src/sqliteLimit.h

   1 /*
   2 ** 2007 May 7
   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 **
  13 ** This file defines various limits of what SQLite can process.
  14 */
  15
  16 /*
  17 ** The maximum length of a TEXT or BLOB in bytes.   This also
  18 ** limits the size of a row in a table or index.
  19 **
  20 ** The hard limit is the ability of a 32-bit signed integer
  21 ** to count the size: 2^31-1 or 2147483647.
  22 */
  23 #ifndef SQLITE_MAX_LENGTH
  24 # define SQLITE_MAX_LENGTH 1000000000
  25 #endif
  26
  27 /*
  28 ** This is the maximum number of
  29 **
  30 **    * Columns in a table
  31 **    * Columns in an index
  32 **    * Columns in a view
  33 **    * Terms in the SET clause of an UPDATE statement
  34 **    * Terms in the result set of a SELECT statement
  35 **    * Terms in the GROUP BY or ORDER BY clauses of a SELECT statement.
  36 **    * Terms in the VALUES clause of an INSERT statement
  37 **
  38 ** The hard upper limit here is 32676.  Most database people will
  39 ** tell you that in a well-normalized database, you usually should
  40 ** not have more than a dozen or so columns in any table.  And if
  41 ** that is the case, there is no point in having more than a few
  42 ** dozen values in any of the other situations described above.
  43 */
  44 #ifndef SQLITE_MAX_COLUMN
  45 # define SQLITE_MAX_COLUMN 2000
  46 #endif
  47
  48 /*
  49 ** The maximum length of a single SQL statement in bytes.
  50 **
  51 ** It used to be the case that setting this value to zero would
  52 ** turn the limit off.  That is no longer true.  It is not possible
  53 ** to turn this limit off.
  54 */
  55 #ifndef SQLITE_MAX_SQL_LENGTH
  56 # define SQLITE_MAX_SQL_LENGTH 1000000000
  57 #endif
  58
  59 /*
  60 ** The maximum depth of an expression tree. This is limited to
  61 ** some extent by SQLITE_MAX_SQL_LENGTH. But sometime you might
  62 ** want to place more severe limits on the complexity of an
  63 ** expression.
  64 **
  65 ** A value of 0 used to mean that the limit was not enforced.
  66 ** But that is no longer true.  The limit is now strictly enforced
  67 ** at all times.
  68 */
  69 #ifndef SQLITE_MAX_EXPR_DEPTH
  70 # define SQLITE_MAX_EXPR_DEPTH 1000
  71 #endif
  72
  73 /*
  74 ** The maximum number of terms in a compound SELECT statement.
  75 ** The code generator for compound SELECT statements does one
  76 ** level of recursion for each term.  A stack overflow can result
  77 ** if the number of terms is too large.  In practice, most SQL
  78 ** never has more than 3 or 4 terms.  Use a value of 0 to disable
  79 ** any limit on the number of terms in a compount SELECT.
  80 */
  81 #ifndef SQLITE_MAX_COMPOUND_SELECT
  82 # define SQLITE_MAX_COMPOUND_SELECT 500
  83 #endif
  84
  85 /*
  86 ** The maximum number of opcodes in a VDBE program.
  87 ** Not currently enforced.
  88 */
  89 #ifndef SQLITE_MAX_VDBE_OP
  90 # define SQLITE_MAX_VDBE_OP 250000000
  91 #endif
  92
  93 /*
  94 ** The maximum number of arguments to an SQL function.
  95 */
  96 #ifndef SQLITE_MAX_FUNCTION_ARG
  97 # define SQLITE_MAX_FUNCTION_ARG 127
  98 #endif
  99
 100 /*
 101 ** The suggested maximum number of in-memory pages to use for
 102 ** the main database table and for temporary tables.
 103 **
 104 ** IMPLEMENTATION-OF: R-30185-15359 The default suggested cache size is -2000,
 105 ** which means the cache size is limited to 2048000 bytes of memory.
 106 ** IMPLEMENTATION-OF: R-48205-43578 The default suggested cache size can be
 107 ** altered using the SQLITE_DEFAULT_CACHE_SIZE compile-time options.
 108 */
 109 #ifndef SQLITE_DEFAULT_CACHE_SIZE
 110 # define SQLITE_DEFAULT_CACHE_SIZE  -2000
 111 #endif
 112
 113 /*
 114 ** The default number of frames to accumulate in the log file before
 115 ** checkpointing the database in WAL mode.
 116 */
 117 #ifndef SQLITE_DEFAULT_WAL_AUTOCHECKPOINT
 118 # define SQLITE_DEFAULT_WAL_AUTOCHECKPOINT  1000
 119 #endif
 120
 121 /*
 122 ** The maximum number of attached databases.  This must be between 0
 123 ** and 125.  The upper bound of 125 is because the attached databases are
 124 ** counted using a signed 8-bit integer which has a maximum value of 127
 125 ** and we have to allow 2 extra counts for the "main" and "temp" databases.
 126 */
 127 #ifndef SQLITE_MAX_ATTACHED
 128 # define SQLITE_MAX_ATTACHED 10
 129 #endif
 130
 131
 132 /*
 133 ** The maximum value of a ?nnn wildcard that the parser will accept.
 134 */
 135 #ifndef SQLITE_MAX_VARIABLE_NUMBER
 136 # define SQLITE_MAX_VARIABLE_NUMBER 999
 137 #endif
 138
 139 /* Maximum page size.  The upper bound on this value is 65536.  This a limit
 140 ** imposed by the use of 16-bit offsets within each page.
 141 **
 142 ** Earlier versions of SQLite allowed the user to change this value at
 143 ** compile time. This is no longer permitted, on the grounds that it creates
 144 ** a library that is technically incompatible with an SQLite library
 145 ** compiled with a different limit. If a process operating on a database
 146 ** with a page-size of 65536 bytes crashes, then an instance of SQLite
 147 ** compiled with the default page-size limit will not be able to rollback
 148 ** the aborted transaction. This could lead to database corruption.
 149 */
 150 #ifdef SQLITE_MAX_PAGE_SIZE
 151 # undef SQLITE_MAX_PAGE_SIZE
 152 #endif
 153 #define SQLITE_MAX_PAGE_SIZE 65536
 154
 155
 156 /*
 157 ** The default size of a database page.
 158 */
 159 #ifndef SQLITE_DEFAULT_PAGE_SIZE
 160 # define SQLITE_DEFAULT_PAGE_SIZE 4096
 161 #endif
 162 #if SQLITE_DEFAULT_PAGE_SIZE>SQLITE_MAX_PAGE_SIZE
 163 # undef SQLITE_DEFAULT_PAGE_SIZE
 164 # define SQLITE_DEFAULT_PAGE_SIZE SQLITE_MAX_PAGE_SIZE
 165 #endif
 166
 167 /*
 168 ** Ordinarily, if no value is explicitly provided, SQLite creates databases
 169 ** with page size SQLITE_DEFAULT_PAGE_SIZE. However, based on certain
 170 ** device characteristics (sector-size and atomic write() support),
 171 ** SQLite may choose a larger value. This constant is the maximum value
 172 ** SQLite will choose on its own.
 173 */
 174 #ifndef SQLITE_MAX_DEFAULT_PAGE_SIZE
 175 # define SQLITE_MAX_DEFAULT_PAGE_SIZE 8192
 176 #endif
 177 #if SQLITE_MAX_DEFAULT_PAGE_SIZE>SQLITE_MAX_PAGE_SIZE
 178 # undef SQLITE_MAX_DEFAULT_PAGE_SIZE
 179 # define SQLITE_MAX_DEFAULT_PAGE_SIZE SQLITE_MAX_PAGE_SIZE
 180 #endif
 181
 182
 183 /*
 184 ** Maximum number of pages in one database file.
 185 **
 186 ** This is really just the default value for the max_page_count pragma.
 187 ** This value can be lowered (or raised) at run-time using that the
 188 ** max_page_count macro.
 189 */
 190 #ifndef SQLITE_MAX_PAGE_COUNT
 191 # define SQLITE_MAX_PAGE_COUNT 1073741823
 192 #endif
 193
 194 /*
 195 ** Maximum length (in bytes) of the pattern in a LIKE or GLOB
 196 ** operator.
 197 */
 198 #ifndef SQLITE_MAX_LIKE_PATTERN_LENGTH
 199 # define SQLITE_MAX_LIKE_PATTERN_LENGTH 50000
 200 #endif
 201
 202 /*
 203 ** Maximum depth of recursion for triggers.
 204 **
 205 ** A value of 1 means that a trigger program will not be able to itself
 206 ** fire any triggers. A value of 0 means that no trigger programs at all
 207 ** may be executed.
 208 */
 209 #ifndef SQLITE_MAX_TRIGGER_DEPTH
 210 # define SQLITE_MAX_TRIGGER_DEPTH 1000
 211 #endif