] structure before the call to
1443 ** [sqlite3_config()] returns. ^If SQLite is compiled with
1444 ** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
1445 ** the entire mutexing subsystem is omitted from the build and hence calls to
1446 ** [sqlite3_config()] with the SQLITE_CONFIG_MUTEX configuration option will
1447 ** return [SQLITE_ERROR].</dd>
1448 **
1449 ** [[SQLITE_CONFIG_GETMUTEX]] <dt>SQLITE_CONFIG_GETMUTEX</dt>
1450 ** <dd> ^(This option takes a single argument which is a pointer to an
1451 ** instance of the [sqlite3_mutex_methods] structure. The
1452 ** [sqlite3_mutex_methods]
1453 ** structure is filled with the currently defined mutex routines.)^
1454 ** This option can be used to overload the default mutex allocation
1455 ** routines with a wrapper used to track mutex usage for performance
1456 ** profiling or testing, for example. ^If SQLite is compiled with
1457 ** the [SQLITE_THREADSAFE | SQLITE_THREADSAFE=0] compile-time option then
1458 ** the entire mutexing subsystem is omitted from the build and hence calls to
1459 ** [sqlite3_config()] with the SQLITE_CONFIG_GETMUTEX configuration option will
1460 ** return [SQLITE_ERROR].</dd>
1461 **
1462 ** [[SQLITE_CONFIG_LOOKASIDE]] <dt>SQLITE_CONFIG_LOOKASIDE</dt>
1463 ** <dd> ^(This option takes two arguments that determine the default
1464 ** memory allocation for the lookaside memory allocator on each
1465 ** [database connection]. The first argument is the
1466 ** size of each lookaside buffer slot and the second is the number of
1467 ** slots allocated to each database connection.)^ ^(This option sets the
1468 ** <i>default</i> lookaside size. The [SQLITE_DBCONFIG_LOOKASIDE]
1469 ** verb to [sqlite3_db_config()] can be used to change the lookaside
1470 ** configuration on individual connections.)^ </dd>
1471 **
1472 ** [[SQLITE_CONFIG_PCACHE2]] <dt>SQLITE_CONFIG_PCACHE2</dt>
1473 ** <dd> ^(This option takes a single argument which is a pointer to
1474 ** an [sqlite3_pcache_methods2] object. This object specifies the interface
1475 ** to a custom page cache implementation.)^ ^SQLite makes a copy of the
1476 ** object and uses it for page cache memory allocations.</dd>
1477 **
1478 ** [[SQLITE_CONFIG_GETPCACHE2]] <dt>SQLITE_CONFIG_GETPCACHE2</dt>
1479 ** <dd> ^(This option takes a single argument which is a pointer to an
1480 ** [sqlite3_pcache_methods2] object. SQLite copies of the current
1481 ** page cache implementation into that object.)^ </dd>
1482 **
1483 ** [[SQLITE_CONFIG_LOG]] <dt>SQLITE_CONFIG_LOG</dt>
1484 ** <dd> ^The SQLITE_CONFIG_LOG option takes two arguments: a pointer to a
1485 ** function with a call signature of void(*)(void*,int,const char*),
1486 ** and a pointer to void. ^If the function pointer is not NULL, it is
1487 ** invoked by [sqlite3_log()] to process each logging event. ^If the
1488 ** function pointer is NULL, the [sqlite3_log()] interface becomes a no-op.
1489 ** ^The void pointer that is the second argument to SQLITE_CONFIG_LOG is
1490 ** passed through as the first parameter to the application-defined logger
1491 ** function whenever that function is invoked. ^The second parameter to
1492 ** the logger function is a copy of the first parameter to the corresponding
1493 ** [sqlite3_log()] call and is intended to be a [result code] or an
1494 ** [extended result code]. ^The third parameter passed to the logger is
1495 ** log message after formatting via [sqlite3_snprintf()].
1496 ** The SQLite logging interface is not reentrant; the logger function
1497 ** supplied by the application must not invoke any SQLite interface.
1498 ** In a multi-threaded application, the application-defined logger
1499 ** function must be threadsafe. </dd>
1500 **
1501 ** [[SQLITE_CONFIG_URI]] <dt>SQLITE_CONFIG_URI
1502 ** <dd> This option takes a single argument of type int. If non-zero, then
1503 ** URI handling is globally enabled. If the parameter is zero, then URI handling
1504 ** is globally disabled. If URI handling is globally enabled, all filenames
1505 ** passed to [sqlite3_open()], [sqlite3_open_v2()], [sqlite3_open16()] or
1506 ** specified as part of [ATTACH] commands are interpreted as URIs, regardless
1507 ** of whether or not the [SQLITE_OPEN_URI] flag is set when the database
1508 ** connection is opened. If it is globally disabled, filenames are
1509 ** only interpreted as URIs if the SQLITE_OPEN_URI flag is set when the
1510 ** database connection is opened. By default, URI handling is globally
1511 ** disabled. The default value may be changed by compiling with the
1512 ** [SQLITE_USE_URI] symbol defined.
1513 **
1514 ** [[SQLITE_CONFIG_PCACHE]] [[SQLITE_CONFIG_GETPCACHE]]
1515 ** <dt>SQLITE_CONFIG_PCACHE and SQLITE_CONFNIG_GETPCACHE
1516 ** <dd> These options are obsolete and should not be used by new code.
1517 ** They are retained for backwards compatibility but are now no-ops.
1518 ** </dl>
1519 */
1531 /* previously SQLITE_CONFIG_CHUNKALLOC 12 which is now unused. */
1540 /*
1541 ** CAPI3REF: Database Connection Configuration Options
1542 **
1543 ** These constants are the available integer configuration options that
1544 ** can be passed as the second argument to the [sqlite3_db_config()] interface.
1545 **
1546 ** New configuration options may be added in future releases of SQLite.
1547 ** Existing configuration options might be discontinued. Applications
1548 ** should check the return code from [sqlite3_db_config()] to make sure that
1549 ** the call worked. ^The [sqlite3_db_config()] interface will return a
1550 ** non-zero [error code] if a discontinued or unsupported configuration option
1551 ** is invoked.
1552 **
1553 ** <dl>
1554 ** <dt>SQLITE_DBCONFIG_LOOKASIDE</dt>
1555 ** <dd> ^This option takes three additional arguments that determine the
1556 ** [lookaside memory allocator] configuration for the [database connection].
1557 ** ^The first argument (the third parameter to [sqlite3_db_config()] is a
1558 ** pointer to a memory buffer to use for lookaside memory.
1559 ** ^The first argument after the SQLITE_DBCONFIG_LOOKASIDE verb
1560 ** may be NULL in which case SQLite will allocate the
1561 ** lookaside buffer itself using [sqlite3_malloc()]. ^The second argument is the
1562 ** size of each lookaside buffer slot. ^The third argument is the number of
1563 ** slots. The size of the buffer in the first argument must be greater than
1564 ** or equal to the product of the second and third arguments. The buffer
1565 ** must be aligned to an 8-byte boundary. ^If the second argument to
1566 ** SQLITE_DBCONFIG_LOOKASIDE is not a multiple of 8, it is internally
1567 ** rounded down to the next smaller multiple of 8. ^(The lookaside memory
1568 ** configuration for a database connection can only be changed when that
1569 ** connection is not currently using lookaside memory, or in other words
1570 ** when the "current value" returned by
1571 ** [sqlite3_db_status](D,[SQLITE_CONFIG_LOOKASIDE],...) is zero.
1572 ** Any attempt to change the lookaside memory configuration when lookaside
1573 ** memory is in use leaves the configuration unchanged and returns
1574 ** [SQLITE_BUSY].)^</dd>
1575 **
1576 ** <dt>SQLITE_DBCONFIG_ENABLE_FKEY</dt>
1577 ** <dd> ^This option is used to enable or disable the enforcement of
1578 ** [foreign key constraints]. There should be two additional arguments.
1579 ** The first argument is an integer which is 0 to disable FK enforcement,
1580 ** positive to enable FK enforcement or negative to leave FK enforcement
1581 ** unchanged. The second parameter is a pointer to an integer into which
1582 ** is written 0 or 1 to indicate whether FK enforcement is off or on
1583 ** following this call. The second parameter may be a NULL pointer, in
1584 ** which case the FK enforcement setting is not reported back. </dd>
1585 **
1586 ** <dt>SQLITE_DBCONFIG_ENABLE_TRIGGER</dt>
1587 ** <dd> ^This option is used to enable or disable [CREATE TRIGGER | triggers].
1588 ** There should be two additional arguments.
1589 ** The first argument is an integer which is 0 to disable triggers,
1590 ** positive to enable triggers or negative to leave the setting unchanged.
1591 ** The second parameter is a pointer to an integer into which
1592 ** is written 0 or 1 to indicate whether triggers are disabled or enabled
1593 ** following this call. The second parameter may be a NULL pointer, in
1594 ** which case the trigger setting is not reported back. </dd>
1595 **
1596 ** </dl>
1597 */
1603 /*
1604 ** CAPI3REF: Enable Or Disable Extended Result Codes
1605 **
1606 ** ^The sqlite3_extended_result_codes() routine enables or disables the
1607 ** [extended result codes] feature of SQLite. ^The extended result
1608 ** codes are disabled by default for historical compatibility.
1609 */
1612 /*
1613 ** CAPI3REF: Last Insert Rowid
1614 **
1615 ** ^Each entry in an SQLite table has a unique 64-bit signed
1616 ** integer key called the [ROWID | "rowid"]. ^The rowid is always available
1617 ** as an undeclared column named ROWID, OID, or _ROWID_ as long as those
1618 ** names are not also used by explicitly declared columns. ^If
1619 ** the table has a column of type [INTEGER PRIMARY KEY] then that column
1620 ** is another alias for the rowid.
1621 **
1622 ** ^This routine returns the [rowid] of the most recent
1623 ** successful [INSERT] into the database from the [database connection]
1624 ** in the first argument. ^As of SQLite version 3.7.7, this routines
1625 ** records the last insert rowid of both ordinary tables and [virtual tables].
1626 ** ^If no successful [INSERT]s
1627 ** have ever occurred on that database connection, zero is returned.
1628 **
1629 ** ^(If an [INSERT] occurs within a trigger or within a [virtual table]
1630 ** method, then this routine will return the [rowid] of the inserted
1631 ** row as long as the trigger or virtual table method is running.
1632 ** But once the trigger or virtual table method ends, the value returned
1633 ** by this routine reverts to what it was before the trigger or virtual
1634 ** table method began.)^
1635 **
1636 ** ^An [INSERT] that fails due to a constraint violation is not a
1637 ** successful [INSERT] and does not change the value returned by this
1638 ** routine. ^Thus INSERT OR FAIL, INSERT OR IGNORE, INSERT OR ROLLBACK,
1639 ** and INSERT OR ABORT make no changes to the return value of this
1640 ** routine when their insertion fails. ^(When INSERT OR REPLACE
1641 ** encounters a constraint violation, it does not fail. The
1642 ** INSERT continues to completion after deleting rows that caused
1643 ** the constraint problem so INSERT OR REPLACE will always change
1644 ** the return value of this interface.)^
1645 **
1646 ** ^For the purposes of this routine, an [INSERT] is considered to
1647 ** be successful even if it is subsequently rolled back.
1648 **
1649 ** This function is accessible to SQL statements via the
1650 ** [last_insert_rowid() SQL function].
1651 **
1652 ** If a separate thread performs a new [INSERT] on the same
1653 ** database connection while the [sqlite3_last_insert_rowid()]
1654 ** function is running and thus changes the last insert [rowid],
1655 ** then the value returned by [sqlite3_last_insert_rowid()] is
1656 ** unpredictable and might not equal either the old or the new
1657 ** last insert [rowid].
1658 */
1661 /*
1662 ** CAPI3REF: Count The Number Of Rows Modified
1663 **
1664 ** ^This function returns the number of database rows that were changed
1665 ** or inserted or deleted by the most recently completed SQL statement
1666 ** on the [database connection] specified by the first parameter.
1667 ** ^(Only changes that are directly specified by the [INSERT], [UPDATE],
1668 ** or [DELETE] statement are counted. Auxiliary changes caused by
1669 ** triggers or [foreign key actions] are not counted.)^ Use the
1670 ** [sqlite3_total_changes()] function to find the total number of changes
1671 ** including changes caused by triggers and foreign key actions.
1672 **
1673 ** ^Changes to a view that are simulated by an [INSTEAD OF trigger]
1674 ** are not counted. Only real table changes are counted.
1675 **
1676 ** ^(A "row change" is a change to a single row of a single table
1677 ** caused by an INSERT, DELETE, or UPDATE statement. Rows that
1678 ** are changed as side effects of [REPLACE] constraint resolution,
1679 ** rollback, ABORT processing, [DROP TABLE], or by any other
1680 ** mechanisms do not count as direct row changes.)^
1681 **
1682 ** A "trigger context" is a scope of execution that begins and
1683 ** ends with the script of a [CREATE TRIGGER | trigger].
1684 ** Most SQL statements are
1685 ** evaluated outside of any trigger. This is the "top level"
1686 ** trigger context. If a trigger fires from the top level, a
1687 ** new trigger context is entered for the duration of that one
1688 ** trigger. Subtriggers create subcontexts for their duration.
1689 **
1690 ** ^Calling [sqlite3_exec()] or [sqlite3_step()] recursively does
1691 ** not create a new trigger context.
1692 **
1693 ** ^This function returns the number of direct row changes in the
1694 ** most recent INSERT, UPDATE, or DELETE statement within the same
1695 ** trigger context.
1696 **
1697 ** ^Thus, when called from the top level, this function returns the
1698 ** number of changes in the most recent INSERT, UPDATE, or DELETE
1699 ** that also occurred at the top level. ^(Within the body of a trigger,
1700 ** the sqlite3_changes() interface can be called to find the number of
1701 ** changes in the most recently completed INSERT, UPDATE, or DELETE
1702 ** statement within the body of the same trigger.
1703 ** However, the number returned does not include changes
1704 ** caused by subtriggers since those have their own context.)^
1705 **
1706 ** See also the [sqlite3_total_changes()] interface, the
1707 ** [count_changes pragma], and the [changes() SQL function].
1708 **
1709 ** If a separate thread makes changes on the same database connection
1710 ** while [sqlite3_changes()] is running then the value returned
1711 ** is unpredictable and not meaningful.
1712 */
1715 /*
1716 ** CAPI3REF: Total Number Of Rows Modified
1717 **
1718 ** ^This function returns the number of row changes caused by [INSERT],
1719 ** [UPDATE] or [DELETE] statements since the [database connection] was opened.
1720 ** ^(The count returned by sqlite3_total_changes() includes all changes
1721 ** from all [CREATE TRIGGER | trigger] contexts and changes made by
1722 ** [foreign key actions]. However,
1723 ** the count does not include changes used to implement [REPLACE] constraints,
1724 ** do rollbacks or ABORT processing, or [DROP TABLE] processing. The
1725 ** count does not include rows of views that fire an [INSTEAD OF trigger],
1726 ** though if the INSTEAD OF trigger makes changes of its own, those changes
1727 ** are counted.)^
1728 ** ^The sqlite3_total_changes() function counts the changes as soon as
1729 ** the statement that makes them is completed (when the statement handle
1730 ** is passed to [sqlite3_reset()] or [sqlite3_finalize()]).
1731 **
1732 ** See also the [sqlite3_changes()] interface, the
1733 ** [count_changes pragma], and the [total_changes() SQL function].
1734 **
1735 ** If a separate thread makes changes on the same database connection
1736 ** while [sqlite3_total_changes()] is running then the value
1737 ** returned is unpredictable and not meaningful.
1738 */
1741 /*
1742 ** CAPI3REF: Interrupt A Long-Running Query
1743 **
1744 ** ^This function causes any pending database operation to abort and
1745 ** return at its earliest opportunity. This routine is typically
1746 ** called in response to a user action such as pressing "Cancel"
1747 ** or Ctrl-C where the user wants a long query operation to halt
1748 ** immediately.
1749 **
1750 ** ^It is safe to call this routine from a thread different from the
1751 ** thread that is currently running the database operation. But it
1752 ** is not safe to call this routine with a [database connection] that
1753 ** is closed or might close before sqlite3_interrupt() returns.
1754 **
1755 ** ^If an SQL operation is very nearly finished at the time when
1756 ** sqlite3_interrupt() is called, then it might not have an opportunity
1757 ** to be interrupted and might continue to completion.
1758 **
1759 ** ^An SQL operation that is interrupted will return [SQLITE_INTERRUPT].
1760 ** ^If the interrupted SQL operation is an INSERT, UPDATE, or DELETE
1761 ** that is inside an explicit transaction, then the entire transaction
1762 ** will be rolled back automatically.
1763 **
1764 ** ^The sqlite3_interrupt(D) call is in effect until all currently running
1765 ** SQL statements on [database connection] D complete. ^Any new SQL statements
1766 ** that are started after the sqlite3_interrupt() call and before the
1767 ** running statements reaches zero are interrupted as if they had been
1768 ** running prior to the sqlite3_interrupt() call. ^New SQL statements
1769 ** that are started after the running statement count reaches zero are
1770 ** not effected by the sqlite3_interrupt().
1771 ** ^A call to sqlite3_interrupt(D) that occurs when there are no running
1772 ** SQL statements is a no-op and has no effect on SQL statements
1773 ** that are started after the sqlite3_interrupt() call returns.
1774 **
1775 ** If the database connection closes while [sqlite3_interrupt()]
1776 ** is running then bad things will likely happen.
1777 */
1780 /*
1781 ** CAPI3REF: Determine If An SQL Statement Is Complete
1782 **
1783 ** These routines are useful during command-line input to determine if the
1784 ** currently entered text seems to form a complete SQL statement or
1785 ** if additional input is needed before sending the text into
1786 ** SQLite for parsing. ^These routines return 1 if the input string
1787 ** appears to be a complete SQL statement. ^A statement is judged to be
1788 ** complete if it ends with a semicolon token and is not a prefix of a
1789 ** well-formed CREATE TRIGGER statement. ^Semicolons that are embedded within
1790 ** string literals or quoted identifier names or comments are not
1791 ** independent tokens (they are part of the token in which they are
1792 ** embedded) and thus do not count as a statement terminator. ^Whitespace
1793 ** and comments that follow the final semicolon are ignored.
1794 **
1795 ** ^These routines return 0 if the statement is incomplete. ^If a
1796 ** memory allocation fails, then SQLITE_NOMEM is returned.
1797 **
1798 ** ^These routines do not parse the SQL statements thus
1799 ** will not detect syntactically incorrect SQL.
1800 **
1801 ** ^(If SQLite has not been initialized using [sqlite3_initialize()] prior
1802 ** to invoking sqlite3_complete16() then sqlite3_initialize() is invoked
1803 ** automatically by sqlite3_complete16(). If that initialization fails,
1804 ** then the return value from sqlite3_complete16() will be non-zero
1805 ** regardless of whether or not the input SQL is complete.)^
1806 **
1807 ** The input to [sqlite3_complete()] must be a zero-terminated
1808 ** UTF-8 string.
1809 **
1810 ** The input to [sqlite3_complete16()] must be a zero-terminated
1811 ** UTF-16 string in native byte order.
1812 */
1816 /*
1817 ** CAPI3REF: Register A Callback To Handle SQLITE_BUSY Errors
1818 **
1819 ** ^This routine sets a callback function that might be invoked whenever
1820 ** an attempt is made to open a database table that another thread
1821 ** or process has locked.
1822 **
1823 ** ^If the busy callback is NULL, then [SQLITE_BUSY] or [SQLITE_IOERR_BLOCKED]
1824 ** is returned immediately upon encountering the lock. ^If the busy callback
1825 ** is not NULL, then the callback might be invoked with two arguments.
1826 **
1827 ** ^The first argument to the busy handler is a copy of the void* pointer which
1828 ** is the third argument to sqlite3_busy_handler(). ^The second argument to
1829 ** the busy handler callback is the number of times that the busy handler has
1830 ** been invoked for this locking event. ^If the
1831 ** busy callback returns 0, then no additional attempts are made to
1832 ** access the database and [SQLITE_BUSY] or [SQLITE_IOERR_BLOCKED] is returned.
1833 ** ^If the callback returns non-zero, then another attempt
1834 ** is made to open the database for reading and the cycle repeats.
1835 **
1836 ** The presence of a busy handler does not guarantee that it will be invoked
1837 ** when there is lock contention. ^If SQLite determines that invoking the busy
1838 ** handler could result in a deadlock, it will go ahead and return [SQLITE_BUSY]
1839 ** or [SQLITE_IOERR_BLOCKED] instead of invoking the busy handler.
1840 ** Consider a scenario where one process is holding a read lock that
1841 ** it is trying to promote to a reserved lock and
1842 ** a second process is holding a reserved lock that it is trying
1843 ** to promote to an exclusive lock. The first process cannot proceed
1844 ** because it is blocked by the second and the second process cannot
1845 ** proceed because it is blocked by the first. If both processes
1846 ** invoke the busy handlers, neither will make any progress. Therefore,
1847 ** SQLite returns [SQLITE_BUSY] for the first process, hoping that this
1848 ** will induce the first process to release its read lock and allow
1849 ** the second process to proceed.
1850 **
1851 ** ^The default busy callback is NULL.
1852 **
1853 ** ^The [SQLITE_BUSY] error is converted to [SQLITE_IOERR_BLOCKED]
1854 ** when SQLite is in the middle of a large transaction where all the
1855 ** changes will not fit into the in-memory cache. SQLite will
1856 ** already hold a RESERVED lock on the database file, but it needs
1857 ** to promote this lock to EXCLUSIVE so that it can spill cache
1858 ** pages into the database file without harm to concurrent
1859 ** readers. ^If it is unable to promote the lock, then the in-memory
1860 ** cache will be left in an inconsistent state and so the error
1861 ** code is promoted from the relatively benign [SQLITE_BUSY] to
1862 ** the more severe [SQLITE_IOERR_BLOCKED]. ^This error code promotion
1863 ** forces an automatic rollback of the changes. See the
1864 ** <a href="/cvstrac/wiki?p=CorruptionFollowingBusyError">
1865 ** CorruptionFollowingBusyError</a> wiki page for a discussion of why
1866 ** this is important.
1867 **
1868 ** ^(There can only be a single busy handler defined for each
1869 ** [database connection]. Setting a new busy handler clears any
1870 ** previously set handler.)^ ^Note that calling [sqlite3_busy_timeout()]
1871 ** will also set or clear the busy handler.
1872 **
1873 ** The busy callback should not take any actions which modify the
1874 ** database connection that invoked the busy handler. Any such actions
1875 ** result in undefined behavior.
1876 **
1877 ** A busy handler must not close the database connection
1878 ** or [prepared statement] that invoked the busy handler.
1879 */
1882 /*
1883 ** CAPI3REF: Set A Busy Timeout
1884 **
1885 ** ^This routine sets a [sqlite3_busy_handler | busy handler] that sleeps
1886 ** for a specified amount of time when a table is locked. ^The handler
1887 ** will sleep multiple times until at least "ms" milliseconds of sleeping
1888 ** have accumulated. ^After at least "ms" milliseconds of sleeping,
1889 ** the handler returns 0 which causes [sqlite3_step()] to return
1890 ** [SQLITE_BUSY] or [SQLITE_IOERR_BLOCKED].
1891 **
1892 ** ^Calling this routine with an argument less than or equal to zero
1893 ** turns off all busy handlers.
1894 **
1895 ** ^(There can only be a single busy handler for a particular
1896 ** [database connection] any any given moment. If another busy handler
1897 ** was defined (using [sqlite3_busy_handler()]) prior to calling
1898 ** this routine, that other busy handler is cleared.)^
1899 */
1902 /*
1903 ** CAPI3REF: Convenience Routines For Running Queries
1904 **
1905 ** This is a legacy interface that is preserved for backwards compatibility.
1906 ** Use of this interface is not recommended.
1907 **
1908 ** Definition: A <b>result table</b> is memory data structure created by the
1909 ** [sqlite3_get_table()] interface. A result table records the
1910 ** complete query results from one or more queries.
1911 **
1912 ** The table conceptually has a number of rows and columns. But
1913 ** these numbers are not part of the result table itself. These
1914 ** numbers are obtained separately. Let N be the number of rows
1915 ** and M be the number of columns.
1916 **
1917 ** A result table is an array of pointers to zero-terminated UTF-8 strings.
1918 ** There are (N+1)*M elements in the array. The first M pointers point
1919 ** to zero-terminated strings that contain the names of the columns.
1920 ** The remaining entries all point to query results. NULL values result
1921 ** in NULL pointers. All other values are in their UTF-8 zero-terminated
1922 ** string representation as returned by [sqlite3_column_text()].
1923 **
1924 ** A result table might consist of one or more memory allocations.
1925 ** It is not safe to pass a result table directly to [sqlite3_free()].
1926 ** A result table should be deallocated using [sqlite3_free_table()].
1927 **
1928 ** ^(As an example of the result table format, suppose a query result
1929 ** is as follows:
1930 **
1931 ** <blockquote><pre>
1932 ** Name | Age
1933 ** -----------------------
1934 ** Alice | 43
1935 ** Bob | 28
1936 ** Cindy | 21
1937 ** </pre></blockquote>
1938 **
1939 ** There are two column (M==2) and three rows (N==3). Thus the
1940 ** result table has 8 entries. Suppose the result table is stored
1941 ** in an array names azResult. Then azResult holds this content:
1942 **
1943 ** <blockquote><pre>
1944 ** azResult[0] = "Name";
1945 ** azResult[1] = "Age";
1946 ** azResult[2] = "Alice";
1947 ** azResult[3] = "43";
1948 ** azResult[4] = "Bob";
1949 ** azResult[5] = "28";
1950 ** azResult[6] = "Cindy";
1951 ** azResult[7] = "21";
1952 ** </pre></blockquote>)^
1953 **
1954 ** ^The sqlite3_get_table() function evaluates one or more
1955 ** semicolon-separated SQL statements in the zero-terminated UTF-8
1956 ** string of its 2nd parameter and returns a result table to the
1957 ** pointer given in its 3rd parameter.
1958 **
1959 ** After the application has finished with the result from sqlite3_get_table(),
1960 ** it must pass the result table pointer to sqlite3_free_table() in order to
1961 ** release the memory that was malloced. Because of the way the
1962 ** [sqlite3_malloc()] happens within sqlite3_get_table(), the calling
1963 ** function must not try to call [sqlite3_free()] directly. Only
1964 ** [sqlite3_free_table()] is able to release the memory properly and safely.
1965 **
1966 ** The sqlite3_get_table() interface is implemented as a wrapper around
1967 ** [sqlite3_exec()]. The sqlite3_get_table() routine does not have access
1968 ** to any internal data structures of SQLite. It uses only the public
1969 ** interface defined here. As a consequence, errors that occur in the
1970 ** wrapper layer outside of the internal [sqlite3_exec()] call are not
1971 ** reflected in subsequent calls to [sqlite3_errcode()] or
1972 ** [sqlite3_errmsg()].
1973 */
1981 );
1984 /*
1985 ** CAPI3REF: Formatted String Printing Functions
1986 **
1987 ** These routines are work-alikes of the "printf()" family of functions
1988 ** from the standard C library.
1989 **
1990 ** ^The sqlite3_mprintf() and sqlite3_vmprintf() routines write their
1991 ** results into memory obtained from [sqlite3_malloc()].
1992 ** The strings returned by these two routines should be
1993 ** released by [sqlite3_free()]. ^Both routines return a
1994 ** NULL pointer if [sqlite3_malloc()] is unable to allocate enough
1995 ** memory to hold the resulting string.
1996 **
1997 ** ^(The sqlite3_snprintf() routine is similar to "snprintf()" from
1998 ** the standard C library. The result is written into the
1999 ** buffer supplied as the second parameter whose size is given by
2000 ** the first parameter. Note that the order of the
2001 ** first two parameters is reversed from snprintf().)^ This is an
2002 ** historical accident that cannot be fixed without breaking
2003 ** backwards compatibility. ^(Note also that sqlite3_snprintf()
2004 ** returns a pointer to its buffer instead of the number of
2005 ** characters actually written into the buffer.)^ We admit that
2006 ** the number of characters written would be a more useful return
2007 ** value but we cannot change the implementation of sqlite3_snprintf()
2008 ** now without breaking compatibility.
2009 **
2010 ** ^As long as the buffer size is greater than zero, sqlite3_snprintf()
2011 ** guarantees that the buffer is always zero-terminated. ^The first
2012 ** parameter "n" is the total size of the buffer, including space for
2013 ** the zero terminator. So the longest string that can be completely
2014 ** written will be n-1 characters.
2015 **
2016 ** ^The sqlite3_vsnprintf() routine is a varargs version of sqlite3_snprintf().
2017 **
2018 ** These routines all implement some additional formatting
2019 ** options that are useful for constructing SQL statements.
2020 ** All of the usual printf() formatting options apply. In addition, there
2021 ** is are "%q", "%Q", and "%z" options.
2022 **
2023 ** ^(The %q option works like %s in that it substitutes a nul-terminated
2024 ** string from the argument list. But %q also doubles every '\'' character.
2025 ** %q is designed for use inside a string literal.)^ By doubling each '\''
2026 ** character it escapes that character and allows it to be inserted into
2027 ** the string.
2028 **
2029 ** For example, assume the string variable zText contains text as follows:
2030 **
2031 ** <blockquote><pre>
2032 ** char *zText = "It's a happy day!";
2033 ** </pre></blockquote>
2034 **
2035 ** One can use this text in an SQL statement as follows:
2036 **
2037 ** <blockquote><pre>
2038 ** char *zSQL = sqlite3_mprintf("INSERT INTO table VALUES('%q')", zText);
2039 ** sqlite3_exec(db, zSQL, 0, 0, 0);
2040 ** sqlite3_free(zSQL);
2041 ** </pre></blockquote>
2042 **
2043 ** Because the %q format string is used, the '\'' character in zText
2044 ** is escaped and the SQL generated is as follows:
2045 **
2046 ** <blockquote><pre>
2047 ** INSERT INTO table1 VALUES('It''s a happy day!')
2048 ** </pre></blockquote>
2049 **
2050 ** This is correct. Had we used %s instead of %q, the generated SQL
2051 ** would have looked like this:
2052 **
2053 ** <blockquote><pre>
2054 ** INSERT INTO table1 VALUES('It's a happy day!');
2055 ** </pre></blockquote>
2056 **
2057 ** This second example is an SQL syntax error. As a general rule you should
2058 ** always use %q instead of %s when inserting text into a string literal.
2059 **
2060 ** ^(The %Q option works like %q except it also adds single quotes around
2061 ** the outside of the total string. Additionally, if the parameter in the
2062 ** argument list is a NULL pointer, %Q substitutes the text "NULL" (without
2063 ** single quotes).)^ So, for example, one could say:
2064 **
2065 ** <blockquote><pre>
2066 ** char *zSQL = sqlite3_mprintf("INSERT INTO table VALUES(%Q)", zText);
2067 ** sqlite3_exec(db, zSQL, 0, 0, 0);
2068 ** sqlite3_free(zSQL);
2069 ** </pre></blockquote>
2070 **
2071 ** The code above will render a correct SQL statement in the zSQL
2072 ** variable even if the zText variable is a NULL pointer.
2073 **
2074 ** ^(The "%z" formatting option works like "%s" but with the
2075 ** addition that after the string has been read and copied into
2076 ** the result, [sqlite3_free()] is called on the input string.)^
2077 */
2083 /*
2084 ** CAPI3REF: Memory Allocation Subsystem
2085 **
2086 ** The SQLite core uses these three routines for all of its own
2087 ** internal memory allocation needs. "Core" in the previous sentence
2088 ** does not include operating-system specific VFS implementation. The
2089 ** Windows VFS uses native malloc() and free() for some operations.
2090 **
2091 ** ^The sqlite3_malloc() routine returns a pointer to a block
2092 ** of memory at least N bytes in length, where N is the parameter.
2093 ** ^If sqlite3_malloc() is unable to obtain sufficient free
2094 ** memory, it returns a NULL pointer. ^If the parameter N to
2095 ** sqlite3_malloc() is zero or negative then sqlite3_malloc() returns
2096 ** a NULL pointer.
2097 **
2098 ** ^Calling sqlite3_free() with a pointer previously returned
2099 ** by sqlite3_malloc() or sqlite3_realloc() releases that memory so
2100 ** that it might be reused. ^The sqlite3_free() routine is
2101 ** a no-op if is called with a NULL pointer. Passing a NULL pointer
2102 ** to sqlite3_free() is harmless. After being freed, memory
2103 ** should neither be read nor written. Even reading previously freed
2104 ** memory might result in a segmentation fault or other severe error.
2105 ** Memory corruption, a segmentation fault, or other severe error
2106 ** might result if sqlite3_free() is called with a non-NULL pointer that
2107 ** was not obtained from sqlite3_malloc() or sqlite3_realloc().
2108 **
2109 ** ^(The sqlite3_realloc() interface attempts to resize a
2110 ** prior memory allocation to be at least N bytes, where N is the
2111 ** second parameter. The memory allocation to be resized is the first
2112 ** parameter.)^ ^ If the first parameter to sqlite3_realloc()
2113 ** is a NULL pointer then its behavior is identical to calling
2114 ** sqlite3_malloc(N) where N is the second parameter to sqlite3_realloc().
2115 ** ^If the second parameter to sqlite3_realloc() is zero or
2116 ** negative then the behavior is exactly the same as calling
2117 ** sqlite3_free(P) where P is the first parameter to sqlite3_realloc().
2118 ** ^sqlite3_realloc() returns a pointer to a memory allocation
2119 ** of at least N bytes in size or NULL if sufficient memory is unavailable.
2120 ** ^If M is the size of the prior allocation, then min(N,M) bytes
2121 ** of the prior allocation are copied into the beginning of buffer returned
2122 ** by sqlite3_realloc() and the prior allocation is freed.
2123 ** ^If sqlite3_realloc() returns NULL, then the prior allocation
2124 ** is not freed.
2125 **
2126 ** ^The memory returned by sqlite3_malloc() and sqlite3_realloc()
2127 ** is always aligned to at least an 8 byte boundary, or to a
2128 ** 4 byte boundary if the [SQLITE_4_BYTE_ALIGNED_MALLOC] compile-time
2129 ** option is used.
2130 **
2131 ** In SQLite version 3.5.0 and 3.5.1, it was possible to define
2132 ** the SQLITE_OMIT_MEMORY_ALLOCATION which would cause the built-in
2133 ** implementation of these routines to be omitted. That capability
2134 ** is no longer provided. Only built-in memory allocators can be used.
2135 **
2136 ** The Windows OS interface layer calls
2137 ** the system malloc() and free() directly when converting
2138 ** filenames between the UTF-8 encoding used by SQLite
2139 ** and whatever filename encoding is used by the particular Windows
2140 ** installation. Memory allocation errors are detected, but
2141 ** they are reported back as [SQLITE_CANTOPEN] or
2142 ** [SQLITE_IOERR] rather than [SQLITE_NOMEM].
2143 **
2144 ** The pointer arguments to [sqlite3_free()] and [sqlite3_realloc()]
2145 ** must be either NULL or else pointers obtained from a prior
2146 ** invocation of [sqlite3_malloc()] or [sqlite3_realloc()] that have
2147 ** not yet been released.
2148 **
2149 ** The application must not read or write any part of
2150 ** a block of memory after it has been released using
2151 ** [sqlite3_free()] or [sqlite3_realloc()].
2152 */
2157 /*
2158 ** CAPI3REF: Memory Allocator Statistics
2159 **
2160 ** SQLite provides these two interfaces for reporting on the status
2161 ** of the [sqlite3_malloc()], [sqlite3_free()], and [sqlite3_realloc()]
2162 ** routines, which form the built-in memory allocation subsystem.
2163 **
2164 ** ^The [sqlite3_memory_used()] routine returns the number of bytes
2165 ** of memory currently outstanding (malloced but not freed).
2166 ** ^The [sqlite3_memory_highwater()] routine returns the maximum
2167 ** value of [sqlite3_memory_used()] since the high-water mark
2168 ** was last reset. ^The values returned by [sqlite3_memory_used()] and
2169 ** [sqlite3_memory_highwater()] include any overhead
2170 ** added by SQLite in its implementation of [sqlite3_malloc()],
2171 ** but not overhead added by the any underlying system library
2172 ** routines that [sqlite3_malloc()] may call.
2173 **
2174 ** ^The memory high-water mark is reset to the current value of
2175 ** [sqlite3_memory_used()] if and only if the parameter to
2176 ** [sqlite3_memory_highwater()] is true. ^The value returned
2177 ** by [sqlite3_memory_highwater(1)] is the high-water mark
2178 ** prior to the reset.
2179 */
2183 /*
2184 ** CAPI3REF: Pseudo-Random Number Generator
2185 **
2186 ** SQLite contains a high-quality pseudo-random number generator (PRNG) used to
2187 ** select random [ROWID | ROWIDs] when inserting new records into a table that
2188 ** already uses the largest possible [ROWID]. The PRNG is also used for
2189 ** the build-in random() and randomblob() SQL functions. This interface allows
2190 ** applications to access the same PRNG for other purposes.
2191 **
2192 ** ^A call to this routine stores N bytes of randomness into buffer P.
2193 **
2194 ** ^The first time this routine is invoked (either internally or by
2195 ** the application) the PRNG is seeded using randomness obtained
2196 ** from the xRandomness method of the default [sqlite3_vfs] object.
2197 ** ^On all subsequent invocations, the pseudo-randomness is generated
2198 ** internally and without recourse to the [sqlite3_vfs] xRandomness
2199 ** method.
2200 */
2203 /*
2204 ** CAPI3REF: Compile-Time Authorization Callbacks
2205 **
2206 ** ^This routine registers an authorizer callback with a particular
2207 ** [database connection], supplied in the first argument.
2208 ** ^The authorizer callback is invoked as SQL statements are being compiled
2209 ** by [sqlite3_prepare()] or its variants [sqlite3_prepare_v2()],
2210 ** [sqlite3_prepare16()] and [sqlite3_prepare16_v2()]. ^At various
2211 ** points during the compilation process, as logic is being created
2212 ** to perform various actions, the authorizer callback is invoked to
2213 ** see if those actions are allowed. ^The authorizer callback should
2214 ** return [SQLITE_OK] to allow the action, [SQLITE_IGNORE] to disallow the
2215 ** specific action but allow the SQL statement to continue to be
2216 ** compiled, or [SQLITE_DENY] to cause the entire SQL statement to be
2217 ** rejected with an error. ^If the authorizer callback returns
2218 ** any value other than [SQLITE_IGNORE], [SQLITE_OK], or [SQLITE_DENY]
2219 ** then the [sqlite3_prepare_v2()] or equivalent call that triggered
2220 ** the authorizer will fail with an error message.
2221 **
2222 ** When the callback returns [SQLITE_OK], that means the operation
2223 ** requested is ok. ^When the callback returns [SQLITE_DENY], the
2224 ** [sqlite3_prepare_v2()] or equivalent call that triggered the
2225 ** authorizer will fail with an error message explaining that
2226 ** access is denied.
2227 **
2228 ** ^The first parameter to the authorizer callback is a copy of the third
2229 ** parameter to the sqlite3_set_authorizer() interface. ^The second parameter
2230 ** to the callback is an integer [SQLITE_COPY | action code] that specifies
2231 ** the particular action to be authorized. ^The third through sixth parameters
2232 ** to the callback are zero-terminated strings that contain additional
2233 ** details about the action to be authorized.
2234 **
2235 ** ^If the action code is [SQLITE_READ]
2236 ** and the callback returns [SQLITE_IGNORE] then the
2237 ** [prepared statement] statement is constructed to substitute
2238 ** a NULL value in place of the table column that would have
2239 ** been read if [SQLITE_OK] had been returned. The [SQLITE_IGNORE]
2240 ** return can be used to deny an untrusted user access to individual
2241 ** columns of a table.
2242 ** ^If the action code is [SQLITE_DELETE] and the callback returns
2243 ** [SQLITE_IGNORE] then the [DELETE] operation proceeds but the
2244 ** [truncate optimization] is disabled and all rows are deleted individually.
2245 **
2246 ** An authorizer is used when [sqlite3_prepare | preparing]
2247 ** SQL statements from an untrusted source, to ensure that the SQL statements
2248 ** do not try to access data they are not allowed to see, or that they do not
2249 ** try to execute malicious statements that damage the database. For
2250 ** example, an application may allow a user to enter arbitrary
2251 ** SQL queries for evaluation by a database. But the application does
2252 ** not want the user to be able to make arbitrary changes to the
2253 ** database. An authorizer could then be put in place while the
2254 ** user-entered SQL is being [sqlite3_prepare | prepared] that
2255 ** disallows everything except [SELECT] statements.
2256 **
2257 ** Applications that need to process SQL from untrusted sources
2258 ** might also consider lowering resource limits using [sqlite3_limit()]
2259 ** and limiting database size using the [max_page_count] [PRAGMA]
2260 ** in addition to using an authorizer.
2261 **
2262 ** ^(Only a single authorizer can be in place on a database connection
2263 ** at a time. Each call to sqlite3_set_authorizer overrides the
2264 ** previous call.)^ ^Disable the authorizer by installing a NULL callback.
2265 ** The authorizer is disabled by default.
2266 **
2267 ** The authorizer callback must not do anything that will modify
2268 ** the database connection that invoked the authorizer callback.
2269 ** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
2270 ** database connections for the meaning of "modify" in this paragraph.
2271 **
2272 ** ^When [sqlite3_prepare_v2()] is used to prepare a statement, the
2273 ** statement might be re-prepared during [sqlite3_step()] due to a
2274 ** schema change. Hence, the application should ensure that the
2275 ** correct authorizer callback remains in place during the [sqlite3_step()].
2276 **
2277 ** ^Note that the authorizer callback is invoked only during
2278 ** [sqlite3_prepare()] or its variants. Authorization is not
2279 ** performed during statement evaluation in [sqlite3_step()], unless
2280 ** as stated in the previous paragraph, sqlite3_step() invokes
2281 ** sqlite3_prepare_v2() to reprepare a statement after a schema change.
2282 */
2284 sqlite3*,
2287 );
2289 /*
2290 ** CAPI3REF: Authorizer Return Codes
2291 **
2292 ** The [sqlite3_set_authorizer | authorizer callback function] must
2293 ** return either [SQLITE_OK] or one of these two constants in order
2294 ** to signal SQLite whether or not the action is permitted. See the
2295 ** [sqlite3_set_authorizer | authorizer documentation] for additional
2296 ** information.
2297 **
2298 ** Note that SQLITE_IGNORE is also used as a [SQLITE_ROLLBACK | return code]
2299 ** from the [sqlite3_vtab_on_conflict()] interface.
2300 */
2304 /*
2305 ** CAPI3REF: Authorizer Action Codes
2306 **
2307 ** The [sqlite3_set_authorizer()] interface registers a callback function
2308 ** that is invoked to authorize certain SQL statement actions. The
2309 ** second parameter to the callback is an integer code that specifies
2310 ** what action is being authorized. These are the integer action codes that
2311 ** the authorizer callback may be passed.
2312 **
2313 ** These action code values signify what kind of operation is to be
2314 ** authorized. The 3rd and 4th parameters to the authorization
2315 ** callback function will be parameters or NULL depending on which of these
2316 ** codes is used as the second parameter. ^(The 5th parameter to the
2317 ** authorizer callback is the name of the database ("main", "temp",
2318 ** etc.) if applicable.)^ ^The 6th parameter to the authorizer callback
2319 ** is the name of the inner-most trigger or view that is responsible for
2320 ** the access attempt or NULL if this access attempt is directly from
2321 ** top-level SQL code.
2322 */
2323 /******************************************* 3rd ************ 4th ***********/
2358 /*
2359 ** CAPI3REF: Tracing And Profiling Functions
2360 **
2361 ** These routines register callback functions that can be used for
2362 ** tracing and profiling the execution of SQL statements.
2363 **
2364 ** ^The callback function registered by sqlite3_trace() is invoked at
2365 ** various times when an SQL statement is being run by [sqlite3_step()].
2366 ** ^The sqlite3_trace() callback is invoked with a UTF-8 rendering of the
2367 ** SQL statement text as the statement first begins executing.
2368 ** ^(Additional sqlite3_trace() callbacks might occur
2369 ** as each triggered subprogram is entered. The callbacks for triggers
2370 ** contain a UTF-8 SQL comment that identifies the trigger.)^
2371 **
2372 ** ^The callback function registered by sqlite3_profile() is invoked
2373 ** as each SQL statement finishes. ^The profile callback contains
2374 ** the original statement text and an estimate of wall-clock time
2375 ** of how long that statement took to run. ^The profile callback
2376 ** time is in units of nanoseconds, however the current implementation
2377 ** is only capable of millisecond resolution so the six least significant
2378 ** digits in the time are meaningless. Future versions of SQLite
2379 ** might provide greater resolution on the profiler callback. The
2380 ** sqlite3_profile() function is considered experimental and is
2381 ** subject to change in future versions of SQLite.
2382 */
2387 /*
2388 ** CAPI3REF: Query Progress Callbacks
2389 **
2390 ** ^The sqlite3_progress_handler(D,N,X,P) interface causes the callback
2391 ** function X to be invoked periodically during long running calls to
2392 ** [sqlite3_exec()], [sqlite3_step()] and [sqlite3_get_table()] for
2393 ** database connection D. An example use for this
2394 ** interface is to keep a GUI updated during a large query.
2395 **
2396 ** ^The parameter P is passed through as the only parameter to the
2397 ** callback function X. ^The parameter N is the number of
2398 ** [virtual machine instructions] that are evaluated between successive
2399 ** invocations of the callback X.
2400 **
2401 ** ^Only a single progress handler may be defined at one time per
2402 ** [database connection]; setting a new progress handler cancels the
2403 ** old one. ^Setting parameter X to NULL disables the progress handler.
2404 ** ^The progress handler is also disabled by setting N to a value less
2405 ** than 1.
2406 **
2407 ** ^If the progress callback returns non-zero, the operation is
2408 ** interrupted. This feature can be used to implement a
2409 ** "Cancel" button on a GUI progress dialog box.
2410 **
2411 ** The progress handler callback must not do anything that will modify
2412 ** the database connection that invoked the progress handler.
2413 ** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
2414 ** database connections for the meaning of "modify" in this paragraph.
2415 **
2416 */
2419 /*
2420 ** CAPI3REF: Opening A New Database Connection
2421 **
2422 ** ^These routines open an SQLite database file as specified by the
2423 ** filename argument. ^The filename argument is interpreted as UTF-8 for
2424 ** sqlite3_open() and sqlite3_open_v2() and as UTF-16 in the native byte
2425 ** order for sqlite3_open16(). ^(A [database connection] handle is usually
2426 ** returned in *ppDb, even if an error occurs. The only exception is that
2427 ** if SQLite is unable to allocate memory to hold the [sqlite3] object,
2428 ** a NULL will be written into *ppDb instead of a pointer to the [sqlite3]
2429 ** object.)^ ^(If the database is opened (and/or created) successfully, then
2430 ** [SQLITE_OK] is returned. Otherwise an [error code] is returned.)^ ^The
2431 ** [sqlite3_errmsg()] or [sqlite3_errmsg16()] routines can be used to obtain
2432 ** an English language description of the error following a failure of any
2433 ** of the sqlite3_open() routines.
2434 **
2435 ** ^The default encoding for the database will be UTF-8 if
2436 ** sqlite3_open() or sqlite3_open_v2() is called and
2437 ** UTF-16 in the native byte order if sqlite3_open16() is used.
2438 **
2439 ** Whether or not an error occurs when it is opened, resources
2440 ** associated with the [database connection] handle should be released by
2441 ** passing it to [sqlite3_close()] when it is no longer required.
2442 **
2443 ** The sqlite3_open_v2() interface works like sqlite3_open()
2444 ** except that it accepts two additional parameters for additional control
2445 ** over the new database connection. ^(The flags parameter to
2446 ** sqlite3_open_v2() can take one of
2447 ** the following three values, optionally combined with the
2448 ** [SQLITE_OPEN_NOMUTEX], [SQLITE_OPEN_FULLMUTEX], [SQLITE_OPEN_SHAREDCACHE],
2449 ** [SQLITE_OPEN_PRIVATECACHE], and/or [SQLITE_OPEN_URI] flags:)^
2450 **
2451 ** <dl>
2452 ** ^(<dt>[SQLITE_OPEN_READONLY]</dt>
2453 ** <dd>The database is opened in read-only mode. If the database does not
2454 ** already exist, an error is returned.</dd>)^
2455 **
2456 ** ^(<dt>[SQLITE_OPEN_READWRITE]</dt>
2457 ** <dd>The database is opened for reading and writing if possible, or reading
2458 ** only if the file is write protected by the operating system. In either
2459 ** case the database must already exist, otherwise an error is returned.</dd>)^
2460 **
2461 ** ^(<dt>[SQLITE_OPEN_READWRITE] | [SQLITE_OPEN_CREATE]</dt>
2462 ** <dd>The database is opened for reading and writing, and is created if
2463 ** it does not already exist. This is the behavior that is always used for
2464 ** sqlite3_open() and sqlite3_open16().</dd>)^
2465 ** </dl>
2466 **
2467 ** If the 3rd parameter to sqlite3_open_v2() is not one of the
2468 ** combinations shown above optionally combined with other
2469 ** [SQLITE_OPEN_READONLY | SQLITE_OPEN_* bits]
2470 ** then the behavior is undefined.
2471 **
2472 ** ^If the [SQLITE_OPEN_NOMUTEX] flag is set, then the database connection
2473 ** opens in the multi-thread [threading mode] as long as the single-thread
2474 ** mode has not been set at compile-time or start-time. ^If the
2475 ** [SQLITE_OPEN_FULLMUTEX] flag is set then the database connection opens
2476 ** in the serialized [threading mode] unless single-thread was
2477 ** previously selected at compile-time or start-time.
2478 ** ^The [SQLITE_OPEN_SHAREDCACHE] flag causes the database connection to be
2479 ** eligible to use [shared cache mode], regardless of whether or not shared
2480 ** cache is enabled using [sqlite3_enable_shared_cache()]. ^The
2481 ** [SQLITE_OPEN_PRIVATECACHE] flag causes the database connection to not
2482 ** participate in [shared cache mode] even if it is enabled.
2483 **
2484 ** ^The fourth parameter to sqlite3_open_v2() is the name of the
2485 ** [sqlite3_vfs] object that defines the operating system interface that
2486 ** the new database connection should use. ^If the fourth parameter is
2487 ** a NULL pointer then the default [sqlite3_vfs] object is used.
2488 **
2489 ** ^If the filename is ":memory:", then a private, temporary in-memory database
2490 ** is created for the connection. ^This in-memory database will vanish when
2491 ** the database connection is closed. Future versions of SQLite might
2492 ** make use of additional special filenames that begin with the ":" character.
2493 ** It is recommended that when a database filename actually does begin with
2494 ** a ":" character you should prefix the filename with a pathname such as
2495 ** "./" to avoid ambiguity.
2496 **
2497 ** ^If the filename is an empty string, then a private, temporary
2498 ** on-disk database will be created. ^This private database will be
2499 ** automatically deleted as soon as the database connection is closed.
2500 **
2501 ** [[URI filenames in sqlite3_open()]] <h3>URI Filenames</h3>
2502 **
2503 ** ^If [URI filename] interpretation is enabled, and the filename argument
2504 ** begins with "file:", then the filename is interpreted as a URI. ^URI
2505 ** filename interpretation is enabled if the [SQLITE_OPEN_URI] flag is
2506 ** set in the fourth argument to sqlite3_open_v2(), or if it has
2507 ** been enabled globally using the [SQLITE_CONFIG_URI] option with the
2508 ** [sqlite3_config()] method or by the [SQLITE_USE_URI] compile-time option.
2509 ** As of SQLite version 3.7.7, URI filename interpretation is turned off
2510 ** by default, but future releases of SQLite might enable URI filename
2511 ** interpretation by default. See "[URI filenames]" for additional
2512 ** information.
2513 **
2514 ** URI filenames are parsed according to RFC 3986. ^If the URI contains an
2515 ** authority, then it must be either an empty string or the string
2516 ** "localhost". ^If the authority is not an empty string or "localhost", an
2517 ** error is returned to the caller. ^The fragment component of a URI, if
2518 ** present, is ignored.
2519 **
2520 ** ^SQLite uses the path component of the URI as the name of the disk file
2521 ** which contains the database. ^If the path begins with a '/' character,
2522 ** then it is interpreted as an absolute path. ^If the path does not begin
2523 ** with a '/' (meaning that the authority section is omitted from the URI)
2524 ** then the path is interpreted as a relative path.
2525 ** ^On windows, the first component of an absolute path
2526 ** is a drive specification (e.g. "C:").
2527 **
2528 ** [[core URI query parameters]]
2529 ** The query component of a URI may contain parameters that are interpreted
2530 ** either by SQLite itself, or by a [VFS | custom VFS implementation].
2531 ** SQLite interprets the following three query parameters:
2532 **
2533 ** <ul>
2534 ** <li> <b>vfs</b>: ^The "vfs" parameter may be used to specify the name of
2535 ** a VFS object that provides the operating system interface that should
2536 ** be used to access the database file on disk. ^If this option is set to
2537 ** an empty string the default VFS object is used. ^Specifying an unknown
2538 ** VFS is an error. ^If sqlite3_open_v2() is used and the vfs option is
2539 ** present, then the VFS specified by the option takes precedence over
2540 ** the value passed as the fourth parameter to sqlite3_open_v2().
2541 **
2542 ** <li> <b>mode</b>: ^(The mode parameter may be set to either "ro", "rw" or
2543 ** "rwc". Attempting to set it to any other value is an error)^.
2544 ** ^If "ro" is specified, then the database is opened for read-only
2545 ** access, just as if the [SQLITE_OPEN_READONLY] flag had been set in the
2546 ** third argument to sqlite3_prepare_v2(). ^If the mode option is set to
2547 ** "rw", then the database is opened for read-write (but not create)
2548 ** access, as if SQLITE_OPEN_READWRITE (but not SQLITE_OPEN_CREATE) had
2549 ** been set. ^Value "rwc" is equivalent to setting both
2550 ** SQLITE_OPEN_READWRITE and SQLITE_OPEN_CREATE. ^If sqlite3_open_v2() is
2551 ** used, it is an error to specify a value for the mode parameter that is
2552 ** less restrictive than that specified by the flags passed as the third
2553 ** parameter.
2554 **
2555 ** <li> <b>cache</b>: ^The cache parameter may be set to either "shared" or
2556 ** "private". ^Setting it to "shared" is equivalent to setting the
2557 ** SQLITE_OPEN_SHAREDCACHE bit in the flags argument passed to
2558 ** sqlite3_open_v2(). ^Setting the cache parameter to "private" is
2559 ** equivalent to setting the SQLITE_OPEN_PRIVATECACHE bit.
2560 ** ^If sqlite3_open_v2() is used and the "cache" parameter is present in
2561 ** a URI filename, its value overrides any behaviour requested by setting
2562 ** SQLITE_OPEN_PRIVATECACHE or SQLITE_OPEN_SHAREDCACHE flag.
2563 ** </ul>
2564 **
2565 ** ^Specifying an unknown parameter in the query component of a URI is not an
2566 ** error. Future versions of SQLite might understand additional query
2567 ** parameters. See "[query parameters with special meaning to SQLite]" for
2568 ** additional information.
2569 **
2570 ** [[URI filename examples]] <h3>URI filename examples</h3>
2571 **
2572 ** <table border="1" align=center cellpadding=5>
2573 ** <tr><th> URI filenames <th> Results
2574 ** <tr><td> file:data.db <td>
2575 ** Open the file "data.db" in the current directory.
2576 ** <tr><td> file:/home/fred/data.db<br>
2577 ** file:///home/fred/data.db <br>
2578 ** file://localhost/home/fred/data.db <br> <td>
2579 ** Open the database file "/home/fred/data.db".
2580 ** <tr><td> file://darkstar/home/fred/data.db <td>
2581 ** An error. "darkstar" is not a recognized authority.
2582 ** <tr><td style="white-space:nowrap">
2583 ** file:///C:/Documents%20and%20Settings/fred/Desktop/data.db
2584 ** <td> Windows only: Open the file "data.db" on fred's desktop on drive
2585 ** C:. Note that the %20 escaping in this example is not strictly
2586 ** necessary - space characters can be used literally
2587 ** in URI filenames.
2588 ** <tr><td> file:data.db?mode=ro&cache=private <td>
2589 ** Open file "data.db" in the current directory for read-only access.
2590 ** Regardless of whether or not shared-cache mode is enabled by
2591 ** default, use a private cache.
2592 ** <tr><td> file:/home/fred/data.db?vfs=unix-nolock <td>
2593 ** Open file "/home/fred/data.db". Use the special VFS "unix-nolock".
2594 ** <tr><td> file:data.db?mode=readonly <td>
2595 ** An error. "readonly" is not a valid option for the "mode" parameter.
2596 ** </table>
2597 **
2598 ** ^URI hexadecimal escape sequences (%HH) are supported within the path and
2599 ** query components of a URI. A hexadecimal escape sequence consists of a
2600 ** percent sign - "%" - followed by exactly two hexadecimal digits
2601 ** specifying an octet value. ^Before the path or query components of a
2602 ** URI filename are interpreted, they are encoded using UTF-8 and all
2603 ** hexadecimal escape sequences replaced by a single byte containing the
2604 ** corresponding octet. If this process generates an invalid UTF-8 encoding,
2605 ** the results are undefined.
2606 **
2607 ** <b>Note to Windows users:</b> The encoding used for the filename argument
2608 ** of sqlite3_open() and sqlite3_open_v2() must be UTF-8, not whatever
2609 ** codepage is currently defined. Filenames containing international
2610 ** characters must be converted to UTF-8 prior to passing them into
2611 ** sqlite3_open() or sqlite3_open_v2().
2612 */
2616 );
2620 );
2626 );
2628 /*
2629 ** CAPI3REF: Obtain Values For URI Parameters
2630 **
2631 ** These are utility routines, useful to VFS implementations, that check
2632 ** to see if a database file was a URI that contained a specific query
2633 ** parameter, and if so obtains the value of that query parameter.
2634 **
2635 ** If F is the database filename pointer passed into the xOpen() method of
2636 ** a VFS implementation when the flags parameter to xOpen() has one or
2637 ** more of the [SQLITE_OPEN_URI] or [SQLITE_OPEN_MAIN_DB] bits set and
2638 ** P is the name of the query parameter, then
2639 ** sqlite3_uri_parameter(F,P) returns the value of the P
2640 ** parameter if it exists or a NULL pointer if P does not appear as a
2641 ** query parameter on F. If P is a query parameter of F
2642 ** has no explicit value, then sqlite3_uri_parameter(F,P) returns
2643 ** a pointer to an empty string.
2644 **
2645 ** The sqlite3_uri_boolean(F,P,B) routine assumes that P is a boolean
2646 ** parameter and returns true (1) or false (0) according to the value
2647 ** of P. The value of P is true if it is "yes" or "true" or "on" or
2648 ** a non-zero number and is false otherwise. If P is not a query parameter
2649 ** on F then sqlite3_uri_boolean(F,P,B) returns (B!=0).
2650 **
2651 ** The sqlite3_uri_int64(F,P,D) routine converts the value of P into a
2652 ** 64-bit signed integer and returns that integer, or D if P does not
2653 ** exist. If the value of P is something other than an integer, then
2654 ** zero is returned.
2655 **
2656 ** If F is a NULL pointer, then sqlite3_uri_parameter(F,P) returns NULL and
2657 ** sqlite3_uri_boolean(F,P,B) returns B. If F is not a NULL pointer and
2658 ** is not a database file pathname pointer that SQLite passed into the xOpen
2659 ** VFS method, then the behavior of this routine is undefined and probably
2660 ** undesirable.
2661 */
2667 /*
2668 ** CAPI3REF: Error Codes And Messages
2669 **
2670 ** ^The sqlite3_errcode() interface returns the numeric [result code] or
2671 ** [extended result code] for the most recent failed sqlite3_* API call
2672 ** associated with a [database connection]. If a prior API call failed
2673 ** but the most recent API call succeeded, the return value from
2674 ** sqlite3_errcode() is undefined. ^The sqlite3_extended_errcode()
2675 ** interface is the same except that it always returns the
2676 ** [extended result code] even when extended result codes are
2677 ** disabled.
2678 **
2679 ** ^The sqlite3_errmsg() and sqlite3_errmsg16() return English-language
2680 ** text that describes the error, as either UTF-8 or UTF-16 respectively.
2681 ** ^(Memory to hold the error message string is managed internally.
2682 ** The application does not need to worry about freeing the result.
2683 ** However, the error string might be overwritten or deallocated by
2684 ** subsequent calls to other SQLite interface functions.)^
2685 **
2686 ** When the serialized [threading mode] is in use, it might be the
2687 ** case that a second error occurs on a separate thread in between
2688 ** the time of the first error and the call to these interfaces.
2689 ** When that happens, the second error will be reported since these
2690 ** interfaces always report the most recent result. To avoid
2691 ** this, each thread can obtain exclusive use of the [database connection] D
2692 ** by invoking [sqlite3_mutex_enter]([sqlite3_db_mutex](D)) before beginning
2693 ** to use D and invoking [sqlite3_mutex_leave]([sqlite3_db_mutex](D)) after
2694 ** all calls to the interfaces listed here are completed.
2695 **
2696 ** If an interface fails with SQLITE_MISUSE, that means the interface
2697 ** was invoked incorrectly by the application. In that case, the
2698 ** error code and message may or may not be set.
2699 */
2705 /*
2706 ** CAPI3REF: SQL Statement Object
2707 ** KEYWORDS: {prepared statement} {prepared statements}
2708 **
2709 ** An instance of this object represents a single SQL statement.
2710 ** This object is variously known as a "prepared statement" or a
2711 ** "compiled SQL statement" or simply as a "statement".
2712 **
2713 ** The life of a statement object goes something like this:
2714 **
2715 ** <ol>
2716 ** <li> Create the object using [sqlite3_prepare_v2()] or a related
2717 ** function.
2718 ** <li> Bind values to [host parameters] using the sqlite3_bind_*()
2719 ** interfaces.
2720 ** <li> Run the SQL by calling [sqlite3_step()] one or more times.
2721 ** <li> Reset the statement using [sqlite3_reset()] then go back
2722 ** to step 2. Do this zero or more times.
2723 ** <li> Destroy the object using [sqlite3_finalize()].
2724 ** </ol>
2725 **
2726 ** Refer to documentation on individual methods above for additional
2727 ** information.
2728 */
2731 /*
2732 ** CAPI3REF: Run-time Limits
2733 **
2734 ** ^(This interface allows the size of various constructs to be limited
2735 ** on a connection by connection basis. The first parameter is the
2736 ** [database connection] whose limit is to be set or queried. The
2737 ** second parameter is one of the [limit categories] that define a
2738 ** class of constructs to be size limited. The third parameter is the
2739 ** new limit for that construct.)^
2740 **
2741 ** ^If the new limit is a negative number, the limit is unchanged.
2742 ** ^(For each limit category SQLITE_LIMIT_<i>NAME</i> there is a
2743 ** [limits | hard upper bound]
2744 ** set at compile-time by a C preprocessor macro called
2745 ** [limits | SQLITE_MAX_<i>NAME</i>].
2746 ** (The "_LIMIT_" in the name is changed to "_MAX_".))^
2747 ** ^Attempts to increase a limit above its hard upper bound are
2748 ** silently truncated to the hard upper bound.
2749 **
2750 ** ^Regardless of whether or not the limit was changed, the
2751 ** [sqlite3_limit()] interface returns the prior value of the limit.
2752 ** ^Hence, to find the current value of a limit without changing it,
2753 ** simply invoke this interface with the third parameter set to -1.
2754 **
2755 ** Run-time limits are intended for use in applications that manage
2756 ** both their own internal database and also databases that are controlled
2757 ** by untrusted external sources. An example application might be a
2758 ** web browser that has its own databases for storing history and
2759 ** separate databases controlled by JavaScript applications downloaded
2760 ** off the Internet. The internal databases can be given the
2761 ** large, default limits. Databases managed by external sources can
2762 ** be given much smaller limits designed to prevent a denial of service
2763 ** attack. Developers might also want to use the [sqlite3_set_authorizer()]
2764 ** interface to further control untrusted SQL. The size of the database
2765 ** created by an untrusted script can be contained using the
2766 ** [max_page_count] [PRAGMA].
2767 **
2768 ** New run-time limit categories may be added in future releases.
2769 */
2772 /*
2773 ** CAPI3REF: Run-Time Limit Categories
2774 ** KEYWORDS: {limit category} {*limit categories}
2775 **
2776 ** These constants define various performance limits
2777 ** that can be lowered at run-time using [sqlite3_limit()].
2778 ** The synopsis of the meanings of the various limits is shown below.
2779 ** Additional information is available at [limits | Limits in SQLite].
2780 **
2781 ** <dl>
2782 ** [[SQLITE_LIMIT_LENGTH]] ^(<dt>SQLITE_LIMIT_LENGTH</dt>
2783 ** <dd>The maximum size of any string or BLOB or table row, in bytes.<dd>)^
2784 **
2785 ** [[SQLITE_LIMIT_SQL_LENGTH]] ^(<dt>SQLITE_LIMIT_SQL_LENGTH</dt>
2786 ** <dd>The maximum length of an SQL statement, in bytes.</dd>)^
2787 **
2788 ** [[SQLITE_LIMIT_COLUMN]] ^(<dt>SQLITE_LIMIT_COLUMN</dt>
2789 ** <dd>The maximum number of columns in a table definition or in the
2790 ** result set of a [SELECT] or the maximum number of columns in an index
2791 ** or in an ORDER BY or GROUP BY clause.</dd>)^
2792 **
2793 ** [[SQLITE_LIMIT_EXPR_DEPTH]] ^(<dt>SQLITE_LIMIT_EXPR_DEPTH</dt>
2794 ** <dd>The maximum depth of the parse tree on any expression.</dd>)^
2795 **
2796 ** [[SQLITE_LIMIT_COMPOUND_SELECT]] ^(<dt>SQLITE_LIMIT_COMPOUND_SELECT</dt>
2797 ** <dd>The maximum number of terms in a compound SELECT statement.</dd>)^
2798 **
2799 ** [[SQLITE_LIMIT_VDBE_OP]] ^(<dt>SQLITE_LIMIT_VDBE_OP</dt>
2800 ** <dd>The maximum number of instructions in a virtual machine program
2801 ** used to implement an SQL statement. This limit is not currently
2802 ** enforced, though that might be added in some future release of
2803 ** SQLite.</dd>)^
2804 **
2805 ** [[SQLITE_LIMIT_FUNCTION_ARG]] ^(<dt>SQLITE_LIMIT_FUNCTION_ARG</dt>
2806 ** <dd>The maximum number of arguments on a function.</dd>)^
2807 **
2808 ** [[SQLITE_LIMIT_ATTACHED]] ^(<dt>SQLITE_LIMIT_ATTACHED</dt>
2809 ** <dd>The maximum number of [ATTACH | attached databases].)^</dd>
2810 **
2811 ** [[SQLITE_LIMIT_LIKE_PATTERN_LENGTH]]
2812 ** ^(<dt>SQLITE_LIMIT_LIKE_PATTERN_LENGTH</dt>
2813 ** <dd>The maximum length of the pattern argument to the [LIKE] or
2814 ** [GLOB] operators.</dd>)^
2815 **
2816 ** [[SQLITE_LIMIT_VARIABLE_NUMBER]]
2817 ** ^(<dt>SQLITE_LIMIT_VARIABLE_NUMBER</dt>
2818 ** <dd>The maximum index number of any [parameter] in an SQL statement.)^
2819 **
2820 ** [[SQLITE_LIMIT_TRIGGER_DEPTH]] ^(<dt>SQLITE_LIMIT_TRIGGER_DEPTH</dt>
2821 ** <dd>The maximum depth of recursion for triggers.</dd>)^
2822 ** </dl>
2823 */
2824 #define SQLITE_LIMIT_LENGTH 0
2825 #define SQLITE_LIMIT_SQL_LENGTH 1
2826 #define SQLITE_LIMIT_COLUMN 2
2827 #define SQLITE_LIMIT_EXPR_DEPTH 3
2828 #define SQLITE_LIMIT_COMPOUND_SELECT 4
2829 #define SQLITE_LIMIT_VDBE_OP 5
2830 #define SQLITE_LIMIT_FUNCTION_ARG 6
2831 #define SQLITE_LIMIT_ATTACHED 7
2832 #define SQLITE_LIMIT_LIKE_PATTERN_LENGTH 8
2833 #define SQLITE_LIMIT_VARIABLE_NUMBER 9
2834 #define SQLITE_LIMIT_TRIGGER_DEPTH 10
2836 /*
2837 ** CAPI3REF: Compiling An SQL Statement
2838 ** KEYWORDS: {SQL statement compiler}
2839 **
2840 ** To execute an SQL query, it must first be compiled into a byte-code
2841 ** program using one of these routines.
2842 **
2843 ** The first argument, "db", is a [database connection] obtained from a
2844 ** prior successful call to [sqlite3_open()], [sqlite3_open_v2()] or
2845 ** [sqlite3_open16()]. The database connection must not have been closed.
2846 **
2847 ** The second argument, "zSql", is the statement to be compiled, encoded
2848 ** as either UTF-8 or UTF-16. The sqlite3_prepare() and sqlite3_prepare_v2()
2849 ** interfaces use UTF-8, and sqlite3_prepare16() and sqlite3_prepare16_v2()
2850 ** use UTF-16.
2851 **
2852 ** ^If the nByte argument is less than zero, then zSql is read up to the
2853 ** first zero terminator. ^If nByte is non-negative, then it is the maximum
2854 ** number of bytes read from zSql. ^When nByte is non-negative, the
2855 ** zSql string ends at either the first '\000' or '\u0000' character or
2856 ** the nByte-th byte, whichever comes first. If the caller knows
2857 ** that the supplied string is nul-terminated, then there is a small
2858 ** performance advantage to be gained by passing an nByte parameter that
2859 ** is equal to the number of bytes in the input string <i>including</i>
2860 ** the nul-terminator bytes as this saves SQLite from having to
2861 ** make a copy of the input string.
2862 **
2863 ** ^If pzTail is not NULL then *pzTail is made to point to the first byte
2864 ** past the end of the first SQL statement in zSql. These routines only
2865 ** compile the first statement in zSql, so *pzTail is left pointing to
2866 ** what remains uncompiled.
2867 **
2868 ** ^*ppStmt is left pointing to a compiled [prepared statement] that can be
2869 ** executed using [sqlite3_step()]. ^If there is an error, *ppStmt is set
2870 ** to NULL. ^If the input text contains no SQL (if the input is an empty
2871 ** string or a comment) then *ppStmt is set to NULL.
2872 ** The calling procedure is responsible for deleting the compiled
2873 ** SQL statement using [sqlite3_finalize()] after it has finished with it.
2874 ** ppStmt may not be NULL.
2875 **
2876 ** ^On success, the sqlite3_prepare() family of routines return [SQLITE_OK];
2877 ** otherwise an [error code] is returned.
2878 **
2879 ** The sqlite3_prepare_v2() and sqlite3_prepare16_v2() interfaces are
2880 ** recommended for all new programs. The two older interfaces are retained
2881 ** for backwards compatibility, but their use is discouraged.
2882 ** ^In the "v2" interfaces, the prepared statement
2883 ** that is returned (the [sqlite3_stmt] object) contains a copy of the
2884 ** original SQL text. This causes the [sqlite3_step()] interface to
2885 ** behave differently in three ways:
2886 **
2887 ** <ol>
2888 ** <li>
2889 ** ^If the database schema changes, instead of returning [SQLITE_SCHEMA] as it
2890 ** always used to do, [sqlite3_step()] will automatically recompile the SQL
2891 ** statement and try to run it again.
2892 ** </li>
2893 **
2894 ** <li>
2895 ** ^When an error occurs, [sqlite3_step()] will return one of the detailed
2896 ** [error codes] or [extended error codes]. ^The legacy behavior was that
2897 ** [sqlite3_step()] would only return a generic [SQLITE_ERROR] result code
2898 ** and the application would have to make a second call to [sqlite3_reset()]
2899 ** in order to find the underlying cause of the problem. With the "v2" prepare
2900 ** interfaces, the underlying reason for the error is returned immediately.
2901 ** </li>
2902 **
2903 ** <li>
2904 ** ^If the specific value bound to [parameter | host parameter] in the
2905 ** WHERE clause might influence the choice of query plan for a statement,
2906 ** then the statement will be automatically recompiled, as if there had been
2907 ** a schema change, on the first [sqlite3_step()] call following any change
2908 ** to the [sqlite3_bind_text | bindings] of that [parameter].
2909 ** ^The specific value of WHERE-clause [parameter] might influence the
2910 ** choice of query plan if the parameter is the left-hand side of a [LIKE]
2911 ** or [GLOB] operator or if the parameter is compared to an indexed column
2912 ** and the [SQLITE_ENABLE_STAT3] compile-time option is enabled.
2913 ** the
2914 ** </li>
2915 ** </ol>
2916 */
2923 );
2930 );
2937 );
2944 );
2946 /*
2947 ** CAPI3REF: Retrieving Statement SQL
2948 **
2949 ** ^This interface can be used to retrieve a saved copy of the original
2950 ** SQL text used to create a [prepared statement] if that statement was
2951 ** compiled using either [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()].
2952 */
2955 /*
2956 ** CAPI3REF: Determine If An SQL Statement Writes The Database
2957 **
2958 ** ^The sqlite3_stmt_readonly(X) interface returns true (non-zero) if
2959 ** and only if the [prepared statement] X makes no direct changes to
2960 ** the content of the database file.
2961 **
2962 ** Note that [application-defined SQL functions] or
2963 ** [virtual tables] might change the database indirectly as a side effect.
2964 ** ^(For example, if an application defines a function "eval()" that
2965 ** calls [sqlite3_exec()], then the following SQL statement would
2966 ** change the database file through side-effects:
2967 **
2968 ** <blockquote><pre>
2969 ** SELECT eval('DELETE FROM t1') FROM t2;
2970 ** </pre></blockquote>
2971 **
2972 ** But because the [SELECT] statement does not change the database file
2973 ** directly, sqlite3_stmt_readonly() would still return true.)^
2974 **
2975 ** ^Transaction control statements such as [BEGIN], [COMMIT], [ROLLBACK],
2976 ** [SAVEPOINT], and [RELEASE] cause sqlite3_stmt_readonly() to return true,
2977 ** since the statements themselves do not actually modify the database but
2978 ** rather they control the timing of when other statements modify the
2979 ** database. ^The [ATTACH] and [DETACH] statements also cause
2980 ** sqlite3_stmt_readonly() to return true since, while those statements
2981 ** change the configuration of a database connection, they do not make
2982 ** changes to the content of the database files on disk.
2983 */
2986 /*
2987 ** CAPI3REF: Determine If A Prepared Statement Has Been Reset
2988 **
2989 ** ^The sqlite3_stmt_busy(S) interface returns true (non-zero) if the
2990 ** [prepared statement] S has been stepped at least once using
2991 ** [sqlite3_step(S)] but has not run to completion and/or has not
2992 ** been reset using [sqlite3_reset(S)]. ^The sqlite3_stmt_busy(S)
2993 ** interface returns false if S is a NULL pointer. If S is not a
2994 ** NULL pointer and is not a pointer to a valid [prepared statement]
2995 ** object, then the behavior is undefined and probably undesirable.
2996 **
2997 ** This interface can be used in combination [sqlite3_next_stmt()]
2998 ** to locate all prepared statements associated with a database
2999 ** connection that are in need of being reset. This can be used,
3000 ** for example, in diagnostic routines to search for prepared
3001 ** statements that are holding a transaction open.
3002 */
3005 /*
3006 ** CAPI3REF: Dynamically Typed Value Object
3007 ** KEYWORDS: {protected sqlite3_value} {unprotected sqlite3_value}
3008 **
3009 ** SQLite uses the sqlite3_value object to represent all values
3010 ** that can be stored in a database table. SQLite uses dynamic typing
3011 ** for the values it stores. ^Values stored in sqlite3_value objects
3012 ** can be integers, floating point values, strings, BLOBs, or NULL.
3013 **
3014 ** An sqlite3_value object may be either "protected" or "unprotected".
3015 ** Some interfaces require a protected sqlite3_value. Other interfaces
3016 ** will accept either a protected or an unprotected sqlite3_value.
3017 ** Every interface that accepts sqlite3_value arguments specifies
3018 ** whether or not it requires a protected sqlite3_value.
3019 **
3020 ** The terms "protected" and "unprotected" refer to whether or not
3021 ** a mutex is held. An internal mutex is held for a protected
3022 ** sqlite3_value object but no mutex is held for an unprotected
3023 ** sqlite3_value object. If SQLite is compiled to be single-threaded
3024 ** (with [SQLITE_THREADSAFE=0] and with [sqlite3_threadsafe()] returning 0)
3025 ** or if SQLite is run in one of reduced mutex modes
3026 ** [SQLITE_CONFIG_SINGLETHREAD] or [SQLITE_CONFIG_MULTITHREAD]
3027 ** then there is no distinction between protected and unprotected
3028 ** sqlite3_value objects and they can be used interchangeably. However,
3029 ** for maximum code portability it is recommended that applications
3030 ** still make the distinction between protected and unprotected
3031 ** sqlite3_value objects even when not strictly required.
3032 **
3033 ** ^The sqlite3_value objects that are passed as parameters into the
3034 ** implementation of [application-defined SQL functions] are protected.
3035 ** ^The sqlite3_value object returned by
3036 ** [sqlite3_column_value()] is unprotected.
3037 ** Unprotected sqlite3_value objects may only be used with
3038 ** [sqlite3_result_value()] and [sqlite3_bind_value()].
3039 ** The [sqlite3_value_blob | sqlite3_value_type()] family of
3040 ** interfaces require protected sqlite3_value objects.
3041 */
3044 /*
3045 ** CAPI3REF: SQL Function Context Object
3046 **
3047 ** The context in which an SQL function executes is stored in an
3048 ** sqlite3_context object. ^A pointer to an sqlite3_context object
3049 ** is always first parameter to [application-defined SQL functions].
3050 ** The application-defined SQL function implementation will pass this
3051 ** pointer through into calls to [sqlite3_result_int | sqlite3_result()],
3052 ** [sqlite3_aggregate_context()], [sqlite3_user_data()],
3053 ** [sqlite3_context_db_handle()], [sqlite3_get_auxdata()],
3054 ** and/or [sqlite3_set_auxdata()].
3055 */
3058 /*
3059 ** CAPI3REF: Binding Values To Prepared Statements
3060 ** KEYWORDS: {host parameter} {host parameters} {host parameter name}
3061 ** KEYWORDS: {SQL parameter} {SQL parameters} {parameter binding}
3062 **
3063 ** ^(In the SQL statement text input to [sqlite3_prepare_v2()] and its variants,
3064 ** literals may be replaced by a [parameter] that matches one of following
3065 ** templates:
3066 **
3067 ** <ul>
3068 ** <li> ?
3069 ** <li> ?NNN
3070 ** <li> :VVV
3071 ** <li> @VVV
3072 ** <li> $VVV
3073 ** </ul>
3074 **
3075 ** In the templates above, NNN represents an integer literal,
3076 ** and VVV represents an alphanumeric identifier.)^ ^The values of these
3077 ** parameters (also called "host parameter names" or "SQL parameters")
3078 ** can be set using the sqlite3_bind_*() routines defined here.
3079 **
3080 ** ^The first argument to the sqlite3_bind_*() routines is always
3081 ** a pointer to the [sqlite3_stmt] object returned from
3082 ** [sqlite3_prepare_v2()] or its variants.
3083 **
3084 ** ^The second argument is the index of the SQL parameter to be set.
3085 ** ^The leftmost SQL parameter has an index of 1. ^When the same named
3086 ** SQL parameter is used more than once, second and subsequent
3087 ** occurrences have the same index as the first occurrence.
3088 ** ^The index for named parameters can be looked up using the
3089 ** [sqlite3_bind_parameter_index()] API if desired. ^The index
3090 ** for "?NNN" parameters is the value of NNN.
3091 ** ^The NNN value must be between 1 and the [sqlite3_limit()]
3092 ** parameter [SQLITE_LIMIT_VARIABLE_NUMBER] (default value: 999).
3093 **
3094 ** ^The third argument is the value to bind to the parameter.
3095 **
3096 ** ^(In those routines that have a fourth argument, its value is the
3097 ** number of bytes in the parameter. To be clear: the value is the
3098 ** number of <u>bytes</u> in the value, not the number of characters.)^
3099 ** ^If the fourth parameter is negative, the length of the string is
3100 ** the number of bytes up to the first zero terminator.
3101 ** If a non-negative fourth parameter is provided to sqlite3_bind_text()
3102 ** or sqlite3_bind_text16() then that parameter must be the byte offset
3103 ** where the NUL terminator would occur assuming the string were NUL
3104 ** terminated. If any NUL characters occur at byte offsets less than
3105 ** the value of the fourth parameter then the resulting string value will
3106 ** contain embedded NULs. The result of expressions involving strings
3107 ** with embedded NULs is undefined.
3108 **
3109 ** ^The fifth argument to sqlite3_bind_blob(), sqlite3_bind_text(), and
3110 ** sqlite3_bind_text16() is a destructor used to dispose of the BLOB or
3111 ** string after SQLite has finished with it. ^The destructor is called
3112 ** to dispose of the BLOB or string even if the call to sqlite3_bind_blob(),
3113 ** sqlite3_bind_text(), or sqlite3_bind_text16() fails.
3114 ** ^If the fifth argument is
3115 ** the special value [SQLITE_STATIC], then SQLite assumes that the
3116 ** information is in static, unmanaged space and does not need to be freed.
3117 ** ^If the fifth argument has the value [SQLITE_TRANSIENT], then
3118 ** SQLite makes its own private copy of the data immediately, before
3119 ** the sqlite3_bind_*() routine returns.
3120 **
3121 ** ^The sqlite3_bind_zeroblob() routine binds a BLOB of length N that
3122 ** is filled with zeroes. ^A zeroblob uses a fixed amount of memory
3123 ** (just an integer to hold its size) while it is being processed.
3124 ** Zeroblobs are intended to serve as placeholders for BLOBs whose
3125 ** content is later written using
3126 ** [sqlite3_blob_open | incremental BLOB I/O] routines.
3127 ** ^A negative value for the zeroblob results in a zero-length BLOB.
3128 **
3129 ** ^If any of the sqlite3_bind_*() routines are called with a NULL pointer
3130 ** for the [prepared statement] or with a prepared statement for which
3131 ** [sqlite3_step()] has been called more recently than [sqlite3_reset()],
3132 ** then the call will return [SQLITE_MISUSE]. If any sqlite3_bind_()
3133 ** routine is passed a [prepared statement] that has been finalized, the
3134 ** result is undefined and probably harmful.
3135 **
3136 ** ^Bindings are not cleared by the [sqlite3_reset()] routine.
3137 ** ^Unbound parameters are interpreted as NULL.
3138 **
3139 ** ^The sqlite3_bind_* routines return [SQLITE_OK] on success or an
3140 ** [error code] if anything goes wrong.
3141 ** ^[SQLITE_RANGE] is returned if the parameter
3142 ** index is out of range. ^[SQLITE_NOMEM] is returned if malloc() fails.
3143 **
3144 ** See also: [sqlite3_bind_parameter_count()],
3145 ** [sqlite3_bind_parameter_name()], and [sqlite3_bind_parameter_index()].
3146 */
3157 /*
3158 ** CAPI3REF: Number Of SQL Parameters
3159 **
3160 ** ^This routine can be used to find the number of [SQL parameters]
3161 ** in a [prepared statement]. SQL parameters are tokens of the
3162 ** form "?", "?NNN", ":AAA", "$AAA", or "@AAA" that serve as
3163 ** placeholders for values that are [sqlite3_bind_blob | bound]
3164 ** to the parameters at a later time.
3165 **
3166 ** ^(This routine actually returns the index of the largest (rightmost)
3167 ** parameter. For all forms except ?NNN, this will correspond to the
3168 ** number of unique parameters. If parameters of the ?NNN form are used,
3169 ** there may be gaps in the list.)^
3170 **
3171 ** See also: [sqlite3_bind_blob|sqlite3_bind()],
3172 ** [sqlite3_bind_parameter_name()], and
3173 ** [sqlite3_bind_parameter_index()].
3174 */
3177 /*
3178 ** CAPI3REF: Name Of A Host Parameter
3179 **
3180 ** ^The sqlite3_bind_parameter_name(P,N) interface returns
3181 ** the name of the N-th [SQL parameter] in the [prepared statement] P.
3182 ** ^(SQL parameters of the form "?NNN" or ":AAA" or "@AAA" or "$AAA"
3183 ** have a name which is the string "?NNN" or ":AAA" or "@AAA" or "$AAA"
3184 ** respectively.
3185 ** In other words, the initial ":" or "$" or "@" or "?"
3186 ** is included as part of the name.)^
3187 ** ^Parameters of the form "?" without a following integer have no name
3188 ** and are referred to as "nameless" or "anonymous parameters".
3189 **
3190 ** ^The first host parameter has an index of 1, not 0.
3191 **
3192 ** ^If the value N is out of range or if the N-th parameter is
3193 ** nameless, then NULL is returned. ^The returned string is
3194 ** always in UTF-8 encoding even if the named parameter was
3195 ** originally specified as UTF-16 in [sqlite3_prepare16()] or
3196 ** [sqlite3_prepare16_v2()].
3197 **
3198 ** See also: [sqlite3_bind_blob|sqlite3_bind()],
3199 ** [sqlite3_bind_parameter_count()], and
3200 ** [sqlite3_bind_parameter_index()].
3201 */
3204 /*
3205 ** CAPI3REF: Index Of A Parameter With A Given Name
3206 **
3207 ** ^Return the index of an SQL parameter given its name. ^The
3208 ** index value returned is suitable for use as the second
3209 ** parameter to [sqlite3_bind_blob|sqlite3_bind()]. ^A zero
3210 ** is returned if no matching parameter is found. ^The parameter
3211 ** name must be given in UTF-8 even if the original statement
3212 ** was prepared from UTF-16 text using [sqlite3_prepare16_v2()].
3213 **
3214 ** See also: [sqlite3_bind_blob|sqlite3_bind()],
3215 ** [sqlite3_bind_parameter_count()], and
3216 ** [sqlite3_bind_parameter_index()].
3217 */
3220 /*
3221 ** CAPI3REF: Reset All Bindings On A Prepared Statement
3222 **
3223 ** ^Contrary to the intuition of many, [sqlite3_reset()] does not reset
3224 ** the [sqlite3_bind_blob | bindings] on a [prepared statement].
3225 ** ^Use this routine to reset all host parameters to NULL.
3226 */
3229 /*
3230 ** CAPI3REF: Number Of Columns In A Result Set
3231 **
3232 ** ^Return the number of columns in the result set returned by the
3233 ** [prepared statement]. ^This routine returns 0 if pStmt is an SQL
3234 ** statement that does not return data (for example an [UPDATE]).
3235 **
3236 ** See also: [sqlite3_data_count()]
3237 */
3240 /*
3241 ** CAPI3REF: Column Names In A Result Set
3242 **
3243 ** ^These routines return the name assigned to a particular column
3244 ** in the result set of a [SELECT] statement. ^The sqlite3_column_name()
3245 ** interface returns a pointer to a zero-terminated UTF-8 string
3246 ** and sqlite3_column_name16() returns a pointer to a zero-terminated
3247 ** UTF-16 string. ^The first parameter is the [prepared statement]
3248 ** that implements the [SELECT] statement. ^The second parameter is the
3249 ** column number. ^The leftmost column is number 0.
3250 **
3251 ** ^The returned string pointer is valid until either the [prepared statement]
3252 ** is destroyed by [sqlite3_finalize()] or until the statement is automatically
3253 ** reprepared by the first call to [sqlite3_step()] for a particular run
3254 ** or until the next call to
3255 ** sqlite3_column_name() or sqlite3_column_name16() on the same column.
3256 **
3257 ** ^If sqlite3_malloc() fails during the processing of either routine
3258 ** (for example during a conversion from UTF-8 to UTF-16) then a
3259 ** NULL pointer is returned.
3260 **
3261 ** ^The name of a result column is the value of the "AS" clause for
3262 ** that column, if there is an AS clause. If there is no AS clause
3263 ** then the name of the column is unspecified and may change from
3264 ** one release of SQLite to the next.
3265 */
3269 /*
3270 ** CAPI3REF: Source Of Data In A Query Result
3271 **
3272 ** ^These routines provide a means to determine the database, table, and
3273 ** table column that is the origin of a particular result column in
3274 ** [SELECT] statement.
3275 ** ^The name of the database or table or column can be returned as
3276 ** either a UTF-8 or UTF-16 string. ^The _database_ routines return
3277 ** the database name, the _table_ routines return the table name, and
3278 ** the origin_ routines return the column name.
3279 ** ^The returned string is valid until the [prepared statement] is destroyed
3280 ** using [sqlite3_finalize()] or until the statement is automatically
3281 ** reprepared by the first call to [sqlite3_step()] for a particular run
3282 ** or until the same information is requested
3283 ** again in a different encoding.
3284 **
3285 ** ^The names returned are the original un-aliased names of the
3286 ** database, table, and column.
3287 **
3288 ** ^The first argument to these interfaces is a [prepared statement].
3289 ** ^These functions return information about the Nth result column returned by
3290 ** the statement, where N is the second function argument.
3291 ** ^The left-most column is column 0 for these routines.
3292 **
3293 ** ^If the Nth column returned by the statement is an expression or
3294 ** subquery and is not a column value, then all of these functions return
3295 ** NULL. ^These routine might also return NULL if a memory allocation error
3296 ** occurs. ^Otherwise, they return the name of the attached database, table,
3297 ** or column that query result column was extracted from.
3298 **
3299 ** ^As with all other SQLite APIs, those whose names end with "16" return
3300 ** UTF-16 encoded strings and the other functions return UTF-8.
3301 **
3302 ** ^These APIs are only available if the library was compiled with the
3303 ** [SQLITE_ENABLE_COLUMN_METADATA] C-preprocessor symbol.
3304 **
3305 ** If two or more threads call one or more of these routines against the same
3306 ** prepared statement and column at the same time then the results are
3307 ** undefined.
3308 **
3309 ** If two or more threads call one or more
3310 ** [sqlite3_column_database_name | column metadata interfaces]
3311 ** for the same [prepared statement] and result column
3312 ** at the same time then the results are undefined.
3313 */
3321 /*
3322 ** CAPI3REF: Declared Datatype Of A Query Result
3323 **
3324 ** ^(The first parameter is a [prepared statement].
3325 ** If this statement is a [SELECT] statement and the Nth column of the
3326 ** returned result set of that [SELECT] is a table column (not an
3327 ** expression or subquery) then the declared type of the table
3328 ** column is returned.)^ ^If the Nth column of the result set is an
3329 ** expression or subquery, then a NULL pointer is returned.
3330 ** ^The returned string is always UTF-8 encoded.
3331 **
3332 ** ^(For example, given the database schema:
3333 **
3334 ** CREATE TABLE t1(c1 VARIANT);
3335 **
3336 ** and the following statement to be compiled:
3337 **
3338 ** SELECT c1 + 1, c1 FROM t1;
3339 **
3340 ** this routine would return the string "VARIANT" for the second result
3341 ** column (i==1), and a NULL pointer for the first result column (i==0).)^
3342 **
3343 ** ^SQLite uses dynamic run-time typing. ^So just because a column
3344 ** is declared to contain a particular type does not mean that the
3345 ** data stored in that column is of the declared type. SQLite is
3346 ** strongly typed, but the typing is dynamic not static. ^Type
3347 ** is associated with individual values, not with the containers
3348 ** used to hold those values.
3349 */
3353 /*
3354 ** CAPI3REF: Evaluate An SQL Statement
3355 **
3356 ** After a [prepared statement] has been prepared using either
3357 ** [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()] or one of the legacy
3358 ** interfaces [sqlite3_prepare()] or [sqlite3_prepare16()], this function
3359 ** must be called one or more times to evaluate the statement.
3360 **
3361 ** The details of the behavior of the sqlite3_step() interface depend
3362 ** on whether the statement was prepared using the newer "v2" interface
3363 ** [sqlite3_prepare_v2()] and [sqlite3_prepare16_v2()] or the older legacy
3364 ** interface [sqlite3_prepare()] and [sqlite3_prepare16()]. The use of the
3365 ** new "v2" interface is recommended for new applications but the legacy
3366 ** interface will continue to be supported.
3367 **
3368 ** ^In the legacy interface, the return value will be either [SQLITE_BUSY],
3369 ** [SQLITE_DONE], [SQLITE_ROW], [SQLITE_ERROR], or [SQLITE_MISUSE].
3370 ** ^With the "v2" interface, any of the other [result codes] or
3371 ** [extended result codes] might be returned as well.
3372 **
3373 ** ^[SQLITE_BUSY] means that the database engine was unable to acquire the
3374 ** database locks it needs to do its job. ^If the statement is a [COMMIT]
3375 ** or occurs outside of an explicit transaction, then you can retry the
3376 ** statement. If the statement is not a [COMMIT] and occurs within an
3377 ** explicit transaction then you should rollback the transaction before
3378 ** continuing.
3379 **
3380 ** ^[SQLITE_DONE] means that the statement has finished executing
3381 ** successfully. sqlite3_step() should not be called again on this virtual
3382 ** machine without first calling [sqlite3_reset()] to reset the virtual
3383 ** machine back to its initial state.
3384 **
3385 ** ^If the SQL statement being executed returns any data, then [SQLITE_ROW]
3386 ** is returned each time a new row of data is ready for processing by the
3387 ** caller. The values may be accessed using the [column access functions].
3388 ** sqlite3_step() is called again to retrieve the next row of data.
3389 **
3390 ** ^[SQLITE_ERROR] means that a run-time error (such as a constraint
3391 ** violation) has occurred. sqlite3_step() should not be called again on
3392 ** the VM. More information may be found by calling [sqlite3_errmsg()].
3393 ** ^With the legacy interface, a more specific error code (for example,
3394 ** [SQLITE_INTERRUPT], [SQLITE_SCHEMA], [SQLITE_CORRUPT], and so forth)
3395 ** can be obtained by calling [sqlite3_reset()] on the
3396 ** [prepared statement]. ^In the "v2" interface,
3397 ** the more specific error code is returned directly by sqlite3_step().
3398 **
3399 ** [SQLITE_MISUSE] means that the this routine was called inappropriately.
3400 ** Perhaps it was called on a [prepared statement] that has
3401 ** already been [sqlite3_finalize | finalized] or on one that had
3402 ** previously returned [SQLITE_ERROR] or [SQLITE_DONE]. Or it could
3403 ** be the case that the same database connection is being used by two or
3404 ** more threads at the same moment in time.
3405 **
3406 ** For all versions of SQLite up to and including 3.6.23.1, a call to
3407 ** [sqlite3_reset()] was required after sqlite3_step() returned anything
3408 ** other than [SQLITE_ROW] before any subsequent invocation of
3409 ** sqlite3_step(). Failure to reset the prepared statement using
3410 ** [sqlite3_reset()] would result in an [SQLITE_MISUSE] return from
3411 ** sqlite3_step(). But after version 3.6.23.1, sqlite3_step() began
3412 ** calling [sqlite3_reset()] automatically in this circumstance rather
3413 ** than returning [SQLITE_MISUSE]. This is not considered a compatibility
3414 ** break because any application that ever receives an SQLITE_MISUSE error
3415 ** is broken by definition. The [SQLITE_OMIT_AUTORESET] compile-time option
3416 ** can be used to restore the legacy behavior.
3417 **
3418 ** <b>Goofy Interface Alert:</b> In the legacy interface, the sqlite3_step()
3419 ** API always returns a generic error code, [SQLITE_ERROR], following any
3420 ** error other than [SQLITE_BUSY] and [SQLITE_MISUSE]. You must call
3421 ** [sqlite3_reset()] or [sqlite3_finalize()] in order to find one of the
3422 ** specific [error codes] that better describes the error.
3423 ** We admit that this is a goofy design. The problem has been fixed
3424 ** with the "v2" interface. If you prepare all of your SQL statements
3425 ** using either [sqlite3_prepare_v2()] or [sqlite3_prepare16_v2()] instead
3426 ** of the legacy [sqlite3_prepare()] and [sqlite3_prepare16()] interfaces,
3427 ** then the more specific [error codes] are returned directly
3428 ** by sqlite3_step(). The use of the "v2" interface is recommended.
3429 */
3432 /*
3433 ** CAPI3REF: Number of columns in a result set
3434 **
3435 ** ^The sqlite3_data_count(P) interface returns the number of columns in the
3436 ** current row of the result set of [prepared statement] P.
3437 ** ^If prepared statement P does not have results ready to return
3438 ** (via calls to the [sqlite3_column_int | sqlite3_column_*()] of
3439 ** interfaces) then sqlite3_data_count(P) returns 0.
3440 ** ^The sqlite3_data_count(P) routine also returns 0 if P is a NULL pointer.
3441 ** ^The sqlite3_data_count(P) routine returns 0 if the previous call to
3442 ** [sqlite3_step](P) returned [SQLITE_DONE]. ^The sqlite3_data_count(P)
3443 ** will return non-zero if previous call to [sqlite3_step](P) returned
3444 ** [SQLITE_ROW], except in the case of the [PRAGMA incremental_vacuum]
3445 ** where it always returns zero since each step of that multi-step
3446 ** pragma returns 0 columns of data.
3447 **
3448 ** See also: [sqlite3_column_count()]
3449 */
3452 /*
3453 ** CAPI3REF: Fundamental Datatypes
3454 ** KEYWORDS: SQLITE_TEXT
3455 **
3456 ** ^(Every value in SQLite has one of five fundamental datatypes:
3457 **
3458 ** <ul>
3459 ** <li> 64-bit signed integer
3460 ** <li> 64-bit IEEE floating point number
3461 ** <li> string
3462 ** <li> BLOB
3463 ** <li> NULL
3464 ** </ul>)^
3465 **
3466 ** These constants are codes for each of those types.
3467 **
3468 ** Note that the SQLITE_TEXT constant was also used in SQLite version 2
3469 ** for a completely different meaning. Software that links against both
3470 ** SQLite version 2 and SQLite version 3 should use SQLITE3_TEXT, not
3471 ** SQLITE_TEXT.
3472 */
3473 #define SQLITE_INTEGER 1
3474 #define SQLITE_FLOAT 2
3475 #define SQLITE_BLOB 4
3476 #define SQLITE_NULL 5
3477 #ifdef SQLITE_TEXT
3478 # undef SQLITE_TEXT
3479 #else
3480 # define SQLITE_TEXT 3
3481 #endif
3482 #define SQLITE3_TEXT 3
3484 /*
3485 ** CAPI3REF: Result Values From A Query
3486 ** KEYWORDS: {column access functions}
3487 **
3488 ** These routines form the "result set" interface.
3489 **
3490 ** ^These routines return information about a single column of the current
3491 ** result row of a query. ^In every case the first argument is a pointer
3492 ** to the [prepared statement] that is being evaluated (the [sqlite3_stmt*]
3493 ** that was returned from [sqlite3_prepare_v2()] or one of its variants)
3494 ** and the second argument is the index of the column for which information
3495 ** should be returned. ^The leftmost column of the result set has the index 0.
3496 ** ^The number of columns in the result can be determined using
3497 ** [sqlite3_column_count()].
3498 **
3499 ** If the SQL statement does not currently point to a valid row, or if the
3500 ** column index is out of range, the result is undefined.
3501 ** These routines may only be called when the most recent call to
3502 ** [sqlite3_step()] has returned [SQLITE_ROW] and neither
3503 ** [sqlite3_reset()] nor [sqlite3_finalize()] have been called subsequently.
3504 ** If any of these routines are called after [sqlite3_reset()] or
3505 ** [sqlite3_finalize()] or after [sqlite3_step()] has returned
3506 ** something other than [SQLITE_ROW], the results are undefined.
3507 ** If [sqlite3_step()] or [sqlite3_reset()] or [sqlite3_finalize()]
3508 ** are called from a different thread while any of these routines
3509 ** are pending, then the results are undefined.
3510 **
3511 ** ^The sqlite3_column_type() routine returns the
3512 ** [SQLITE_INTEGER | datatype code] for the initial data type
3513 ** of the result column. ^The returned value is one of [SQLITE_INTEGER],
3514 ** [SQLITE_FLOAT], [SQLITE_TEXT], [SQLITE_BLOB], or [SQLITE_NULL]. The value
3515 ** returned by sqlite3_column_type() is only meaningful if no type
3516 ** conversions have occurred as described below. After a type conversion,
3517 ** the value returned by sqlite3_column_type() is undefined. Future
3518 ** versions of SQLite may change the behavior of sqlite3_column_type()
3519 ** following a type conversion.
3520 **
3521 ** ^If the result is a BLOB or UTF-8 string then the sqlite3_column_bytes()
3522 ** routine returns the number of bytes in that BLOB or string.
3523 ** ^If the result is a UTF-16 string, then sqlite3_column_bytes() converts
3524 ** the string to UTF-8 and then returns the number of bytes.
3525 ** ^If the result is a numeric value then sqlite3_column_bytes() uses
3526 ** [sqlite3_snprintf()] to convert that value to a UTF-8 string and returns
3527 ** the number of bytes in that string.
3528 ** ^If the result is NULL, then sqlite3_column_bytes() returns zero.
3529 **
3530 ** ^If the result is a BLOB or UTF-16 string then the sqlite3_column_bytes16()
3531 ** routine returns the number of bytes in that BLOB or string.
3532 ** ^If the result is a UTF-8 string, then sqlite3_column_bytes16() converts
3533 ** the string to UTF-16 and then returns the number of bytes.
3534 ** ^If the result is a numeric value then sqlite3_column_bytes16() uses
3535 ** [sqlite3_snprintf()] to convert that value to a UTF-16 string and returns
3536 ** the number of bytes in that string.
3537 ** ^If the result is NULL, then sqlite3_column_bytes16() returns zero.
3538 **
3539 ** ^The values returned by [sqlite3_column_bytes()] and
3540 ** [sqlite3_column_bytes16()] do not include the zero terminators at the end
3541 ** of the string. ^For clarity: the values returned by
3542 ** [sqlite3_column_bytes()] and [sqlite3_column_bytes16()] are the number of
3543 ** bytes in the string, not the number of characters.
3544 **
3545 ** ^Strings returned by sqlite3_column_text() and sqlite3_column_text16(),
3546 ** even empty strings, are always zero-terminated. ^The return
3547 ** value from sqlite3_column_blob() for a zero-length BLOB is a NULL pointer.
3548 **
3549 ** ^The object returned by [sqlite3_column_value()] is an
3550 ** [unprotected sqlite3_value] object. An unprotected sqlite3_value object
3551 ** may only be used with [sqlite3_bind_value()] and [sqlite3_result_value()].
3552 ** If the [unprotected sqlite3_value] object returned by
3553 ** [sqlite3_column_value()] is used in any other way, including calls
3554 ** to routines like [sqlite3_value_int()], [sqlite3_value_text()],
3555 ** or [sqlite3_value_bytes()], then the behavior is undefined.
3556 **
3557 ** These routines attempt to convert the value where appropriate. ^For
3558 ** example, if the internal representation is FLOAT and a text result
3559 ** is requested, [sqlite3_snprintf()] is used internally to perform the
3560 ** conversion automatically. ^(The following table details the conversions
3561 ** that are applied:
3562 **
3563 ** <blockquote>
3564 ** <table border="1">
3565 ** <tr><th> Internal<br>Type <th> Requested<br>Type <th> Conversion
3566 **
3567 ** <tr><td> NULL <td> INTEGER <td> Result is 0
3568 ** <tr><td> NULL <td> FLOAT <td> Result is 0.0
3569 ** <tr><td> NULL <td> TEXT <td> Result is NULL pointer
3570 ** <tr><td> NULL <td> BLOB <td> Result is NULL pointer
3571 ** <tr><td> INTEGER <td> FLOAT <td> Convert from integer to float
3572 ** <tr><td> INTEGER <td> TEXT <td> ASCII rendering of the integer
3573 ** <tr><td> INTEGER <td> BLOB <td> Same as INTEGER->TEXT
3574 ** <tr><td> FLOAT <td> INTEGER <td> Convert from float to integer
3575 ** <tr><td> FLOAT <td> TEXT <td> ASCII rendering of the float
3576 ** <tr><td> FLOAT <td> BLOB <td> Same as FLOAT->TEXT
3577 ** <tr><td> TEXT <td> INTEGER <td> Use atoi()
3578 ** <tr><td> TEXT <td> FLOAT <td> Use atof()
3579 ** <tr><td> TEXT <td> BLOB <td> No change
3580 ** <tr><td> BLOB <td> INTEGER <td> Convert to TEXT then use atoi()
3581 ** <tr><td> BLOB <td> FLOAT <td> Convert to TEXT then use atof()
3582 ** <tr><td> BLOB <td> TEXT <td> Add a zero terminator if needed
3583 ** </table>
3584 ** </blockquote>)^
3585 **
3586 ** The table above makes reference to standard C library functions atoi()
3587 ** and atof(). SQLite does not really use these functions. It has its
3588 ** own equivalent internal routines. The atoi() and atof() names are
3589 ** used in the table for brevity and because they are familiar to most
3590 ** C programmers.
3591 **
3592 ** Note that when type conversions occur, pointers returned by prior
3593 ** calls to sqlite3_column_blob(), sqlite3_column_text(), and/or
3594 ** sqlite3_column_text16() may be invalidated.
3595 ** Type conversions and pointer invalidations might occur
3596 ** in the following cases:
3597 **
3598 ** <ul>
3599 ** <li> The initial content is a BLOB and sqlite3_column_text() or
3600 ** sqlite3_column_text16() is called. A zero-terminator might
3601 ** need to be added to the string.</li>
3602 ** <li> The initial content is UTF-8 text and sqlite3_column_bytes16() or
3603 ** sqlite3_column_text16() is called. The content must be converted
3604 ** to UTF-16.</li>
3605 ** <li> The initial content is UTF-16 text and sqlite3_column_bytes() or
3606 ** sqlite3_column_text() is called. The content must be converted
3607 ** to UTF-8.</li>
3608 ** </ul>
3609 **
3610 ** ^Conversions between UTF-16be and UTF-16le are always done in place and do
3611 ** not invalidate a prior pointer, though of course the content of the buffer
3612 ** that the prior pointer references will have been modified. Other kinds
3613 ** of conversion are done in place when it is possible, but sometimes they
3614 ** are not possible and in those cases prior pointers are invalidated.
3615 **
3616 ** The safest and easiest to remember policy is to invoke these routines
3617 ** in one of the following ways:
3618 **
3619 ** <ul>
3620 ** <li>sqlite3_column_text() followed by sqlite3_column_bytes()</li>
3621 ** <li>sqlite3_column_blob() followed by sqlite3_column_bytes()</li>
3622 ** <li>sqlite3_column_text16() followed by sqlite3_column_bytes16()</li>
3623 ** </ul>
3624 **
3625 ** In other words, you should call sqlite3_column_text(),
3626 ** sqlite3_column_blob(), or sqlite3_column_text16() first to force the result
3627 ** into the desired format, then invoke sqlite3_column_bytes() or
3628 ** sqlite3_column_bytes16() to find the size of the result. Do not mix calls
3629 ** to sqlite3_column_text() or sqlite3_column_blob() with calls to
3630 ** sqlite3_column_bytes16(), and do not mix calls to sqlite3_column_text16()
3631 ** with calls to sqlite3_column_bytes().
3632 **
3633 ** ^The pointers returned are valid until a type conversion occurs as
3634 ** described above, or until [sqlite3_step()] or [sqlite3_reset()] or
3635 ** [sqlite3_finalize()] is called. ^The memory space used to hold strings
3636 ** and BLOBs is freed automatically. Do <b>not</b> pass the pointers returned
3637 ** [sqlite3_column_blob()], [sqlite3_column_text()], etc. into
3638 ** [sqlite3_free()].
3639 **
3640 ** ^(If a memory allocation error occurs during the evaluation of any
3641 ** of these routines, a default value is returned. The default value
3642 ** is either the integer 0, the floating point number 0.0, or a NULL
3643 ** pointer. Subsequent calls to [sqlite3_errcode()] will return
3644 ** [SQLITE_NOMEM].)^
3645 */
3657 /*
3658 ** CAPI3REF: Destroy A Prepared Statement Object
3659 **
3660 ** ^The sqlite3_finalize() function is called to delete a [prepared statement].
3661 ** ^If the most recent evaluation of the statement encountered no errors
3662 ** or if the statement is never been evaluated, then sqlite3_finalize() returns
3663 ** SQLITE_OK. ^If the most recent evaluation of statement S failed, then
3664 ** sqlite3_finalize(S) returns the appropriate [error code] or
3665 ** [extended error code].
3666 **
3667 ** ^The sqlite3_finalize(S) routine can be called at any point during
3668 ** the life cycle of [prepared statement] S:
3669 ** before statement S is ever evaluated, after
3670 ** one or more calls to [sqlite3_reset()], or after any call
3671 ** to [sqlite3_step()] regardless of whether or not the statement has
3672 ** completed execution.
3673 **
3674 ** ^Invoking sqlite3_finalize() on a NULL pointer is a harmless no-op.
3675 **
3676 ** The application must finalize every [prepared statement] in order to avoid
3677 ** resource leaks. It is a grievous error for the application to try to use
3678 ** a prepared statement after it has been finalized. Any use of a prepared
3679 ** statement after it has been finalized can result in undefined and
3680 ** undesirable behavior such as segfaults and heap corruption.
3681 */
3684 /*
3685 ** CAPI3REF: Reset A Prepared Statement Object
3686 **
3687 ** The sqlite3_reset() function is called to reset a [prepared statement]
3688 ** object back to its initial state, ready to be re-executed.
3689 ** ^Any SQL statement variables that had values bound to them using
3690 ** the [sqlite3_bind_blob | sqlite3_bind_*() API] retain their values.
3691 ** Use [sqlite3_clear_bindings()] to reset the bindings.
3692 **
3693 ** ^The [sqlite3_reset(S)] interface resets the [prepared statement] S
3694 ** back to the beginning of its program.
3695 **
3696 ** ^If the most recent call to [sqlite3_step(S)] for the
3697 ** [prepared statement] S returned [SQLITE_ROW] or [SQLITE_DONE],
3698 ** or if [sqlite3_step(S)] has never before been called on S,
3699 ** then [sqlite3_reset(S)] returns [SQLITE_OK].
3700 **
3701 ** ^If the most recent call to [sqlite3_step(S)] for the
3702 ** [prepared statement] S indicated an error, then
3703 ** [sqlite3_reset(S)] returns an appropriate [error code].
3704 **
3705 ** ^The [sqlite3_reset(S)] interface does not change the values
3706 ** of any [sqlite3_bind_blob|bindings] on the [prepared statement] S.
3707 */
3710 /*
3711 ** CAPI3REF: Create Or Redefine SQL Functions
3712 ** KEYWORDS: {function creation routines}
3713 ** KEYWORDS: {application-defined SQL function}
3714 ** KEYWORDS: {application-defined SQL functions}
3715 **
3716 ** ^These functions (collectively known as "function creation routines")
3717 ** are used to add SQL functions or aggregates or to redefine the behavior
3718 ** of existing SQL functions or aggregates. The only differences between
3719 ** these routines are the text encoding expected for
3720 ** the second parameter (the name of the function being created)
3721 ** and the presence or absence of a destructor callback for
3722 ** the application data pointer.
3723 **
3724 ** ^The first parameter is the [database connection] to which the SQL
3725 ** function is to be added. ^If an application uses more than one database
3726 ** connection then application-defined SQL functions must be added
3727 ** to each database connection separately.
3728 **
3729 ** ^The second parameter is the name of the SQL function to be created or
3730 ** redefined. ^The length of the name is limited to 255 bytes in a UTF-8
3731 ** representation, exclusive of the zero-terminator. ^Note that the name
3732 ** length limit is in UTF-8 bytes, not characters nor UTF-16 bytes.
3733 ** ^Any attempt to create a function with a longer name
3734 ** will result in [SQLITE_MISUSE] being returned.
3735 **
3736 ** ^The third parameter (nArg)
3737 ** is the number of arguments that the SQL function or
3738 ** aggregate takes. ^If this parameter is -1, then the SQL function or
3739 ** aggregate may take any number of arguments between 0 and the limit
3740 ** set by [sqlite3_limit]([SQLITE_LIMIT_FUNCTION_ARG]). If the third
3741 ** parameter is less than -1 or greater than 127 then the behavior is
3742 ** undefined.
3743 **
3744 ** ^The fourth parameter, eTextRep, specifies what
3745 ** [SQLITE_UTF8 | text encoding] this SQL function prefers for
3746 ** its parameters. Every SQL function implementation must be able to work
3747 ** with UTF-8, UTF-16le, or UTF-16be. But some implementations may be
3748 ** more efficient with one encoding than another. ^An application may
3749 ** invoke sqlite3_create_function() or sqlite3_create_function16() multiple
3750 ** times with the same function but with different values of eTextRep.
3751 ** ^When multiple implementations of the same function are available, SQLite
3752 ** will pick the one that involves the least amount of data conversion.
3753 ** If there is only a single implementation which does not care what text
3754 ** encoding is used, then the fourth argument should be [SQLITE_ANY].
3755 **
3756 ** ^(The fifth parameter is an arbitrary pointer. The implementation of the
3757 ** function can gain access to this pointer using [sqlite3_user_data()].)^
3758 **
3759 ** ^The sixth, seventh and eighth parameters, xFunc, xStep and xFinal, are
3760 ** pointers to C-language functions that implement the SQL function or
3761 ** aggregate. ^A scalar SQL function requires an implementation of the xFunc
3762 ** callback only; NULL pointers must be passed as the xStep and xFinal
3763 ** parameters. ^An aggregate SQL function requires an implementation of xStep
3764 ** and xFinal and NULL pointer must be passed for xFunc. ^To delete an existing
3765 ** SQL function or aggregate, pass NULL pointers for all three function
3766 ** callbacks.
3767 **
3768 ** ^(If the ninth parameter to sqlite3_create_function_v2() is not NULL,
3769 ** then it is destructor for the application data pointer.
3770 ** The destructor is invoked when the function is deleted, either by being
3771 ** overloaded or when the database connection closes.)^
3772 ** ^The destructor is also invoked if the call to
3773 ** sqlite3_create_function_v2() fails.
3774 ** ^When the destructor callback of the tenth parameter is invoked, it
3775 ** is passed a single argument which is a copy of the application data
3776 ** pointer which was the fifth parameter to sqlite3_create_function_v2().
3777 **
3778 ** ^It is permitted to register multiple implementations of the same
3779 ** functions with the same name but with either differing numbers of
3780 ** arguments or differing preferred text encodings. ^SQLite will use
3781 ** the implementation that most closely matches the way in which the
3782 ** SQL function is used. ^A function implementation with a non-negative
3783 ** nArg parameter is a better match than a function implementation with
3784 ** a negative nArg. ^A function where the preferred text encoding
3785 ** matches the database encoding is a better
3786 ** match than a function where the encoding is different.
3787 ** ^A function where the encoding difference is between UTF16le and UTF16be
3788 ** is a closer match than a function where the encoding difference is
3789 ** between UTF8 and UTF16.
3790 **
3791 ** ^Built-in functions may be overloaded by new application-defined functions.
3792 **
3793 ** ^An application-defined function is permitted to call other
3794 ** SQLite interfaces. However, such calls must not
3795 ** close the database connection nor finalize or reset the prepared
3796 ** statement in which the function is running.
3797 */
3807 );
3817 );
3828 );
3830 /*
3831 ** CAPI3REF: Text Encodings
3832 **
3833 ** These constant define integer codes that represent the various
3834 ** text encodings supported by SQLite.
3835 */
3836 #define SQLITE_UTF8 1
3837 #define SQLITE_UTF16LE 2
3838 #define SQLITE_UTF16BE 3
3843 /*
3844 ** CAPI3REF: Deprecated Functions
3845 ** DEPRECATED
3846 **
3847 ** These functions are [deprecated]. In order to maintain
3848 ** backwards compatibility with older code, these functions continue
3849 ** to be supported. However, new applications should avoid
3850 ** the use of these functions. To help encourage people to avoid
3851 ** using these functions, we are not going to tell you what they do.
3852 */
3853 #ifndef SQLITE_OMIT_DEPRECATED
3859 SQLITE_API SQLITE_DEPRECATED int sqlite3_memory_alarm(void(*)(void*,sqlite3_int64,int),void*,sqlite3_int64);
3860 #endif
3862 /*
3863 ** CAPI3REF: Obtaining SQL Function Parameter Values
3864 **
3865 ** The C-language implementation of SQL functions and aggregates uses
3866 ** this set of interface routines to access the parameter values on
3867 ** the function or aggregate.
3868 **
3869 ** The xFunc (for scalar functions) or xStep (for aggregates) parameters
3870 ** to [sqlite3_create_function()] and [sqlite3_create_function16()]
3871 ** define callbacks that implement the SQL functions and aggregates.
3872 ** The 3rd parameter to these callbacks is an array of pointers to
3873 ** [protected sqlite3_value] objects. There is one [sqlite3_value] object for
3874 ** each parameter to the SQL function. These routines are used to
3875 ** extract values from the [sqlite3_value] objects.
3876 **
3877 ** These routines work only with [protected sqlite3_value] objects.
3878 ** Any attempt to use these routines on an [unprotected sqlite3_value]
3879 ** object results in undefined behavior.
3880 **
3881 ** ^These routines work just like the corresponding [column access functions]
3882 ** except that these routines take a single [protected sqlite3_value] object
3883 ** pointer instead of a [sqlite3_stmt*] pointer and an integer column number.
3884 **
3885 ** ^The sqlite3_value_text16() interface extracts a UTF-16 string
3886 ** in the native byte-order of the host machine. ^The
3887 ** sqlite3_value_text16be() and sqlite3_value_text16le() interfaces
3888 ** extract UTF-16 strings as big-endian and little-endian respectively.
3889 **
3890 ** ^(The sqlite3_value_numeric_type() interface attempts to apply
3891 ** numeric affinity to the value. This means that an attempt is
3892 ** made to convert the value to an integer or floating point. If
3893 ** such a conversion is possible without loss of information (in other
3894 ** words, if the value is a string that looks like a number)
3895 ** then the conversion is performed. Otherwise no conversion occurs.
3896 ** The [SQLITE_INTEGER | datatype] after conversion is returned.)^
3897 **
3898 ** Please pay particular attention to the fact that the pointer returned
3899 ** from [sqlite3_value_blob()], [sqlite3_value_text()], or
3900 ** [sqlite3_value_text16()] can be invalidated by a subsequent call to
3901 ** [sqlite3_value_bytes()], [sqlite3_value_bytes16()], [sqlite3_value_text()],
3902 ** or [sqlite3_value_text16()].
3903 **
3904 ** These routines must be called from the same thread as
3905 ** the SQL function that supplied the [sqlite3_value*] parameters.
3906 */
3920 /*
3921 ** CAPI3REF: Obtain Aggregate Function Context
3922 **
3923 ** Implementations of aggregate SQL functions use this
3924 ** routine to allocate memory for storing their state.
3925 **
3926 ** ^The first time the sqlite3_aggregate_context(C,N) routine is called
3927 ** for a particular aggregate function, SQLite
3928 ** allocates N of memory, zeroes out that memory, and returns a pointer
3929 ** to the new memory. ^On second and subsequent calls to
3930 ** sqlite3_aggregate_context() for the same aggregate function instance,
3931 ** the same buffer is returned. Sqlite3_aggregate_context() is normally
3932 ** called once for each invocation of the xStep callback and then one
3933 ** last time when the xFinal callback is invoked. ^(When no rows match
3934 ** an aggregate query, the xStep() callback of the aggregate function
3935 ** implementation is never called and xFinal() is called exactly once.
3936 ** In those cases, sqlite3_aggregate_context() might be called for the
3937 ** first time from within xFinal().)^
3938 **
3939 ** ^The sqlite3_aggregate_context(C,N) routine returns a NULL pointer if N is
3940 ** less than or equal to zero or if a memory allocate error occurs.
3941 **
3942 ** ^(The amount of space allocated by sqlite3_aggregate_context(C,N) is
3943 ** determined by the N parameter on first successful call. Changing the
3944 ** value of N in subsequent call to sqlite3_aggregate_context() within
3945 ** the same aggregate function instance will not resize the memory
3946 ** allocation.)^
3947 **
3948 ** ^SQLite automatically frees the memory allocated by
3949 ** sqlite3_aggregate_context() when the aggregate query concludes.
3950 **
3951 ** The first parameter must be a copy of the
3952 ** [sqlite3_context | SQL function context] that is the first parameter
3953 ** to the xStep or xFinal callback routine that implements the aggregate
3954 ** function.
3955 **
3956 ** This routine must be called from the same thread in which
3957 ** the aggregate SQL function is running.
3958 */
3961 /*
3962 ** CAPI3REF: User Data For Functions
3963 **
3964 ** ^The sqlite3_user_data() interface returns a copy of
3965 ** the pointer that was the pUserData parameter (the 5th parameter)
3966 ** of the [sqlite3_create_function()]
3967 ** and [sqlite3_create_function16()] routines that originally
3968 ** registered the application defined function.
3969 **
3970 ** This routine must be called from the same thread in which
3971 ** the application-defined function is running.
3972 */
3975 /*
3976 ** CAPI3REF: Database Connection For Functions
3977 **
3978 ** ^The sqlite3_context_db_handle() interface returns a copy of
3979 ** the pointer to the [database connection] (the 1st parameter)
3980 ** of the [sqlite3_create_function()]
3981 ** and [sqlite3_create_function16()] routines that originally
3982 ** registered the application defined function.
3983 */
3986 /*
3987 ** CAPI3REF: Function Auxiliary Data
3988 **
3989 ** The following two functions may be used by scalar SQL functions to
3990 ** associate metadata with argument values. If the same value is passed to
3991 ** multiple invocations of the same SQL function during query execution, under
3992 ** some circumstances the associated metadata may be preserved. This may
3993 ** be used, for example, to add a regular-expression matching scalar
3994 ** function. The compiled version of the regular expression is stored as
3995 ** metadata associated with the SQL value passed as the regular expression
3996 ** pattern. The compiled regular expression can be reused on multiple
3997 ** invocations of the same function so that the original pattern string
3998 ** does not need to be recompiled on each invocation.
3999 **
4000 ** ^The sqlite3_get_auxdata() interface returns a pointer to the metadata
4001 ** associated by the sqlite3_set_auxdata() function with the Nth argument
4002 ** value to the application-defined function. ^If no metadata has been ever
4003 ** been set for the Nth argument of the function, or if the corresponding
4004 ** function parameter has changed since the meta-data was set,
4005 ** then sqlite3_get_auxdata() returns a NULL pointer.
4006 **
4007 ** ^The sqlite3_set_auxdata() interface saves the metadata
4008 ** pointed to by its 3rd parameter as the metadata for the N-th
4009 ** argument of the application-defined function. Subsequent
4010 ** calls to sqlite3_get_auxdata() might return this data, if it has
4011 ** not been destroyed.
4012 ** ^If it is not NULL, SQLite will invoke the destructor
4013 ** function given by the 4th parameter to sqlite3_set_auxdata() on
4014 ** the metadata when the corresponding function parameter changes
4015 ** or when the SQL statement completes, whichever comes first.
4016 **
4017 ** SQLite is free to call the destructor and drop metadata on any
4018 ** parameter of any function at any time. ^The only guarantee is that
4019 ** the destructor will be called before the metadata is dropped.
4020 **
4021 ** ^(In practice, metadata is preserved between function calls for
4022 ** expressions that are constant at compile time. This includes literal
4023 ** values and [parameters].)^
4024 **
4025 ** These routines must be called from the same thread in which
4026 ** the SQL function is running.
4027 */
4032 /*
4033 ** CAPI3REF: Constants Defining Special Destructor Behavior
4034 **
4035 ** These are special values for the destructor that is passed in as the
4036 ** final argument to routines like [sqlite3_result_blob()]. ^If the destructor
4037 ** argument is SQLITE_STATIC, it means that the content pointer is constant
4038 ** and will never change. It does not need to be destroyed. ^The
4039 ** SQLITE_TRANSIENT value means that the content will likely change in
4040 ** the near future and that SQLite should make its own private copy of
4041 ** the content before returning.
4042 **
4043 ** The typedef is necessary to work around problems in certain
4044 ** C++ compilers. See ticket #2191.
4045 */
4047 #define SQLITE_STATIC ((sqlite3_destructor_type)0)
4048 #define SQLITE_TRANSIENT ((sqlite3_destructor_type)-1)
4050 /*
4051 ** CAPI3REF: Setting The Result Of An SQL Function
4052 **
4053 ** These routines are used by the xFunc or xFinal callbacks that
4054 ** implement SQL functions and aggregates. See
4055 ** [sqlite3_create_function()] and [sqlite3_create_function16()]
4056 ** for additional information.
4057 **
4058 ** These functions work very much like the [parameter binding] family of
4059 ** functions used to bind values to host parameters in prepared statements.
4060 ** Refer to the [SQL parameter] documentation for additional information.
4061 **
4062 ** ^The sqlite3_result_blob() interface sets the result from
4063 ** an application-defined function to be the BLOB whose content is pointed
4064 ** to by the second parameter and which is N bytes long where N is the
4065 ** third parameter.
4066 **
4067 ** ^The sqlite3_result_zeroblob() interfaces set the result of
4068 ** the application-defined function to be a BLOB containing all zero
4069 ** bytes and N bytes in size, where N is the value of the 2nd parameter.
4070 **
4071 ** ^The sqlite3_result_double() interface sets the result from
4072 ** an application-defined function to be a floating point value specified
4073 ** by its 2nd argument.
4074 **
4075 ** ^The sqlite3_result_error() and sqlite3_result_error16() functions
4076 ** cause the implemented SQL function to throw an exception.
4077 ** ^SQLite uses the string pointed to by the
4078 ** 2nd parameter of sqlite3_result_error() or sqlite3_result_error16()
4079 ** as the text of an error message. ^SQLite interprets the error
4080 ** message string from sqlite3_result_error() as UTF-8. ^SQLite
4081 ** interprets the string from sqlite3_result_error16() as UTF-16 in native
4082 ** byte order. ^If the third parameter to sqlite3_result_error()
4083 ** or sqlite3_result_error16() is negative then SQLite takes as the error
4084 ** message all text up through the first zero character.
4085 ** ^If the third parameter to sqlite3_result_error() or
4086 ** sqlite3_result_error16() is non-negative then SQLite takes that many
4087 ** bytes (not characters) from the 2nd parameter as the error message.
4088 ** ^The sqlite3_result_error() and sqlite3_result_error16()
4089 ** routines make a private copy of the error message text before
4090 ** they return. Hence, the calling function can deallocate or
4091 ** modify the text after they return without harm.
4092 ** ^The sqlite3_result_error_code() function changes the error code
4093 ** returned by SQLite as a result of an error in a function. ^By default,
4094 ** the error code is SQLITE_ERROR. ^A subsequent call to sqlite3_result_error()
4095 ** or sqlite3_result_error16() resets the error code to SQLITE_ERROR.
4096 **
4097 ** ^The sqlite3_result_toobig() interface causes SQLite to throw an error
4098 ** indicating that a string or BLOB is too long to represent.
4099 **
4100 ** ^The sqlite3_result_nomem() interface causes SQLite to throw an error
4101 ** indicating that a memory allocation failed.
4102 **
4103 ** ^The sqlite3_result_int() interface sets the return value
4104 ** of the application-defined function to be the 32-bit signed integer
4105 ** value given in the 2nd argument.
4106 ** ^The sqlite3_result_int64() interface sets the return value
4107 ** of the application-defined function to be the 64-bit signed integer
4108 ** value given in the 2nd argument.
4109 **
4110 ** ^The sqlite3_result_null() interface sets the return value
4111 ** of the application-defined function to be NULL.
4112 **
4113 ** ^The sqlite3_result_text(), sqlite3_result_text16(),
4114 ** sqlite3_result_text16le(), and sqlite3_result_text16be() interfaces
4115 ** set the return value of the application-defined function to be
4116 ** a text string which is represented as UTF-8, UTF-16 native byte order,
4117 ** UTF-16 little endian, or UTF-16 big endian, respectively.
4118 ** ^SQLite takes the text result from the application from
4119 ** the 2nd parameter of the sqlite3_result_text* interfaces.
4120 ** ^If the 3rd parameter to the sqlite3_result_text* interfaces
4121 ** is negative, then SQLite takes result text from the 2nd parameter
4122 ** through the first zero character.
4123 ** ^If the 3rd parameter to the sqlite3_result_text* interfaces
4124 ** is non-negative, then as many bytes (not characters) of the text
4125 ** pointed to by the 2nd parameter are taken as the application-defined
4126 ** function result. If the 3rd parameter is non-negative, then it
4127 ** must be the byte offset into the string where the NUL terminator would
4128 ** appear if the string where NUL terminated. If any NUL characters occur
4129 ** in the string at a byte offset that is less than the value of the 3rd
4130 ** parameter, then the resulting string will contain embedded NULs and the
4131 ** result of expressions operating on strings with embedded NULs is undefined.
4132 ** ^If the 4th parameter to the sqlite3_result_text* interfaces
4133 ** or sqlite3_result_blob is a non-NULL pointer, then SQLite calls that
4134 ** function as the destructor on the text or BLOB result when it has
4135 ** finished using that result.
4136 ** ^If the 4th parameter to the sqlite3_result_text* interfaces or to
4137 ** sqlite3_result_blob is the special constant SQLITE_STATIC, then SQLite
4138 ** assumes that the text or BLOB result is in constant space and does not
4139 ** copy the content of the parameter nor call a destructor on the content
4140 ** when it has finished using that result.
4141 ** ^If the 4th parameter to the sqlite3_result_text* interfaces
4142 ** or sqlite3_result_blob is the special constant SQLITE_TRANSIENT
4143 ** then SQLite makes a copy of the result into space obtained from
4144 ** from [sqlite3_malloc()] before it returns.
4145 **
4146 ** ^The sqlite3_result_value() interface sets the result of
4147 ** the application-defined function to be a copy the
4148 ** [unprotected sqlite3_value] object specified by the 2nd parameter. ^The
4149 ** sqlite3_result_value() interface makes a copy of the [sqlite3_value]
4150 ** so that the [sqlite3_value] specified in the parameter may change or
4151 ** be deallocated after sqlite3_result_value() returns without harm.
4152 ** ^A [protected sqlite3_value] object may always be used where an
4153 ** [unprotected sqlite3_value] object is required, so either
4154 ** kind of [sqlite3_value] object can be used with this interface.
4155 **
4156 ** If these routines are called from within the different thread
4157 ** than the one containing the application-defined function that received
4158 ** the [sqlite3_context] pointer, the results are undefined.
4159 */
4177 /*
4178 ** CAPI3REF: Define New Collating Sequences
4179 **
4180 ** ^These functions add, remove, or modify a [collation] associated
4181 ** with the [database connection] specified as the first argument.
4182 **
4183 ** ^The name of the collation is a UTF-8 string
4184 ** for sqlite3_create_collation() and sqlite3_create_collation_v2()
4185 ** and a UTF-16 string in native byte order for sqlite3_create_collation16().
4186 ** ^Collation names that compare equal according to [sqlite3_strnicmp()] are
4187 ** considered to be the same name.
4188 **
4189 ** ^(The third argument (eTextRep) must be one of the constants:
4190 ** <ul>
4191 ** <li> [SQLITE_UTF8],
4192 ** <li> [SQLITE_UTF16LE],
4193 ** <li> [SQLITE_UTF16BE],
4194 ** <li> [SQLITE_UTF16], or
4195 ** <li> [SQLITE_UTF16_ALIGNED].
4196 ** </ul>)^
4197 ** ^The eTextRep argument determines the encoding of strings passed
4198 ** to the collating function callback, xCallback.
4199 ** ^The [SQLITE_UTF16] and [SQLITE_UTF16_ALIGNED] values for eTextRep
4200 ** force strings to be UTF16 with native byte order.
4201 ** ^The [SQLITE_UTF16_ALIGNED] value for eTextRep forces strings to begin
4202 ** on an even byte address.
4203 **
4204 ** ^The fourth argument, pArg, is an application data pointer that is passed
4205 ** through as the first argument to the collating function callback.
4206 **
4207 ** ^The fifth argument, xCallback, is a pointer to the collating function.
4208 ** ^Multiple collating functions can be registered using the same name but
4209 ** with different eTextRep parameters and SQLite will use whichever
4210 ** function requires the least amount of data transformation.
4211 ** ^If the xCallback argument is NULL then the collating function is
4212 ** deleted. ^When all collating functions having the same name are deleted,
4213 ** that collation is no longer usable.
4214 **
4215 ** ^The collating function callback is invoked with a copy of the pArg
4216 ** application data pointer and with two strings in the encoding specified
4217 ** by the eTextRep argument. The collating function must return an
4218 ** integer that is negative, zero, or positive
4219 ** if the first string is less than, equal to, or greater than the second,
4220 ** respectively. A collating function must always return the same answer
4221 ** given the same inputs. If two or more collating functions are registered
4222 ** to the same collation name (using different eTextRep values) then all
4223 ** must give an equivalent answer when invoked with equivalent strings.
4224 ** The collating function must obey the following properties for all
4225 ** strings A, B, and C:
4226 **
4227 ** <ol>
4228 ** <li> If A==B then B==A.
4229 ** <li> If A==B and B==C then A==C.
4230 ** <li> If A<B THEN B>A.
4231 ** <li> If A<B and B<C then A<C.
4232 ** </ol>
4233 **
4234 ** If a collating function fails any of the above constraints and that
4235 ** collating function is registered and used, then the behavior of SQLite
4236 ** is undefined.
4237 **
4238 ** ^The sqlite3_create_collation_v2() works like sqlite3_create_collation()
4239 ** with the addition that the xDestroy callback is invoked on pArg when
4240 ** the collating function is deleted.
4241 ** ^Collating functions are deleted when they are overridden by later
4242 ** calls to the collation creation functions or when the
4243 ** [database connection] is closed using [sqlite3_close()].
4244 **
4245 ** ^The xDestroy callback is <u>not</u> called if the
4246 ** sqlite3_create_collation_v2() function fails. Applications that invoke
4247 ** sqlite3_create_collation_v2() with a non-NULL xDestroy argument should
4248 ** check the return code and dispose of the application data pointer
4249 ** themselves rather than expecting SQLite to deal with it for them.
4250 ** This is different from every other SQLite interface. The inconsistency
4251 ** is unfortunate but cannot be changed without breaking backwards
4252 ** compatibility.
4253 **
4254 ** See also: [sqlite3_collation_needed()] and [sqlite3_collation_needed16()].
4255 */
4257 sqlite3*,
4262 );
4264 sqlite3*,
4270 );
4272 sqlite3*,
4277 );
4279 /*
4280 ** CAPI3REF: Collation Needed Callbacks
4281 **
4282 ** ^To avoid having to register all collation sequences before a database
4283 ** can be used, a single callback function may be registered with the
4284 ** [database connection] to be invoked whenever an undefined collation
4285 ** sequence is required.
4286 **
4287 ** ^If the function is registered using the sqlite3_collation_needed() API,
4288 ** then it is passed the names of undefined collation sequences as strings
4289 ** encoded in UTF-8. ^If sqlite3_collation_needed16() is used,
4290 ** the names are passed as UTF-16 in machine native byte order.
4291 ** ^A call to either function replaces the existing collation-needed callback.
4292 **
4293 ** ^(When the callback is invoked, the first argument passed is a copy
4294 ** of the second argument to sqlite3_collation_needed() or
4295 ** sqlite3_collation_needed16(). The second argument is the database
4296 ** connection. The third argument is one of [SQLITE_UTF8], [SQLITE_UTF16BE],
4297 ** or [SQLITE_UTF16LE], indicating the most desirable form of the collation
4298 ** sequence function required. The fourth parameter is the name of the
4299 ** required collation sequence.)^
4300 **
4301 ** The callback function should register the desired collation using
4302 ** [sqlite3_create_collation()], [sqlite3_create_collation16()], or
4303 ** [sqlite3_create_collation_v2()].
4304 */
4306 sqlite3*,
4309 );
4311 sqlite3*,
4314 );
4316 #ifdef SQLITE_HAS_CODEC
4317 /*
4318 ** Specify the key for an encrypted database. This routine should be
4319 ** called right after sqlite3_open().
4320 **
4321 ** The code to implement this API is not available in the public release
4322 ** of SQLite.
4323 */
4327 );
4329 /*
4330 ** Change the key on an open database. If the current database is not
4331 ** encrypted, this routine will encrypt it. If pNew==0 or nNew==0, the
4332 ** database is decrypted.
4333 **
4334 ** The code to implement this API is not available in the public release
4335 ** of SQLite.
4336 */
4340 );
4342 /*
4343 ** Specify the activation key for a SEE database. Unless
4344 ** activated, none of the SEE routines will work.
4345 */
4348 );
4349 #endif
4351 #ifdef SQLITE_ENABLE_CEROD
4352 /*
4353 ** Specify the activation key for a CEROD database. Unless
4354 ** activated, none of the CEROD routines will work.
4355 */
4358 );
4359 #endif
4361 /*
4362 ** CAPI3REF: Suspend Execution For A Short Time
4363 **
4364 ** The sqlite3_sleep() function causes the current thread to suspend execution
4365 ** for at least a number of milliseconds specified in its parameter.
4366 **
4367 ** If the operating system does not support sleep requests with
4368 ** millisecond time resolution, then the time will be rounded up to
4369 ** the nearest second. The number of milliseconds of sleep actually
4370 ** requested from the operating system is returned.
4371 **
4372 ** ^SQLite implements this interface by calling the xSleep()
4373 ** method of the default [sqlite3_vfs] object. If the xSleep() method
4374 ** of the default VFS is not implemented correctly, or not implemented at
4375 ** all, then the behavior of sqlite3_sleep() may deviate from the description
4376 ** in the previous paragraphs.
4377 */
4380 /*
4381 ** CAPI3REF: Name Of The Folder Holding Temporary Files
4382 **
4383 ** ^(If this global variable is made to point to a string which is
4384 ** the name of a folder (a.k.a. directory), then all temporary files
4385 ** created by SQLite when using a built-in [sqlite3_vfs | VFS]
4386 ** will be placed in that directory.)^ ^If this variable
4387 ** is a NULL pointer, then SQLite performs a search for an appropriate
4388 ** temporary file directory.
4389 **
4390 ** It is not safe to read or modify this variable in more than one
4391 ** thread at a time. It is not safe to read or modify this variable
4392 ** if a [database connection] is being used at the same time in a separate
4393 ** thread.
4394 ** It is intended that this variable be set once
4395 ** as part of process initialization and before any SQLite interface
4396 ** routines have been called and that this variable remain unchanged
4397 ** thereafter.
4398 **
4399 ** ^The [temp_store_directory pragma] may modify this variable and cause
4400 ** it to point to memory obtained from [sqlite3_malloc]. ^Furthermore,
4401 ** the [temp_store_directory pragma] always assumes that any string
4402 ** that this variable points to is held in memory obtained from
4403 ** [sqlite3_malloc] and the pragma may attempt to free that memory
4404 ** using [sqlite3_free].
4405 ** Hence, if this variable is modified directly, either it should be
4406 ** made NULL or made to point to memory obtained from [sqlite3_malloc]
4407 ** or else the use of the [temp_store_directory pragma] should be avoided.
4408 */
4411 /*
4412 ** CAPI3REF: Test For Auto-Commit Mode
4413 ** KEYWORDS: {autocommit mode}
4414 **
4415 ** ^The sqlite3_get_autocommit() interface returns non-zero or
4416 ** zero if the given database connection is or is not in autocommit mode,
4417 ** respectively. ^Autocommit mode is on by default.
4418 ** ^Autocommit mode is disabled by a [BEGIN] statement.
4419 ** ^Autocommit mode is re-enabled by a [COMMIT] or [ROLLBACK].
4420 **
4421 ** If certain kinds of errors occur on a statement within a multi-statement
4422 ** transaction (errors including [SQLITE_FULL], [SQLITE_IOERR],
4423 ** [SQLITE_NOMEM], [SQLITE_BUSY], and [SQLITE_INTERRUPT]) then the
4424 ** transaction might be rolled back automatically. The only way to
4425 ** find out whether SQLite automatically rolled back the transaction after
4426 ** an error is to use this function.
4427 **
4428 ** If another thread changes the autocommit status of the database
4429 ** connection while this routine is running, then the return value
4430 ** is undefined.
4431 */
4434 /*
4435 ** CAPI3REF: Find The Database Handle Of A Prepared Statement
4436 **
4437 ** ^The sqlite3_db_handle interface returns the [database connection] handle
4438 ** to which a [prepared statement] belongs. ^The [database connection]
4439 ** returned by sqlite3_db_handle is the same [database connection]
4440 ** that was the first argument
4441 ** to the [sqlite3_prepare_v2()] call (or its variants) that was used to
4442 ** create the statement in the first place.
4443 */
4446 /*
4447 ** CAPI3REF: Return The Filename For A Database Connection
4448 **
4449 ** ^The sqlite3_db_filename(D,N) interface returns a pointer to a filename
4450 ** associated with database N of connection D. ^The main database file
4451 ** has the name "main". If there is no attached database N on the database
4452 ** connection D, or if database N is a temporary or in-memory database, then
4453 ** a NULL pointer is returned.
4454 **
4455 ** ^The filename returned by this function is the output of the
4456 ** xFullPathname method of the [VFS]. ^In other words, the filename
4457 ** will be an absolute pathname, even if the filename used
4458 ** to open the database originally was a URI or relative pathname.
4459 */
4462 /*
4463 ** CAPI3REF: Find the next prepared statement
4464 **
4465 ** ^This interface returns a pointer to the next [prepared statement] after
4466 ** pStmt associated with the [database connection] pDb. ^If pStmt is NULL
4467 ** then this interface returns a pointer to the first prepared statement
4468 ** associated with the database connection pDb. ^If no prepared statement
4469 ** satisfies the conditions of this routine, it returns NULL.
4470 **
4471 ** The [database connection] pointer D in a call to
4472 ** [sqlite3_next_stmt(D,S)] must refer to an open database
4473 ** connection and in particular must not be a NULL pointer.
4474 */
4477 /*
4478 ** CAPI3REF: Commit And Rollback Notification Callbacks
4479 **
4480 ** ^The sqlite3_commit_hook() interface registers a callback
4481 ** function to be invoked whenever a transaction is [COMMIT | committed].
4482 ** ^Any callback set by a previous call to sqlite3_commit_hook()
4483 ** for the same database connection is overridden.
4484 ** ^The sqlite3_rollback_hook() interface registers a callback
4485 ** function to be invoked whenever a transaction is [ROLLBACK | rolled back].
4486 ** ^Any callback set by a previous call to sqlite3_rollback_hook()
4487 ** for the same database connection is overridden.
4488 ** ^The pArg argument is passed through to the callback.
4489 ** ^If the callback on a commit hook function returns non-zero,
4490 ** then the commit is converted into a rollback.
4491 **
4492 ** ^The sqlite3_commit_hook(D,C,P) and sqlite3_rollback_hook(D,C,P) functions
4493 ** return the P argument from the previous call of the same function
4494 ** on the same [database connection] D, or NULL for
4495 ** the first call for each function on D.
4496 **
4497 ** The commit and rollback hook callbacks are not reentrant.
4498 ** The callback implementation must not do anything that will modify
4499 ** the database connection that invoked the callback. Any actions
4500 ** to modify the database connection must be deferred until after the
4501 ** completion of the [sqlite3_step()] call that triggered the commit
4502 ** or rollback hook in the first place.
4503 ** Note that running any other SQL statements, including SELECT statements,
4504 ** or merely calling [sqlite3_prepare_v2()] and [sqlite3_step()] will modify
4505 ** the database connections for the meaning of "modify" in this paragraph.
4506 **
4507 ** ^Registering a NULL function disables the callback.
4508 **
4509 ** ^When the commit hook callback routine returns zero, the [COMMIT]
4510 ** operation is allowed to continue normally. ^If the commit hook
4511 ** returns non-zero, then the [COMMIT] is converted into a [ROLLBACK].
4512 ** ^The rollback hook is invoked on a rollback that results from a commit
4513 ** hook returning non-zero, just as it would be with any other rollback.
4514 **
4515 ** ^For the purposes of this API, a transaction is said to have been
4516 ** rolled back if an explicit "ROLLBACK" statement is executed, or
4517 ** an error or constraint causes an implicit rollback to occur.
4518 ** ^The rollback callback is not invoked if a transaction is
4519 ** automatically rolled back because the database connection is closed.
4520 **
4521 ** See also the [sqlite3_update_hook()] interface.
4522 */
4526 /*
4527 ** CAPI3REF: Data Change Notification Callbacks
4528 **
4529 ** ^The sqlite3_update_hook() interface registers a callback function
4530 ** with the [database connection] identified by the first argument
4531 ** to be invoked whenever a row is updated, inserted or deleted.
4532 ** ^Any callback set by a previous call to this function
4533 ** for the same database connection is overridden.
4534 **
4535 ** ^The second argument is a pointer to the function to invoke when a
4536 ** row is updated, inserted or deleted.
4537 ** ^The first argument to the callback is a copy of the third argument
4538 ** to sqlite3_update_hook().
4539 ** ^The second callback argument is one of [SQLITE_INSERT], [SQLITE_DELETE],
4540 ** or [SQLITE_UPDATE], depending on the operation that caused the callback
4541 ** to be invoked.
4542 ** ^The third and fourth arguments to the callback contain pointers to the
4543 ** database and table name containing the affected row.
4544 ** ^The final callback parameter is the [rowid] of the row.
4545 ** ^In the case of an update, this is the [rowid] after the update takes place.
4546 **
4547 ** ^(The update hook is not invoked when internal system tables are
4548 ** modified (i.e. sqlite_master and sqlite_sequence).)^
4549 **
4550 ** ^In the current implementation, the update hook
4551 ** is not invoked when duplication rows are deleted because of an
4552 ** [ON CONFLICT | ON CONFLICT REPLACE] clause. ^Nor is the update hook
4553 ** invoked when rows are deleted using the [truncate optimization].
4554 ** The exceptions defined in this paragraph might change in a future
4555 ** release of SQLite.
4556 **
4557 ** The update hook implementation must not do anything that will modify
4558 ** the database connection that invoked the update hook. Any actions
4559 ** to modify the database connection must be deferred until after the
4560 ** completion of the [sqlite3_step()] call that triggered the update hook.
4561 ** Note that [sqlite3_prepare_v2()] and [sqlite3_step()] both modify their
4562 ** database connections for the meaning of "modify" in this paragraph.
4563 **
4564 ** ^The sqlite3_update_hook(D,C,P) function
4565 ** returns the P argument from the previous call
4566 ** on the same [database connection] D, or NULL for
4567 ** the first call on D.
4568 **
4569 ** See also the [sqlite3_commit_hook()] and [sqlite3_rollback_hook()]
4570 ** interfaces.
4571 */
4573 sqlite3*,
4576 );
4578 /*
4579 ** CAPI3REF: Enable Or Disable Shared Pager Cache
4580 ** KEYWORDS: {shared cache}
4581 **
4582 ** ^(This routine enables or disables the sharing of the database cache
4583 ** and schema data structures between [database connection | connections]
4584 ** to the same database. Sharing is enabled if the argument is true
4585 ** and disabled if the argument is false.)^
4586 **
4587 ** ^Cache sharing is enabled and disabled for an entire process.
4588 ** This is a change as of SQLite version 3.5.0. In prior versions of SQLite,
4589 ** sharing was enabled or disabled for each thread separately.
4590 **
4591 ** ^(The cache sharing mode set by this interface effects all subsequent
4592 ** calls to [sqlite3_open()], [sqlite3_open_v2()], and [sqlite3_open16()].
4593 ** Existing database connections continue use the sharing mode
4594 ** that was in effect at the time they were opened.)^
4595 **
4596 ** ^(This routine returns [SQLITE_OK] if shared cache was enabled or disabled
4597 ** successfully. An [error code] is returned otherwise.)^
4598 **
4599 ** ^Shared cache is disabled by default. But this might change in
4600 ** future releases of SQLite. Applications that care about shared
4601 ** cache setting should set it explicitly.
4602 **
4603 ** See Also: [SQLite Shared-Cache Mode]
4604 */
4607 /*
4608 ** CAPI3REF: Attempt To Free Heap Memory
4609 **
4610 ** ^The sqlite3_release_memory() interface attempts to free N bytes
4611 ** of heap memory by deallocating non-essential memory allocations
4612 ** held by the database library. Memory used to cache database
4613 ** pages to improve performance is an example of non-essential memory.
4614 ** ^sqlite3_release_memory() returns the number of bytes actually freed,
4615 ** which might be more or less than the amount requested.
4616 ** ^The sqlite3_release_memory() routine is a no-op returning zero
4617 ** if SQLite is not compiled with [SQLITE_ENABLE_MEMORY_MANAGEMENT].
4618 **
4619 ** See also: [sqlite3_db_release_memory()]
4620 */
4623 /*
4624 ** CAPI3REF: Free Memory Used By A Database Connection
4625 **
4626 ** ^The sqlite3_db_release_memory(D) interface attempts to free as much heap
4627 ** memory as possible from database connection D. Unlike the
4628 ** [sqlite3_release_memory()] interface, this interface is effect even
4629 ** when then [SQLITE_ENABLE_MEMORY_MANAGEMENT] compile-time option is
4630 ** omitted.
4631 **
4632 ** See also: [sqlite3_release_memory()]
4633 */
4636 /*
4637 ** CAPI3REF: Impose A Limit On Heap Size
4638 **
4639 ** ^The sqlite3_soft_heap_limit64() interface sets and/or queries the
4640 ** soft limit on the amount of heap memory that may be allocated by SQLite.
4641 ** ^SQLite strives to keep heap memory utilization below the soft heap
4642 ** limit by reducing the number of pages held in the page cache
4643 ** as heap memory usages approaches the limit.
4644 ** ^The soft heap limit is "soft" because even though SQLite strives to stay
4645 ** below the limit, it will exceed the limit rather than generate
4646 ** an [SQLITE_NOMEM] error. In other words, the soft heap limit
4647 ** is advisory only.
4648 **
4649 ** ^The return value from sqlite3_soft_heap_limit64() is the size of
4650 ** the soft heap limit prior to the call, or negative in the case of an
4651 ** error. ^If the argument N is negative
4652 ** then no change is made to the soft heap limit. Hence, the current
4653 ** size of the soft heap limit can be determined by invoking
4654 ** sqlite3_soft_heap_limit64() with a negative argument.
4655 **
4656 ** ^If the argument N is zero then the soft heap limit is disabled.
4657 **
4658 ** ^(The soft heap limit is not enforced in the current implementation
4659 ** if one or more of following conditions are true:
4660 **
4661 ** <ul>
4662 ** <li> The soft heap limit is set to zero.
4663 ** <li> Memory accounting is disabled using a combination of the
4664 ** [sqlite3_config]([SQLITE_CONFIG_MEMSTATUS],...) start-time option and
4665 ** the [SQLITE_DEFAULT_MEMSTATUS] compile-time option.
4666 ** <li> An alternative page cache implementation is specified using
4667 ** [sqlite3_config]([SQLITE_CONFIG_PCACHE2],...).
4668 ** <li> The page cache allocates from its own memory pool supplied
4669 ** by [sqlite3_config]([SQLITE_CONFIG_PAGECACHE],...) rather than
4670 ** from the heap.
4671 ** </ul>)^
4672 **
4673 ** Beginning with SQLite version 3.7.3, the soft heap limit is enforced
4674 ** regardless of whether or not the [SQLITE_ENABLE_MEMORY_MANAGEMENT]
4675 ** compile-time option is invoked. With [SQLITE_ENABLE_MEMORY_MANAGEMENT],
4676 ** the soft heap limit is enforced on every memory allocation. Without
4677 ** [SQLITE_ENABLE_MEMORY_MANAGEMENT], the soft heap limit is only enforced
4678 ** when memory is allocated by the page cache. Testing suggests that because
4679 ** the page cache is the predominate memory user in SQLite, most
4680 ** applications will achieve adequate soft heap limit enforcement without
4681 ** the use of [SQLITE_ENABLE_MEMORY_MANAGEMENT].
4682 **
4683 ** The circumstances under which SQLite will enforce the soft heap limit may
4684 ** changes in future releases of SQLite.
4685 */
4688 /*
4689 ** CAPI3REF: Deprecated Soft Heap Limit Interface
4690 ** DEPRECATED
4691 **
4692 ** This is a deprecated version of the [sqlite3_soft_heap_limit64()]
4693 ** interface. This routine is provided for historical compatibility
4694 ** only. All new applications should use the
4695 ** [sqlite3_soft_heap_limit64()] interface rather than this one.
4696 */
4700 /*
4701 ** CAPI3REF: Extract Metadata About A Column Of A Table
4702 **
4703 ** ^This routine returns metadata about a specific column of a specific
4704 ** database table accessible using the [database connection] handle
4705 ** passed as the first function argument.
4706 **
4707 ** ^The column is identified by the second, third and fourth parameters to
4708 ** this function. ^The second parameter is either the name of the database
4709 ** (i.e. "main", "temp", or an attached database) containing the specified
4710 ** table or NULL. ^If it is NULL, then all attached databases are searched
4711 ** for the table using the same algorithm used by the database engine to
4712 ** resolve unqualified table references.
4713 **
4714 ** ^The third and fourth parameters to this function are the table and column
4715 ** name of the desired column, respectively. Neither of these parameters
4716 ** may be NULL.
4717 **
4718 ** ^Metadata is returned by writing to the memory locations passed as the 5th
4719 ** and subsequent parameters to this function. ^Any of these arguments may be
4720 ** NULL, in which case the corresponding element of metadata is omitted.
4721 **
4722 ** ^(<blockquote>
4723 ** <table border="1">
4724 ** <tr><th> Parameter <th> Output<br>Type <th> Description
4725 **
4726 ** <tr><td> 5th <td> const char* <td> Data type
4727 ** <tr><td> 6th <td> const char* <td> Name of default collation sequence
4728 ** <tr><td> 7th <td> int <td> True if column has a NOT NULL constraint
4729 ** <tr><td> 8th <td> int <td> True if column is part of the PRIMARY KEY
4730 ** <tr><td> 9th <td> int <td> True if column is [AUTOINCREMENT]
4731 ** </table>
4732 ** </blockquote>)^
4733 **
4734 ** ^The memory pointed to by the character pointers returned for the
4735 ** declaration type and collation sequence is valid only until the next
4736 ** call to any SQLite API function.
4737 **
4738 ** ^If the specified table is actually a view, an [error code] is returned.
4739 **
4740 ** ^If the specified column is "rowid", "oid" or "_rowid_" and an
4741 ** [INTEGER PRIMARY KEY] column has been explicitly declared, then the output
4742 ** parameters are set for the explicitly declared column. ^(If there is no
4743 ** explicitly declared [INTEGER PRIMARY KEY] column, then the output
4744 ** parameters are set as follows:
4745 **
4746 ** <pre>
4747 ** data type: "INTEGER"
4748 ** collation sequence: "BINARY"
4749 ** not null: 0
4750 ** primary key: 1
4751 ** auto increment: 0
4752 ** </pre>)^
4753 **
4754 ** ^(This function may load one or more schemas from database files. If an
4755 ** error occurs during this process, or if the requested table or column
4756 ** cannot be found, an [error code] is returned and an error message left
4757 ** in the [database connection] (to be retrieved using sqlite3_errmsg()).)^
4758 **
4759 ** ^This API is only available if the library was compiled with the
4760 ** [SQLITE_ENABLE_COLUMN_METADATA] C-preprocessor symbol defined.
4761 */
4772 );
4774 /*
4775 ** CAPI3REF: Load An Extension
4776 **
4777 ** ^This interface loads an SQLite extension library from the named file.
4778 **
4779 ** ^The sqlite3_load_extension() interface attempts to load an
4780 ** SQLite extension library contained in the file zFile.
4781 **
4782 ** ^The entry point is zProc.
4783 ** ^zProc may be 0, in which case the name of the entry point
4784 ** defaults to "sqlite3_extension_init".
4785 ** ^The sqlite3_load_extension() interface returns
4786 ** [SQLITE_OK] on success and [SQLITE_ERROR] if something goes wrong.
4787 ** ^If an error occurs and pzErrMsg is not 0, then the
4788 ** [sqlite3_load_extension()] interface shall attempt to
4789 ** fill *pzErrMsg with error message text stored in memory
4790 ** obtained from [sqlite3_malloc()]. The calling function
4791 ** should free this memory by calling [sqlite3_free()].
4792 **
4793 ** ^Extension loading must be enabled using
4794 ** [sqlite3_enable_load_extension()] prior to calling this API,
4795 ** otherwise an error will be returned.
4796 **
4797 ** See also the [load_extension() SQL function].
4798 */
4804 );
4806 /*
4807 ** CAPI3REF: Enable Or Disable Extension Loading
4808 **
4809 ** ^So as not to open security holes in older applications that are
4810 ** unprepared to deal with extension loading, and as a means of disabling
4811 ** extension loading while evaluating user-entered SQL, the following API
4812 ** is provided to turn the [sqlite3_load_extension()] mechanism on and off.
4813 **
4814 ** ^Extension loading is off by default. See ticket #1863.
4815 ** ^Call the sqlite3_enable_load_extension() routine with onoff==1
4816 ** to turn extension loading on and call it with onoff==0 to turn
4817 ** it back off again.
4818 */
4821 /*
4822 ** CAPI3REF: Automatically Load Statically Linked Extensions
4823 **
4824 ** ^This interface causes the xEntryPoint() function to be invoked for
4825 ** each new [database connection] that is created. The idea here is that
4826 ** xEntryPoint() is the entry point for a statically linked SQLite extension
4827 ** that is to be automatically loaded into all new database connections.
4828 **
4829 ** ^(Even though the function prototype shows that xEntryPoint() takes
4830 ** no arguments and returns void, SQLite invokes xEntryPoint() with three
4831 ** arguments and expects and integer result as if the signature of the
4832 ** entry point where as follows:
4833 **
4834 ** <blockquote><pre>
4835 ** int xEntryPoint(
4836 ** sqlite3 *db,
4837 ** const char **pzErrMsg,
4838 ** const struct sqlite3_api_routines *pThunk
4839 ** );
4840 ** </pre></blockquote>)^
4841 **
4842 ** If the xEntryPoint routine encounters an error, it should make *pzErrMsg
4843 ** point to an appropriate error message (obtained from [sqlite3_mprintf()])
4844 ** and return an appropriate [error code]. ^SQLite ensures that *pzErrMsg
4845 ** is NULL before calling the xEntryPoint(). ^SQLite will invoke
4846 ** [sqlite3_free()] on *pzErrMsg after xEntryPoint() returns. ^If any
4847 ** xEntryPoint() returns an error, the [sqlite3_open()], [sqlite3_open16()],
4848 ** or [sqlite3_open_v2()] call that provoked the xEntryPoint() will fail.
4849 **
4850 ** ^Calling sqlite3_auto_extension(X) with an entry point X that is already
4851 ** on the list of automatic extensions is a harmless no-op. ^No entry point
4852 ** will be called more than once for each database connection that is opened.
4853 **
4854 ** See also: [sqlite3_reset_auto_extension()].
4855 */
4858 /*
4859 ** CAPI3REF: Reset Automatic Extension Loading
4860 **
4861 ** ^This interface disables all automatic extensions previously
4862 ** registered using [sqlite3_auto_extension()].
4863 */
4866 /*
4867 ** The interface to the virtual-table mechanism is currently considered
4868 ** to be experimental. The interface might change in incompatible ways.
4869 ** If this is a problem for you, do not use the interface at this time.
4870 **
4871 ** When the virtual-table mechanism stabilizes, we will declare the
4872 ** interface fixed, support it indefinitely, and remove this comment.
4873 */
4875 /*
4876 ** Structures used by the virtual table interface
4877 */
4883 /*
4884 ** CAPI3REF: Virtual Table Object
4885 ** KEYWORDS: sqlite3_module {virtual table module}
4886 **
4887 ** This structure, sometimes called a "virtual table module",
4888 ** defines the implementation of a [virtual tables].
4889 ** This structure consists mostly of methods for the module.
4890 **
4891 ** ^A virtual table module is created by filling in a persistent
4892 ** instance of this structure and passing a pointer to that instance
4893 ** to [sqlite3_create_module()] or [sqlite3_create_module_v2()].
4894 ** ^The registration remains valid until it is replaced by a different
4895 ** module or until the [database connection] closes. The content
4896 ** of this structure must not change while it is registered with
4897 ** any database connection.
4898 */
4927 /* The methods above are in version 1 of the sqlite_module object. Those
4928 ** below are for version 2 and greater. */
4932 };
4934 /*
4935 ** CAPI3REF: Virtual Table Indexing Information
4936 ** KEYWORDS: sqlite3_index_info
4937 **
4938 ** The sqlite3_index_info structure and its substructures is used as part
4939 ** of the [virtual table] interface to
4940 ** pass information into and receive the reply from the [xBestIndex]
4941 ** method of a [virtual table module]. The fields under **Inputs** are the
4942 ** inputs to xBestIndex and are read-only. xBestIndex inserts its
4943 ** results into the **Outputs** fields.
4944 **
4945 ** ^(The aConstraint[] array records WHERE clause constraints of the form:
4946 **
4947 ** <blockquote>column OP expr</blockquote>
4948 **
4949 ** where OP is =, <, <=, >, or >=.)^ ^(The particular operator is
4950 ** stored in aConstraint[].op using one of the
4951 ** [SQLITE_INDEX_CONSTRAINT_EQ | SQLITE_INDEX_CONSTRAINT_ values].)^
4952 ** ^(The index of the column is stored in
4953 ** aConstraint[].iColumn.)^ ^(aConstraint[].usable is TRUE if the
4954 ** expr on the right-hand side can be evaluated (and thus the constraint
4955 ** is usable) and false if it cannot.)^
4956 **
4957 ** ^The optimizer automatically inverts terms of the form "expr OP column"
4958 ** and makes other simplifications to the WHERE clause in an attempt to
4959 ** get as many WHERE clause terms into the form shown above as possible.
4960 ** ^The aConstraint[] array only reports WHERE clause terms that are
4961 ** relevant to the particular virtual table being queried.
4962 **
4963 ** ^Information about the ORDER BY clause is stored in aOrderBy[].
4964 ** ^Each term of aOrderBy records a column of the ORDER BY clause.
4965 **
4966 ** The [xBestIndex] method must fill aConstraintUsage[] with information
4967 ** about what parameters to pass to xFilter. ^If argvIndex>0 then
4968 ** the right-hand side of the corresponding aConstraint[] is evaluated
4969 ** and becomes the argvIndex-th entry in argv. ^(If aConstraintUsage[].omit
4970 ** is true, then the constraint is assumed to be fully handled by the
4971 ** virtual table and is not checked again by SQLite.)^
4972 **
4973 ** ^The idxNum and idxPtr values are recorded and passed into the
4974 ** [xFilter] method.
4975 ** ^[sqlite3_free()] is used to free idxPtr if and only if
4976 ** needToFreeIdxPtr is true.
4977 **
4978 ** ^The orderByConsumed means that output from [xFilter]/[xNext] will occur in
4979 ** the correct order to satisfy the ORDER BY clause so that no separate
4980 ** sorting step is required.
4981 **
4982 ** ^The estimatedCost value is an estimate of the cost of doing the
4983 ** particular lookup. A full scan of a table with N entries should have
4984 ** a cost of N. A binary search of a table of N entries should have a
4985 ** cost of approximately log(N).
4986 */
4988 /* Inputs */
5001 /* Outputs */
5011 };
5013 /*
5014 ** CAPI3REF: Virtual Table Constraint Operator Codes
5015 **
5016 ** These macros defined the allowed values for the
5017 ** [sqlite3_index_info].aConstraint[].op field. Each value represents
5018 ** an operator that is part of a constraint term in the wHERE clause of
5019 ** a query that uses a [virtual table].
5020 */
5021 #define SQLITE_INDEX_CONSTRAINT_EQ 2
5022 #define SQLITE_INDEX_CONSTRAINT_GT 4
5023 #define SQLITE_INDEX_CONSTRAINT_LE 8
5024 #define SQLITE_INDEX_CONSTRAINT_LT 16
5025 #define SQLITE_INDEX_CONSTRAINT_GE 32
5026 #define SQLITE_INDEX_CONSTRAINT_MATCH 64
5028 /*
5029 ** CAPI3REF: Register A Virtual Table Implementation
5030 **
5031 ** ^These routines are used to register a new [virtual table module] name.
5032 ** ^Module names must be registered before
5033 ** creating a new [virtual table] using the module and before using a
5034 ** preexisting [virtual table] for the module.
5035 **
5036 ** ^The module name is registered on the [database connection] specified
5037 ** by the first parameter. ^The name of the module is given by the
5038 ** second parameter. ^The third parameter is a pointer to
5039 ** the implementation of the [virtual table module]. ^The fourth
5040 ** parameter is an arbitrary client data pointer that is passed through
5041 ** into the [xCreate] and [xConnect] methods of the virtual table module
5042 ** when a new virtual table is be being created or reinitialized.
5043 **
5044 ** ^The sqlite3_create_module_v2() interface has a fifth parameter which
5045 ** is a pointer to a destructor for the pClientData. ^SQLite will
5046 ** invoke the destructor function (if it is not NULL) when SQLite
5047 ** no longer needs the pClientData pointer. ^The destructor will also
5048 ** be invoked if the call to sqlite3_create_module_v2() fails.
5049 ** ^The sqlite3_create_module()
5050 ** interface is equivalent to sqlite3_create_module_v2() with a NULL
5051 ** destructor.
5052 */
5058 );
5065 );
5067 /*
5068 ** CAPI3REF: Virtual Table Instance Object
5069 ** KEYWORDS: sqlite3_vtab
5070 **
5071 ** Every [virtual table module] implementation uses a subclass
5072 ** of this object to describe a particular instance
5073 ** of the [virtual table]. Each subclass will
5074 ** be tailored to the specific needs of the module implementation.
5075 ** The purpose of this superclass is to define certain fields that are
5076 ** common to all module implementations.
5077 **
5078 ** ^Virtual tables methods can set an error message by assigning a
5079 ** string obtained from [sqlite3_mprintf()] to zErrMsg. The method should
5080 ** take care that any prior string is freed by a call to [sqlite3_free()]
5081 ** prior to assigning a new string to zErrMsg. ^After the error message
5082 ** is delivered up to the client application, the string will be automatically
5083 ** freed by sqlite3_free() and the zErrMsg field will be zeroed.
5084 */
5089 /* Virtual table implementations will typically add additional fields */
5090 };
5092 /*
5093 ** CAPI3REF: Virtual Table Cursor Object
5094 ** KEYWORDS: sqlite3_vtab_cursor {virtual table cursor}
5095 **
5096 ** Every [virtual table module] implementation uses a subclass of the
5097 ** following structure to describe cursors that point into the
5098 ** [virtual table] and are used
5099 ** to loop through the virtual table. Cursors are created using the
5100 ** [sqlite3_module.xOpen | xOpen] method of the module and are destroyed
5101 ** by the [sqlite3_module.xClose | xClose] method. Cursors are used
5102 ** by the [xFilter], [xNext], [xEof], [xColumn], and [xRowid] methods
5103 ** of the module. Each module implementation will define
5104 ** the content of a cursor structure to suit its own needs.
5105 **
5106 ** This superclass exists in order to define fields of the cursor that
5107 ** are common to all implementations.
5108 */
5111 /* Virtual table implementations will typically add additional fields */
5112 };
5114 /*
5115 ** CAPI3REF: Declare The Schema Of A Virtual Table
5116 **
5117 ** ^The [xCreate] and [xConnect] methods of a
5118 ** [virtual table module] call this interface
5119 ** to declare the format (the names and datatypes of the columns) of
5120 ** the virtual tables they implement.
5121 */
5124 /*
5125 ** CAPI3REF: Overload A Function For A Virtual Table
5126 **
5127 ** ^(Virtual tables can provide alternative implementations of functions
5128 ** using the [xFindFunction] method of the [virtual table module].
5129 ** But global versions of those functions
5130 ** must exist in order to be overloaded.)^
5131 **
5132 ** ^(This API makes sure a global version of a function with a particular
5133 ** name and number of parameters exists. If no such function exists
5134 ** before this API is called, a new function is created.)^ ^The implementation
5135 ** of the new function always causes an exception to be thrown. So
5136 ** the new function is not good for anything by itself. Its only
5137 ** purpose is to be a placeholder function that can be overloaded
5138 ** by a [virtual table].
5139 */
5142 /*
5143 ** The interface to the virtual-table mechanism defined above (back up
5144 ** to a comment remarkably similar to this one) is currently considered
5145 ** to be experimental. The interface might change in incompatible ways.
5146 ** If this is a problem for you, do not use the interface at this time.
5147 **
5148 ** When the virtual-table mechanism stabilizes, we will declare the
5149 ** interface fixed, support it indefinitely, and remove this comment.
5150 */
5152 /*
5153 ** CAPI3REF: A Handle To An Open BLOB
5154 ** KEYWORDS: {BLOB handle} {BLOB handles}
5155 **
5156 ** An instance of this object represents an open BLOB on which
5157 ** [sqlite3_blob_open | incremental BLOB I/O] can be performed.
5158 ** ^Objects of this type are created by [sqlite3_blob_open()]
5159 ** and destroyed by [sqlite3_blob_close()].
5160 ** ^The [sqlite3_blob_read()] and [sqlite3_blob_write()] interfaces
5161 ** can be used to read or write small subsections of the BLOB.
5162 ** ^The [sqlite3_blob_bytes()] interface returns the size of the BLOB in bytes.
5163 */
5166 /*
5167 ** CAPI3REF: Open A BLOB For Incremental I/O
5168 **
5169 ** ^(This interfaces opens a [BLOB handle | handle] to the BLOB located
5170 ** in row iRow, column zColumn, table zTable in database zDb;
5171 ** in other words, the same BLOB that would be selected by:
5172 **
5173 ** <pre>
5174 ** SELECT zColumn FROM zDb.zTable WHERE [rowid] = iRow;
5175 ** </pre>)^
5176 **
5177 ** ^If the flags parameter is non-zero, then the BLOB is opened for read
5178 ** and write access. ^If it is zero, the BLOB is opened for read access.
5179 ** ^It is not possible to open a column that is part of an index or primary
5180 ** key for writing. ^If [foreign key constraints] are enabled, it is
5181 ** not possible to open a column that is part of a [child key] for writing.
5182 **
5183 ** ^Note that the database name is not the filename that contains
5184 ** the database but rather the symbolic name of the database that
5185 ** appears after the AS keyword when the database is connected using [ATTACH].
5186 ** ^For the main database file, the database name is "main".
5187 ** ^For TEMP tables, the database name is "temp".
5188 **
5189 ** ^(On success, [SQLITE_OK] is returned and the new [BLOB handle] is written
5190 ** to *ppBlob. Otherwise an [error code] is returned and *ppBlob is set
5191 ** to be a null pointer.)^
5192 ** ^This function sets the [database connection] error code and message
5193 ** accessible via [sqlite3_errcode()] and [sqlite3_errmsg()] and related
5194 ** functions. ^Note that the *ppBlob variable is always initialized in a
5195 ** way that makes it safe to invoke [sqlite3_blob_close()] on *ppBlob
5196 ** regardless of the success or failure of this routine.
5197 **
5198 ** ^(If the row that a BLOB handle points to is modified by an
5199 ** [UPDATE], [DELETE], or by [ON CONFLICT] side-effects
5200 ** then the BLOB handle is marked as "expired".
5201 ** This is true if any column of the row is changed, even a column
5202 ** other than the one the BLOB handle is open on.)^
5203 ** ^Calls to [sqlite3_blob_read()] and [sqlite3_blob_write()] for
5204 ** an expired BLOB handle fail with a return code of [SQLITE_ABORT].
5205 ** ^(Changes written into a BLOB prior to the BLOB expiring are not
5206 ** rolled back by the expiration of the BLOB. Such changes will eventually
5207 ** commit if the transaction continues to completion.)^
5208 **
5209 ** ^Use the [sqlite3_blob_bytes()] interface to determine the size of
5210 ** the opened blob. ^The size of a blob may not be changed by this
5211 ** interface. Use the [UPDATE] SQL command to change the size of a
5212 ** blob.
5213 **
5214 ** ^The [sqlite3_bind_zeroblob()] and [sqlite3_result_zeroblob()] interfaces
5215 ** and the built-in [zeroblob] SQL function can be used, if desired,
5216 ** to create an empty, zero-filled blob in which to read or write using
5217 ** this interface.
5218 **
5219 ** To avoid a resource leak, every open [BLOB handle] should eventually
5220 ** be released by a call to [sqlite3_blob_close()].
5221 */
5223 sqlite3*,
5227 sqlite3_int64 iRow,
5229 sqlite3_blob **ppBlob
5230 );
5232 /*
5233 ** CAPI3REF: Move a BLOB Handle to a New Row
5234 **
5235 ** ^This function is used to move an existing blob handle so that it points
5236 ** to a different row of the same database table. ^The new row is identified
5237 ** by the rowid value passed as the second argument. Only the row can be
5238 ** changed. ^The database, table and column on which the blob handle is open
5239 ** remain the same. Moving an existing blob handle to a new row can be
5240 ** faster than closing the existing handle and opening a new one.
5241 **
5242 ** ^(The new row must meet the same criteria as for [sqlite3_blob_open()] -
5243 ** it must exist and there must be either a blob or text value stored in
5244 ** the nominated column.)^ ^If the new row is not present in the table, or if
5245 ** it does not contain a blob or text value, or if another error occurs, an
5246 ** SQLite error code is returned and the blob handle is considered aborted.
5247 ** ^All subsequent calls to [sqlite3_blob_read()], [sqlite3_blob_write()] or
5248 ** [sqlite3_blob_reopen()] on an aborted blob handle immediately return
5249 ** SQLITE_ABORT. ^Calling [sqlite3_blob_bytes()] on an aborted blob handle
5250 ** always returns zero.
5251 **
5252 ** ^This function sets the database handle error code and message.
5253 */
5256 /*
5257 ** CAPI3REF: Close A BLOB Handle
5258 **
5259 ** ^Closes an open [BLOB handle].
5260 **
5261 ** ^Closing a BLOB shall cause the current transaction to commit
5262 ** if there are no other BLOBs, no pending prepared statements, and the
5263 ** database connection is in [autocommit mode].
5264 ** ^If any writes were made to the BLOB, they might be held in cache
5265 ** until the close operation if they will fit.
5266 **
5267 ** ^(Closing the BLOB often forces the changes
5268 ** out to disk and so if any I/O errors occur, they will likely occur
5269 ** at the time when the BLOB is closed. Any errors that occur during
5270 ** closing are reported as a non-zero return value.)^
5271 **
5272 ** ^(The BLOB is closed unconditionally. Even if this routine returns
5273 ** an error code, the BLOB is still closed.)^
5274 **
5275 ** ^Calling this routine with a null pointer (such as would be returned
5276 ** by a failed call to [sqlite3_blob_open()]) is a harmless no-op.
5277 */
5280 /*
5281 ** CAPI3REF: Return The Size Of An Open BLOB
5282 **
5283 ** ^Returns the size in bytes of the BLOB accessible via the
5284 ** successfully opened [BLOB handle] in its only argument. ^The
5285 ** incremental blob I/O routines can only read or overwriting existing
5286 ** blob content; they cannot change the size of a blob.
5287 **
5288 ** This routine only works on a [BLOB handle] which has been created
5289 ** by a prior successful call to [sqlite3_blob_open()] and which has not
5290 ** been closed by [sqlite3_blob_close()]. Passing any other pointer in
5291 ** to this routine results in undefined and probably undesirable behavior.
5292 */
5295 /*
5296 ** CAPI3REF: Read Data From A BLOB Incrementally
5297 **
5298 ** ^(This function is used to read data from an open [BLOB handle] into a
5299 ** caller-supplied buffer. N bytes of data are copied into buffer Z
5300 ** from the open BLOB, starting at offset iOffset.)^
5301 **
5302 ** ^If offset iOffset is less than N bytes from the end of the BLOB,
5303 ** [SQLITE_ERROR] is returned and no data is read. ^If N or iOffset is
5304 ** less than zero, [SQLITE_ERROR] is returned and no data is read.
5305 ** ^The size of the blob (and hence the maximum value of N+iOffset)
5306 ** can be determined using the [sqlite3_blob_bytes()] interface.
5307 **
5308 ** ^An attempt to read from an expired [BLOB handle] fails with an
5309 ** error code of [SQLITE_ABORT].
5310 **
5311 ** ^(On success, sqlite3_blob_read() returns SQLITE_OK.
5312 ** Otherwise, an [error code] or an [extended error code] is returned.)^
5313 **
5314 ** This routine only works on a [BLOB handle] which has been created
5315 ** by a prior successful call to [sqlite3_blob_open()] and which has not
5316 ** been closed by [sqlite3_blob_close()]. Passing any other pointer in
5317 ** to this routine results in undefined and probably undesirable behavior.
5318 **
5319 ** See also: [sqlite3_blob_write()].
5320 */
5323 /*
5324 ** CAPI3REF: Write Data Into A BLOB Incrementally
5325 **
5326 ** ^This function is used to write data into an open [BLOB handle] from a
5327 ** caller-supplied buffer. ^N bytes of data are copied from the buffer Z
5328 ** into the open BLOB, starting at offset iOffset.
5329 **
5330 ** ^If the [BLOB handle] passed as the first argument was not opened for
5331 ** writing (the flags parameter to [sqlite3_blob_open()] was zero),
5332 ** this function returns [SQLITE_READONLY].
5333 **
5334 ** ^This function may only modify the contents of the BLOB; it is
5335 ** not possible to increase the size of a BLOB using this API.
5336 ** ^If offset iOffset is less than N bytes from the end of the BLOB,
5337 ** [SQLITE_ERROR] is returned and no data is written. ^If N is
5338 ** less than zero [SQLITE_ERROR] is returned and no data is written.
5339 ** The size of the BLOB (and hence the maximum value of N+iOffset)
5340 ** can be determined using the [sqlite3_blob_bytes()] interface.
5341 **
5342 ** ^An attempt to write to an expired [BLOB handle] fails with an
5343 ** error code of [SQLITE_ABORT]. ^Writes to the BLOB that occurred
5344 ** before the [BLOB handle] expired are not rolled back by the
5345 ** expiration of the handle, though of course those changes might
5346 ** have been overwritten by the statement that expired the BLOB handle
5347 ** or by other independent statements.
5348 **
5349 ** ^(On success, sqlite3_blob_write() returns SQLITE_OK.
5350 ** Otherwise, an [error code] or an [extended error code] is returned.)^
5351 **
5352 ** This routine only works on a [BLOB handle] which has been created
5353 ** by a prior successful call to [sqlite3_blob_open()] and which has not
5354 ** been closed by [sqlite3_blob_close()]. Passing any other pointer in
5355 ** to this routine results in undefined and probably undesirable behavior.
5356 **
5357 ** See also: [sqlite3_blob_read()].
5358 */
5361 /*
5362 ** CAPI3REF: Virtual File System Objects
5363 **
5364 ** A virtual filesystem (VFS) is an [sqlite3_vfs] object
5365 ** that SQLite uses to interact
5366 ** with the underlying operating system. Most SQLite builds come with a
5367 ** single default VFS that is appropriate for the host computer.
5368 ** New VFSes can be registered and existing VFSes can be unregistered.
5369 ** The following interfaces are provided.
5370 **
5371 ** ^The sqlite3_vfs_find() interface returns a pointer to a VFS given its name.
5372 ** ^Names are case sensitive.
5373 ** ^Names are zero-terminated UTF-8 strings.
5374 ** ^If there is no match, a NULL pointer is returned.
5375 ** ^If zVfsName is NULL then the default VFS is returned.
5376 **
5377 ** ^New VFSes are registered with sqlite3_vfs_register().
5378 ** ^Each new VFS becomes the default VFS if the makeDflt flag is set.
5379 ** ^The same VFS can be registered multiple times without injury.
5380 ** ^To make an existing VFS into the default VFS, register it again
5381 ** with the makeDflt flag set. If two different VFSes with the
5382 ** same name are registered, the behavior is undefined. If a
5383 ** VFS is registered with a name that is NULL or an empty string,
5384 ** then the behavior is undefined.
5385 **
5386 ** ^Unregister a VFS with the sqlite3_vfs_unregister() interface.
5387 ** ^(If the default VFS is unregistered, another VFS is chosen as
5388 ** the default. The choice for the new VFS is arbitrary.)^
5389 */
5394 /*
5395 ** CAPI3REF: Mutexes
5396 **
5397 ** The SQLite core uses these routines for thread
5398 ** synchronization. Though they are intended for internal
5399 ** use by SQLite, code that links against SQLite is
5400 ** permitted to use any of these routines.
5401 **
5402 ** The SQLite source code contains multiple implementations
5403 ** of these mutex routines. An appropriate implementation
5404 ** is selected automatically at compile-time. ^(The following
5405 ** implementations are available in the SQLite core:
5406 **
5407 ** <ul>
5408 ** <li> SQLITE_MUTEX_OS2
5409 ** <li> SQLITE_MUTEX_PTHREADS
5410 ** <li> SQLITE_MUTEX_W32
5411 ** <li> SQLITE_MUTEX_NOOP
5412 ** </ul>)^
5413 **
5414 ** ^The SQLITE_MUTEX_NOOP implementation is a set of routines
5415 ** that does no real locking and is appropriate for use in
5416 ** a single-threaded application. ^The SQLITE_MUTEX_OS2,
5417 ** SQLITE_MUTEX_PTHREADS, and SQLITE_MUTEX_W32 implementations
5418 ** are appropriate for use on OS/2, Unix, and Windows.
5419 **
5420 ** ^(If SQLite is compiled with the SQLITE_MUTEX_APPDEF preprocessor
5421 ** macro defined (with "-DSQLITE_MUTEX_APPDEF=1"), then no mutex
5422 ** implementation is included with the library. In this case the
5423 ** application must supply a custom mutex implementation using the
5424 ** [SQLITE_CONFIG_MUTEX] option of the sqlite3_config() function
5425 ** before calling sqlite3_initialize() or any other public sqlite3_
5426 ** function that calls sqlite3_initialize().)^
5427 **
5428 ** ^The sqlite3_mutex_alloc() routine allocates a new
5429 ** mutex and returns a pointer to it. ^If it returns NULL
5430 ** that means that a mutex could not be allocated. ^SQLite
5431 ** will unwind its stack and return an error. ^(The argument
5432 ** to sqlite3_mutex_alloc() is one of these integer constants:
5433 **
5434 ** <ul>
5435 ** <li> SQLITE_MUTEX_FAST
5436 ** <li> SQLITE_MUTEX_RECURSIVE
5437 ** <li> SQLITE_MUTEX_STATIC_MASTER
5438 ** <li> SQLITE_MUTEX_STATIC_MEM
5439 ** <li> SQLITE_MUTEX_STATIC_MEM2
5440 ** <li> SQLITE_MUTEX_STATIC_PRNG
5441 ** <li> SQLITE_MUTEX_STATIC_LRU
5442 ** <li> SQLITE_MUTEX_STATIC_LRU2
5443 ** </ul>)^
5444 **
5445 ** ^The first two constants (SQLITE_MUTEX_FAST and SQLITE_MUTEX_RECURSIVE)
5446 ** cause sqlite3_mutex_alloc() to create
5447 ** a new mutex. ^The new mutex is recursive when SQLITE_MUTEX_RECURSIVE
5448 ** is used but not necessarily so when SQLITE_MUTEX_FAST is used.
5449 ** The mutex implementation does not need to make a distinction
5450 ** between SQLITE_MUTEX_RECURSIVE and SQLITE_MUTEX_FAST if it does
5451 ** not want to. ^SQLite will only request a recursive mutex in
5452 ** cases where it really needs one. ^If a faster non-recursive mutex
5453 ** implementation is available on the host platform, the mutex subsystem
5454 ** might return such a mutex in response to SQLITE_MUTEX_FAST.
5455 **
5456 ** ^The other allowed parameters to sqlite3_mutex_alloc() (anything other
5457 ** than SQLITE_MUTEX_FAST and SQLITE_MUTEX_RECURSIVE) each return
5458 ** a pointer to a static preexisting mutex. ^Six static mutexes are
5459 ** used by the current version of SQLite. Future versions of SQLite
5460 ** may add additional static mutexes. Static mutexes are for internal
5461 ** use by SQLite only. Applications that use SQLite mutexes should
5462 ** use only the dynamic mutexes returned by SQLITE_MUTEX_FAST or
5463 ** SQLITE_MUTEX_RECURSIVE.
5464 **
5465 ** ^Note that if one of the dynamic mutex parameters (SQLITE_MUTEX_FAST
5466 ** or SQLITE_MUTEX_RECURSIVE) is used then sqlite3_mutex_alloc()
5467 ** returns a different mutex on every call. ^But for the static
5468 ** mutex types, the same mutex is returned on every call that has
5469 ** the same type number.
5470 **
5471 ** ^The sqlite3_mutex_free() routine deallocates a previously
5472 ** allocated dynamic mutex. ^SQLite is careful to deallocate every
5473 ** dynamic mutex that it allocates. The dynamic mutexes must not be in
5474 ** use when they are deallocated. Attempting to deallocate a static
5475 ** mutex results in undefined behavior. ^SQLite never deallocates
5476 ** a static mutex.
5477 **
5478 ** ^The sqlite3_mutex_enter() and sqlite3_mutex_try() routines attempt
5479 ** to enter a mutex. ^If another thread is already within the mutex,
5480 ** sqlite3_mutex_enter() will block and sqlite3_mutex_try() will return
5481 ** SQLITE_BUSY. ^The sqlite3_mutex_try() interface returns [SQLITE_OK]
5482 ** upon successful entry. ^(Mutexes created using
5483 ** SQLITE_MUTEX_RECURSIVE can be entered multiple times by the same thread.
5484 ** In such cases the,
5485 ** mutex must be exited an equal number of times before another thread
5486 ** can enter.)^ ^(If the same thread tries to enter any other
5487 ** kind of mutex more than once, the behavior is undefined.
5488 ** SQLite will never exhibit
5489 ** such behavior in its own use of mutexes.)^
5490 **
5491 ** ^(Some systems (for example, Windows 95) do not support the operation
5492 ** implemented by sqlite3_mutex_try(). On those systems, sqlite3_mutex_try()
5493 ** will always return SQLITE_BUSY. The SQLite core only ever uses
5494 ** sqlite3_mutex_try() as an optimization so this is acceptable behavior.)^
5495 **
5496 ** ^The sqlite3_mutex_leave() routine exits a mutex that was
5497 ** previously entered by the same thread. ^(The behavior
5498 ** is undefined if the mutex is not currently entered by the
5499 ** calling thread or is not currently allocated. SQLite will
5500 ** never do either.)^
5501 **
5502 ** ^If the argument to sqlite3_mutex_enter(), sqlite3_mutex_try(), or
5503 ** sqlite3_mutex_leave() is a NULL pointer, then all three routines
5504 ** behave as no-ops.
5505 **
5506 ** See also: [sqlite3_mutex_held()] and [sqlite3_mutex_notheld()].
5507 */
5514 /*
5515 ** CAPI3REF: Mutex Methods Object
5516 **
5517 ** An instance of this structure defines the low-level routines
5518 ** used to allocate and use mutexes.
5519 **
5520 ** Usually, the default mutex implementations provided by SQLite are
5521 ** sufficient, however the user has the option of substituting a custom
5522 ** implementation for specialized deployments or systems for which SQLite
5523 ** does not provide a suitable implementation. In this case, the user
5524 ** creates and populates an instance of this structure to pass
5525 ** to sqlite3_config() along with the [SQLITE_CONFIG_MUTEX] option.
5526 ** Additionally, an instance of this structure can be used as an
5527 ** output variable when querying the system for the current mutex
5528 ** implementation, using the [SQLITE_CONFIG_GETMUTEX] option.
5529 **
5530 ** ^The xMutexInit method defined by this structure is invoked as
5531 ** part of system initialization by the sqlite3_initialize() function.
5532 ** ^The xMutexInit routine is called by SQLite exactly once for each
5533 ** effective call to [sqlite3_initialize()].
5534 **
5535 ** ^The xMutexEnd method defined by this structure is invoked as
5536 ** part of system shutdown by the sqlite3_shutdown() function. The
5537 ** implementation of this method is expected to release all outstanding
5538 ** resources obtained by the mutex methods implementation, especially
5539 ** those obtained by the xMutexInit method. ^The xMutexEnd()
5540 ** interface is invoked exactly once for each call to [sqlite3_shutdown()].
5541 **
5542 ** ^(The remaining seven methods defined by this structure (xMutexAlloc,
5543 ** xMutexFree, xMutexEnter, xMutexTry, xMutexLeave, xMutexHeld and
5544 ** xMutexNotheld) implement the following interfaces (respectively):
5545 **
5546 ** <ul>
5547 ** <li> [sqlite3_mutex_alloc()] </li>
5548 ** <li> [sqlite3_mutex_free()] </li>
5549 ** <li> [sqlite3_mutex_enter()] </li>
5550 ** <li> [sqlite3_mutex_try()] </li>
5551 ** <li> [sqlite3_mutex_leave()] </li>
5552 ** <li> [sqlite3_mutex_held()] </li>
5553 ** <li> [sqlite3_mutex_notheld()] </li>
5554 ** </ul>)^
5555 **
5556 ** The only difference is that the public sqlite3_XXX functions enumerated
5557 ** above silently ignore any invocations that pass a NULL pointer instead
5558 ** of a valid mutex handle. The implementations of the methods defined
5559 ** by this structure are not required to handle this case, the results
5560 ** of passing a NULL pointer instead of a valid mutex handle are undefined
5561 ** (i.e. it is acceptable to provide an implementation that segfaults if
5562 ** it is passed a NULL pointer).
5563 **
5564 ** The xMutexInit() method must be threadsafe. ^It must be harmless to
5565 ** invoke xMutexInit() multiple times within the same process and without
5566 ** intervening calls to xMutexEnd(). Second and subsequent calls to
5567 ** xMutexInit() must be no-ops.
5568 **
5569 ** ^xMutexInit() must not use SQLite memory allocation ([sqlite3_malloc()]
5570 ** and its associates). ^Similarly, xMutexAlloc() must not use SQLite memory
5571 ** allocation for a static mutex. ^However xMutexAlloc() may use SQLite
5572 ** memory allocation for a fast or recursive mutex.
5573 **
5574 ** ^SQLite will invoke the xMutexEnd() method when [sqlite3_shutdown()] is
5575 ** called, but only if the prior call to xMutexInit returned SQLITE_OK.
5576 ** If xMutexInit fails in any way, it is expected to clean up after itself
5577 ** prior to returning.
5578 */
5590 };
5592 /*
5593 ** CAPI3REF: Mutex Verification Routines
5594 **
5595 ** The sqlite3_mutex_held() and sqlite3_mutex_notheld() routines
5596 ** are intended for use inside assert() statements. ^The SQLite core
5597 ** never uses these routines except inside an assert() and applications
5598 ** are advised to follow the lead of the core. ^The SQLite core only
5599 ** provides implementations for these routines when it is compiled
5600 ** with the SQLITE_DEBUG flag. ^External mutex implementations
5601 ** are only required to provide these routines if SQLITE_DEBUG is
5602 ** defined and if NDEBUG is not defined.
5603 **
5604 ** ^These routines should return true if the mutex in their argument
5605 ** is held or not held, respectively, by the calling thread.
5606 **
5607 ** ^The implementation is not required to provide versions of these
5608 ** routines that actually work. If the implementation does not provide working
5609 ** versions of these routines, it should at least provide stubs that always
5610 ** return true so that one does not get spurious assertion failures.
5611 **
5612 ** ^If the argument to sqlite3_mutex_held() is a NULL pointer then
5613 ** the routine should return 1. This seems counter-intuitive since
5614 ** clearly the mutex cannot be held if it does not exist. But
5615 ** the reason the mutex does not exist is because the build is not
5616 ** using mutexes. And we do not want the assert() containing the
5617 ** call to sqlite3_mutex_held() to fail, so a non-zero return is
5618 ** the appropriate thing to do. ^The sqlite3_mutex_notheld()
5619 ** interface should also return 1 when given a NULL pointer.
5620 */
5621 #ifndef NDEBUG
5624 #endif
5626 /*
5627 ** CAPI3REF: Mutex Types
5628 **
5629 ** The [sqlite3_mutex_alloc()] interface takes a single argument
5630 ** which is one of these integer constants.
5631 **
5632 ** The set of static mutexes may change from one SQLite release to the
5633 ** next. Applications that override the built-in mutex logic must be
5634 ** prepared to accommodate additional static mutexes.
5635 */
5636 #define SQLITE_MUTEX_FAST 0
5637 #define SQLITE_MUTEX_RECURSIVE 1
5638 #define SQLITE_MUTEX_STATIC_MASTER 2
5647 /*
5648 ** CAPI3REF: Retrieve the mutex for a database connection
5649 **
5650 ** ^This interface returns a pointer the [sqlite3_mutex] object that
5651 ** serializes access to the [database connection] given in the argument
5652 ** when the [threading mode] is Serialized.
5653 ** ^If the [threading mode] is Single-thread or Multi-thread then this
5654 ** routine returns a NULL pointer.
5655 */
5658 /*
5659 ** CAPI3REF: Low-Level Control Of Database Files
5660 **
5661 ** ^The [sqlite3_file_control()] interface makes a direct call to the
5662 ** xFileControl method for the [sqlite3_io_methods] object associated
5663 ** with a particular database identified by the second argument. ^The
5664 ** name of the database is "main" for the main database or "temp" for the
5665 ** TEMP database, or the name that appears after the AS keyword for
5666 ** databases that are added using the [ATTACH] SQL command.
5667 ** ^A NULL pointer can be used in place of "main" to refer to the
5668 ** main database file.
5669 ** ^The third and fourth parameters to this routine
5670 ** are passed directly through to the second and third parameters of
5671 ** the xFileControl method. ^The return value of the xFileControl
5672 ** method becomes the return value of this routine.
5673 **
5674 ** ^The SQLITE_FCNTL_FILE_POINTER value for the op parameter causes
5675 ** a pointer to the underlying [sqlite3_file] object to be written into
5676 ** the space pointed to by the 4th parameter. ^The SQLITE_FCNTL_FILE_POINTER
5677 ** case is a short-circuit path which does not actually invoke the
5678 ** underlying sqlite3_io_methods.xFileControl method.
5679 **
5680 ** ^If the second parameter (zDbName) does not match the name of any
5681 ** open database file, then SQLITE_ERROR is returned. ^This error
5682 ** code is not remembered and will not be recalled by [sqlite3_errcode()]
5683 ** or [sqlite3_errmsg()]. The underlying xFileControl method might
5684 ** also return SQLITE_ERROR. There is no way to distinguish between
5685 ** an incorrect zDbName and an SQLITE_ERROR return from the underlying
5686 ** xFileControl method.
5687 **
5688 ** See also: [SQLITE_FCNTL_LOCKSTATE]
5689 */
5692 /*
5693 ** CAPI3REF: Testing Interface
5694 **
5695 ** ^The sqlite3_test_control() interface is used to read out internal
5696 ** state of SQLite and to inject faults into SQLite for testing
5697 ** purposes. ^The first parameter is an operation code that determines
5698 ** the number, meaning, and operation of all subsequent parameters.
5699 **
5700 ** This interface is not for use by applications. It exists solely
5701 ** for verifying the correct operation of the SQLite library. Depending
5702 ** on how the SQLite library is compiled, this interface might not exist.
5703 **
5704 ** The details of the operation codes, their meanings, the parameters
5705 ** they take, and what they do are all subject to change without notice.
5706 ** Unlike most of the SQLite API, this function is not guaranteed to
5707 ** operate consistently from one release to the next.
5708 */
5711 /*
5712 ** CAPI3REF: Testing Interface Operation Codes
5713 **
5714 ** These constants are the valid operation code parameters used
5715 ** as the first argument to [sqlite3_test_control()].
5716 **
5717 ** These parameters and their meanings are subject to change
5718 ** without notice. These values are for testing purposes only.
5719 ** Applications should not use any of these parameters or the
5720 ** [sqlite3_test_control()] interface.
5721 */
5722 #define SQLITE_TESTCTRL_FIRST 5
5723 #define SQLITE_TESTCTRL_PRNG_SAVE 5
5724 #define SQLITE_TESTCTRL_PRNG_RESTORE 6
5725 #define SQLITE_TESTCTRL_PRNG_RESET 7
5726 #define SQLITE_TESTCTRL_BITVEC_TEST 8
5727 #define SQLITE_TESTCTRL_FAULT_INSTALL 9
5728 #define SQLITE_TESTCTRL_BENIGN_MALLOC_HOOKS 10
5729 #define SQLITE_TESTCTRL_PENDING_BYTE 11
5730 #define SQLITE_TESTCTRL_ASSERT 12
5731 #define SQLITE_TESTCTRL_ALWAYS 13
5732 #define SQLITE_TESTCTRL_RESERVE 14
5733 #define SQLITE_TESTCTRL_OPTIMIZATIONS 15
5734 #define SQLITE_TESTCTRL_ISKEYWORD 16
5735 #define SQLITE_TESTCTRL_SCRATCHMALLOC 17
5736 #define SQLITE_TESTCTRL_LOCALTIME_FAULT 18
5737 #define SQLITE_TESTCTRL_EXPLAIN_STMT 19
5738 #define SQLITE_TESTCTRL_LAST 19
5740 /*
5741 ** CAPI3REF: SQLite Runtime Status
5742 **
5743 ** ^This interface is used to retrieve runtime status information
5744 ** about the performance of SQLite, and optionally to reset various
5745 ** highwater marks. ^The first argument is an integer code for
5746 ** the specific parameter to measure. ^(Recognized integer codes
5747 ** are of the form [status parameters | SQLITE_STATUS_...].)^
5748 ** ^The current value of the parameter is returned into *pCurrent.
5749 ** ^The highest recorded value is returned in *pHighwater. ^If the
5750 ** resetFlag is true, then the highest record value is reset after
5751 ** *pHighwater is written. ^(Some parameters do not record the highest
5752 ** value. For those parameters
5753 ** nothing is written into *pHighwater and the resetFlag is ignored.)^
5754 ** ^(Other parameters record only the highwater mark and not the current
5755 ** value. For these latter parameters nothing is written into *pCurrent.)^
5756 **
5757 ** ^The sqlite3_status() routine returns SQLITE_OK on success and a
5758 ** non-zero [error code] on failure.
5759 **
5760 ** This routine is threadsafe but is not atomic. This routine can be
5761 ** called while other threads are running the same or different SQLite
5762 ** interfaces. However the values returned in *pCurrent and
5763 ** *pHighwater reflect the status of SQLite at different points in time
5764 ** and it is possible that another thread might change the parameter
5765 ** in between the times when *pCurrent and *pHighwater are written.
5766 **
5767 ** See also: [sqlite3_db_status()]
5768 */
5772 /*
5773 ** CAPI3REF: Status Parameters
5774 ** KEYWORDS: {status parameters}
5775 **
5776 ** These integer constants designate various run-time status parameters
5777 ** that can be returned by [sqlite3_status()].
5778 **
5779 ** <dl>
5780 ** [[SQLITE_STATUS_MEMORY_USED]] ^(<dt>SQLITE_STATUS_MEMORY_USED</dt>
5781 ** <dd>This parameter is the current amount of memory checked out
5782 ** using [sqlite3_malloc()], either directly or indirectly. The
5783 ** figure includes calls made to [sqlite3_malloc()] by the application
5784 ** and internal memory usage by the SQLite library. Scratch memory
5785 ** controlled by [SQLITE_CONFIG_SCRATCH] and auxiliary page-cache
5786 ** memory controlled by [SQLITE_CONFIG_PAGECACHE] is not included in
5787 ** this parameter. The amount returned is the sum of the allocation
5788 ** sizes as reported by the xSize method in [sqlite3_mem_methods].</dd>)^
5789 **
5790 ** [[SQLITE_STATUS_MALLOC_SIZE]] ^(<dt>SQLITE_STATUS_MALLOC_SIZE</dt>
5791 ** <dd>This parameter records the largest memory allocation request
5792 ** handed to [sqlite3_malloc()] or [sqlite3_realloc()] (or their
5793 ** internal equivalents). Only the value returned in the
5794 ** *pHighwater parameter to [sqlite3_status()] is of interest.
5795 ** The value written into the *pCurrent parameter is undefined.</dd>)^
5796 **
5797 ** [[SQLITE_STATUS_MALLOC_COUNT]] ^(<dt>SQLITE_STATUS_MALLOC_COUNT</dt>
5798 ** <dd>This parameter records the number of separate memory allocations
5799 ** currently checked out.</dd>)^
5800 **
5801 ** [[SQLITE_STATUS_PAGECACHE_USED]] ^(<dt>SQLITE_STATUS_PAGECACHE_USED</dt>
5802 ** <dd>This parameter returns the number of pages used out of the
5803 ** [pagecache memory allocator] that was configured using
5804 ** [SQLITE_CONFIG_PAGECACHE]. The
5805 ** value returned is in pages, not in bytes.</dd>)^
5806 **
5807 ** [[SQLITE_STATUS_PAGECACHE_OVERFLOW]]
5808 ** ^(<dt>SQLITE_STATUS_PAGECACHE_OVERFLOW</dt>
5809 ** <dd>This parameter returns the number of bytes of page cache
5810 ** allocation which could not be satisfied by the [SQLITE_CONFIG_PAGECACHE]
5811 ** buffer and where forced to overflow to [sqlite3_malloc()]. The
5812 ** returned value includes allocations that overflowed because they
5813 ** where too large (they were larger than the "sz" parameter to
5814 ** [SQLITE_CONFIG_PAGECACHE]) and allocations that overflowed because
5815 ** no space was left in the page cache.</dd>)^
5816 **
5817 ** [[SQLITE_STATUS_PAGECACHE_SIZE]] ^(<dt>SQLITE_STATUS_PAGECACHE_SIZE</dt>
5818 ** <dd>This parameter records the largest memory allocation request
5819 ** handed to [pagecache memory allocator]. Only the value returned in the
5820 ** *pHighwater parameter to [sqlite3_status()] is of interest.
5821 ** The value written into the *pCurrent parameter is undefined.</dd>)^
5822 **
5823 ** [[SQLITE_STATUS_SCRATCH_USED]] ^(<dt>SQLITE_STATUS_SCRATCH_USED</dt>
5824 ** <dd>This parameter returns the number of allocations used out of the
5825 ** [scratch memory allocator] configured using
5826 ** [SQLITE_CONFIG_SCRATCH]. The value returned is in allocations, not
5827 ** in bytes. Since a single thread may only have one scratch allocation
5828 ** outstanding at time, this parameter also reports the number of threads
5829 ** using scratch memory at the same time.</dd>)^
5830 **
5831 ** [[SQLITE_STATUS_SCRATCH_OVERFLOW]] ^(<dt>SQLITE_STATUS_SCRATCH_OVERFLOW</dt>
5832 ** <dd>This parameter returns the number of bytes of scratch memory
5833 ** allocation which could not be satisfied by the [SQLITE_CONFIG_SCRATCH]
5834 ** buffer and where forced to overflow to [sqlite3_malloc()]. The values
5835 ** returned include overflows because the requested allocation was too
5836 ** larger (that is, because the requested allocation was larger than the
5837 ** "sz" parameter to [SQLITE_CONFIG_SCRATCH]) and because no scratch buffer
5838 ** slots were available.
5839 ** </dd>)^
5840 **
5841 ** [[SQLITE_STATUS_SCRATCH_SIZE]] ^(<dt>SQLITE_STATUS_SCRATCH_SIZE</dt>
5842 ** <dd>This parameter records the largest memory allocation request
5843 ** handed to [scratch memory allocator]. Only the value returned in the
5844 ** *pHighwater parameter to [sqlite3_status()] is of interest.
5845 ** The value written into the *pCurrent parameter is undefined.</dd>)^
5846 **
5847 ** [[SQLITE_STATUS_PARSER_STACK]] ^(<dt>SQLITE_STATUS_PARSER_STACK</dt>
5848 ** <dd>This parameter records the deepest parser stack. It is only
5849 ** meaningful if SQLite is compiled with [YYTRACKMAXSTACKDEPTH].</dd>)^
5850 ** </dl>
5851 **
5852 ** New status parameters may be added from time to time.
5853 */
5854 #define SQLITE_STATUS_MEMORY_USED 0
5855 #define SQLITE_STATUS_PAGECACHE_USED 1
5856 #define SQLITE_STATUS_PAGECACHE_OVERFLOW 2
5857 #define SQLITE_STATUS_SCRATCH_USED 3
5858 #define SQLITE_STATUS_SCRATCH_OVERFLOW 4
5859 #define SQLITE_STATUS_MALLOC_SIZE 5
5860 #define SQLITE_STATUS_PARSER_STACK 6
5861 #define SQLITE_STATUS_PAGECACHE_SIZE 7
5862 #define SQLITE_STATUS_SCRATCH_SIZE 8
5863 #define SQLITE_STATUS_MALLOC_COUNT 9
5865 /*
5866 ** CAPI3REF: Database Connection Status
5867 **
5868 ** ^This interface is used to retrieve runtime status information
5869 ** about a single [database connection]. ^The first argument is the
5870 ** database connection object to be interrogated. ^The second argument
5871 ** is an integer constant, taken from the set of
5872 ** [SQLITE_DBSTATUS options], that
5873 ** determines the parameter to interrogate. The set of
5874 ** [SQLITE_DBSTATUS options] is likely
5875 ** to grow in future releases of SQLite.
5876 **
5877 ** ^The current value of the requested parameter is written into *pCur
5878 ** and the highest instantaneous value is written into *pHiwtr. ^If
5879 ** the resetFlg is true, then the highest instantaneous value is
5880 ** reset back down to the current value.
5881 **
5882 ** ^The sqlite3_db_status() routine returns SQLITE_OK on success and a
5883 ** non-zero [error code] on failure.
5884 **
5885 ** See also: [sqlite3_status()] and [sqlite3_stmt_status()].
5886 */
5889 /*
5890 ** CAPI3REF: Status Parameters for database connections
5891 ** KEYWORDS: {SQLITE_DBSTATUS options}
5892 **
5893 ** These constants are the available integer "verbs" that can be passed as
5894 ** the second argument to the [sqlite3_db_status()] interface.
5895 **
5896 ** New verbs may be added in future releases of SQLite. Existing verbs
5897 ** might be discontinued. Applications should check the return code from
5898 ** [sqlite3_db_status()] to make sure that the call worked.
5899 ** The [sqlite3_db_status()] interface will return a non-zero error code
5900 ** if a discontinued or unsupported verb is invoked.
5901 **
5902 ** <dl>
5903 ** [[SQLITE_DBSTATUS_LOOKASIDE_USED]] ^(<dt>SQLITE_DBSTATUS_LOOKASIDE_USED</dt>
5904 ** <dd>This parameter returns the number of lookaside memory slots currently
5905 ** checked out.</dd>)^
5906 **
5907 ** [[SQLITE_DBSTATUS_LOOKASIDE_HIT]] ^(<dt>SQLITE_DBSTATUS_LOOKASIDE_HIT</dt>
5908 ** <dd>This parameter returns the number malloc attempts that were
5909 ** satisfied using lookaside memory. Only the high-water value is meaningful;
5910 ** the current value is always zero.)^
5911 **
5912 ** [[SQLITE_DBSTATUS_LOOKASIDE_MISS_SIZE]]
5913 ** ^(<dt>SQLITE_DBSTATUS_LOOKASIDE_MISS_SIZE</dt>
5914 ** <dd>This parameter returns the number malloc attempts that might have
5915 ** been satisfied using lookaside memory but failed due to the amount of
5916 ** memory requested being larger than the lookaside slot size.
5917 ** Only the high-water value is meaningful;
5918 ** the current value is always zero.)^
5919 **
5920 ** [[SQLITE_DBSTATUS_LOOKASIDE_MISS_FULL]]
5921 ** ^(<dt>SQLITE_DBSTATUS_LOOKASIDE_MISS_FULL</dt>
5922 ** <dd>This parameter returns the number malloc attempts that might have
5923 ** been satisfied using lookaside memory but failed due to all lookaside
5924 ** memory already being in use.
5925 ** Only the high-water value is meaningful;
5926 ** the current value is always zero.)^
5927 **
5928 ** [[SQLITE_DBSTATUS_CACHE_USED]] ^(<dt>SQLITE_DBSTATUS_CACHE_USED</dt>
5929 ** <dd>This parameter returns the approximate number of of bytes of heap
5930 ** memory used by all pager caches associated with the database connection.)^
5931 ** ^The highwater mark associated with SQLITE_DBSTATUS_CACHE_USED is always 0.
5932 **
5933 ** [[SQLITE_DBSTATUS_SCHEMA_USED]] ^(<dt>SQLITE_DBSTATUS_SCHEMA_USED</dt>
5934 ** <dd>This parameter returns the approximate number of of bytes of heap
5935 ** memory used to store the schema for all databases associated
5936 ** with the connection - main, temp, and any [ATTACH]-ed databases.)^
5937 ** ^The full amount of memory used by the schemas is reported, even if the
5938 ** schema memory is shared with other database connections due to
5939 ** [shared cache mode] being enabled.
5940 ** ^The highwater mark associated with SQLITE_DBSTATUS_SCHEMA_USED is always 0.
5941 **
5942 ** [[SQLITE_DBSTATUS_STMT_USED]] ^(<dt>SQLITE_DBSTATUS_STMT_USED</dt>
5943 ** <dd>This parameter returns the approximate number of of bytes of heap
5944 ** and lookaside memory used by all prepared statements associated with
5945 ** the database connection.)^
5946 ** ^The highwater mark associated with SQLITE_DBSTATUS_STMT_USED is always 0.
5947 ** </dd>
5948 **
5949 ** [[SQLITE_DBSTATUS_CACHE_HIT]] ^(<dt>SQLITE_DBSTATUS_CACHE_HIT</dt>
5950 ** <dd>This parameter returns the number of pager cache hits that have
5951 ** occurred.)^ ^The highwater mark associated with SQLITE_DBSTATUS_CACHE_HIT
5952 ** is always 0.
5953 ** </dd>
5954 **
5955 ** [[SQLITE_DBSTATUS_CACHE_MISS]] ^(<dt>SQLITE_DBSTATUS_CACHE_MISS</dt>
5956 ** <dd>This parameter returns the number of pager cache misses that have
5957 ** occurred.)^ ^The highwater mark associated with SQLITE_DBSTATUS_CACHE_MISS
5958 ** is always 0.
5959 ** </dd>
5960 ** </dl>
5961 */
5962 #define SQLITE_DBSTATUS_LOOKASIDE_USED 0
5963 #define SQLITE_DBSTATUS_CACHE_USED 1
5964 #define SQLITE_DBSTATUS_SCHEMA_USED 2
5965 #define SQLITE_DBSTATUS_STMT_USED 3
5966 #define SQLITE_DBSTATUS_LOOKASIDE_HIT 4
5967 #define SQLITE_DBSTATUS_LOOKASIDE_MISS_SIZE 5
5968 #define SQLITE_DBSTATUS_LOOKASIDE_MISS_FULL 6
5969 #define SQLITE_DBSTATUS_CACHE_HIT 7
5970 #define SQLITE_DBSTATUS_CACHE_MISS 8
5974 /*
5975 ** CAPI3REF: Prepared Statement Status
5976 **
5977 ** ^(Each prepared statement maintains various
5978 ** [SQLITE_STMTSTATUS counters] that measure the number
5979 ** of times it has performed specific operations.)^ These counters can
5980 ** be used to monitor the performance characteristics of the prepared
5981 ** statements. For example, if the number of table steps greatly exceeds
5982 ** the number of table searches or result rows, that would tend to indicate
5983 ** that the prepared statement is using a full table scan rather than
5984 ** an index.
5985 **
5986 ** ^(This interface is used to retrieve and reset counter values from
5987 ** a [prepared statement]. The first argument is the prepared statement
5988 ** object to be interrogated. The second argument
5989 ** is an integer code for a specific [SQLITE_STMTSTATUS counter]
5990 ** to be interrogated.)^
5991 ** ^The current value of the requested counter is returned.
5992 ** ^If the resetFlg is true, then the counter is reset to zero after this
5993 ** interface call returns.
5994 **
5995 ** See also: [sqlite3_status()] and [sqlite3_db_status()].
5996 */
5999 /*
6000 ** CAPI3REF: Status Parameters for prepared statements
6001 ** KEYWORDS: {SQLITE_STMTSTATUS counter} {SQLITE_STMTSTATUS counters}
6002 **
6003 ** These preprocessor macros define integer codes that name counter
6004 ** values associated with the [sqlite3_stmt_status()] interface.
6005 ** The meanings of the various counters are as follows:
6006 **
6007 ** <dl>
6008 ** [[SQLITE_STMTSTATUS_FULLSCAN_STEP]] <dt>SQLITE_STMTSTATUS_FULLSCAN_STEP</dt>
6009 ** <dd>^This is the number of times that SQLite has stepped forward in
6010 ** a table as part of a full table scan. Large numbers for this counter
6011 ** may indicate opportunities for performance improvement through
6012 ** careful use of indices.</dd>
6013 **
6014 ** [[SQLITE_STMTSTATUS_SORT]] <dt>SQLITE_STMTSTATUS_SORT</dt>
6015 ** <dd>^This is the number of sort operations that have occurred.
6016 ** A non-zero value in this counter may indicate an opportunity to
6017 ** improvement performance through careful use of indices.</dd>
6018 **
6019 ** [[SQLITE_STMTSTATUS_AUTOINDEX]] <dt>SQLITE_STMTSTATUS_AUTOINDEX</dt>
6020 ** <dd>^This is the number of rows inserted into transient indices that
6021 ** were created automatically in order to help joins run faster.
6022 ** A non-zero value in this counter may indicate an opportunity to
6023 ** improvement performance by adding permanent indices that do not
6024 ** need to be reinitialized each time the statement is run.</dd>
6025 ** </dl>
6026 */
6027 #define SQLITE_STMTSTATUS_FULLSCAN_STEP 1
6028 #define SQLITE_STMTSTATUS_SORT 2
6029 #define SQLITE_STMTSTATUS_AUTOINDEX 3
6031 /*
6032 ** CAPI3REF: Custom Page Cache Object
6033 **
6034 ** The sqlite3_pcache type is opaque. It is implemented by
6035 ** the pluggable module. The SQLite core has no knowledge of
6036 ** its size or internal structure and never deals with the
6037 ** sqlite3_pcache object except by holding and passing pointers
6038 ** to the object.
6039 **
6040 ** See [sqlite3_pcache_methods2] for additional information.
6041 */
6044 /*
6045 ** CAPI3REF: Custom Page Cache Object
6046 **
6047 ** The sqlite3_pcache_page object represents a single page in the
6048 ** page cache. The page cache will allocate instances of this
6049 ** object. Various methods of the page cache use pointers to instances
6050 ** of this object as parameters or as their return value.
6051 **
6052 ** See [sqlite3_pcache_methods2] for additional information.
6053 */
6058 };
6060 /*
6061 ** CAPI3REF: Application Defined Page Cache.
6062 ** KEYWORDS: {page cache}
6063 **
6064 ** ^(The [sqlite3_config]([SQLITE_CONFIG_PCACHE2], ...) interface can
6065 ** register an alternative page cache implementation by passing in an
6066 ** instance of the sqlite3_pcache_methods2 structure.)^
6067 ** In many applications, most of the heap memory allocated by
6068 ** SQLite is used for the page cache.
6069 ** By implementing a
6070 ** custom page cache using this API, an application can better control
6071 ** the amount of memory consumed by SQLite, the way in which
6072 ** that memory is allocated and released, and the policies used to
6073 ** determine exactly which parts of a database file are cached and for
6074 ** how long.
6075 **
6076 ** The alternative page cache mechanism is an
6077 ** extreme measure that is only needed by the most demanding applications.
6078 ** The built-in page cache is recommended for most uses.
6079 **
6080 ** ^(The contents of the sqlite3_pcache_methods2 structure are copied to an
6081 ** internal buffer by SQLite within the call to [sqlite3_config]. Hence
6082 ** the application may discard the parameter after the call to
6083 ** [sqlite3_config()] returns.)^
6084 **
6085 ** [[the xInit() page cache method]]
6086 ** ^(The xInit() method is called once for each effective
6087 ** call to [sqlite3_initialize()])^
6088 ** (usually only once during the lifetime of the process). ^(The xInit()
6089 ** method is passed a copy of the sqlite3_pcache_methods2.pArg value.)^
6090 ** The intent of the xInit() method is to set up global data structures
6091 ** required by the custom page cache implementation.
6092 ** ^(If the xInit() method is NULL, then the
6093 ** built-in default page cache is used instead of the application defined
6094 ** page cache.)^
6095 **
6096 ** [[the xShutdown() page cache method]]
6097 ** ^The xShutdown() method is called by [sqlite3_shutdown()].
6098 ** It can be used to clean up
6099 ** any outstanding resources before process shutdown, if required.
6100 ** ^The xShutdown() method may be NULL.
6101 **
6102 ** ^SQLite automatically serializes calls to the xInit method,
6103 ** so the xInit method need not be threadsafe. ^The
6104 ** xShutdown method is only called from [sqlite3_shutdown()] so it does
6105 ** not need to be threadsafe either. All other methods must be threadsafe
6106 ** in multithreaded applications.
6107 **
6108 ** ^SQLite will never invoke xInit() more than once without an intervening
6109 ** call to xShutdown().
6110 **
6111 ** [[the xCreate() page cache methods]]
6112 ** ^SQLite invokes the xCreate() method to construct a new cache instance.
6113 ** SQLite will typically create one cache instance for each open database file,
6114 ** though this is not guaranteed. ^The
6115 ** first parameter, szPage, is the size in bytes of the pages that must
6116 ** be allocated by the cache. ^szPage will always a power of two. ^The
6117 ** second parameter szExtra is a number of bytes of extra storage
6118 ** associated with each page cache entry. ^The szExtra parameter will
6119 ** a number less than 250. SQLite will use the
6120 ** extra szExtra bytes on each page to store metadata about the underlying
6121 ** database page on disk. The value passed into szExtra depends
6122 ** on the SQLite version, the target platform, and how SQLite was compiled.
6123 ** ^The third argument to xCreate(), bPurgeable, is true if the cache being
6124 ** created will be used to cache database pages of a file stored on disk, or
6125 ** false if it is used for an in-memory database. The cache implementation
6126 ** does not have to do anything special based with the value of bPurgeable;
6127 ** it is purely advisory. ^On a cache where bPurgeable is false, SQLite will
6128 ** never invoke xUnpin() except to deliberately delete a page.
6129 ** ^In other words, calls to xUnpin() on a cache with bPurgeable set to
6130 ** false will always have the "discard" flag set to true.
6131 ** ^Hence, a cache created with bPurgeable false will
6132 ** never contain any unpinned pages.
6133 **
6134 ** [[the xCachesize() page cache method]]
6135 ** ^(The xCachesize() method may be called at any time by SQLite to set the
6136 ** suggested maximum cache-size (number of pages stored by) the cache
6137 ** instance passed as the first argument. This is the value configured using
6138 ** the SQLite "[PRAGMA cache_size]" command.)^ As with the bPurgeable
6139 ** parameter, the implementation is not required to do anything with this
6140 ** value; it is advisory only.
6141 **
6142 ** [[the xPagecount() page cache methods]]
6143 ** The xPagecount() method must return the number of pages currently
6144 ** stored in the cache, both pinned and unpinned.
6145 **
6146 ** [[the xFetch() page cache methods]]
6147 ** The xFetch() method locates a page in the cache and returns a pointer to
6148 ** an sqlite3_pcache_page object associated with that page, or a NULL pointer.
6149 ** The pBuf element of the returned sqlite3_pcache_page object will be a
6150 ** pointer to a buffer of szPage bytes used to store the content of a
6151 ** single database page. The pExtra element of sqlite3_pcache_page will be
6152 ** a pointer to the szExtra bytes of extra storage that SQLite has requested
6153 ** for each entry in the page cache.
6154 **
6155 ** The page to be fetched is determined by the key. ^The minimum key value
6156 ** is 1. After it has been retrieved using xFetch, the page is considered
6157 ** to be "pinned".
6158 **
6159 ** If the requested page is already in the page cache, then the page cache
6160 ** implementation must return a pointer to the page buffer with its content
6161 ** intact. If the requested page is not already in the cache, then the
6162 ** cache implementation should use the value of the createFlag
6163 ** parameter to help it determined what action to take:
6164 **
6165 ** <table border=1 width=85% align=center>
6166 ** <tr><th> createFlag <th> Behaviour when page is not already in cache
6167 ** <tr><td> 0 <td> Do not allocate a new page. Return NULL.
6168 ** <tr><td> 1 <td> Allocate a new page if it easy and convenient to do so.
6169 ** Otherwise return NULL.
6170 ** <tr><td> 2 <td> Make every effort to allocate a new page. Only return
6171 ** NULL if allocating a new page is effectively impossible.
6172 ** </table>
6173 **
6174 ** ^(SQLite will normally invoke xFetch() with a createFlag of 0 or 1. SQLite
6175 ** will only use a createFlag of 2 after a prior call with a createFlag of 1
6176 ** failed.)^ In between the to xFetch() calls, SQLite may
6177 ** attempt to unpin one or more cache pages by spilling the content of
6178 ** pinned pages to disk and synching the operating system disk cache.
6179 **
6180 ** [[the xUnpin() page cache method]]
6181 ** ^xUnpin() is called by SQLite with a pointer to a currently pinned page
6182 ** as its second argument. If the third parameter, discard, is non-zero,
6183 ** then the page must be evicted from the cache.
6184 ** ^If the discard parameter is
6185 ** zero, then the page may be discarded or retained at the discretion of
6186 ** page cache implementation. ^The page cache implementation
6187 ** may choose to evict unpinned pages at any time.
6188 **
6189 ** The cache must not perform any reference counting. A single
6190 ** call to xUnpin() unpins the page regardless of the number of prior calls
6191 ** to xFetch().
6192 **
6193 ** [[the xRekey() page cache methods]]
6194 ** The xRekey() method is used to change the key value associated with the
6195 ** page passed as the second argument. If the cache
6196 ** previously contains an entry associated with newKey, it must be
6197 ** discarded. ^Any prior cache entry associated with newKey is guaranteed not
6198 ** to be pinned.
6199 **
6200 ** When SQLite calls the xTruncate() method, the cache must discard all
6201 ** existing cache entries with page numbers (keys) greater than or equal
6202 ** to the value of the iLimit parameter passed to xTruncate(). If any
6203 ** of these pages are pinned, they are implicitly unpinned, meaning that
6204 ** they can be safely discarded.
6205 **
6206 ** [[the xDestroy() page cache method]]
6207 ** ^The xDestroy() method is used to delete a cache allocated by xCreate().
6208 ** All resources associated with the specified cache should be freed. ^After
6209 ** calling the xDestroy() method, SQLite considers the [sqlite3_pcache*]
6210 ** handle invalid, and will not use it with any other sqlite3_pcache_methods2
6211 ** functions.
6212 **
6213 ** [[the xShrink() page cache method]]
6214 ** ^SQLite invokes the xShrink() method when it wants the page cache to
6215 ** free up as much of heap memory as possible. The page cache implementation
6216 ** is not obligated to free any memory, but well-behaved implementations should
6217 ** do their best.
6218 */
6235 };
6237 /*
6238 ** This is the obsolete pcache_methods object that has now been replaced
6239 ** by sqlite3_pcache_methods2. This object is not used by SQLite. It is
6240 ** retained in the header file for backwards compatibility only.
6241 */
6255 };
6258 /*
6259 ** CAPI3REF: Online Backup Object
6260 **
6261 ** The sqlite3_backup object records state information about an ongoing
6262 ** online backup operation. ^The sqlite3_backup object is created by
6263 ** a call to [sqlite3_backup_init()] and is destroyed by a call to
6264 ** [sqlite3_backup_finish()].
6265 **
6266 ** See Also: [Using the SQLite Online Backup API]
6267 */
6270 /*
6271 ** CAPI3REF: Online Backup API.
6272 **
6273 ** The backup API copies the content of one database into another.
6274 ** It is useful either for creating backups of databases or
6275 ** for copying in-memory databases to or from persistent files.
6276 **
6277 ** See Also: [Using the SQLite Online Backup API]
6278 **
6279 ** ^SQLite holds a write transaction open on the destination database file
6280 ** for the duration of the backup operation.
6281 ** ^The source database is read-locked only while it is being read;
6282 ** it is not locked continuously for the entire backup operation.
6283 ** ^Thus, the backup may be performed on a live source database without
6284 ** preventing other database connections from
6285 ** reading or writing to the source database while the backup is underway.
6286 **
6287 ** ^(To perform a backup operation:
6288 ** <ol>
6289 ** <li><b>sqlite3_backup_init()</b> is called once to initialize the
6290 ** backup,
6291 ** <li><b>sqlite3_backup_step()</b> is called one or more times to transfer
6292 ** the data between the two databases, and finally
6293 ** <li><b>sqlite3_backup_finish()</b> is called to release all resources
6294 ** associated with the backup operation.
6295 ** </ol>)^
6296 ** There should be exactly one call to sqlite3_backup_finish() for each
6297 ** successful call to sqlite3_backup_init().
6298 **
6299 ** [[sqlite3_backup_init()]] <b>sqlite3_backup_init()</b>
6300 **
6301 ** ^The D and N arguments to sqlite3_backup_init(D,N,S,M) are the
6302 ** [database connection] associated with the destination database
6303 ** and the database name, respectively.
6304 ** ^The database name is "main" for the main database, "temp" for the
6305 ** temporary database, or the name specified after the AS keyword in
6306 ** an [ATTACH] statement for an attached database.
6307 ** ^The S and M arguments passed to
6308 ** sqlite3_backup_init(D,N,S,M) identify the [database connection]
6309 ** and database name of the source database, respectively.
6310 ** ^The source and destination [database connections] (parameters S and D)
6311 ** must be different or else sqlite3_backup_init(D,N,S,M) will fail with
6312 ** an error.
6313 **
6314 ** ^If an error occurs within sqlite3_backup_init(D,N,S,M), then NULL is
6315 ** returned and an error code and error message are stored in the
6316 ** destination [database connection] D.
6317 ** ^The error code and message for the failed call to sqlite3_backup_init()
6318 ** can be retrieved using the [sqlite3_errcode()], [sqlite3_errmsg()], and/or
6319 ** [sqlite3_errmsg16()] functions.
6320 ** ^A successful call to sqlite3_backup_init() returns a pointer to an
6321 ** [sqlite3_backup] object.
6322 ** ^The [sqlite3_backup] object may be used with the sqlite3_backup_step() and
6323 ** sqlite3_backup_finish() functions to perform the specified backup
6324 ** operation.
6325 **
6326 ** [[sqlite3_backup_step()]] <b>sqlite3_backup_step()</b>
6327 **
6328 ** ^Function sqlite3_backup_step(B,N) will copy up to N pages between
6329 ** the source and destination databases specified by [sqlite3_backup] object B.
6330 ** ^If N is negative, all remaining source pages are copied.
6331 ** ^If sqlite3_backup_step(B,N) successfully copies N pages and there
6332 ** are still more pages to be copied, then the function returns [SQLITE_OK].
6333 ** ^If sqlite3_backup_step(B,N) successfully finishes copying all pages
6334 ** from source to destination, then it returns [SQLITE_DONE].
6335 ** ^If an error occurs while running sqlite3_backup_step(B,N),
6336 ** then an [error code] is returned. ^As well as [SQLITE_OK] and
6337 ** [SQLITE_DONE], a call to sqlite3_backup_step() may return [SQLITE_READONLY],
6338 ** [SQLITE_NOMEM], [SQLITE_BUSY], [SQLITE_LOCKED], or an
6339 ** [SQLITE_IOERR_ACCESS | SQLITE_IOERR_XXX] extended error code.
6340 **
6341 ** ^(The sqlite3_backup_step() might return [SQLITE_READONLY] if
6342 ** <ol>
6343 ** <li> the destination database was opened read-only, or
6344 ** <li> the destination database is using write-ahead-log journaling
6345 ** and the destination and source page sizes differ, or
6346 ** <li> the destination database is an in-memory database and the
6347 ** destination and source page sizes differ.
6348 ** </ol>)^
6349 **
6350 ** ^If sqlite3_backup_step() cannot obtain a required file-system lock, then
6351 ** the [sqlite3_busy_handler | busy-handler function]
6352 ** is invoked (if one is specified). ^If the
6353 ** busy-handler returns non-zero before the lock is available, then
6354 ** [SQLITE_BUSY] is returned to the caller. ^In this case the call to
6355 ** sqlite3_backup_step() can be retried later. ^If the source
6356 ** [database connection]
6357 ** is being used to write to the source database when sqlite3_backup_step()
6358 ** is called, then [SQLITE_LOCKED] is returned immediately. ^Again, in this
6359 ** case the call to sqlite3_backup_step() can be retried later on. ^(If
6360 ** [SQLITE_IOERR_ACCESS | SQLITE_IOERR_XXX], [SQLITE_NOMEM], or
6361 ** [SQLITE_READONLY] is returned, then
6362 ** there is no point in retrying the call to sqlite3_backup_step(). These
6363 ** errors are considered fatal.)^ The application must accept
6364 ** that the backup operation has failed and pass the backup operation handle
6365 ** to the sqlite3_backup_finish() to release associated resources.
6366 **
6367 ** ^The first call to sqlite3_backup_step() obtains an exclusive lock
6368 ** on the destination file. ^The exclusive lock is not released until either
6369 ** sqlite3_backup_finish() is called or the backup operation is complete
6370 ** and sqlite3_backup_step() returns [SQLITE_DONE]. ^Every call to
6371 ** sqlite3_backup_step() obtains a [shared lock] on the source database that
6372 ** lasts for the duration of the sqlite3_backup_step() call.
6373 ** ^Because the source database is not locked between calls to
6374 ** sqlite3_backup_step(), the source database may be modified mid-way
6375 ** through the backup process. ^If the source database is modified by an
6376 ** external process or via a database connection other than the one being
6377 ** used by the backup operation, then the backup will be automatically
6378 ** restarted by the next call to sqlite3_backup_step(). ^If the source
6379 ** database is modified by the using the same database connection as is used
6380 ** by the backup operation, then the backup database is automatically
6381 ** updated at the same time.
6382 **
6383 ** [[sqlite3_backup_finish()]] <b>sqlite3_backup_finish()</b>
6384 **
6385 ** When sqlite3_backup_step() has returned [SQLITE_DONE], or when the
6386 ** application wishes to abandon the backup operation, the application
6387 ** should destroy the [sqlite3_backup] by passing it to sqlite3_backup_finish().
6388 ** ^The sqlite3_backup_finish() interfaces releases all
6389 ** resources associated with the [sqlite3_backup] object.
6390 ** ^If sqlite3_backup_step() has not yet returned [SQLITE_DONE], then any
6391 ** active write-transaction on the destination database is rolled back.
6392 ** The [sqlite3_backup] object is invalid
6393 ** and may not be used following a call to sqlite3_backup_finish().
6394 **
6395 ** ^The value returned by sqlite3_backup_finish is [SQLITE_OK] if no
6396 ** sqlite3_backup_step() errors occurred, regardless or whether or not
6397 ** sqlite3_backup_step() completed.
6398 ** ^If an out-of-memory condition or IO error occurred during any prior
6399 ** sqlite3_backup_step() call on the same [sqlite3_backup] object, then
6400 ** sqlite3_backup_finish() returns the corresponding [error code].
6401 **
6402 ** ^A return of [SQLITE_BUSY] or [SQLITE_LOCKED] from sqlite3_backup_step()
6403 ** is not a permanent error and does not affect the return value of
6404 ** sqlite3_backup_finish().
6405 **
6406 ** [[sqlite3_backup__remaining()]] [[sqlite3_backup_pagecount()]]
6407 ** <b>sqlite3_backup_remaining() and sqlite3_backup_pagecount()</b>
6408 **
6409 ** ^Each call to sqlite3_backup_step() sets two values inside
6410 ** the [sqlite3_backup] object: the number of pages still to be backed
6411 ** up and the total number of pages in the source database file.
6412 ** The sqlite3_backup_remaining() and sqlite3_backup_pagecount() interfaces
6413 ** retrieve these two values, respectively.
6414 **
6415 ** ^The values returned by these functions are only updated by
6416 ** sqlite3_backup_step(). ^If the source database is modified during a backup
6417 ** operation, then the values are not updated to account for any extra
6418 ** pages that need to be updated or the size of the source database file
6419 ** changing.
6420 **
6421 ** <b>Concurrent Usage of Database Handles</b>
6422 **
6423 ** ^The source [database connection] may be used by the application for other
6424 ** purposes while a backup operation is underway or being initialized.
6425 ** ^If SQLite is compiled and configured to support threadsafe database
6426 ** connections, then the source database connection may be used concurrently
6427 ** from within other threads.
6428 **
6429 ** However, the application must guarantee that the destination
6430 ** [database connection] is not passed to any other API (by any thread) after
6431 ** sqlite3_backup_init() is called and before the corresponding call to
6432 ** sqlite3_backup_finish(). SQLite does not currently check to see
6433 ** if the application incorrectly accesses the destination [database connection]
6434 ** and so no error code is reported, but the operations may malfunction
6435 ** nevertheless. Use of the destination database connection while a
6436 ** backup is in progress might also also cause a mutex deadlock.
6437 **
6438 ** If running in [shared cache mode], the application must
6439 ** guarantee that the shared cache used by the destination database
6440 ** is not accessed while the backup is running. In practice this means
6441 ** that the application must guarantee that the disk file being
6442 ** backed up to is not accessed by any connection within the process,
6443 ** not just the specific connection that was passed to sqlite3_backup_init().
6444 **
6445 ** The [sqlite3_backup] object itself is partially threadsafe. Multiple
6446 ** threads may safely make multiple concurrent calls to sqlite3_backup_step().
6447 ** However, the sqlite3_backup_remaining() and sqlite3_backup_pagecount()
6448 ** APIs are not strictly speaking threadsafe. If they are invoked at the
6449 ** same time as another thread is invoking sqlite3_backup_step() it is
6450 ** possible that they return invalid values.
6451 */
6457 );
6463 /*
6464 ** CAPI3REF: Unlock Notification
6465 **
6466 ** ^When running in shared-cache mode, a database operation may fail with
6467 ** an [SQLITE_LOCKED] error if the required locks on the shared-cache or
6468 ** individual tables within the shared-cache cannot be obtained. See
6469 ** [SQLite Shared-Cache Mode] for a description of shared-cache locking.
6470 ** ^This API may be used to register a callback that SQLite will invoke
6471 ** when the connection currently holding the required lock relinquishes it.
6472 ** ^This API is only available if the library was compiled with the
6473 ** [SQLITE_ENABLE_UNLOCK_NOTIFY] C-preprocessor symbol defined.
6474 **
6475 ** See Also: [Using the SQLite Unlock Notification Feature].
6476 **
6477 ** ^Shared-cache locks are released when a database connection concludes
6478 ** its current transaction, either by committing it or rolling it back.
6479 **
6480 ** ^When a connection (known as the blocked connection) fails to obtain a
6481 ** shared-cache lock and SQLITE_LOCKED is returned to the caller, the
6482 ** identity of the database connection (the blocking connection) that
6483 ** has locked the required resource is stored internally. ^After an
6484 ** application receives an SQLITE_LOCKED error, it may call the
6485 ** sqlite3_unlock_notify() method with the blocked connection handle as
6486 ** the first argument to register for a callback that will be invoked
6487 ** when the blocking connections current transaction is concluded. ^The
6488 ** callback is invoked from within the [sqlite3_step] or [sqlite3_close]
6489 ** call that concludes the blocking connections transaction.
6490 **
6491 ** ^(If sqlite3_unlock_notify() is called in a multi-threaded application,
6492 ** there is a chance that the blocking connection will have already
6493 ** concluded its transaction by the time sqlite3_unlock_notify() is invoked.
6494 ** If this happens, then the specified callback is invoked immediately,
6495 ** from within the call to sqlite3_unlock_notify().)^
6496 **
6497 ** ^If the blocked connection is attempting to obtain a write-lock on a
6498 ** shared-cache table, and more than one other connection currently holds
6499 ** a read-lock on the same table, then SQLite arbitrarily selects one of
6500 ** the other connections to use as the blocking connection.
6501 **
6502 ** ^(There may be at most one unlock-notify callback registered by a
6503 ** blocked connection. If sqlite3_unlock_notify() is called when the
6504 ** blocked connection already has a registered unlock-notify callback,
6505 ** then the new callback replaces the old.)^ ^If sqlite3_unlock_notify() is
6506 ** called with a NULL pointer as its second argument, then any existing
6507 ** unlock-notify callback is canceled. ^The blocked connections
6508 ** unlock-notify callback may also be canceled by closing the blocked
6509 ** connection using [sqlite3_close()].
6510 **
6511 ** The unlock-notify callback is not reentrant. If an application invokes
6512 ** any sqlite3_xxx API functions from within an unlock-notify callback, a
6513 ** crash or deadlock may be the result.
6514 **
6515 ** ^Unless deadlock is detected (see below), sqlite3_unlock_notify() always
6516 ** returns SQLITE_OK.
6517 **
6518 ** <b>Callback Invocation Details</b>
6519 **
6520 ** When an unlock-notify callback is registered, the application provides a
6521 ** single void* pointer that is passed to the callback when it is invoked.
6522 ** However, the signature of the callback function allows SQLite to pass
6523 ** it an array of void* context pointers. The first argument passed to
6524 ** an unlock-notify callback is a pointer to an array of void* pointers,
6525 ** and the second is the number of entries in the array.
6526 **
6527 ** When a blocking connections transaction is concluded, there may be
6528 ** more than one blocked connection that has registered for an unlock-notify
6529 ** callback. ^If two or more such blocked connections have specified the
6530 ** same callback function, then instead of invoking the callback function
6531 ** multiple times, it is invoked once with the set of void* context pointers
6532 ** specified by the blocked connections bundled together into an array.
6533 ** This gives the application an opportunity to prioritize any actions
6534 ** related to the set of unblocked database connections.
6535 **
6536 ** <b>Deadlock Detection</b>
6537 **
6538 ** Assuming that after registering for an unlock-notify callback a
6539 ** database waits for the callback to be issued before taking any further
6540 ** action (a reasonable assumption), then using this API may cause the
6541 ** application to deadlock. For example, if connection X is waiting for
6542 ** connection Y's transaction to be concluded, and similarly connection
6543 ** Y is waiting on connection X's transaction, then neither connection
6544 ** will proceed and the system may remain deadlocked indefinitely.
6545 **
6546 ** To avoid this scenario, the sqlite3_unlock_notify() performs deadlock
6547 ** detection. ^If a given call to sqlite3_unlock_notify() would put the
6548 ** system in a deadlocked state, then SQLITE_LOCKED is returned and no
6549 ** unlock-notify callback is registered. The system is said to be in
6550 ** a deadlocked state if connection A has registered for an unlock-notify
6551 ** callback on the conclusion of connection B's transaction, and connection
6552 ** B has itself registered for an unlock-notify callback when connection
6553 ** A's transaction is concluded. ^Indirect deadlock is also detected, so
6554 ** the system is also considered to be deadlocked if connection B has
6555 ** registered for an unlock-notify callback on the conclusion of connection
6556 ** C's transaction, where connection C is waiting on connection A. ^Any
6557 ** number of levels of indirection are allowed.
6558 **
6559 ** <b>The "DROP TABLE" Exception</b>
6560 **
6561 ** When a call to [sqlite3_step()] returns SQLITE_LOCKED, it is almost
6562 ** always appropriate to call sqlite3_unlock_notify(). There is however,
6563 ** one exception. When executing a "DROP TABLE" or "DROP INDEX" statement,
6564 ** SQLite checks if there are any currently executing SELECT statements
6565 ** that belong to the same connection. If there are, SQLITE_LOCKED is
6566 ** returned. In this case there is no "blocking connection", so invoking
6567 ** sqlite3_unlock_notify() results in the unlock-notify callback being
6568 ** invoked immediately. If the application then re-attempts the "DROP TABLE"
6569 ** or "DROP INDEX" query, an infinite loop might be the result.
6570 **
6571 ** One way around this problem is to check the extended error code returned
6572 ** by an sqlite3_step() call. ^(If there is a blocking connection, then the
6573 ** extended error code is set to SQLITE_LOCKED_SHAREDCACHE. Otherwise, in
6574 ** the special "DROP TABLE/INDEX" case, the extended error code is just
6575 ** SQLITE_LOCKED.)^
6576 */
6581 );
6584 /*
6585 ** CAPI3REF: String Comparison
6586 **
6587 ** ^The [sqlite3_strnicmp()] API allows applications and extensions to
6588 ** compare the contents of two buffers containing UTF-8 strings in a
6589 ** case-independent fashion, using the same definition of case independence
6590 ** that SQLite uses internally when comparing identifiers.
6591 */
6594 /*
6595 ** CAPI3REF: Error Logging Interface
6596 **
6597 ** ^The [sqlite3_log()] interface writes a message into the error log
6598 ** established by the [SQLITE_CONFIG_LOG] option to [sqlite3_config()].
6599 ** ^If logging is enabled, the zFormat string and subsequent arguments are
6600 ** used with [sqlite3_snprintf()] to generate the final output string.
6601 **
6602 ** The sqlite3_log() interface is intended for use by extensions such as
6603 ** virtual tables, collating functions, and SQL functions. While there is
6604 ** nothing to prevent an application from calling sqlite3_log(), doing so
6605 ** is considered bad form.
6606 **
6607 ** The zFormat string must not be NULL.
6608 **
6609 ** To avoid deadlocks and other threading problems, the sqlite3_log() routine
6610 ** will not use dynamically allocated memory. The log message is stored in
6611 ** a fixed-length buffer on the stack. If the log message is longer than
6612 ** a few hundred characters, it will be truncated to the length of the
6613 ** buffer.
6614 */
6617 /*
6618 ** CAPI3REF: Write-Ahead Log Commit Hook
6619 **
6620 ** ^The [sqlite3_wal_hook()] function is used to register a callback that
6621 ** will be invoked each time a database connection commits data to a
6622 ** [write-ahead log] (i.e. whenever a transaction is committed in
6623 ** [journal_mode | journal_mode=WAL mode]).
6624 **
6625 ** ^The callback is invoked by SQLite after the commit has taken place and
6626 ** the associated write-lock on the database released, so the implementation
6627 ** may read, write or [checkpoint] the database as required.
6628 **
6629 ** ^The first parameter passed to the callback function when it is invoked
6630 ** is a copy of the third parameter passed to sqlite3_wal_hook() when
6631 ** registering the callback. ^The second is a copy of the database handle.
6632 ** ^The third parameter is the name of the database that was written to -
6633 ** either "main" or the name of an [ATTACH]-ed database. ^The fourth parameter
6634 ** is the number of pages currently in the write-ahead log file,
6635 ** including those that were just committed.
6636 **
6637 ** The callback function should normally return [SQLITE_OK]. ^If an error
6638 ** code is returned, that error will propagate back up through the
6639 ** SQLite code base to cause the statement that provoked the callback
6640 ** to report an error, though the commit will have still occurred. If the
6641 ** callback returns [SQLITE_ROW] or [SQLITE_DONE], or if it returns a value
6642 ** that does not correspond to any valid SQLite error code, the results
6643 ** are undefined.
6644 **
6645 ** A single database handle may have at most a single write-ahead log callback
6646 ** registered at one time. ^Calling [sqlite3_wal_hook()] replaces any
6647 ** previously registered write-ahead log callback. ^Note that the
6648 ** [sqlite3_wal_autocheckpoint()] interface and the
6649 ** [wal_autocheckpoint pragma] both invoke [sqlite3_wal_hook()] and will
6650 ** those overwrite any prior [sqlite3_wal_hook()] settings.
6651 */
6653 sqlite3*,
6656 );
6658 /*
6659 ** CAPI3REF: Configure an auto-checkpoint
6660 **
6661 ** ^The [sqlite3_wal_autocheckpoint(D,N)] is a wrapper around
6662 ** [sqlite3_wal_hook()] that causes any database on [database connection] D
6663 ** to automatically [checkpoint]
6664 ** after committing a transaction if there are N or
6665 ** more frames in the [write-ahead log] file. ^Passing zero or
6666 ** a negative value as the nFrame parameter disables automatic
6667 ** checkpoints entirely.
6668 **
6669 ** ^The callback registered by this function replaces any existing callback
6670 ** registered using [sqlite3_wal_hook()]. ^Likewise, registering a callback
6671 ** using [sqlite3_wal_hook()] disables the automatic checkpoint mechanism
6672 ** configured by this function.
6673 **
6674 ** ^The [wal_autocheckpoint pragma] can be used to invoke this interface
6675 ** from SQL.
6676 **
6677 ** ^Every new [database connection] defaults to having the auto-checkpoint
6678 ** enabled with a threshold of 1000 or [SQLITE_DEFAULT_WAL_AUTOCHECKPOINT]
6679 ** pages. The use of this interface
6680 ** is only necessary if the default setting is found to be suboptimal
6681 ** for a particular application.
6682 */
6685 /*
6686 ** CAPI3REF: Checkpoint a database
6687 **
6688 ** ^The [sqlite3_wal_checkpoint(D,X)] interface causes database named X
6689 ** on [database connection] D to be [checkpointed]. ^If X is NULL or an
6690 ** empty string, then a checkpoint is run on all databases of
6691 ** connection D. ^If the database connection D is not in
6692 ** [WAL | write-ahead log mode] then this interface is a harmless no-op.
6693 **
6694 ** ^The [wal_checkpoint pragma] can be used to invoke this interface
6695 ** from SQL. ^The [sqlite3_wal_autocheckpoint()] interface and the
6696 ** [wal_autocheckpoint pragma] can be used to cause this interface to be
6697 ** run whenever the WAL reaches a certain size threshold.
6698 **
6699 ** See also: [sqlite3_wal_checkpoint_v2()]
6700 */
6703 /*
6704 ** CAPI3REF: Checkpoint a database
6705 **
6706 ** Run a checkpoint operation on WAL database zDb attached to database
6707 ** handle db. The specific operation is determined by the value of the
6708 ** eMode parameter:
6709 **
6710 ** <dl>
6711 ** <dt>SQLITE_CHECKPOINT_PASSIVE<dd>
6712 ** Checkpoint as many frames as possible without waiting for any database
6713 ** readers or writers to finish. Sync the db file if all frames in the log
6714 ** are checkpointed. This mode is the same as calling
6715 ** sqlite3_wal_checkpoint(). The busy-handler callback is never invoked.
6716 **
6717 ** <dt>SQLITE_CHECKPOINT_FULL<dd>
6718 ** This mode blocks (calls the busy-handler callback) until there is no
6719 ** database writer and all readers are reading from the most recent database
6720 ** snapshot. It then checkpoints all frames in the log file and syncs the
6721 ** database file. This call blocks database writers while it is running,
6722 ** but not database readers.
6723 **
6724 ** <dt>SQLITE_CHECKPOINT_RESTART<dd>
6725 ** This mode works the same way as SQLITE_CHECKPOINT_FULL, except after
6726 ** checkpointing the log file it blocks (calls the busy-handler callback)
6727 ** until all readers are reading from the database file only. This ensures
6728 ** that the next client to write to the database file restarts the log file
6729 ** from the beginning. This call blocks database writers while it is running,
6730 ** but not database readers.
6731 ** </dl>
6732 **
6733 ** If pnLog is not NULL, then *pnLog is set to the total number of frames in
6734 ** the log file before returning. If pnCkpt is not NULL, then *pnCkpt is set to
6735 ** the total number of checkpointed frames (including any that were already
6736 ** checkpointed when this function is called). *pnLog and *pnCkpt may be
6737 ** populated even if sqlite3_wal_checkpoint_v2() returns other than SQLITE_OK.
6738 ** If no values are available because of an error, they are both set to -1
6739 ** before returning to communicate this to the caller.
6740 **
6741 ** All calls obtain an exclusive "checkpoint" lock on the database file. If
6742 ** any other process is running a checkpoint operation at the same time, the
6743 ** lock cannot be obtained and SQLITE_BUSY is returned. Even if there is a
6744 ** busy-handler configured, it will not be invoked in this case.
6745 **
6746 ** The SQLITE_CHECKPOINT_FULL and RESTART modes also obtain the exclusive
6747 ** "writer" lock on the database file. If the writer lock cannot be obtained
6748 ** immediately, and a busy-handler is configured, it is invoked and the writer
6749 ** lock retried until either the busy-handler returns 0 or the lock is
6750 ** successfully obtained. The busy-handler is also invoked while waiting for
6751 ** database readers as described above. If the busy-handler returns 0 before
6752 ** the writer lock is obtained or while waiting for database readers, the
6753 ** checkpoint operation proceeds from that point in the same way as
6754 ** SQLITE_CHECKPOINT_PASSIVE - checkpointing as many frames as possible
6755 ** without blocking any further. SQLITE_BUSY is returned in this case.
6756 **
6757 ** If parameter zDb is NULL or points to a zero length string, then the
6758 ** specified operation is attempted on all WAL databases. In this case the
6759 ** values written to output parameters *pnLog and *pnCkpt are undefined. If
6760 ** an SQLITE_BUSY error is encountered when processing one or more of the
6761 ** attached WAL databases, the operation is still attempted on any remaining
6762 ** attached databases and SQLITE_BUSY is returned to the caller. If any other
6763 ** error occurs while processing an attached database, processing is abandoned
6764 ** and the error code returned to the caller immediately. If no error
6765 ** (SQLITE_BUSY or otherwise) is encountered while processing the attached
6766 ** databases, SQLITE_OK is returned.
6767 **
6768 ** If database zDb is the name of an attached database that is not in WAL
6769 ** mode, SQLITE_OK is returned and both *pnLog and *pnCkpt set to -1. If
6770 ** zDb is not NULL (or a zero length string) and is not the name of any
6771 ** attached database, SQLITE_ERROR is returned to the caller.
6772 */
6779 );
6781 /*
6782 ** CAPI3REF: Checkpoint operation parameters
6783 **
6784 ** These constants can be used as the 3rd parameter to
6785 ** [sqlite3_wal_checkpoint_v2()]. See the [sqlite3_wal_checkpoint_v2()]
6786 ** documentation for additional information about the meaning and use of
6787 ** each of these values.
6788 */
6789 #define SQLITE_CHECKPOINT_PASSIVE 0
6790 #define SQLITE_CHECKPOINT_FULL 1
6791 #define SQLITE_CHECKPOINT_RESTART 2
6793 /*
6794 ** CAPI3REF: Virtual Table Interface Configuration
6795 **
6796 ** This function may be called by either the [xConnect] or [xCreate] method
6797 ** of a [virtual table] implementation to configure
6798 ** various facets of the virtual table interface.
6799 **
6800 ** If this interface is invoked outside the context of an xConnect or
6801 ** xCreate virtual table method then the behavior is undefined.
6802 **
6803 ** At present, there is only one option that may be configured using
6804 ** this function. (See [SQLITE_VTAB_CONSTRAINT_SUPPORT].) Further options
6805 ** may be added in the future.
6806 */
6809 /*
6810 ** CAPI3REF: Virtual Table Configuration Options
6811 **
6812 ** These macros define the various options to the
6813 ** [sqlite3_vtab_config()] interface that [virtual table] implementations
6814 ** can use to customize and optimize their behavior.
6815 **
6816 ** <dl>
6817 ** <dt>SQLITE_VTAB_CONSTRAINT_SUPPORT
6818 ** <dd>Calls of the form
6819 ** [sqlite3_vtab_config](db,SQLITE_VTAB_CONSTRAINT_SUPPORT,X) are supported,
6820 ** where X is an integer. If X is zero, then the [virtual table] whose
6821 ** [xCreate] or [xConnect] method invoked [sqlite3_vtab_config()] does not
6822 ** support constraints. In this configuration (which is the default) if
6823 ** a call to the [xUpdate] method returns [SQLITE_CONSTRAINT], then the entire
6824 ** statement is rolled back as if [ON CONFLICT | OR ABORT] had been
6825 ** specified as part of the users SQL statement, regardless of the actual
6826 ** ON CONFLICT mode specified.
6827 **
6828 ** If X is non-zero, then the virtual table implementation guarantees
6829 ** that if [xUpdate] returns [SQLITE_CONSTRAINT], it will do so before
6830 ** any modifications to internal or persistent data structures have been made.
6831 ** If the [ON CONFLICT] mode is ABORT, FAIL, IGNORE or ROLLBACK, SQLite
6832 ** is able to roll back a statement or database transaction, and abandon
6833 ** or continue processing the current SQL statement as appropriate.
6834 ** If the ON CONFLICT mode is REPLACE and the [xUpdate] method returns
6835 ** [SQLITE_CONSTRAINT], SQLite handles this as if the ON CONFLICT mode
6836 ** had been ABORT.
6837 **
6838 ** Virtual table implementations that are required to handle OR REPLACE
6839 ** must do so within the [xUpdate] method. If a call to the
6840 ** [sqlite3_vtab_on_conflict()] function indicates that the current ON
6841 ** CONFLICT policy is REPLACE, the virtual table implementation should
6842 ** silently replace the appropriate rows within the xUpdate callback and
6843 ** return SQLITE_OK. Or, if this is not possible, it may return
6844 ** SQLITE_CONSTRAINT, in which case SQLite falls back to OR ABORT
6845 ** constraint handling.
6846 ** </dl>
6847 */
6848 #define SQLITE_VTAB_CONSTRAINT_SUPPORT 1
6850 /*
6851 ** CAPI3REF: Determine The Virtual Table Conflict Policy
6852 **
6853 ** This function may only be called from within a call to the [xUpdate] method
6854 ** of a [virtual table] implementation for an INSERT or UPDATE operation. ^The
6855 ** value returned is one of [SQLITE_ROLLBACK], [SQLITE_IGNORE], [SQLITE_FAIL],
6856 ** [SQLITE_ABORT], or [SQLITE_REPLACE], according to the [ON CONFLICT] mode
6857 ** of the SQL statement that triggered the call to the [xUpdate] method of the
6858 ** [virtual table].
6859 */
6862 /*
6863 ** CAPI3REF: Conflict resolution modes
6864 **
6865 ** These constants are returned by [sqlite3_vtab_on_conflict()] to
6866 ** inform a [virtual table] implementation what the [ON CONFLICT] mode
6867 ** is for the SQL statement being evaluated.
6868 **
6869 ** Note that the [SQLITE_IGNORE] constant is also used as a potential
6870 ** return value from the [sqlite3_set_authorizer()] callback and that
6871 ** [SQLITE_ABORT] is also a [result code].
6872 */
6873 #define SQLITE_ROLLBACK 1
6874 /* #define SQLITE_IGNORE 2 // Also used by sqlite3_authorizer() callback */
6875 #define SQLITE_FAIL 3
6876 /* #define SQLITE_ABORT 4 // Also an error code */
6877 #define SQLITE_REPLACE 5
6881 /*
6882 ** Undo the hack that converts floating point types to integer for
6883 ** builds on processors without floating point support.
6884 */
6885 #ifdef SQLITE_OMIT_FLOATING_POINT
6886 # undef double
6887 #endif
6889 #ifdef __cplusplus
6891 #endif
6892 #endif
6894 /*
6895 ** 2010 August 30
6896 **
6897 ** The author disclaims copyright to this source code. In place of
6898 ** a legal notice, here is a blessing:
6899 **
6900 ** May you do good and not evil.
6901 ** May you find forgiveness for yourself and forgive others.
6902 ** May you share freely, never taking more than you give.
6903 **
6904 *************************************************************************
6905 */
6907 #ifndef _SQLITE3RTREE_H_
6908 #define _SQLITE3RTREE_H_
6911 #ifdef __cplusplus
6913 #endif
6917 /*
6918 ** Register a geometry callback named zGeom that can be used as part of an
6919 ** R-Tree geometry query as follows:
6920 **
6921 ** SELECT ... FROM <rtree> WHERE <rtree col> MATCH $zGeom(... params ...)
6922 */
6928 );
6931 /*
6932 ** A pointer to a structure of the following type is passed as the first
6933 ** argument to callbacks registered using rtree_geometry_callback().
6934 */
6941 };
6944 #ifdef __cplusplus
6946 #endif