4 ** The author disclaims copyright to this source code. In place of
5 ** a legal notice, here is a blessing:
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.
11 *************************************************************************
12 ** This module contains C code that generates VDBE code used to process
13 ** the WHERE clause of SQL statements. This module is responsible for
14 ** generating the code that loops through a table looking for applicable
15 ** rows. Indices are selected and used to speed the search when doing
16 ** so is applicable. Because this module is responsible for selecting
17 ** indices, you might also think of this module as the "query optimizer".
19 #include "sqliteInt.h"
23 ** Extra information appended to the end of sqlite3_index_info but not
24 ** visible to the xBestIndex function, at least not directly. The
25 ** sqlite3_vtab_collation() interface knows how to reach it, however.
27 ** This object is not an API and can be changed from one release to the
28 ** next. As long as allocateIndexInfo() and sqlite3_vtab_collation()
29 ** agree on the structure, all will be well.
31 typedef struct HiddenIndexInfo HiddenIndexInfo
;
32 struct HiddenIndexInfo
{
33 WhereClause
*pWC
; /* The Where clause being analyzed */
34 Parse
*pParse
; /* The parsing context */
37 /* Forward declaration of methods */
38 static int whereLoopResize(sqlite3
*, WhereLoop
*, int);
40 /* Test variable that can be set to enable WHERE tracing */
41 #if defined(SQLITE_TEST) || defined(SQLITE_DEBUG)
42 /***/ int sqlite3WhereTrace
= 0;
47 ** Return the estimated number of output rows from a WHERE clause
49 LogEst
sqlite3WhereOutputRowCount(WhereInfo
*pWInfo
){
50 return pWInfo
->nRowOut
;
54 ** Return one of the WHERE_DISTINCT_xxxxx values to indicate how this
55 ** WHERE clause returns outputs for DISTINCT processing.
57 int sqlite3WhereIsDistinct(WhereInfo
*pWInfo
){
58 return pWInfo
->eDistinct
;
62 ** Return TRUE if the WHERE clause returns rows in ORDER BY order.
63 ** Return FALSE if the output needs to be sorted.
65 int sqlite3WhereIsOrdered(WhereInfo
*pWInfo
){
66 return pWInfo
->nOBSat
;
70 ** In the ORDER BY LIMIT optimization, if the inner-most loop is known
71 ** to emit rows in increasing order, and if the last row emitted by the
72 ** inner-most loop did not fit within the sorter, then we can skip all
73 ** subsequent rows for the current iteration of the inner loop (because they
74 ** will not fit in the sorter either) and continue with the second inner
75 ** loop - the loop immediately outside the inner-most.
77 ** When a row does not fit in the sorter (because the sorter already
78 ** holds LIMIT+OFFSET rows that are smaller), then a jump is made to the
79 ** label returned by this function.
81 ** If the ORDER BY LIMIT optimization applies, the jump destination should
82 ** be the continuation for the second-inner-most loop. If the ORDER BY
83 ** LIMIT optimization does not apply, then the jump destination should
84 ** be the continuation for the inner-most loop.
86 ** It is always safe for this routine to return the continuation of the
87 ** inner-most loop, in the sense that a correct answer will result.
88 ** Returning the continuation the second inner loop is an optimization
89 ** that might make the code run a little faster, but should not change
92 int sqlite3WhereOrderByLimitOptLabel(WhereInfo
*pWInfo
){
94 if( !pWInfo
->bOrderedInnerLoop
){
95 /* The ORDER BY LIMIT optimization does not apply. Jump to the
96 ** continuation of the inner-most loop. */
97 return pWInfo
->iContinue
;
99 pInner
= &pWInfo
->a
[pWInfo
->nLevel
-1];
100 assert( pInner
->addrNxt
!=0 );
101 return pInner
->addrNxt
;
105 ** Return the VDBE address or label to jump to in order to continue
106 ** immediately with the next row of a WHERE clause.
108 int sqlite3WhereContinueLabel(WhereInfo
*pWInfo
){
109 assert( pWInfo
->iContinue
!=0 );
110 return pWInfo
->iContinue
;
114 ** Return the VDBE address or label to jump to in order to break
115 ** out of a WHERE loop.
117 int sqlite3WhereBreakLabel(WhereInfo
*pWInfo
){
118 return pWInfo
->iBreak
;
122 ** Return ONEPASS_OFF (0) if an UPDATE or DELETE statement is unable to
123 ** operate directly on the rowids returned by a WHERE clause. Return
124 ** ONEPASS_SINGLE (1) if the statement can operation directly because only
125 ** a single row is to be changed. Return ONEPASS_MULTI (2) if the one-pass
126 ** optimization can be used on multiple
128 ** If the ONEPASS optimization is used (if this routine returns true)
129 ** then also write the indices of open cursors used by ONEPASS
130 ** into aiCur[0] and aiCur[1]. iaCur[0] gets the cursor of the data
131 ** table and iaCur[1] gets the cursor used by an auxiliary index.
132 ** Either value may be -1, indicating that cursor is not used.
133 ** Any cursors returned will have been opened for writing.
135 ** aiCur[0] and aiCur[1] both get -1 if the where-clause logic is
136 ** unable to use the ONEPASS optimization.
138 int sqlite3WhereOkOnePass(WhereInfo
*pWInfo
, int *aiCur
){
139 memcpy(aiCur
, pWInfo
->aiCurOnePass
, sizeof(int)*2);
140 #ifdef WHERETRACE_ENABLED
141 if( sqlite3WhereTrace
&& pWInfo
->eOnePass
!=ONEPASS_OFF
){
142 sqlite3DebugPrintf("%s cursors: %d %d\n",
143 pWInfo
->eOnePass
==ONEPASS_SINGLE
? "ONEPASS_SINGLE" : "ONEPASS_MULTI",
147 return pWInfo
->eOnePass
;
151 ** Return TRUE if the WHERE loop uses the OP_DeferredSeek opcode to move
152 ** the data cursor to the row selected by the index cursor.
154 int sqlite3WhereUsesDeferredSeek(WhereInfo
*pWInfo
){
155 return pWInfo
->bDeferredSeek
;
159 ** Move the content of pSrc into pDest
161 static void whereOrMove(WhereOrSet
*pDest
, WhereOrSet
*pSrc
){
163 memcpy(pDest
->a
, pSrc
->a
, pDest
->n
*sizeof(pDest
->a
[0]));
167 ** Try to insert a new prerequisite/cost entry into the WhereOrSet pSet.
169 ** The new entry might overwrite an existing entry, or it might be
170 ** appended, or it might be discarded. Do whatever is the right thing
171 ** so that pSet keeps the N_OR_COST best entries seen so far.
173 static int whereOrInsert(
174 WhereOrSet
*pSet
, /* The WhereOrSet to be updated */
175 Bitmask prereq
, /* Prerequisites of the new entry */
176 LogEst rRun
, /* Run-cost of the new entry */
177 LogEst nOut
/* Number of outputs for the new entry */
181 for(i
=pSet
->n
, p
=pSet
->a
; i
>0; i
--, p
++){
182 if( rRun
<=p
->rRun
&& (prereq
& p
->prereq
)==prereq
){
183 goto whereOrInsert_done
;
185 if( p
->rRun
<=rRun
&& (p
->prereq
& prereq
)==p
->prereq
){
189 if( pSet
->n
<N_OR_COST
){
190 p
= &pSet
->a
[pSet
->n
++];
194 for(i
=1; i
<pSet
->n
; i
++){
195 if( p
->rRun
>pSet
->a
[i
].rRun
) p
= pSet
->a
+ i
;
197 if( p
->rRun
<=rRun
) return 0;
202 if( p
->nOut
>nOut
) p
->nOut
= nOut
;
207 ** Return the bitmask for the given cursor number. Return 0 if
208 ** iCursor is not in the set.
210 Bitmask
sqlite3WhereGetMask(WhereMaskSet
*pMaskSet
, int iCursor
){
212 assert( pMaskSet
->n
<=(int)sizeof(Bitmask
)*8 );
213 for(i
=0; i
<pMaskSet
->n
; i
++){
214 if( pMaskSet
->ix
[i
]==iCursor
){
222 ** Create a new mask for cursor iCursor.
224 ** There is one cursor per table in the FROM clause. The number of
225 ** tables in the FROM clause is limited by a test early in the
226 ** sqlite3WhereBegin() routine. So we know that the pMaskSet->ix[]
227 ** array will never overflow.
229 static void createMask(WhereMaskSet
*pMaskSet
, int iCursor
){
230 assert( pMaskSet
->n
< ArraySize(pMaskSet
->ix
) );
231 pMaskSet
->ix
[pMaskSet
->n
++] = iCursor
;
235 ** Advance to the next WhereTerm that matches according to the criteria
236 ** established when the pScan object was initialized by whereScanInit().
237 ** Return NULL if there are no more matching WhereTerms.
239 static WhereTerm
*whereScanNext(WhereScan
*pScan
){
240 int iCur
; /* The cursor on the LHS of the term */
241 i16 iColumn
; /* The column on the LHS of the term. -1 for IPK */
242 Expr
*pX
; /* An expression being tested */
243 WhereClause
*pWC
; /* Shorthand for pScan->pWC */
244 WhereTerm
*pTerm
; /* The term being tested */
245 int k
= pScan
->k
; /* Where to start scanning */
247 assert( pScan
->iEquiv
<=pScan
->nEquiv
);
250 iColumn
= pScan
->aiColumn
[pScan
->iEquiv
-1];
251 iCur
= pScan
->aiCur
[pScan
->iEquiv
-1];
254 for(pTerm
=pWC
->a
+k
; k
<pWC
->nTerm
; k
++, pTerm
++){
255 if( pTerm
->leftCursor
==iCur
256 && pTerm
->u
.leftColumn
==iColumn
258 || sqlite3ExprCompareSkip(pTerm
->pExpr
->pLeft
,
259 pScan
->pIdxExpr
,iCur
)==0)
260 && (pScan
->iEquiv
<=1 || !ExprHasProperty(pTerm
->pExpr
, EP_FromJoin
))
262 if( (pTerm
->eOperator
& WO_EQUIV
)!=0
263 && pScan
->nEquiv
<ArraySize(pScan
->aiCur
)
264 && (pX
= sqlite3ExprSkipCollateAndLikely(pTerm
->pExpr
->pRight
))->op
268 for(j
=0; j
<pScan
->nEquiv
; j
++){
269 if( pScan
->aiCur
[j
]==pX
->iTable
270 && pScan
->aiColumn
[j
]==pX
->iColumn
){
274 if( j
==pScan
->nEquiv
){
275 pScan
->aiCur
[j
] = pX
->iTable
;
276 pScan
->aiColumn
[j
] = pX
->iColumn
;
280 if( (pTerm
->eOperator
& pScan
->opMask
)!=0 ){
281 /* Verify the affinity and collating sequence match */
282 if( pScan
->zCollName
&& (pTerm
->eOperator
& WO_ISNULL
)==0 ){
284 Parse
*pParse
= pWC
->pWInfo
->pParse
;
286 if( !sqlite3IndexAffinityOk(pX
, pScan
->idxaff
) ){
290 pColl
= sqlite3ExprCompareCollSeq(pParse
, pX
);
291 if( pColl
==0 ) pColl
= pParse
->db
->pDfltColl
;
292 if( sqlite3StrICmp(pColl
->zName
, pScan
->zCollName
) ){
296 if( (pTerm
->eOperator
& (WO_EQ
|WO_IS
))!=0
297 && (pX
= pTerm
->pExpr
->pRight
)->op
==TK_COLUMN
298 && pX
->iTable
==pScan
->aiCur
[0]
299 && pX
->iColumn
==pScan
->aiColumn
[0]
301 testcase( pTerm
->eOperator
& WO_IS
);
313 if( pScan
->iEquiv
>=pScan
->nEquiv
) break;
314 pWC
= pScan
->pOrigWC
;
322 ** This is whereScanInit() for the case of an index on an expression.
323 ** It is factored out into a separate tail-recursion subroutine so that
324 ** the normal whereScanInit() routine, which is a high-runner, does not
325 ** need to push registers onto the stack as part of its prologue.
327 static SQLITE_NOINLINE WhereTerm
*whereScanInitIndexExpr(WhereScan
*pScan
){
328 pScan
->idxaff
= sqlite3ExprAffinity(pScan
->pIdxExpr
);
329 return whereScanNext(pScan
);
333 ** Initialize a WHERE clause scanner object. Return a pointer to the
334 ** first match. Return NULL if there are no matches.
336 ** The scanner will be searching the WHERE clause pWC. It will look
337 ** for terms of the form "X <op> <expr>" where X is column iColumn of table
338 ** iCur. Or if pIdx!=0 then X is column iColumn of index pIdx. pIdx
339 ** must be one of the indexes of table iCur.
341 ** The <op> must be one of the operators described by opMask.
343 ** If the search is for X and the WHERE clause contains terms of the
344 ** form X=Y then this routine might also return terms of the form
345 ** "Y <op> <expr>". The number of levels of transitivity is limited,
346 ** but is enough to handle most commonly occurring SQL statements.
348 ** If X is not the INTEGER PRIMARY KEY then X must be compatible with
351 static WhereTerm
*whereScanInit(
352 WhereScan
*pScan
, /* The WhereScan object being initialized */
353 WhereClause
*pWC
, /* The WHERE clause to be scanned */
354 int iCur
, /* Cursor to scan for */
355 int iColumn
, /* Column to scan for */
356 u32 opMask
, /* Operator(s) to scan for */
357 Index
*pIdx
/* Must be compatible with this index */
359 pScan
->pOrigWC
= pWC
;
363 pScan
->zCollName
= 0;
364 pScan
->opMask
= opMask
;
366 pScan
->aiCur
[0] = iCur
;
371 iColumn
= pIdx
->aiColumn
[j
];
372 if( iColumn
==XN_EXPR
){
373 pScan
->pIdxExpr
= pIdx
->aColExpr
->a
[j
].pExpr
;
374 pScan
->zCollName
= pIdx
->azColl
[j
];
375 pScan
->aiColumn
[0] = XN_EXPR
;
376 return whereScanInitIndexExpr(pScan
);
377 }else if( iColumn
==pIdx
->pTable
->iPKey
){
379 }else if( iColumn
>=0 ){
380 pScan
->idxaff
= pIdx
->pTable
->aCol
[iColumn
].affinity
;
381 pScan
->zCollName
= pIdx
->azColl
[j
];
383 }else if( iColumn
==XN_EXPR
){
386 pScan
->aiColumn
[0] = iColumn
;
387 return whereScanNext(pScan
);
391 ** Search for a term in the WHERE clause that is of the form "X <op> <expr>"
392 ** where X is a reference to the iColumn of table iCur or of index pIdx
393 ** if pIdx!=0 and <op> is one of the WO_xx operator codes specified by
394 ** the op parameter. Return a pointer to the term. Return 0 if not found.
396 ** If pIdx!=0 then it must be one of the indexes of table iCur.
397 ** Search for terms matching the iColumn-th column of pIdx
398 ** rather than the iColumn-th column of table iCur.
400 ** The term returned might by Y=<expr> if there is another constraint in
401 ** the WHERE clause that specifies that X=Y. Any such constraints will be
402 ** identified by the WO_EQUIV bit in the pTerm->eOperator field. The
403 ** aiCur[]/iaColumn[] arrays hold X and all its equivalents. There are 11
404 ** slots in aiCur[]/aiColumn[] so that means we can look for X plus up to 10
405 ** other equivalent values. Hence a search for X will return <expr> if X=A1
406 ** and A1=A2 and A2=A3 and ... and A9=A10 and A10=<expr>.
408 ** If there are multiple terms in the WHERE clause of the form "X <op> <expr>"
409 ** then try for the one with no dependencies on <expr> - in other words where
410 ** <expr> is a constant expression of some kind. Only return entries of
411 ** the form "X <op> Y" where Y is a column in another table if no terms of
412 ** the form "X <op> <const-expr>" exist. If no terms with a constant RHS
413 ** exist, try to return a term that does not use WO_EQUIV.
415 WhereTerm
*sqlite3WhereFindTerm(
416 WhereClause
*pWC
, /* The WHERE clause to be searched */
417 int iCur
, /* Cursor number of LHS */
418 int iColumn
, /* Column number of LHS */
419 Bitmask notReady
, /* RHS must not overlap with this mask */
420 u32 op
, /* Mask of WO_xx values describing operator */
421 Index
*pIdx
/* Must be compatible with this index, if not NULL */
423 WhereTerm
*pResult
= 0;
427 p
= whereScanInit(&scan
, pWC
, iCur
, iColumn
, op
, pIdx
);
430 if( (p
->prereqRight
& notReady
)==0 ){
431 if( p
->prereqRight
==0 && (p
->eOperator
&op
)!=0 ){
432 testcase( p
->eOperator
& WO_IS
);
435 if( pResult
==0 ) pResult
= p
;
437 p
= whereScanNext(&scan
);
443 ** This function searches pList for an entry that matches the iCol-th column
446 ** If such an expression is found, its index in pList->a[] is returned. If
447 ** no expression is found, -1 is returned.
449 static int findIndexCol(
450 Parse
*pParse
, /* Parse context */
451 ExprList
*pList
, /* Expression list to search */
452 int iBase
, /* Cursor for table associated with pIdx */
453 Index
*pIdx
, /* Index to match column of */
454 int iCol
/* Column of index to match */
457 const char *zColl
= pIdx
->azColl
[iCol
];
459 for(i
=0; i
<pList
->nExpr
; i
++){
460 Expr
*p
= sqlite3ExprSkipCollateAndLikely(pList
->a
[i
].pExpr
);
462 && p
->iColumn
==pIdx
->aiColumn
[iCol
]
465 CollSeq
*pColl
= sqlite3ExprNNCollSeq(pParse
, pList
->a
[i
].pExpr
);
466 if( 0==sqlite3StrICmp(pColl
->zName
, zColl
) ){
476 ** Return TRUE if the iCol-th column of index pIdx is NOT NULL
478 static int indexColumnNotNull(Index
*pIdx
, int iCol
){
481 assert( iCol
>=0 && iCol
<pIdx
->nColumn
);
482 j
= pIdx
->aiColumn
[iCol
];
484 return pIdx
->pTable
->aCol
[j
].notNull
;
489 return 0; /* Assume an indexed expression can always yield a NULL */
495 ** Return true if the DISTINCT expression-list passed as the third argument
498 ** A DISTINCT list is redundant if any subset of the columns in the
499 ** DISTINCT list are collectively unique and individually non-null.
501 static int isDistinctRedundant(
502 Parse
*pParse
, /* Parsing context */
503 SrcList
*pTabList
, /* The FROM clause */
504 WhereClause
*pWC
, /* The WHERE clause */
505 ExprList
*pDistinct
/* The result set that needs to be DISTINCT */
512 /* If there is more than one table or sub-select in the FROM clause of
513 ** this query, then it will not be possible to show that the DISTINCT
514 ** clause is redundant. */
515 if( pTabList
->nSrc
!=1 ) return 0;
516 iBase
= pTabList
->a
[0].iCursor
;
517 pTab
= pTabList
->a
[0].pTab
;
519 /* If any of the expressions is an IPK column on table iBase, then return
520 ** true. Note: The (p->iTable==iBase) part of this test may be false if the
521 ** current SELECT is a correlated sub-query.
523 for(i
=0; i
<pDistinct
->nExpr
; i
++){
524 Expr
*p
= sqlite3ExprSkipCollateAndLikely(pDistinct
->a
[i
].pExpr
);
525 if( p
->op
==TK_COLUMN
&& p
->iTable
==iBase
&& p
->iColumn
<0 ) return 1;
528 /* Loop through all indices on the table, checking each to see if it makes
529 ** the DISTINCT qualifier redundant. It does so if:
531 ** 1. The index is itself UNIQUE, and
533 ** 2. All of the columns in the index are either part of the pDistinct
534 ** list, or else the WHERE clause contains a term of the form "col=X",
535 ** where X is a constant value. The collation sequences of the
536 ** comparison and select-list expressions must match those of the index.
538 ** 3. All of those index columns for which the WHERE clause does not
539 ** contain a "col=X" term are subject to a NOT NULL constraint.
541 for(pIdx
=pTab
->pIndex
; pIdx
; pIdx
=pIdx
->pNext
){
542 if( !IsUniqueIndex(pIdx
) ) continue;
543 for(i
=0; i
<pIdx
->nKeyCol
; i
++){
544 if( 0==sqlite3WhereFindTerm(pWC
, iBase
, i
, ~(Bitmask
)0, WO_EQ
, pIdx
) ){
545 if( findIndexCol(pParse
, pDistinct
, iBase
, pIdx
, i
)<0 ) break;
546 if( indexColumnNotNull(pIdx
, i
)==0 ) break;
549 if( i
==pIdx
->nKeyCol
){
550 /* This index implies that the DISTINCT qualifier is redundant. */
560 ** Estimate the logarithm of the input value to base 2.
562 static LogEst
estLog(LogEst N
){
563 return N
<=10 ? 0 : sqlite3LogEst(N
) - 33;
567 ** Convert OP_Column opcodes to OP_Copy in previously generated code.
569 ** This routine runs over generated VDBE code and translates OP_Column
570 ** opcodes into OP_Copy when the table is being accessed via co-routine
571 ** instead of via table lookup.
573 ** If the iAutoidxCur is not zero, then any OP_Rowid instructions on
574 ** cursor iTabCur are transformed into OP_Sequence opcode for the
575 ** iAutoidxCur cursor, in order to generate unique rowids for the
576 ** automatic index being generated.
578 static void translateColumnToCopy(
579 Parse
*pParse
, /* Parsing context */
580 int iStart
, /* Translate from this opcode to the end */
581 int iTabCur
, /* OP_Column/OP_Rowid references to this table */
582 int iRegister
, /* The first column is in this register */
583 int iAutoidxCur
/* If non-zero, cursor of autoindex being generated */
585 Vdbe
*v
= pParse
->pVdbe
;
586 VdbeOp
*pOp
= sqlite3VdbeGetOp(v
, iStart
);
587 int iEnd
= sqlite3VdbeCurrentAddr(v
);
588 if( pParse
->db
->mallocFailed
) return;
589 for(; iStart
<iEnd
; iStart
++, pOp
++){
590 if( pOp
->p1
!=iTabCur
) continue;
591 if( pOp
->opcode
==OP_Column
){
592 pOp
->opcode
= OP_Copy
;
593 pOp
->p1
= pOp
->p2
+ iRegister
;
596 }else if( pOp
->opcode
==OP_Rowid
){
598 pOp
->opcode
= OP_Sequence
;
599 pOp
->p1
= iAutoidxCur
;
601 pOp
->opcode
= OP_Null
;
610 ** Two routines for printing the content of an sqlite3_index_info
611 ** structure. Used for testing and debugging only. If neither
612 ** SQLITE_TEST or SQLITE_DEBUG are defined, then these routines
615 #if !defined(SQLITE_OMIT_VIRTUALTABLE) && defined(WHERETRACE_ENABLED)
616 static void whereTraceIndexInfoInputs(sqlite3_index_info
*p
){
618 if( !sqlite3WhereTrace
) return;
619 for(i
=0; i
<p
->nConstraint
; i
++){
620 sqlite3DebugPrintf(" constraint[%d]: col=%d termid=%d op=%d usabled=%d\n",
622 p
->aConstraint
[i
].iColumn
,
623 p
->aConstraint
[i
].iTermOffset
,
624 p
->aConstraint
[i
].op
,
625 p
->aConstraint
[i
].usable
);
627 for(i
=0; i
<p
->nOrderBy
; i
++){
628 sqlite3DebugPrintf(" orderby[%d]: col=%d desc=%d\n",
630 p
->aOrderBy
[i
].iColumn
,
631 p
->aOrderBy
[i
].desc
);
634 static void whereTraceIndexInfoOutputs(sqlite3_index_info
*p
){
636 if( !sqlite3WhereTrace
) return;
637 for(i
=0; i
<p
->nConstraint
; i
++){
638 sqlite3DebugPrintf(" usage[%d]: argvIdx=%d omit=%d\n",
640 p
->aConstraintUsage
[i
].argvIndex
,
641 p
->aConstraintUsage
[i
].omit
);
643 sqlite3DebugPrintf(" idxNum=%d\n", p
->idxNum
);
644 sqlite3DebugPrintf(" idxStr=%s\n", p
->idxStr
);
645 sqlite3DebugPrintf(" orderByConsumed=%d\n", p
->orderByConsumed
);
646 sqlite3DebugPrintf(" estimatedCost=%g\n", p
->estimatedCost
);
647 sqlite3DebugPrintf(" estimatedRows=%lld\n", p
->estimatedRows
);
650 #define whereTraceIndexInfoInputs(A)
651 #define whereTraceIndexInfoOutputs(A)
654 #ifndef SQLITE_OMIT_AUTOMATIC_INDEX
656 ** Return TRUE if the WHERE clause term pTerm is of a form where it
657 ** could be used with an index to access pSrc, assuming an appropriate
660 static int termCanDriveIndex(
661 WhereTerm
*pTerm
, /* WHERE clause term to check */
662 struct SrcList_item
*pSrc
, /* Table we are trying to access */
663 Bitmask notReady
/* Tables in outer loops of the join */
666 if( pTerm
->leftCursor
!=pSrc
->iCursor
) return 0;
667 if( (pTerm
->eOperator
& (WO_EQ
|WO_IS
))==0 ) return 0;
668 if( (pSrc
->fg
.jointype
& JT_LEFT
)
669 && !ExprHasProperty(pTerm
->pExpr
, EP_FromJoin
)
670 && (pTerm
->eOperator
& WO_IS
)
672 /* Cannot use an IS term from the WHERE clause as an index driver for
673 ** the RHS of a LEFT JOIN. Such a term can only be used if it is from
677 if( (pTerm
->prereqRight
& notReady
)!=0 ) return 0;
678 if( pTerm
->u
.leftColumn
<0 ) return 0;
679 aff
= pSrc
->pTab
->aCol
[pTerm
->u
.leftColumn
].affinity
;
680 if( !sqlite3IndexAffinityOk(pTerm
->pExpr
, aff
) ) return 0;
681 testcase( pTerm
->pExpr
->op
==TK_IS
);
687 #ifndef SQLITE_OMIT_AUTOMATIC_INDEX
689 ** Generate code to construct the Index object for an automatic index
690 ** and to set up the WhereLevel object pLevel so that the code generator
691 ** makes use of the automatic index.
693 static void constructAutomaticIndex(
694 Parse
*pParse
, /* The parsing context */
695 WhereClause
*pWC
, /* The WHERE clause */
696 struct SrcList_item
*pSrc
, /* The FROM clause term to get the next index */
697 Bitmask notReady
, /* Mask of cursors that are not available */
698 WhereLevel
*pLevel
/* Write new index here */
700 int nKeyCol
; /* Number of columns in the constructed index */
701 WhereTerm
*pTerm
; /* A single term of the WHERE clause */
702 WhereTerm
*pWCEnd
; /* End of pWC->a[] */
703 Index
*pIdx
; /* Object describing the transient index */
704 Vdbe
*v
; /* Prepared statement under construction */
705 int addrInit
; /* Address of the initialization bypass jump */
706 Table
*pTable
; /* The table being indexed */
707 int addrTop
; /* Top of the index fill loop */
708 int regRecord
; /* Register holding an index record */
709 int n
; /* Column counter */
710 int i
; /* Loop counter */
711 int mxBitCol
; /* Maximum column in pSrc->colUsed */
712 CollSeq
*pColl
; /* Collating sequence to on a column */
713 WhereLoop
*pLoop
; /* The Loop object */
714 char *zNotUsed
; /* Extra space on the end of pIdx */
715 Bitmask idxCols
; /* Bitmap of columns used for indexing */
716 Bitmask extraCols
; /* Bitmap of additional columns */
717 u8 sentWarning
= 0; /* True if a warnning has been issued */
718 Expr
*pPartial
= 0; /* Partial Index Expression */
719 int iContinue
= 0; /* Jump here to skip excluded rows */
720 struct SrcList_item
*pTabItem
; /* FROM clause term being indexed */
721 int addrCounter
= 0; /* Address where integer counter is initialized */
722 int regBase
; /* Array of registers where record is assembled */
724 /* Generate code to skip over the creation and initialization of the
725 ** transient index on 2nd and subsequent iterations of the loop. */
728 addrInit
= sqlite3VdbeAddOp0(v
, OP_Once
); VdbeCoverage(v
);
730 /* Count the number of columns that will be added to the index
731 ** and used to match WHERE clause constraints */
734 pWCEnd
= &pWC
->a
[pWC
->nTerm
];
735 pLoop
= pLevel
->pWLoop
;
737 for(pTerm
=pWC
->a
; pTerm
<pWCEnd
; pTerm
++){
738 Expr
*pExpr
= pTerm
->pExpr
;
739 assert( !ExprHasProperty(pExpr
, EP_FromJoin
) /* prereq always non-zero */
740 || pExpr
->iRightJoinTable
!=pSrc
->iCursor
/* for the right-hand */
741 || pLoop
->prereq
!=0 ); /* table of a LEFT JOIN */
743 && (pTerm
->wtFlags
& TERM_VIRTUAL
)==0
744 && !ExprHasProperty(pExpr
, EP_FromJoin
)
745 && sqlite3ExprIsTableConstant(pExpr
, pSrc
->iCursor
) ){
746 pPartial
= sqlite3ExprAnd(pParse
, pPartial
,
747 sqlite3ExprDup(pParse
->db
, pExpr
, 0));
749 if( termCanDriveIndex(pTerm
, pSrc
, notReady
) ){
750 int iCol
= pTerm
->u
.leftColumn
;
751 Bitmask cMask
= iCol
>=BMS
? MASKBIT(BMS
-1) : MASKBIT(iCol
);
752 testcase( iCol
==BMS
);
753 testcase( iCol
==BMS
-1 );
755 sqlite3_log(SQLITE_WARNING_AUTOINDEX
,
756 "automatic index on %s(%s)", pTable
->zName
,
757 pTable
->aCol
[iCol
].zName
);
760 if( (idxCols
& cMask
)==0 ){
761 if( whereLoopResize(pParse
->db
, pLoop
, nKeyCol
+1) ){
762 goto end_auto_index_create
;
764 pLoop
->aLTerm
[nKeyCol
++] = pTerm
;
770 pLoop
->u
.btree
.nEq
= pLoop
->nLTerm
= nKeyCol
;
771 pLoop
->wsFlags
= WHERE_COLUMN_EQ
| WHERE_IDX_ONLY
| WHERE_INDEXED
774 /* Count the number of additional columns needed to create a
775 ** covering index. A "covering index" is an index that contains all
776 ** columns that are needed by the query. With a covering index, the
777 ** original table never needs to be accessed. Automatic indices must
778 ** be a covering index because the index will not be updated if the
779 ** original table changes and the index and table cannot both be used
780 ** if they go out of sync.
782 extraCols
= pSrc
->colUsed
& (~idxCols
| MASKBIT(BMS
-1));
783 mxBitCol
= MIN(BMS
-1,pTable
->nCol
);
784 testcase( pTable
->nCol
==BMS
-1 );
785 testcase( pTable
->nCol
==BMS
-2 );
786 for(i
=0; i
<mxBitCol
; i
++){
787 if( extraCols
& MASKBIT(i
) ) nKeyCol
++;
789 if( pSrc
->colUsed
& MASKBIT(BMS
-1) ){
790 nKeyCol
+= pTable
->nCol
- BMS
+ 1;
793 /* Construct the Index object to describe this index */
794 pIdx
= sqlite3AllocateIndexObject(pParse
->db
, nKeyCol
+1, 0, &zNotUsed
);
795 if( pIdx
==0 ) goto end_auto_index_create
;
796 pLoop
->u
.btree
.pIndex
= pIdx
;
797 pIdx
->zName
= "auto-index";
798 pIdx
->pTable
= pTable
;
801 for(pTerm
=pWC
->a
; pTerm
<pWCEnd
; pTerm
++){
802 if( termCanDriveIndex(pTerm
, pSrc
, notReady
) ){
803 int iCol
= pTerm
->u
.leftColumn
;
804 Bitmask cMask
= iCol
>=BMS
? MASKBIT(BMS
-1) : MASKBIT(iCol
);
805 testcase( iCol
==BMS
-1 );
806 testcase( iCol
==BMS
);
807 if( (idxCols
& cMask
)==0 ){
808 Expr
*pX
= pTerm
->pExpr
;
810 pIdx
->aiColumn
[n
] = pTerm
->u
.leftColumn
;
811 pColl
= sqlite3ExprCompareCollSeq(pParse
, pX
);
812 assert( pColl
!=0 || pParse
->nErr
>0 ); /* TH3 collate01.800 */
813 pIdx
->azColl
[n
] = pColl
? pColl
->zName
: sqlite3StrBINARY
;
818 assert( (u32
)n
==pLoop
->u
.btree
.nEq
);
820 /* Add additional columns needed to make the automatic index into
821 ** a covering index */
822 for(i
=0; i
<mxBitCol
; i
++){
823 if( extraCols
& MASKBIT(i
) ){
824 pIdx
->aiColumn
[n
] = i
;
825 pIdx
->azColl
[n
] = sqlite3StrBINARY
;
829 if( pSrc
->colUsed
& MASKBIT(BMS
-1) ){
830 for(i
=BMS
-1; i
<pTable
->nCol
; i
++){
831 pIdx
->aiColumn
[n
] = i
;
832 pIdx
->azColl
[n
] = sqlite3StrBINARY
;
836 assert( n
==nKeyCol
);
837 pIdx
->aiColumn
[n
] = XN_ROWID
;
838 pIdx
->azColl
[n
] = sqlite3StrBINARY
;
840 /* Create the automatic index */
841 assert( pLevel
->iIdxCur
>=0 );
842 pLevel
->iIdxCur
= pParse
->nTab
++;
843 sqlite3VdbeAddOp2(v
, OP_OpenAutoindex
, pLevel
->iIdxCur
, nKeyCol
+1);
844 sqlite3VdbeSetP4KeyInfo(pParse
, pIdx
);
845 VdbeComment((v
, "for %s", pTable
->zName
));
847 /* Fill the automatic index with content */
848 pTabItem
= &pWC
->pWInfo
->pTabList
->a
[pLevel
->iFrom
];
849 if( pTabItem
->fg
.viaCoroutine
){
850 int regYield
= pTabItem
->regReturn
;
851 addrCounter
= sqlite3VdbeAddOp2(v
, OP_Integer
, 0, 0);
852 sqlite3VdbeAddOp3(v
, OP_InitCoroutine
, regYield
, 0, pTabItem
->addrFillSub
);
853 addrTop
= sqlite3VdbeAddOp1(v
, OP_Yield
, regYield
);
855 VdbeComment((v
, "next row of %s", pTabItem
->pTab
->zName
));
857 addrTop
= sqlite3VdbeAddOp1(v
, OP_Rewind
, pLevel
->iTabCur
); VdbeCoverage(v
);
860 iContinue
= sqlite3VdbeMakeLabel(pParse
);
861 sqlite3ExprIfFalse(pParse
, pPartial
, iContinue
, SQLITE_JUMPIFNULL
);
862 pLoop
->wsFlags
|= WHERE_PARTIALIDX
;
864 regRecord
= sqlite3GetTempReg(pParse
);
865 regBase
= sqlite3GenerateIndexKey(
866 pParse
, pIdx
, pLevel
->iTabCur
, regRecord
, 0, 0, 0, 0
868 sqlite3VdbeAddOp2(v
, OP_IdxInsert
, pLevel
->iIdxCur
, regRecord
);
869 sqlite3VdbeChangeP5(v
, OPFLAG_USESEEKRESULT
);
870 if( pPartial
) sqlite3VdbeResolveLabel(v
, iContinue
);
871 if( pTabItem
->fg
.viaCoroutine
){
872 sqlite3VdbeChangeP2(v
, addrCounter
, regBase
+n
);
873 testcase( pParse
->db
->mallocFailed
);
874 assert( pLevel
->iIdxCur
>0 );
875 translateColumnToCopy(pParse
, addrTop
, pLevel
->iTabCur
,
876 pTabItem
->regResult
, pLevel
->iIdxCur
);
877 sqlite3VdbeGoto(v
, addrTop
);
878 pTabItem
->fg
.viaCoroutine
= 0;
880 sqlite3VdbeAddOp2(v
, OP_Next
, pLevel
->iTabCur
, addrTop
+1); VdbeCoverage(v
);
881 sqlite3VdbeChangeP5(v
, SQLITE_STMTSTATUS_AUTOINDEX
);
883 sqlite3VdbeJumpHere(v
, addrTop
);
884 sqlite3ReleaseTempReg(pParse
, regRecord
);
886 /* Jump here when skipping the initialization */
887 sqlite3VdbeJumpHere(v
, addrInit
);
889 end_auto_index_create
:
890 sqlite3ExprDelete(pParse
->db
, pPartial
);
892 #endif /* SQLITE_OMIT_AUTOMATIC_INDEX */
894 #ifndef SQLITE_OMIT_VIRTUALTABLE
896 ** Allocate and populate an sqlite3_index_info structure. It is the
897 ** responsibility of the caller to eventually release the structure
898 ** by passing the pointer returned by this function to sqlite3_free().
900 static sqlite3_index_info
*allocateIndexInfo(
901 Parse
*pParse
, /* The parsing context */
902 WhereClause
*pWC
, /* The WHERE clause being analyzed */
903 Bitmask mUnusable
, /* Ignore terms with these prereqs */
904 struct SrcList_item
*pSrc
, /* The FROM clause term that is the vtab */
905 ExprList
*pOrderBy
, /* The ORDER BY clause */
906 u16
*pmNoOmit
/* Mask of terms not to omit */
910 struct sqlite3_index_constraint
*pIdxCons
;
911 struct sqlite3_index_orderby
*pIdxOrderBy
;
912 struct sqlite3_index_constraint_usage
*pUsage
;
913 struct HiddenIndexInfo
*pHidden
;
916 sqlite3_index_info
*pIdxInfo
;
919 /* Count the number of possible WHERE clause constraints referring
920 ** to this virtual table */
921 for(i
=nTerm
=0, pTerm
=pWC
->a
; i
<pWC
->nTerm
; i
++, pTerm
++){
922 if( pTerm
->leftCursor
!= pSrc
->iCursor
) continue;
923 if( pTerm
->prereqRight
& mUnusable
) continue;
924 assert( IsPowerOfTwo(pTerm
->eOperator
& ~WO_EQUIV
) );
925 testcase( pTerm
->eOperator
& WO_IN
);
926 testcase( pTerm
->eOperator
& WO_ISNULL
);
927 testcase( pTerm
->eOperator
& WO_IS
);
928 testcase( pTerm
->eOperator
& WO_ALL
);
929 if( (pTerm
->eOperator
& ~(WO_EQUIV
))==0 ) continue;
930 if( pTerm
->wtFlags
& TERM_VNULL
) continue;
931 assert( pTerm
->u
.leftColumn
>=(-1) );
935 /* If the ORDER BY clause contains only columns in the current
936 ** virtual table then allocate space for the aOrderBy part of
937 ** the sqlite3_index_info structure.
941 int n
= pOrderBy
->nExpr
;
943 Expr
*pExpr
= pOrderBy
->a
[i
].pExpr
;
944 if( pExpr
->op
!=TK_COLUMN
|| pExpr
->iTable
!=pSrc
->iCursor
) break;
945 if( pOrderBy
->a
[i
].sortFlags
& KEYINFO_ORDER_BIGNULL
) break;
952 /* Allocate the sqlite3_index_info structure
954 pIdxInfo
= sqlite3DbMallocZero(pParse
->db
, sizeof(*pIdxInfo
)
955 + (sizeof(*pIdxCons
) + sizeof(*pUsage
))*nTerm
956 + sizeof(*pIdxOrderBy
)*nOrderBy
+ sizeof(*pHidden
) );
958 sqlite3ErrorMsg(pParse
, "out of memory");
961 pHidden
= (struct HiddenIndexInfo
*)&pIdxInfo
[1];
962 pIdxCons
= (struct sqlite3_index_constraint
*)&pHidden
[1];
963 pIdxOrderBy
= (struct sqlite3_index_orderby
*)&pIdxCons
[nTerm
];
964 pUsage
= (struct sqlite3_index_constraint_usage
*)&pIdxOrderBy
[nOrderBy
];
965 pIdxInfo
->nOrderBy
= nOrderBy
;
966 pIdxInfo
->aConstraint
= pIdxCons
;
967 pIdxInfo
->aOrderBy
= pIdxOrderBy
;
968 pIdxInfo
->aConstraintUsage
= pUsage
;
970 pHidden
->pParse
= pParse
;
971 for(i
=j
=0, pTerm
=pWC
->a
; i
<pWC
->nTerm
; i
++, pTerm
++){
973 if( pTerm
->leftCursor
!= pSrc
->iCursor
) continue;
974 if( pTerm
->prereqRight
& mUnusable
) continue;
975 assert( IsPowerOfTwo(pTerm
->eOperator
& ~WO_EQUIV
) );
976 testcase( pTerm
->eOperator
& WO_IN
);
977 testcase( pTerm
->eOperator
& WO_IS
);
978 testcase( pTerm
->eOperator
& WO_ISNULL
);
979 testcase( pTerm
->eOperator
& WO_ALL
);
980 if( (pTerm
->eOperator
& ~(WO_EQUIV
))==0 ) continue;
981 if( pTerm
->wtFlags
& TERM_VNULL
) continue;
983 /* tag-20191211-002: WHERE-clause constraints are not useful to the
984 ** right-hand table of a LEFT JOIN. See tag-20191211-001 for the
985 ** equivalent restriction for ordinary tables. */
986 if( (pSrc
->fg
.jointype
& JT_LEFT
)!=0
987 && !ExprHasProperty(pTerm
->pExpr
, EP_FromJoin
)
991 assert( pTerm
->u
.leftColumn
>=(-1) );
992 pIdxCons
[j
].iColumn
= pTerm
->u
.leftColumn
;
993 pIdxCons
[j
].iTermOffset
= i
;
994 op
= pTerm
->eOperator
& WO_ALL
;
995 if( op
==WO_IN
) op
= WO_EQ
;
997 pIdxCons
[j
].op
= pTerm
->eMatchOp
;
998 }else if( op
& (WO_ISNULL
|WO_IS
) ){
1000 pIdxCons
[j
].op
= SQLITE_INDEX_CONSTRAINT_ISNULL
;
1002 pIdxCons
[j
].op
= SQLITE_INDEX_CONSTRAINT_IS
;
1005 pIdxCons
[j
].op
= (u8
)op
;
1006 /* The direct assignment in the previous line is possible only because
1007 ** the WO_ and SQLITE_INDEX_CONSTRAINT_ codes are identical. The
1008 ** following asserts verify this fact. */
1009 assert( WO_EQ
==SQLITE_INDEX_CONSTRAINT_EQ
);
1010 assert( WO_LT
==SQLITE_INDEX_CONSTRAINT_LT
);
1011 assert( WO_LE
==SQLITE_INDEX_CONSTRAINT_LE
);
1012 assert( WO_GT
==SQLITE_INDEX_CONSTRAINT_GT
);
1013 assert( WO_GE
==SQLITE_INDEX_CONSTRAINT_GE
);
1014 assert( pTerm
->eOperator
&(WO_IN
|WO_EQ
|WO_LT
|WO_LE
|WO_GT
|WO_GE
|WO_AUX
) );
1016 if( op
& (WO_LT
|WO_LE
|WO_GT
|WO_GE
)
1017 && sqlite3ExprIsVector(pTerm
->pExpr
->pRight
)
1020 if( j
<16 ) mNoOmit
|= (1 << j
);
1021 if( op
==WO_LT
) pIdxCons
[j
].op
= WO_LE
;
1022 if( op
==WO_GT
) pIdxCons
[j
].op
= WO_GE
;
1028 pIdxInfo
->nConstraint
= j
;
1029 for(i
=0; i
<nOrderBy
; i
++){
1030 Expr
*pExpr
= pOrderBy
->a
[i
].pExpr
;
1031 pIdxOrderBy
[i
].iColumn
= pExpr
->iColumn
;
1032 pIdxOrderBy
[i
].desc
= pOrderBy
->a
[i
].sortFlags
& KEYINFO_ORDER_DESC
;
1035 *pmNoOmit
= mNoOmit
;
1040 ** The table object reference passed as the second argument to this function
1041 ** must represent a virtual table. This function invokes the xBestIndex()
1042 ** method of the virtual table with the sqlite3_index_info object that
1043 ** comes in as the 3rd argument to this function.
1045 ** If an error occurs, pParse is populated with an error message and an
1046 ** appropriate error code is returned. A return of SQLITE_CONSTRAINT from
1047 ** xBestIndex is not considered an error. SQLITE_CONSTRAINT indicates that
1048 ** the current configuration of "unusable" flags in sqlite3_index_info can
1049 ** not result in a valid plan.
1051 ** Whether or not an error is returned, it is the responsibility of the
1052 ** caller to eventually free p->idxStr if p->needToFreeIdxStr indicates
1053 ** that this is required.
1055 static int vtabBestIndex(Parse
*pParse
, Table
*pTab
, sqlite3_index_info
*p
){
1056 sqlite3_vtab
*pVtab
= sqlite3GetVTable(pParse
->db
, pTab
)->pVtab
;
1059 whereTraceIndexInfoInputs(p
);
1060 rc
= pVtab
->pModule
->xBestIndex(pVtab
, p
);
1061 whereTraceIndexInfoOutputs(p
);
1063 if( rc
!=SQLITE_OK
&& rc
!=SQLITE_CONSTRAINT
){
1064 if( rc
==SQLITE_NOMEM
){
1065 sqlite3OomFault(pParse
->db
);
1066 }else if( !pVtab
->zErrMsg
){
1067 sqlite3ErrorMsg(pParse
, "%s", sqlite3ErrStr(rc
));
1069 sqlite3ErrorMsg(pParse
, "%s", pVtab
->zErrMsg
);
1072 sqlite3_free(pVtab
->zErrMsg
);
1076 #endif /* !defined(SQLITE_OMIT_VIRTUALTABLE) */
1078 #ifdef SQLITE_ENABLE_STAT4
1080 ** Estimate the location of a particular key among all keys in an
1081 ** index. Store the results in aStat as follows:
1083 ** aStat[0] Est. number of rows less than pRec
1084 ** aStat[1] Est. number of rows equal to pRec
1086 ** Return the index of the sample that is the smallest sample that
1087 ** is greater than or equal to pRec. Note that this index is not an index
1088 ** into the aSample[] array - it is an index into a virtual set of samples
1089 ** based on the contents of aSample[] and the number of fields in record
1092 static int whereKeyStats(
1093 Parse
*pParse
, /* Database connection */
1094 Index
*pIdx
, /* Index to consider domain of */
1095 UnpackedRecord
*pRec
, /* Vector of values to consider */
1096 int roundUp
, /* Round up if true. Round down if false */
1097 tRowcnt
*aStat
/* OUT: stats written here */
1099 IndexSample
*aSample
= pIdx
->aSample
;
1100 int iCol
; /* Index of required stats in anEq[] etc. */
1101 int i
; /* Index of first sample >= pRec */
1102 int iSample
; /* Smallest sample larger than or equal to pRec */
1103 int iMin
= 0; /* Smallest sample not yet tested */
1104 int iTest
; /* Next sample to test */
1105 int res
; /* Result of comparison operation */
1106 int nField
; /* Number of fields in pRec */
1107 tRowcnt iLower
= 0; /* anLt[] + anEq[] of largest sample pRec is > */
1109 #ifndef SQLITE_DEBUG
1110 UNUSED_PARAMETER( pParse
);
1113 assert( pIdx
->nSample
>0 );
1114 assert( pRec
->nField
>0 && pRec
->nField
<=pIdx
->nSampleCol
);
1116 /* Do a binary search to find the first sample greater than or equal
1117 ** to pRec. If pRec contains a single field, the set of samples to search
1118 ** is simply the aSample[] array. If the samples in aSample[] contain more
1119 ** than one fields, all fields following the first are ignored.
1121 ** If pRec contains N fields, where N is more than one, then as well as the
1122 ** samples in aSample[] (truncated to N fields), the search also has to
1123 ** consider prefixes of those samples. For example, if the set of samples
1126 ** aSample[0] = (a, 5)
1127 ** aSample[1] = (a, 10)
1128 ** aSample[2] = (b, 5)
1129 ** aSample[3] = (c, 100)
1130 ** aSample[4] = (c, 105)
1132 ** Then the search space should ideally be the samples above and the
1133 ** unique prefixes [a], [b] and [c]. But since that is hard to organize,
1134 ** the code actually searches this set:
1147 ** For each sample in the aSample[] array, N samples are present in the
1148 ** effective sample array. In the above, samples 0 and 1 are based on
1149 ** sample aSample[0]. Samples 2 and 3 on aSample[1] etc.
1151 ** Often, sample i of each block of N effective samples has (i+1) fields.
1152 ** Except, each sample may be extended to ensure that it is greater than or
1153 ** equal to the previous sample in the array. For example, in the above,
1154 ** sample 2 is the first sample of a block of N samples, so at first it
1155 ** appears that it should be 1 field in size. However, that would make it
1156 ** smaller than sample 1, so the binary search would not work. As a result,
1157 ** it is extended to two fields. The duplicates that this creates do not
1158 ** cause any problems.
1160 nField
= pRec
->nField
;
1162 iSample
= pIdx
->nSample
* nField
;
1164 int iSamp
; /* Index in aSample[] of test sample */
1165 int n
; /* Number of fields in test sample */
1167 iTest
= (iMin
+iSample
)/2;
1168 iSamp
= iTest
/ nField
;
1170 /* The proposed effective sample is a prefix of sample aSample[iSamp].
1171 ** Specifically, the shortest prefix of at least (1 + iTest%nField)
1172 ** fields that is greater than the previous effective sample. */
1173 for(n
=(iTest
% nField
) + 1; n
<nField
; n
++){
1174 if( aSample
[iSamp
-1].anLt
[n
-1]!=aSample
[iSamp
].anLt
[n
-1] ) break;
1181 res
= sqlite3VdbeRecordCompare(aSample
[iSamp
].n
, aSample
[iSamp
].p
, pRec
);
1183 iLower
= aSample
[iSamp
].anLt
[n
-1] + aSample
[iSamp
].anEq
[n
-1];
1185 }else if( res
==0 && n
<nField
){
1186 iLower
= aSample
[iSamp
].anLt
[n
-1];
1193 }while( res
&& iMin
<iSample
);
1194 i
= iSample
/ nField
;
1197 /* The following assert statements check that the binary search code
1198 ** above found the right answer. This block serves no purpose other
1199 ** than to invoke the asserts. */
1200 if( pParse
->db
->mallocFailed
==0 ){
1202 /* If (res==0) is true, then pRec must be equal to sample i. */
1203 assert( i
<pIdx
->nSample
);
1204 assert( iCol
==nField
-1 );
1205 pRec
->nField
= nField
;
1206 assert( 0==sqlite3VdbeRecordCompare(aSample
[i
].n
, aSample
[i
].p
, pRec
)
1207 || pParse
->db
->mallocFailed
1210 /* Unless i==pIdx->nSample, indicating that pRec is larger than
1211 ** all samples in the aSample[] array, pRec must be smaller than the
1212 ** (iCol+1) field prefix of sample i. */
1213 assert( i
<=pIdx
->nSample
&& i
>=0 );
1214 pRec
->nField
= iCol
+1;
1215 assert( i
==pIdx
->nSample
1216 || sqlite3VdbeRecordCompare(aSample
[i
].n
, aSample
[i
].p
, pRec
)>0
1217 || pParse
->db
->mallocFailed
);
1219 /* if i==0 and iCol==0, then record pRec is smaller than all samples
1220 ** in the aSample[] array. Otherwise, if (iCol>0) then pRec must
1221 ** be greater than or equal to the (iCol) field prefix of sample i.
1222 ** If (i>0), then pRec must also be greater than sample (i-1). */
1224 pRec
->nField
= iCol
;
1225 assert( sqlite3VdbeRecordCompare(aSample
[i
].n
, aSample
[i
].p
, pRec
)<=0
1226 || pParse
->db
->mallocFailed
);
1229 pRec
->nField
= nField
;
1230 assert( sqlite3VdbeRecordCompare(aSample
[i
-1].n
, aSample
[i
-1].p
, pRec
)<0
1231 || pParse
->db
->mallocFailed
);
1235 #endif /* ifdef SQLITE_DEBUG */
1238 /* Record pRec is equal to sample i */
1239 assert( iCol
==nField
-1 );
1240 aStat
[0] = aSample
[i
].anLt
[iCol
];
1241 aStat
[1] = aSample
[i
].anEq
[iCol
];
1243 /* At this point, the (iCol+1) field prefix of aSample[i] is the first
1244 ** sample that is greater than pRec. Or, if i==pIdx->nSample then pRec
1245 ** is larger than all samples in the array. */
1246 tRowcnt iUpper
, iGap
;
1247 if( i
>=pIdx
->nSample
){
1248 iUpper
= sqlite3LogEstToInt(pIdx
->aiRowLogEst
[0]);
1250 iUpper
= aSample
[i
].anLt
[iCol
];
1253 if( iLower
>=iUpper
){
1256 iGap
= iUpper
- iLower
;
1263 aStat
[0] = iLower
+ iGap
;
1264 aStat
[1] = pIdx
->aAvgEq
[nField
-1];
1267 /* Restore the pRec->nField value before returning. */
1268 pRec
->nField
= nField
;
1271 #endif /* SQLITE_ENABLE_STAT4 */
1274 ** If it is not NULL, pTerm is a term that provides an upper or lower
1275 ** bound on a range scan. Without considering pTerm, it is estimated
1276 ** that the scan will visit nNew rows. This function returns the number
1277 ** estimated to be visited after taking pTerm into account.
1279 ** If the user explicitly specified a likelihood() value for this term,
1280 ** then the return value is the likelihood multiplied by the number of
1281 ** input rows. Otherwise, this function assumes that an "IS NOT NULL" term
1282 ** has a likelihood of 0.50, and any other term a likelihood of 0.25.
1284 static LogEst
whereRangeAdjust(WhereTerm
*pTerm
, LogEst nNew
){
1287 if( pTerm
->truthProb
<=0 ){
1288 nRet
+= pTerm
->truthProb
;
1289 }else if( (pTerm
->wtFlags
& TERM_VNULL
)==0 ){
1290 nRet
-= 20; assert( 20==sqlite3LogEst(4) );
1297 #ifdef SQLITE_ENABLE_STAT4
1299 ** Return the affinity for a single column of an index.
1301 char sqlite3IndexColumnAffinity(sqlite3
*db
, Index
*pIdx
, int iCol
){
1302 assert( iCol
>=0 && iCol
<pIdx
->nColumn
);
1303 if( !pIdx
->zColAff
){
1304 if( sqlite3IndexAffinityStr(db
, pIdx
)==0 ) return SQLITE_AFF_BLOB
;
1306 assert( pIdx
->zColAff
[iCol
]!=0 );
1307 return pIdx
->zColAff
[iCol
];
1312 #ifdef SQLITE_ENABLE_STAT4
1314 ** This function is called to estimate the number of rows visited by a
1315 ** range-scan on a skip-scan index. For example:
1317 ** CREATE INDEX i1 ON t1(a, b, c);
1318 ** SELECT * FROM t1 WHERE a=? AND c BETWEEN ? AND ?;
1320 ** Value pLoop->nOut is currently set to the estimated number of rows
1321 ** visited for scanning (a=? AND b=?). This function reduces that estimate
1322 ** by some factor to account for the (c BETWEEN ? AND ?) expression based
1323 ** on the stat4 data for the index. this scan will be peformed multiple
1324 ** times (once for each (a,b) combination that matches a=?) is dealt with
1327 ** It does this by scanning through all stat4 samples, comparing values
1328 ** extracted from pLower and pUpper with the corresponding column in each
1329 ** sample. If L and U are the number of samples found to be less than or
1330 ** equal to the values extracted from pLower and pUpper respectively, and
1331 ** N is the total number of samples, the pLoop->nOut value is adjusted
1334 ** nOut = nOut * ( min(U - L, 1) / N )
1336 ** If pLower is NULL, or a value cannot be extracted from the term, L is
1337 ** set to zero. If pUpper is NULL, or a value cannot be extracted from it,
1340 ** Normally, this function sets *pbDone to 1 before returning. However,
1341 ** if no value can be extracted from either pLower or pUpper (and so the
1342 ** estimate of the number of rows delivered remains unchanged), *pbDone
1345 ** If an error occurs, an SQLite error code is returned. Otherwise,
1348 static int whereRangeSkipScanEst(
1349 Parse
*pParse
, /* Parsing & code generating context */
1350 WhereTerm
*pLower
, /* Lower bound on the range. ex: "x>123" Might be NULL */
1351 WhereTerm
*pUpper
, /* Upper bound on the range. ex: "x<455" Might be NULL */
1352 WhereLoop
*pLoop
, /* Update the .nOut value of this loop */
1353 int *pbDone
/* Set to true if at least one expr. value extracted */
1355 Index
*p
= pLoop
->u
.btree
.pIndex
;
1356 int nEq
= pLoop
->u
.btree
.nEq
;
1357 sqlite3
*db
= pParse
->db
;
1359 int nUpper
= p
->nSample
+1;
1361 u8 aff
= sqlite3IndexColumnAffinity(db
, p
, nEq
);
1364 sqlite3_value
*p1
= 0; /* Value extracted from pLower */
1365 sqlite3_value
*p2
= 0; /* Value extracted from pUpper */
1366 sqlite3_value
*pVal
= 0; /* Value extracted from record */
1368 pColl
= sqlite3LocateCollSeq(pParse
, p
->azColl
[nEq
]);
1370 rc
= sqlite3Stat4ValueFromExpr(pParse
, pLower
->pExpr
->pRight
, aff
, &p1
);
1373 if( pUpper
&& rc
==SQLITE_OK
){
1374 rc
= sqlite3Stat4ValueFromExpr(pParse
, pUpper
->pExpr
->pRight
, aff
, &p2
);
1375 nUpper
= p2
? 0 : p
->nSample
;
1381 for(i
=0; rc
==SQLITE_OK
&& i
<p
->nSample
; i
++){
1382 rc
= sqlite3Stat4Column(db
, p
->aSample
[i
].p
, p
->aSample
[i
].n
, nEq
, &pVal
);
1383 if( rc
==SQLITE_OK
&& p1
){
1384 int res
= sqlite3MemCompare(p1
, pVal
, pColl
);
1385 if( res
>=0 ) nLower
++;
1387 if( rc
==SQLITE_OK
&& p2
){
1388 int res
= sqlite3MemCompare(p2
, pVal
, pColl
);
1389 if( res
>=0 ) nUpper
++;
1392 nDiff
= (nUpper
- nLower
);
1393 if( nDiff
<=0 ) nDiff
= 1;
1395 /* If there is both an upper and lower bound specified, and the
1396 ** comparisons indicate that they are close together, use the fallback
1397 ** method (assume that the scan visits 1/64 of the rows) for estimating
1398 ** the number of rows visited. Otherwise, estimate the number of rows
1399 ** using the method described in the header comment for this function. */
1400 if( nDiff
!=1 || pUpper
==0 || pLower
==0 ){
1401 int nAdjust
= (sqlite3LogEst(p
->nSample
) - sqlite3LogEst(nDiff
));
1402 pLoop
->nOut
-= nAdjust
;
1404 WHERETRACE(0x10, ("range skip-scan regions: %u..%u adjust=%d est=%d\n",
1405 nLower
, nUpper
, nAdjust
*-1, pLoop
->nOut
));
1409 assert( *pbDone
==0 );
1412 sqlite3ValueFree(p1
);
1413 sqlite3ValueFree(p2
);
1414 sqlite3ValueFree(pVal
);
1418 #endif /* SQLITE_ENABLE_STAT4 */
1421 ** This function is used to estimate the number of rows that will be visited
1422 ** by scanning an index for a range of values. The range may have an upper
1423 ** bound, a lower bound, or both. The WHERE clause terms that set the upper
1424 ** and lower bounds are represented by pLower and pUpper respectively. For
1425 ** example, assuming that index p is on t1(a):
1427 ** ... FROM t1 WHERE a > ? AND a < ? ...
1432 ** If either of the upper or lower bound is not present, then NULL is passed in
1433 ** place of the corresponding WhereTerm.
1435 ** The value in (pBuilder->pNew->u.btree.nEq) is the number of the index
1436 ** column subject to the range constraint. Or, equivalently, the number of
1437 ** equality constraints optimized by the proposed index scan. For example,
1438 ** assuming index p is on t1(a, b), and the SQL query is:
1440 ** ... FROM t1 WHERE a = ? AND b > ? AND b < ? ...
1442 ** then nEq is set to 1 (as the range restricted column, b, is the second
1443 ** left-most column of the index). Or, if the query is:
1445 ** ... FROM t1 WHERE a > ? AND a < ? ...
1447 ** then nEq is set to 0.
1449 ** When this function is called, *pnOut is set to the sqlite3LogEst() of the
1450 ** number of rows that the index scan is expected to visit without
1451 ** considering the range constraints. If nEq is 0, then *pnOut is the number of
1452 ** rows in the index. Assuming no error occurs, *pnOut is adjusted (reduced)
1453 ** to account for the range constraints pLower and pUpper.
1455 ** In the absence of sqlite_stat4 ANALYZE data, or if such data cannot be
1456 ** used, a single range inequality reduces the search space by a factor of 4.
1457 ** and a pair of constraints (x>? AND x<?) reduces the expected number of
1458 ** rows visited by a factor of 64.
1460 static int whereRangeScanEst(
1461 Parse
*pParse
, /* Parsing & code generating context */
1462 WhereLoopBuilder
*pBuilder
,
1463 WhereTerm
*pLower
, /* Lower bound on the range. ex: "x>123" Might be NULL */
1464 WhereTerm
*pUpper
, /* Upper bound on the range. ex: "x<455" Might be NULL */
1465 WhereLoop
*pLoop
/* Modify the .nOut and maybe .rRun fields */
1468 int nOut
= pLoop
->nOut
;
1471 #ifdef SQLITE_ENABLE_STAT4
1472 Index
*p
= pLoop
->u
.btree
.pIndex
;
1473 int nEq
= pLoop
->u
.btree
.nEq
;
1475 if( p
->nSample
>0 && ALWAYS(nEq
<p
->nSampleCol
)
1476 && OptimizationEnabled(pParse
->db
, SQLITE_Stat4
)
1478 if( nEq
==pBuilder
->nRecValid
){
1479 UnpackedRecord
*pRec
= pBuilder
->pRec
;
1481 int nBtm
= pLoop
->u
.btree
.nBtm
;
1482 int nTop
= pLoop
->u
.btree
.nTop
;
1484 /* Variable iLower will be set to the estimate of the number of rows in
1485 ** the index that are less than the lower bound of the range query. The
1486 ** lower bound being the concatenation of $P and $L, where $P is the
1487 ** key-prefix formed by the nEq values matched against the nEq left-most
1488 ** columns of the index, and $L is the value in pLower.
1490 ** Or, if pLower is NULL or $L cannot be extracted from it (because it
1491 ** is not a simple variable or literal value), the lower bound of the
1492 ** range is $P. Due to a quirk in the way whereKeyStats() works, even
1493 ** if $L is available, whereKeyStats() is called for both ($P) and
1494 ** ($P:$L) and the larger of the two returned values is used.
1496 ** Similarly, iUpper is to be set to the estimate of the number of rows
1497 ** less than the upper bound of the range query. Where the upper bound
1498 ** is either ($P) or ($P:$U). Again, even if $U is available, both values
1499 ** of iUpper are requested of whereKeyStats() and the smaller used.
1501 ** The number of rows between the two bounds is then just iUpper-iLower.
1503 tRowcnt iLower
; /* Rows less than the lower bound */
1504 tRowcnt iUpper
; /* Rows less than the upper bound */
1505 int iLwrIdx
= -2; /* aSample[] for the lower bound */
1506 int iUprIdx
= -1; /* aSample[] for the upper bound */
1509 testcase( pRec
->nField
!=pBuilder
->nRecValid
);
1510 pRec
->nField
= pBuilder
->nRecValid
;
1512 /* Determine iLower and iUpper using ($P) only. */
1515 iUpper
= p
->nRowEst0
;
1517 /* Note: this call could be optimized away - since the same values must
1518 ** have been requested when testing key $P in whereEqualScanEst(). */
1519 whereKeyStats(pParse
, p
, pRec
, 0, a
);
1521 iUpper
= a
[0] + a
[1];
1524 assert( pLower
==0 || (pLower
->eOperator
& (WO_GT
|WO_GE
))!=0 );
1525 assert( pUpper
==0 || (pUpper
->eOperator
& (WO_LT
|WO_LE
))!=0 );
1526 assert( p
->aSortOrder
!=0 );
1527 if( p
->aSortOrder
[nEq
] ){
1528 /* The roles of pLower and pUpper are swapped for a DESC index */
1529 SWAP(WhereTerm
*, pLower
, pUpper
);
1530 SWAP(int, nBtm
, nTop
);
1533 /* If possible, improve on the iLower estimate using ($P:$L). */
1535 int n
; /* Values extracted from pExpr */
1536 Expr
*pExpr
= pLower
->pExpr
->pRight
;
1537 rc
= sqlite3Stat4ProbeSetValue(pParse
, p
, &pRec
, pExpr
, nBtm
, nEq
, &n
);
1538 if( rc
==SQLITE_OK
&& n
){
1540 u16 mask
= WO_GT
|WO_LE
;
1541 if( sqlite3ExprVectorSize(pExpr
)>n
) mask
= (WO_LE
|WO_LT
);
1542 iLwrIdx
= whereKeyStats(pParse
, p
, pRec
, 0, a
);
1543 iNew
= a
[0] + ((pLower
->eOperator
& mask
) ? a
[1] : 0);
1544 if( iNew
>iLower
) iLower
= iNew
;
1550 /* If possible, improve on the iUpper estimate using ($P:$U). */
1552 int n
; /* Values extracted from pExpr */
1553 Expr
*pExpr
= pUpper
->pExpr
->pRight
;
1554 rc
= sqlite3Stat4ProbeSetValue(pParse
, p
, &pRec
, pExpr
, nTop
, nEq
, &n
);
1555 if( rc
==SQLITE_OK
&& n
){
1557 u16 mask
= WO_GT
|WO_LE
;
1558 if( sqlite3ExprVectorSize(pExpr
)>n
) mask
= (WO_LE
|WO_LT
);
1559 iUprIdx
= whereKeyStats(pParse
, p
, pRec
, 1, a
);
1560 iNew
= a
[0] + ((pUpper
->eOperator
& mask
) ? a
[1] : 0);
1561 if( iNew
<iUpper
) iUpper
= iNew
;
1567 pBuilder
->pRec
= pRec
;
1568 if( rc
==SQLITE_OK
){
1569 if( iUpper
>iLower
){
1570 nNew
= sqlite3LogEst(iUpper
- iLower
);
1571 /* TUNING: If both iUpper and iLower are derived from the same
1572 ** sample, then assume they are 4x more selective. This brings
1573 ** the estimated selectivity more in line with what it would be
1574 ** if estimated without the use of STAT4 tables. */
1575 if( iLwrIdx
==iUprIdx
) nNew
-= 20; assert( 20==sqlite3LogEst(4) );
1577 nNew
= 10; assert( 10==sqlite3LogEst(2) );
1582 WHERETRACE(0x10, ("STAT4 range scan: %u..%u est=%d\n",
1583 (u32
)iLower
, (u32
)iUpper
, nOut
));
1587 rc
= whereRangeSkipScanEst(pParse
, pLower
, pUpper
, pLoop
, &bDone
);
1588 if( bDone
) return rc
;
1592 UNUSED_PARAMETER(pParse
);
1593 UNUSED_PARAMETER(pBuilder
);
1594 assert( pLower
|| pUpper
);
1596 assert( pUpper
==0 || (pUpper
->wtFlags
& TERM_VNULL
)==0 );
1597 nNew
= whereRangeAdjust(pLower
, nOut
);
1598 nNew
= whereRangeAdjust(pUpper
, nNew
);
1600 /* TUNING: If there is both an upper and lower limit and neither limit
1601 ** has an application-defined likelihood(), assume the range is
1602 ** reduced by an additional 75%. This means that, by default, an open-ended
1603 ** range query (e.g. col > ?) is assumed to match 1/4 of the rows in the
1604 ** index. While a closed range (e.g. col BETWEEN ? AND ?) is estimated to
1605 ** match 1/64 of the index. */
1606 if( pLower
&& pLower
->truthProb
>0 && pUpper
&& pUpper
->truthProb
>0 ){
1610 nOut
-= (pLower
!=0) + (pUpper
!=0);
1611 if( nNew
<10 ) nNew
= 10;
1612 if( nNew
<nOut
) nOut
= nNew
;
1613 #if defined(WHERETRACE_ENABLED)
1614 if( pLoop
->nOut
>nOut
){
1615 WHERETRACE(0x10,("Range scan lowers nOut from %d to %d\n",
1616 pLoop
->nOut
, nOut
));
1619 pLoop
->nOut
= (LogEst
)nOut
;
1623 #ifdef SQLITE_ENABLE_STAT4
1625 ** Estimate the number of rows that will be returned based on
1626 ** an equality constraint x=VALUE and where that VALUE occurs in
1627 ** the histogram data. This only works when x is the left-most
1628 ** column of an index and sqlite_stat4 histogram data is available
1629 ** for that index. When pExpr==NULL that means the constraint is
1630 ** "x IS NULL" instead of "x=VALUE".
1632 ** Write the estimated row count into *pnRow and return SQLITE_OK.
1633 ** If unable to make an estimate, leave *pnRow unchanged and return
1636 ** This routine can fail if it is unable to load a collating sequence
1637 ** required for string comparison, or if unable to allocate memory
1638 ** for a UTF conversion required for comparison. The error is stored
1639 ** in the pParse structure.
1641 static int whereEqualScanEst(
1642 Parse
*pParse
, /* Parsing & code generating context */
1643 WhereLoopBuilder
*pBuilder
,
1644 Expr
*pExpr
, /* Expression for VALUE in the x=VALUE constraint */
1645 tRowcnt
*pnRow
/* Write the revised row estimate here */
1647 Index
*p
= pBuilder
->pNew
->u
.btree
.pIndex
;
1648 int nEq
= pBuilder
->pNew
->u
.btree
.nEq
;
1649 UnpackedRecord
*pRec
= pBuilder
->pRec
;
1650 int rc
; /* Subfunction return code */
1651 tRowcnt a
[2]; /* Statistics */
1655 assert( nEq
<=p
->nColumn
);
1656 assert( p
->aSample
!=0 );
1657 assert( p
->nSample
>0 );
1658 assert( pBuilder
->nRecValid
<nEq
);
1660 /* If values are not available for all fields of the index to the left
1661 ** of this one, no estimate can be made. Return SQLITE_NOTFOUND. */
1662 if( pBuilder
->nRecValid
<(nEq
-1) ){
1663 return SQLITE_NOTFOUND
;
1666 /* This is an optimization only. The call to sqlite3Stat4ProbeSetValue()
1667 ** below would return the same value. */
1668 if( nEq
>=p
->nColumn
){
1673 rc
= sqlite3Stat4ProbeSetValue(pParse
, p
, &pRec
, pExpr
, 1, nEq
-1, &bOk
);
1674 pBuilder
->pRec
= pRec
;
1675 if( rc
!=SQLITE_OK
) return rc
;
1676 if( bOk
==0 ) return SQLITE_NOTFOUND
;
1677 pBuilder
->nRecValid
= nEq
;
1679 whereKeyStats(pParse
, p
, pRec
, 0, a
);
1680 WHERETRACE(0x10,("equality scan regions %s(%d): %d\n",
1681 p
->zName
, nEq
-1, (int)a
[1]));
1686 #endif /* SQLITE_ENABLE_STAT4 */
1688 #ifdef SQLITE_ENABLE_STAT4
1690 ** Estimate the number of rows that will be returned based on
1691 ** an IN constraint where the right-hand side of the IN operator
1692 ** is a list of values. Example:
1694 ** WHERE x IN (1,2,3,4)
1696 ** Write the estimated row count into *pnRow and return SQLITE_OK.
1697 ** If unable to make an estimate, leave *pnRow unchanged and return
1700 ** This routine can fail if it is unable to load a collating sequence
1701 ** required for string comparison, or if unable to allocate memory
1702 ** for a UTF conversion required for comparison. The error is stored
1703 ** in the pParse structure.
1705 static int whereInScanEst(
1706 Parse
*pParse
, /* Parsing & code generating context */
1707 WhereLoopBuilder
*pBuilder
,
1708 ExprList
*pList
, /* The value list on the RHS of "x IN (v1,v2,v3,...)" */
1709 tRowcnt
*pnRow
/* Write the revised row estimate here */
1711 Index
*p
= pBuilder
->pNew
->u
.btree
.pIndex
;
1712 i64 nRow0
= sqlite3LogEstToInt(p
->aiRowLogEst
[0]);
1713 int nRecValid
= pBuilder
->nRecValid
;
1714 int rc
= SQLITE_OK
; /* Subfunction return code */
1715 tRowcnt nEst
; /* Number of rows for a single term */
1716 tRowcnt nRowEst
= 0; /* New estimate of the number of rows */
1717 int i
; /* Loop counter */
1719 assert( p
->aSample
!=0 );
1720 for(i
=0; rc
==SQLITE_OK
&& i
<pList
->nExpr
; i
++){
1722 rc
= whereEqualScanEst(pParse
, pBuilder
, pList
->a
[i
].pExpr
, &nEst
);
1724 pBuilder
->nRecValid
= nRecValid
;
1727 if( rc
==SQLITE_OK
){
1728 if( nRowEst
> nRow0
) nRowEst
= nRow0
;
1730 WHERETRACE(0x10,("IN row estimate: est=%d\n", nRowEst
));
1732 assert( pBuilder
->nRecValid
==nRecValid
);
1735 #endif /* SQLITE_ENABLE_STAT4 */
1738 #ifdef WHERETRACE_ENABLED
1740 ** Print the content of a WhereTerm object
1742 void sqlite3WhereTermPrint(WhereTerm
*pTerm
, int iTerm
){
1744 sqlite3DebugPrintf("TERM-%-3d NULL\n", iTerm
);
1748 memcpy(zType
, "....", 5);
1749 if( pTerm
->wtFlags
& TERM_VIRTUAL
) zType
[0] = 'V';
1750 if( pTerm
->eOperator
& WO_EQUIV
) zType
[1] = 'E';
1751 if( ExprHasProperty(pTerm
->pExpr
, EP_FromJoin
) ) zType
[2] = 'L';
1752 if( pTerm
->wtFlags
& TERM_CODED
) zType
[3] = 'C';
1753 if( pTerm
->eOperator
& WO_SINGLE
){
1754 sqlite3_snprintf(sizeof(zLeft
),zLeft
,"left={%d:%d}",
1755 pTerm
->leftCursor
, pTerm
->u
.leftColumn
);
1756 }else if( (pTerm
->eOperator
& WO_OR
)!=0 && pTerm
->u
.pOrInfo
!=0 ){
1757 sqlite3_snprintf(sizeof(zLeft
),zLeft
,"indexable=0x%lld",
1758 pTerm
->u
.pOrInfo
->indexable
);
1760 sqlite3_snprintf(sizeof(zLeft
),zLeft
,"left=%d", pTerm
->leftCursor
);
1763 "TERM-%-3d %p %s %-12s op=%03x wtFlags=%04x",
1764 iTerm
, pTerm
, zType
, zLeft
, pTerm
->eOperator
, pTerm
->wtFlags
);
1765 /* The 0x10000 .wheretrace flag causes extra information to be
1766 ** shown about each Term */
1767 if( sqlite3WhereTrace
& 0x10000 ){
1768 sqlite3DebugPrintf(" prob=%-3d prereq=%llx,%llx",
1769 pTerm
->truthProb
, (u64
)pTerm
->prereqAll
, (u64
)pTerm
->prereqRight
);
1771 if( pTerm
->iField
){
1772 sqlite3DebugPrintf(" iField=%d", pTerm
->iField
);
1774 if( pTerm
->iParent
>=0 ){
1775 sqlite3DebugPrintf(" iParent=%d", pTerm
->iParent
);
1777 sqlite3DebugPrintf("\n");
1778 sqlite3TreeViewExpr(0, pTerm
->pExpr
, 0);
1783 #ifdef WHERETRACE_ENABLED
1785 ** Show the complete content of a WhereClause
1787 void sqlite3WhereClausePrint(WhereClause
*pWC
){
1789 for(i
=0; i
<pWC
->nTerm
; i
++){
1790 sqlite3WhereTermPrint(&pWC
->a
[i
], i
);
1795 #ifdef WHERETRACE_ENABLED
1797 ** Print a WhereLoop object for debugging purposes
1799 void sqlite3WhereLoopPrint(WhereLoop
*p
, WhereClause
*pWC
){
1800 WhereInfo
*pWInfo
= pWC
->pWInfo
;
1801 int nb
= 1+(pWInfo
->pTabList
->nSrc
+3)/4;
1802 struct SrcList_item
*pItem
= pWInfo
->pTabList
->a
+ p
->iTab
;
1803 Table
*pTab
= pItem
->pTab
;
1804 Bitmask mAll
= (((Bitmask
)1)<<(nb
*4)) - 1;
1805 sqlite3DebugPrintf("%c%2d.%0*llx.%0*llx", p
->cId
,
1806 p
->iTab
, nb
, p
->maskSelf
, nb
, p
->prereq
& mAll
);
1807 sqlite3DebugPrintf(" %12s",
1808 pItem
->zAlias
? pItem
->zAlias
: pTab
->zName
);
1809 if( (p
->wsFlags
& WHERE_VIRTUALTABLE
)==0 ){
1811 if( p
->u
.btree
.pIndex
&& (zName
= p
->u
.btree
.pIndex
->zName
)!=0 ){
1812 if( strncmp(zName
, "sqlite_autoindex_", 17)==0 ){
1813 int i
= sqlite3Strlen30(zName
) - 1;
1814 while( zName
[i
]!='_' ) i
--;
1817 sqlite3DebugPrintf(".%-16s %2d", zName
, p
->u
.btree
.nEq
);
1819 sqlite3DebugPrintf("%20s","");
1823 if( p
->u
.vtab
.idxStr
){
1824 z
= sqlite3_mprintf("(%d,\"%s\",%#x)",
1825 p
->u
.vtab
.idxNum
, p
->u
.vtab
.idxStr
, p
->u
.vtab
.omitMask
);
1827 z
= sqlite3_mprintf("(%d,%x)", p
->u
.vtab
.idxNum
, p
->u
.vtab
.omitMask
);
1829 sqlite3DebugPrintf(" %-19s", z
);
1832 if( p
->wsFlags
& WHERE_SKIPSCAN
){
1833 sqlite3DebugPrintf(" f %05x %d-%d", p
->wsFlags
, p
->nLTerm
,p
->nSkip
);
1835 sqlite3DebugPrintf(" f %05x N %d", p
->wsFlags
, p
->nLTerm
);
1837 sqlite3DebugPrintf(" cost %d,%d,%d\n", p
->rSetup
, p
->rRun
, p
->nOut
);
1838 if( p
->nLTerm
&& (sqlite3WhereTrace
& 0x100)!=0 ){
1840 for(i
=0; i
<p
->nLTerm
; i
++){
1841 sqlite3WhereTermPrint(p
->aLTerm
[i
], i
);
1848 ** Convert bulk memory into a valid WhereLoop that can be passed
1849 ** to whereLoopClear harmlessly.
1851 static void whereLoopInit(WhereLoop
*p
){
1852 p
->aLTerm
= p
->aLTermSpace
;
1854 p
->nLSlot
= ArraySize(p
->aLTermSpace
);
1859 ** Clear the WhereLoop.u union. Leave WhereLoop.pLTerm intact.
1861 static void whereLoopClearUnion(sqlite3
*db
, WhereLoop
*p
){
1862 if( p
->wsFlags
& (WHERE_VIRTUALTABLE
|WHERE_AUTO_INDEX
) ){
1863 if( (p
->wsFlags
& WHERE_VIRTUALTABLE
)!=0 && p
->u
.vtab
.needFree
){
1864 sqlite3_free(p
->u
.vtab
.idxStr
);
1865 p
->u
.vtab
.needFree
= 0;
1866 p
->u
.vtab
.idxStr
= 0;
1867 }else if( (p
->wsFlags
& WHERE_AUTO_INDEX
)!=0 && p
->u
.btree
.pIndex
!=0 ){
1868 sqlite3DbFree(db
, p
->u
.btree
.pIndex
->zColAff
);
1869 sqlite3DbFreeNN(db
, p
->u
.btree
.pIndex
);
1870 p
->u
.btree
.pIndex
= 0;
1876 ** Deallocate internal memory used by a WhereLoop object
1878 static void whereLoopClear(sqlite3
*db
, WhereLoop
*p
){
1879 if( p
->aLTerm
!=p
->aLTermSpace
) sqlite3DbFreeNN(db
, p
->aLTerm
);
1880 whereLoopClearUnion(db
, p
);
1885 ** Increase the memory allocation for pLoop->aLTerm[] to be at least n.
1887 static int whereLoopResize(sqlite3
*db
, WhereLoop
*p
, int n
){
1889 if( p
->nLSlot
>=n
) return SQLITE_OK
;
1891 paNew
= sqlite3DbMallocRawNN(db
, sizeof(p
->aLTerm
[0])*n
);
1892 if( paNew
==0 ) return SQLITE_NOMEM_BKPT
;
1893 memcpy(paNew
, p
->aLTerm
, sizeof(p
->aLTerm
[0])*p
->nLSlot
);
1894 if( p
->aLTerm
!=p
->aLTermSpace
) sqlite3DbFreeNN(db
, p
->aLTerm
);
1901 ** Transfer content from the second pLoop into the first.
1903 static int whereLoopXfer(sqlite3
*db
, WhereLoop
*pTo
, WhereLoop
*pFrom
){
1904 whereLoopClearUnion(db
, pTo
);
1905 if( whereLoopResize(db
, pTo
, pFrom
->nLTerm
) ){
1906 memset(&pTo
->u
, 0, sizeof(pTo
->u
));
1907 return SQLITE_NOMEM_BKPT
;
1909 memcpy(pTo
, pFrom
, WHERE_LOOP_XFER_SZ
);
1910 memcpy(pTo
->aLTerm
, pFrom
->aLTerm
, pTo
->nLTerm
*sizeof(pTo
->aLTerm
[0]));
1911 if( pFrom
->wsFlags
& WHERE_VIRTUALTABLE
){
1912 pFrom
->u
.vtab
.needFree
= 0;
1913 }else if( (pFrom
->wsFlags
& WHERE_AUTO_INDEX
)!=0 ){
1914 pFrom
->u
.btree
.pIndex
= 0;
1920 ** Delete a WhereLoop object
1922 static void whereLoopDelete(sqlite3
*db
, WhereLoop
*p
){
1923 whereLoopClear(db
, p
);
1924 sqlite3DbFreeNN(db
, p
);
1928 ** Free a WhereInfo structure
1930 static void whereInfoFree(sqlite3
*db
, WhereInfo
*pWInfo
){
1932 assert( pWInfo
!=0 );
1933 for(i
=0; i
<pWInfo
->nLevel
; i
++){
1934 WhereLevel
*pLevel
= &pWInfo
->a
[i
];
1935 if( pLevel
->pWLoop
&& (pLevel
->pWLoop
->wsFlags
& WHERE_IN_ABLE
) ){
1936 sqlite3DbFree(db
, pLevel
->u
.in
.aInLoop
);
1939 sqlite3WhereClauseClear(&pWInfo
->sWC
);
1940 while( pWInfo
->pLoops
){
1941 WhereLoop
*p
= pWInfo
->pLoops
;
1942 pWInfo
->pLoops
= p
->pNextLoop
;
1943 whereLoopDelete(db
, p
);
1945 assert( pWInfo
->pExprMods
==0 );
1946 sqlite3DbFreeNN(db
, pWInfo
);
1950 ** Return TRUE if all of the following are true:
1952 ** (1) X has the same or lower cost that Y
1953 ** (2) X uses fewer WHERE clause terms than Y
1954 ** (3) Every WHERE clause term used by X is also used by Y
1955 ** (4) X skips at least as many columns as Y
1956 ** (5) If X is a covering index, than Y is too
1958 ** Conditions (2) and (3) mean that X is a "proper subset" of Y.
1959 ** If X is a proper subset of Y then Y is a better choice and ought
1960 ** to have a lower cost. This routine returns TRUE when that cost
1961 ** relationship is inverted and needs to be adjusted. Constraint (4)
1962 ** was added because if X uses skip-scan less than Y it still might
1963 ** deserve a lower cost even if it is a proper subset of Y. Constraint (5)
1964 ** was added because a covering index probably deserves to have a lower cost
1965 ** than a non-covering index even if it is a proper subset.
1967 static int whereLoopCheaperProperSubset(
1968 const WhereLoop
*pX
, /* First WhereLoop to compare */
1969 const WhereLoop
*pY
/* Compare against this WhereLoop */
1972 if( pX
->nLTerm
-pX
->nSkip
>= pY
->nLTerm
-pY
->nSkip
){
1973 return 0; /* X is not a subset of Y */
1975 if( pY
->nSkip
> pX
->nSkip
) return 0;
1976 if( pX
->rRun
>= pY
->rRun
){
1977 if( pX
->rRun
> pY
->rRun
) return 0; /* X costs more than Y */
1978 if( pX
->nOut
> pY
->nOut
) return 0; /* X costs more than Y */
1980 for(i
=pX
->nLTerm
-1; i
>=0; i
--){
1981 if( pX
->aLTerm
[i
]==0 ) continue;
1982 for(j
=pY
->nLTerm
-1; j
>=0; j
--){
1983 if( pY
->aLTerm
[j
]==pX
->aLTerm
[i
] ) break;
1985 if( j
<0 ) return 0; /* X not a subset of Y since term X[i] not used by Y */
1987 if( (pX
->wsFlags
&WHERE_IDX_ONLY
)!=0
1988 && (pY
->wsFlags
&WHERE_IDX_ONLY
)==0 ){
1989 return 0; /* Constraint (5) */
1991 return 1; /* All conditions meet */
1995 ** Try to adjust the cost of WhereLoop pTemplate upwards or downwards so
1998 ** (1) pTemplate costs less than any other WhereLoops that are a proper
1999 ** subset of pTemplate
2001 ** (2) pTemplate costs more than any other WhereLoops for which pTemplate
2002 ** is a proper subset.
2004 ** To say "WhereLoop X is a proper subset of Y" means that X uses fewer
2005 ** WHERE clause terms than Y and that every WHERE clause term used by X is
2008 static void whereLoopAdjustCost(const WhereLoop
*p
, WhereLoop
*pTemplate
){
2009 if( (pTemplate
->wsFlags
& WHERE_INDEXED
)==0 ) return;
2010 for(; p
; p
=p
->pNextLoop
){
2011 if( p
->iTab
!=pTemplate
->iTab
) continue;
2012 if( (p
->wsFlags
& WHERE_INDEXED
)==0 ) continue;
2013 if( whereLoopCheaperProperSubset(p
, pTemplate
) ){
2014 /* Adjust pTemplate cost downward so that it is cheaper than its
2016 WHERETRACE(0x80,("subset cost adjustment %d,%d to %d,%d\n",
2017 pTemplate
->rRun
, pTemplate
->nOut
, p
->rRun
, p
->nOut
-1));
2018 pTemplate
->rRun
= p
->rRun
;
2019 pTemplate
->nOut
= p
->nOut
- 1;
2020 }else if( whereLoopCheaperProperSubset(pTemplate
, p
) ){
2021 /* Adjust pTemplate cost upward so that it is costlier than p since
2022 ** pTemplate is a proper subset of p */
2023 WHERETRACE(0x80,("subset cost adjustment %d,%d to %d,%d\n",
2024 pTemplate
->rRun
, pTemplate
->nOut
, p
->rRun
, p
->nOut
+1));
2025 pTemplate
->rRun
= p
->rRun
;
2026 pTemplate
->nOut
= p
->nOut
+ 1;
2032 ** Search the list of WhereLoops in *ppPrev looking for one that can be
2033 ** replaced by pTemplate.
2035 ** Return NULL if pTemplate does not belong on the WhereLoop list.
2036 ** In other words if pTemplate ought to be dropped from further consideration.
2038 ** If pX is a WhereLoop that pTemplate can replace, then return the
2039 ** link that points to pX.
2041 ** If pTemplate cannot replace any existing element of the list but needs
2042 ** to be added to the list as a new entry, then return a pointer to the
2043 ** tail of the list.
2045 static WhereLoop
**whereLoopFindLesser(
2047 const WhereLoop
*pTemplate
2050 for(p
=(*ppPrev
); p
; ppPrev
=&p
->pNextLoop
, p
=*ppPrev
){
2051 if( p
->iTab
!=pTemplate
->iTab
|| p
->iSortIdx
!=pTemplate
->iSortIdx
){
2052 /* If either the iTab or iSortIdx values for two WhereLoop are different
2053 ** then those WhereLoops need to be considered separately. Neither is
2054 ** a candidate to replace the other. */
2057 /* In the current implementation, the rSetup value is either zero
2058 ** or the cost of building an automatic index (NlogN) and the NlogN
2059 ** is the same for compatible WhereLoops. */
2060 assert( p
->rSetup
==0 || pTemplate
->rSetup
==0
2061 || p
->rSetup
==pTemplate
->rSetup
);
2063 /* whereLoopAddBtree() always generates and inserts the automatic index
2064 ** case first. Hence compatible candidate WhereLoops never have a larger
2065 ** rSetup. Call this SETUP-INVARIANT */
2066 assert( p
->rSetup
>=pTemplate
->rSetup
);
2068 /* Any loop using an appliation-defined index (or PRIMARY KEY or
2069 ** UNIQUE constraint) with one or more == constraints is better
2070 ** than an automatic index. Unless it is a skip-scan. */
2071 if( (p
->wsFlags
& WHERE_AUTO_INDEX
)!=0
2072 && (pTemplate
->nSkip
)==0
2073 && (pTemplate
->wsFlags
& WHERE_INDEXED
)!=0
2074 && (pTemplate
->wsFlags
& WHERE_COLUMN_EQ
)!=0
2075 && (p
->prereq
& pTemplate
->prereq
)==pTemplate
->prereq
2080 /* If existing WhereLoop p is better than pTemplate, pTemplate can be
2081 ** discarded. WhereLoop p is better if:
2082 ** (1) p has no more dependencies than pTemplate, and
2083 ** (2) p has an equal or lower cost than pTemplate
2085 if( (p
->prereq
& pTemplate
->prereq
)==p
->prereq
/* (1) */
2086 && p
->rSetup
<=pTemplate
->rSetup
/* (2a) */
2087 && p
->rRun
<=pTemplate
->rRun
/* (2b) */
2088 && p
->nOut
<=pTemplate
->nOut
/* (2c) */
2090 return 0; /* Discard pTemplate */
2093 /* If pTemplate is always better than p, then cause p to be overwritten
2094 ** with pTemplate. pTemplate is better than p if:
2095 ** (1) pTemplate has no more dependences than p, and
2096 ** (2) pTemplate has an equal or lower cost than p.
2098 if( (p
->prereq
& pTemplate
->prereq
)==pTemplate
->prereq
/* (1) */
2099 && p
->rRun
>=pTemplate
->rRun
/* (2a) */
2100 && p
->nOut
>=pTemplate
->nOut
/* (2b) */
2102 assert( p
->rSetup
>=pTemplate
->rSetup
); /* SETUP-INVARIANT above */
2103 break; /* Cause p to be overwritten by pTemplate */
2110 ** Insert or replace a WhereLoop entry using the template supplied.
2112 ** An existing WhereLoop entry might be overwritten if the new template
2113 ** is better and has fewer dependencies. Or the template will be ignored
2114 ** and no insert will occur if an existing WhereLoop is faster and has
2115 ** fewer dependencies than the template. Otherwise a new WhereLoop is
2116 ** added based on the template.
2118 ** If pBuilder->pOrSet is not NULL then we care about only the
2119 ** prerequisites and rRun and nOut costs of the N best loops. That
2120 ** information is gathered in the pBuilder->pOrSet object. This special
2121 ** processing mode is used only for OR clause processing.
2123 ** When accumulating multiple loops (when pBuilder->pOrSet is NULL) we
2124 ** still might overwrite similar loops with the new template if the
2125 ** new template is better. Loops may be overwritten if the following
2126 ** conditions are met:
2128 ** (1) They have the same iTab.
2129 ** (2) They have the same iSortIdx.
2130 ** (3) The template has same or fewer dependencies than the current loop
2131 ** (4) The template has the same or lower cost than the current loop
2133 static int whereLoopInsert(WhereLoopBuilder
*pBuilder
, WhereLoop
*pTemplate
){
2134 WhereLoop
**ppPrev
, *p
;
2135 WhereInfo
*pWInfo
= pBuilder
->pWInfo
;
2136 sqlite3
*db
= pWInfo
->pParse
->db
;
2139 /* Stop the search once we hit the query planner search limit */
2140 if( pBuilder
->iPlanLimit
==0 ){
2141 WHERETRACE(0xffffffff,("=== query planner search limit reached ===\n"));
2142 if( pBuilder
->pOrSet
) pBuilder
->pOrSet
->n
= 0;
2145 pBuilder
->iPlanLimit
--;
2147 whereLoopAdjustCost(pWInfo
->pLoops
, pTemplate
);
2149 /* If pBuilder->pOrSet is defined, then only keep track of the costs
2152 if( pBuilder
->pOrSet
!=0 ){
2153 if( pTemplate
->nLTerm
){
2154 #if WHERETRACE_ENABLED
2155 u16 n
= pBuilder
->pOrSet
->n
;
2158 whereOrInsert(pBuilder
->pOrSet
, pTemplate
->prereq
, pTemplate
->rRun
,
2160 #if WHERETRACE_ENABLED /* 0x8 */
2161 if( sqlite3WhereTrace
& 0x8 ){
2162 sqlite3DebugPrintf(x
?" or-%d: ":" or-X: ", n
);
2163 sqlite3WhereLoopPrint(pTemplate
, pBuilder
->pWC
);
2170 /* Look for an existing WhereLoop to replace with pTemplate
2172 ppPrev
= whereLoopFindLesser(&pWInfo
->pLoops
, pTemplate
);
2175 /* There already exists a WhereLoop on the list that is better
2176 ** than pTemplate, so just ignore pTemplate */
2177 #if WHERETRACE_ENABLED /* 0x8 */
2178 if( sqlite3WhereTrace
& 0x8 ){
2179 sqlite3DebugPrintf(" skip: ");
2180 sqlite3WhereLoopPrint(pTemplate
, pBuilder
->pWC
);
2188 /* If we reach this point it means that either p[] should be overwritten
2189 ** with pTemplate[] if p[] exists, or if p==NULL then allocate a new
2190 ** WhereLoop and insert it.
2192 #if WHERETRACE_ENABLED /* 0x8 */
2193 if( sqlite3WhereTrace
& 0x8 ){
2195 sqlite3DebugPrintf("replace: ");
2196 sqlite3WhereLoopPrint(p
, pBuilder
->pWC
);
2197 sqlite3DebugPrintf(" with: ");
2199 sqlite3DebugPrintf(" add: ");
2201 sqlite3WhereLoopPrint(pTemplate
, pBuilder
->pWC
);
2205 /* Allocate a new WhereLoop to add to the end of the list */
2206 *ppPrev
= p
= sqlite3DbMallocRawNN(db
, sizeof(WhereLoop
));
2207 if( p
==0 ) return SQLITE_NOMEM_BKPT
;
2211 /* We will be overwriting WhereLoop p[]. But before we do, first
2212 ** go through the rest of the list and delete any other entries besides
2213 ** p[] that are also supplated by pTemplate */
2214 WhereLoop
**ppTail
= &p
->pNextLoop
;
2217 ppTail
= whereLoopFindLesser(ppTail
, pTemplate
);
2218 if( ppTail
==0 ) break;
2220 if( pToDel
==0 ) break;
2221 *ppTail
= pToDel
->pNextLoop
;
2222 #if WHERETRACE_ENABLED /* 0x8 */
2223 if( sqlite3WhereTrace
& 0x8 ){
2224 sqlite3DebugPrintf(" delete: ");
2225 sqlite3WhereLoopPrint(pToDel
, pBuilder
->pWC
);
2228 whereLoopDelete(db
, pToDel
);
2231 rc
= whereLoopXfer(db
, p
, pTemplate
);
2232 if( (p
->wsFlags
& WHERE_VIRTUALTABLE
)==0 ){
2233 Index
*pIndex
= p
->u
.btree
.pIndex
;
2234 if( pIndex
&& pIndex
->idxType
==SQLITE_IDXTYPE_IPK
){
2235 p
->u
.btree
.pIndex
= 0;
2242 ** Adjust the WhereLoop.nOut value downward to account for terms of the
2243 ** WHERE clause that reference the loop but which are not used by an
2246 ** For every WHERE clause term that is not used by the index
2247 ** and which has a truth probability assigned by one of the likelihood(),
2248 ** likely(), or unlikely() SQL functions, reduce the estimated number
2249 ** of output rows by the probability specified.
2251 ** TUNING: For every WHERE clause term that is not used by the index
2252 ** and which does not have an assigned truth probability, heuristics
2253 ** described below are used to try to estimate the truth probability.
2254 ** TODO --> Perhaps this is something that could be improved by better
2255 ** table statistics.
2257 ** Heuristic 1: Estimate the truth probability as 93.75%. The 93.75%
2258 ** value corresponds to -1 in LogEst notation, so this means decrement
2259 ** the WhereLoop.nOut field for every such WHERE clause term.
2261 ** Heuristic 2: If there exists one or more WHERE clause terms of the
2262 ** form "x==EXPR" and EXPR is not a constant 0 or 1, then make sure the
2263 ** final output row estimate is no greater than 1/4 of the total number
2264 ** of rows in the table. In other words, assume that x==EXPR will filter
2265 ** out at least 3 out of 4 rows. If EXPR is -1 or 0 or 1, then maybe the
2266 ** "x" column is boolean or else -1 or 0 or 1 is a common default value
2267 ** on the "x" column and so in that case only cap the output row estimate
2268 ** at 1/2 instead of 1/4.
2270 static void whereLoopOutputAdjust(
2271 WhereClause
*pWC
, /* The WHERE clause */
2272 WhereLoop
*pLoop
, /* The loop to adjust downward */
2273 LogEst nRow
/* Number of rows in the entire table */
2275 WhereTerm
*pTerm
, *pX
;
2276 Bitmask notAllowed
= ~(pLoop
->prereq
|pLoop
->maskSelf
);
2278 LogEst iReduce
= 0; /* pLoop->nOut should not exceed nRow-iReduce */
2280 assert( (pLoop
->wsFlags
& WHERE_AUTO_INDEX
)==0 );
2281 for(i
=pWC
->nTerm
, pTerm
=pWC
->a
; i
>0; i
--, pTerm
++){
2283 if( (pTerm
->wtFlags
& TERM_VIRTUAL
)!=0 ) break;
2284 if( (pTerm
->prereqAll
& pLoop
->maskSelf
)==0 ) continue;
2285 if( (pTerm
->prereqAll
& notAllowed
)!=0 ) continue;
2286 for(j
=pLoop
->nLTerm
-1; j
>=0; j
--){
2287 pX
= pLoop
->aLTerm
[j
];
2288 if( pX
==0 ) continue;
2289 if( pX
==pTerm
) break;
2290 if( pX
->iParent
>=0 && (&pWC
->a
[pX
->iParent
])==pTerm
) break;
2293 if( pTerm
->truthProb
<=0 ){
2294 /* If a truth probability is specified using the likelihood() hints,
2295 ** then use the probability provided by the application. */
2296 pLoop
->nOut
+= pTerm
->truthProb
;
2298 /* In the absence of explicit truth probabilities, use heuristics to
2299 ** guess a reasonable truth probability. */
2301 if( (pTerm
->eOperator
&(WO_EQ
|WO_IS
))!=0
2302 && (pTerm
->wtFlags
& TERM_HIGHTRUTH
)==0 /* tag-20200224-1 */
2304 Expr
*pRight
= pTerm
->pExpr
->pRight
;
2306 testcase( pTerm
->pExpr
->op
==TK_IS
);
2307 if( sqlite3ExprIsInteger(pRight
, &k
) && k
>=(-1) && k
<=1 ){
2313 pTerm
->wtFlags
|= TERM_HEURTRUTH
;
2320 if( pLoop
->nOut
> nRow
-iReduce
) pLoop
->nOut
= nRow
- iReduce
;
2324 ** Term pTerm is a vector range comparison operation. The first comparison
2325 ** in the vector can be optimized using column nEq of the index. This
2326 ** function returns the total number of vector elements that can be used
2327 ** as part of the range comparison.
2329 ** For example, if the query is:
2331 ** WHERE a = ? AND (b, c, d) > (?, ?, ?)
2335 ** CREATE INDEX ... ON (a, b, c, d, e)
2337 ** then this function would be invoked with nEq=1. The value returned in
2340 static int whereRangeVectorLen(
2341 Parse
*pParse
, /* Parsing context */
2342 int iCur
, /* Cursor open on pIdx */
2343 Index
*pIdx
, /* The index to be used for a inequality constraint */
2344 int nEq
, /* Number of prior equality constraints on same index */
2345 WhereTerm
*pTerm
/* The vector inequality constraint */
2347 int nCmp
= sqlite3ExprVectorSize(pTerm
->pExpr
->pLeft
);
2350 nCmp
= MIN(nCmp
, (pIdx
->nColumn
- nEq
));
2351 for(i
=1; i
<nCmp
; i
++){
2352 /* Test if comparison i of pTerm is compatible with column (i+nEq)
2353 ** of the index. If not, exit the loop. */
2354 char aff
; /* Comparison affinity */
2355 char idxaff
= 0; /* Indexed columns affinity */
2356 CollSeq
*pColl
; /* Comparison collation sequence */
2357 Expr
*pLhs
= pTerm
->pExpr
->pLeft
->x
.pList
->a
[i
].pExpr
;
2358 Expr
*pRhs
= pTerm
->pExpr
->pRight
;
2359 if( pRhs
->flags
& EP_xIsSelect
){
2360 pRhs
= pRhs
->x
.pSelect
->pEList
->a
[i
].pExpr
;
2362 pRhs
= pRhs
->x
.pList
->a
[i
].pExpr
;
2365 /* Check that the LHS of the comparison is a column reference to
2366 ** the right column of the right source table. And that the sort
2367 ** order of the index column is the same as the sort order of the
2368 ** leftmost index column. */
2369 if( pLhs
->op
!=TK_COLUMN
2370 || pLhs
->iTable
!=iCur
2371 || pLhs
->iColumn
!=pIdx
->aiColumn
[i
+nEq
]
2372 || pIdx
->aSortOrder
[i
+nEq
]!=pIdx
->aSortOrder
[nEq
]
2377 testcase( pLhs
->iColumn
==XN_ROWID
);
2378 aff
= sqlite3CompareAffinity(pRhs
, sqlite3ExprAffinity(pLhs
));
2379 idxaff
= sqlite3TableColumnAffinity(pIdx
->pTable
, pLhs
->iColumn
);
2380 if( aff
!=idxaff
) break;
2382 pColl
= sqlite3BinaryCompareCollSeq(pParse
, pLhs
, pRhs
);
2383 if( pColl
==0 ) break;
2384 if( sqlite3StrICmp(pColl
->zName
, pIdx
->azColl
[i
+nEq
]) ) break;
2390 ** Adjust the cost C by the costMult facter T. This only occurs if
2391 ** compiled with -DSQLITE_ENABLE_COSTMULT
2393 #ifdef SQLITE_ENABLE_COSTMULT
2394 # define ApplyCostMultiplier(C,T) C += T
2396 # define ApplyCostMultiplier(C,T)
2400 ** We have so far matched pBuilder->pNew->u.btree.nEq terms of the
2401 ** index pIndex. Try to match one more.
2403 ** When this function is called, pBuilder->pNew->nOut contains the
2404 ** number of rows expected to be visited by filtering using the nEq
2405 ** terms only. If it is modified, this value is restored before this
2406 ** function returns.
2408 ** If pProbe->idxType==SQLITE_IDXTYPE_IPK, that means pIndex is
2409 ** a fake index used for the INTEGER PRIMARY KEY.
2411 static int whereLoopAddBtreeIndex(
2412 WhereLoopBuilder
*pBuilder
, /* The WhereLoop factory */
2413 struct SrcList_item
*pSrc
, /* FROM clause term being analyzed */
2414 Index
*pProbe
, /* An index on pSrc */
2415 LogEst nInMul
/* log(Number of iterations due to IN) */
2417 WhereInfo
*pWInfo
= pBuilder
->pWInfo
; /* WHERE analyse context */
2418 Parse
*pParse
= pWInfo
->pParse
; /* Parsing context */
2419 sqlite3
*db
= pParse
->db
; /* Database connection malloc context */
2420 WhereLoop
*pNew
; /* Template WhereLoop under construction */
2421 WhereTerm
*pTerm
; /* A WhereTerm under consideration */
2422 int opMask
; /* Valid operators for constraints */
2423 WhereScan scan
; /* Iterator for WHERE terms */
2424 Bitmask saved_prereq
; /* Original value of pNew->prereq */
2425 u16 saved_nLTerm
; /* Original value of pNew->nLTerm */
2426 u16 saved_nEq
; /* Original value of pNew->u.btree.nEq */
2427 u16 saved_nBtm
; /* Original value of pNew->u.btree.nBtm */
2428 u16 saved_nTop
; /* Original value of pNew->u.btree.nTop */
2429 u16 saved_nSkip
; /* Original value of pNew->nSkip */
2430 u32 saved_wsFlags
; /* Original value of pNew->wsFlags */
2431 LogEst saved_nOut
; /* Original value of pNew->nOut */
2432 int rc
= SQLITE_OK
; /* Return code */
2433 LogEst rSize
; /* Number of rows in the table */
2434 LogEst rLogSize
; /* Logarithm of table size */
2435 WhereTerm
*pTop
= 0, *pBtm
= 0; /* Top and bottom range constraints */
2437 pNew
= pBuilder
->pNew
;
2438 if( db
->mallocFailed
) return SQLITE_NOMEM_BKPT
;
2439 WHERETRACE(0x800, ("BEGIN %s.addBtreeIdx(%s), nEq=%d, nSkip=%d\n",
2440 pProbe
->pTable
->zName
,pProbe
->zName
,
2441 pNew
->u
.btree
.nEq
, pNew
->nSkip
));
2443 assert( (pNew
->wsFlags
& WHERE_VIRTUALTABLE
)==0 );
2444 assert( (pNew
->wsFlags
& WHERE_TOP_LIMIT
)==0 );
2445 if( pNew
->wsFlags
& WHERE_BTM_LIMIT
){
2446 opMask
= WO_LT
|WO_LE
;
2448 assert( pNew
->u
.btree
.nBtm
==0 );
2449 opMask
= WO_EQ
|WO_IN
|WO_GT
|WO_GE
|WO_LT
|WO_LE
|WO_ISNULL
|WO_IS
;
2451 if( pProbe
->bUnordered
) opMask
&= ~(WO_GT
|WO_GE
|WO_LT
|WO_LE
);
2453 assert( pNew
->u
.btree
.nEq
<pProbe
->nColumn
);
2455 saved_nEq
= pNew
->u
.btree
.nEq
;
2456 saved_nBtm
= pNew
->u
.btree
.nBtm
;
2457 saved_nTop
= pNew
->u
.btree
.nTop
;
2458 saved_nSkip
= pNew
->nSkip
;
2459 saved_nLTerm
= pNew
->nLTerm
;
2460 saved_wsFlags
= pNew
->wsFlags
;
2461 saved_prereq
= pNew
->prereq
;
2462 saved_nOut
= pNew
->nOut
;
2463 pTerm
= whereScanInit(&scan
, pBuilder
->pWC
, pSrc
->iCursor
, saved_nEq
,
2466 rSize
= pProbe
->aiRowLogEst
[0];
2467 rLogSize
= estLog(rSize
);
2468 for(; rc
==SQLITE_OK
&& pTerm
!=0; pTerm
= whereScanNext(&scan
)){
2469 u16 eOp
= pTerm
->eOperator
; /* Shorthand for pTerm->eOperator */
2471 LogEst nOutUnadjusted
; /* nOut before IN() and WHERE adjustments */
2473 #ifdef SQLITE_ENABLE_STAT4
2474 int nRecValid
= pBuilder
->nRecValid
;
2476 if( (eOp
==WO_ISNULL
|| (pTerm
->wtFlags
&TERM_VNULL
)!=0)
2477 && indexColumnNotNull(pProbe
, saved_nEq
)
2479 continue; /* ignore IS [NOT] NULL constraints on NOT NULL columns */
2481 if( pTerm
->prereqRight
& pNew
->maskSelf
) continue;
2483 /* Do not allow the upper bound of a LIKE optimization range constraint
2484 ** to mix with a lower range bound from some other source */
2485 if( pTerm
->wtFlags
& TERM_LIKEOPT
&& pTerm
->eOperator
==WO_LT
) continue;
2487 /* tag-20191211-001: Do not allow constraints from the WHERE clause to
2488 ** be used by the right table of a LEFT JOIN. Only constraints in the
2489 ** ON clause are allowed. See tag-20191211-002 for the vtab equivalent. */
2490 if( (pSrc
->fg
.jointype
& JT_LEFT
)!=0
2491 && !ExprHasProperty(pTerm
->pExpr
, EP_FromJoin
)
2496 if( IsUniqueIndex(pProbe
) && saved_nEq
==pProbe
->nKeyCol
-1 ){
2497 pBuilder
->bldFlags1
|= SQLITE_BLDF1_UNIQUE
;
2499 pBuilder
->bldFlags1
|= SQLITE_BLDF1_INDEXED
;
2501 pNew
->wsFlags
= saved_wsFlags
;
2502 pNew
->u
.btree
.nEq
= saved_nEq
;
2503 pNew
->u
.btree
.nBtm
= saved_nBtm
;
2504 pNew
->u
.btree
.nTop
= saved_nTop
;
2505 pNew
->nLTerm
= saved_nLTerm
;
2506 if( whereLoopResize(db
, pNew
, pNew
->nLTerm
+1) ) break; /* OOM */
2507 pNew
->aLTerm
[pNew
->nLTerm
++] = pTerm
;
2508 pNew
->prereq
= (saved_prereq
| pTerm
->prereqRight
) & ~pNew
->maskSelf
;
2511 || (pNew
->wsFlags
& WHERE_COLUMN_NULL
)!=0
2512 || (pNew
->wsFlags
& WHERE_COLUMN_IN
)!=0
2513 || (pNew
->wsFlags
& WHERE_SKIPSCAN
)!=0
2517 Expr
*pExpr
= pTerm
->pExpr
;
2518 if( ExprHasProperty(pExpr
, EP_xIsSelect
) ){
2519 /* "x IN (SELECT ...)": TUNING: the SELECT returns 25 rows */
2521 nIn
= 46; assert( 46==sqlite3LogEst(25) );
2523 /* The expression may actually be of the form (x, y) IN (SELECT...).
2524 ** In this case there is a separate term for each of (x) and (y).
2525 ** However, the nIn multiplier should only be applied once, not once
2526 ** for each such term. The following loop checks that pTerm is the
2527 ** first such term in use, and sets nIn back to 0 if it is not. */
2528 for(i
=0; i
<pNew
->nLTerm
-1; i
++){
2529 if( pNew
->aLTerm
[i
] && pNew
->aLTerm
[i
]->pExpr
==pExpr
) nIn
= 0;
2531 }else if( ALWAYS(pExpr
->x
.pList
&& pExpr
->x
.pList
->nExpr
) ){
2532 /* "x IN (value, value, ...)" */
2533 nIn
= sqlite3LogEst(pExpr
->x
.pList
->nExpr
);
2535 if( pProbe
->hasStat1
){
2536 LogEst M
, logK
, safetyMargin
;
2538 ** N = the total number of rows in the table
2539 ** K = the number of entries on the RHS of the IN operator
2540 ** M = the number of rows in the table that match terms to the
2541 ** to the left in the same index. If the IN operator is on
2542 ** the left-most index column, M==N.
2544 ** Given the definitions above, it is better to omit the IN operator
2545 ** from the index lookup and instead do a scan of the M elements,
2546 ** testing each scanned row against the IN operator separately, if:
2548 ** M*log(K) < K*log(N)
2550 ** Our estimates for M, K, and N might be inaccurate, so we build in
2551 ** a safety margin of 2 (LogEst: 10) that favors using the IN operator
2552 ** with the index, as using an index has better worst-case behavior.
2553 ** If we do not have real sqlite_stat1 data, always prefer to use
2556 M
= pProbe
->aiRowLogEst
[saved_nEq
];
2558 safetyMargin
= 10; /* TUNING: extra weight for indexed IN */
2559 if( M
+ logK
+ safetyMargin
< nIn
+ rLogSize
){
2561 ("Scan preferred over IN operator on column %d of \"%s\" (%d<%d)\n",
2562 saved_nEq
, pProbe
->zName
, M
+logK
+10, nIn
+rLogSize
));
2566 ("IN operator preferred on column %d of \"%s\" (%d>=%d)\n",
2567 saved_nEq
, pProbe
->zName
, M
+logK
+10, nIn
+rLogSize
));
2570 pNew
->wsFlags
|= WHERE_COLUMN_IN
;
2571 }else if( eOp
& (WO_EQ
|WO_IS
) ){
2572 int iCol
= pProbe
->aiColumn
[saved_nEq
];
2573 pNew
->wsFlags
|= WHERE_COLUMN_EQ
;
2574 assert( saved_nEq
==pNew
->u
.btree
.nEq
);
2576 || (iCol
>=0 && nInMul
==0 && saved_nEq
==pProbe
->nKeyCol
-1)
2578 if( iCol
==XN_ROWID
|| pProbe
->uniqNotNull
2579 || (pProbe
->nKeyCol
==1 && pProbe
->onError
&& eOp
==WO_EQ
)
2581 pNew
->wsFlags
|= WHERE_ONEROW
;
2583 pNew
->wsFlags
|= WHERE_UNQ_WANTED
;
2586 }else if( eOp
& WO_ISNULL
){
2587 pNew
->wsFlags
|= WHERE_COLUMN_NULL
;
2588 }else if( eOp
& (WO_GT
|WO_GE
) ){
2589 testcase( eOp
& WO_GT
);
2590 testcase( eOp
& WO_GE
);
2591 pNew
->wsFlags
|= WHERE_COLUMN_RANGE
|WHERE_BTM_LIMIT
;
2592 pNew
->u
.btree
.nBtm
= whereRangeVectorLen(
2593 pParse
, pSrc
->iCursor
, pProbe
, saved_nEq
, pTerm
2597 if( pTerm
->wtFlags
& TERM_LIKEOPT
){
2598 /* Range contraints that come from the LIKE optimization are
2599 ** always used in pairs. */
2601 assert( (pTop
-(pTerm
->pWC
->a
))<pTerm
->pWC
->nTerm
);
2602 assert( pTop
->wtFlags
& TERM_LIKEOPT
);
2603 assert( pTop
->eOperator
==WO_LT
);
2604 if( whereLoopResize(db
, pNew
, pNew
->nLTerm
+1) ) break; /* OOM */
2605 pNew
->aLTerm
[pNew
->nLTerm
++] = pTop
;
2606 pNew
->wsFlags
|= WHERE_TOP_LIMIT
;
2607 pNew
->u
.btree
.nTop
= 1;
2610 assert( eOp
& (WO_LT
|WO_LE
) );
2611 testcase( eOp
& WO_LT
);
2612 testcase( eOp
& WO_LE
);
2613 pNew
->wsFlags
|= WHERE_COLUMN_RANGE
|WHERE_TOP_LIMIT
;
2614 pNew
->u
.btree
.nTop
= whereRangeVectorLen(
2615 pParse
, pSrc
->iCursor
, pProbe
, saved_nEq
, pTerm
2618 pBtm
= (pNew
->wsFlags
& WHERE_BTM_LIMIT
)!=0 ?
2619 pNew
->aLTerm
[pNew
->nLTerm
-2] : 0;
2622 /* At this point pNew->nOut is set to the number of rows expected to
2623 ** be visited by the index scan before considering term pTerm, or the
2624 ** values of nIn and nInMul. In other words, assuming that all
2625 ** "x IN(...)" terms are replaced with "x = ?". This block updates
2626 ** the value of pNew->nOut to account for pTerm (but not nIn/nInMul). */
2627 assert( pNew
->nOut
==saved_nOut
);
2628 if( pNew
->wsFlags
& WHERE_COLUMN_RANGE
){
2629 /* Adjust nOut using stat4 data. Or, if there is no stat4
2630 ** data, using some other estimate. */
2631 whereRangeScanEst(pParse
, pBuilder
, pBtm
, pTop
, pNew
);
2633 int nEq
= ++pNew
->u
.btree
.nEq
;
2634 assert( eOp
& (WO_ISNULL
|WO_EQ
|WO_IN
|WO_IS
) );
2636 assert( pNew
->nOut
==saved_nOut
);
2637 if( pTerm
->truthProb
<=0 && pProbe
->aiColumn
[saved_nEq
]>=0 ){
2638 assert( (eOp
& WO_IN
) || nIn
==0 );
2639 testcase( eOp
& WO_IN
);
2640 pNew
->nOut
+= pTerm
->truthProb
;
2643 #ifdef SQLITE_ENABLE_STAT4
2647 && pNew
->u
.btree
.nEq
<=pProbe
->nSampleCol
2648 && ((eOp
& WO_IN
)==0 || !ExprHasProperty(pTerm
->pExpr
, EP_xIsSelect
))
2649 && OptimizationEnabled(db
, SQLITE_Stat4
)
2651 Expr
*pExpr
= pTerm
->pExpr
;
2652 if( (eOp
& (WO_EQ
|WO_ISNULL
|WO_IS
))!=0 ){
2653 testcase( eOp
& WO_EQ
);
2654 testcase( eOp
& WO_IS
);
2655 testcase( eOp
& WO_ISNULL
);
2656 rc
= whereEqualScanEst(pParse
, pBuilder
, pExpr
->pRight
, &nOut
);
2658 rc
= whereInScanEst(pParse
, pBuilder
, pExpr
->x
.pList
, &nOut
);
2660 if( rc
==SQLITE_NOTFOUND
) rc
= SQLITE_OK
;
2661 if( rc
!=SQLITE_OK
) break; /* Jump out of the pTerm loop */
2663 pNew
->nOut
= sqlite3LogEst(nOut
);
2665 /* TUNING: Mark terms as "low selectivity" if they seem likely
2666 ** to be true for half or more of the rows in the table.
2667 ** See tag-202002240-1 */
2668 && pNew
->nOut
+10 > pProbe
->aiRowLogEst
[0]
2670 #if WHERETRACE_ENABLED /* 0x01 */
2671 if( sqlite3WhereTrace
& 0x01 ){
2673 "STAT4 determines term has low selectivity:\n");
2674 sqlite3WhereTermPrint(pTerm
, 999);
2677 pTerm
->wtFlags
|= TERM_HIGHTRUTH
;
2678 if( pTerm
->wtFlags
& TERM_HEURTRUTH
){
2679 /* If the term has previously been used with an assumption of
2680 ** higher selectivity, then set the flag to rerun the
2681 ** loop computations. */
2682 pBuilder
->bldFlags2
|= SQLITE_BLDF2_2NDPASS
;
2685 if( pNew
->nOut
>saved_nOut
) pNew
->nOut
= saved_nOut
;
2692 pNew
->nOut
+= (pProbe
->aiRowLogEst
[nEq
] - pProbe
->aiRowLogEst
[nEq
-1]);
2693 if( eOp
& WO_ISNULL
){
2694 /* TUNING: If there is no likelihood() value, assume that a
2695 ** "col IS NULL" expression matches twice as many rows
2703 /* Set rCostIdx to the cost of visiting selected rows in index. Add
2704 ** it to pNew->rRun, which is currently set to the cost of the index
2705 ** seek only. Then, if this is a non-covering index, add the cost of
2706 ** visiting the rows in the main table. */
2707 assert( pSrc
->pTab
->szTabRow
>0 );
2708 rCostIdx
= pNew
->nOut
+ 1 + (15*pProbe
->szIdxRow
)/pSrc
->pTab
->szTabRow
;
2709 pNew
->rRun
= sqlite3LogEstAdd(rLogSize
, rCostIdx
);
2710 if( (pNew
->wsFlags
& (WHERE_IDX_ONLY
|WHERE_IPK
))==0 ){
2711 pNew
->rRun
= sqlite3LogEstAdd(pNew
->rRun
, pNew
->nOut
+ 16);
2713 ApplyCostMultiplier(pNew
->rRun
, pProbe
->pTable
->costMult
);
2715 nOutUnadjusted
= pNew
->nOut
;
2716 pNew
->rRun
+= nInMul
+ nIn
;
2717 pNew
->nOut
+= nInMul
+ nIn
;
2718 whereLoopOutputAdjust(pBuilder
->pWC
, pNew
, rSize
);
2719 rc
= whereLoopInsert(pBuilder
, pNew
);
2721 if( pNew
->wsFlags
& WHERE_COLUMN_RANGE
){
2722 pNew
->nOut
= saved_nOut
;
2724 pNew
->nOut
= nOutUnadjusted
;
2727 if( (pNew
->wsFlags
& WHERE_TOP_LIMIT
)==0
2728 && pNew
->u
.btree
.nEq
<pProbe
->nColumn
2730 whereLoopAddBtreeIndex(pBuilder
, pSrc
, pProbe
, nInMul
+nIn
);
2732 pNew
->nOut
= saved_nOut
;
2733 #ifdef SQLITE_ENABLE_STAT4
2734 pBuilder
->nRecValid
= nRecValid
;
2737 pNew
->prereq
= saved_prereq
;
2738 pNew
->u
.btree
.nEq
= saved_nEq
;
2739 pNew
->u
.btree
.nBtm
= saved_nBtm
;
2740 pNew
->u
.btree
.nTop
= saved_nTop
;
2741 pNew
->nSkip
= saved_nSkip
;
2742 pNew
->wsFlags
= saved_wsFlags
;
2743 pNew
->nOut
= saved_nOut
;
2744 pNew
->nLTerm
= saved_nLTerm
;
2746 /* Consider using a skip-scan if there are no WHERE clause constraints
2747 ** available for the left-most terms of the index, and if the average
2748 ** number of repeats in the left-most terms is at least 18.
2750 ** The magic number 18 is selected on the basis that scanning 17 rows
2751 ** is almost always quicker than an index seek (even though if the index
2752 ** contains fewer than 2^17 rows we assume otherwise in other parts of
2753 ** the code). And, even if it is not, it should not be too much slower.
2754 ** On the other hand, the extra seeks could end up being significantly
2755 ** more expensive. */
2756 assert( 42==sqlite3LogEst(18) );
2757 if( saved_nEq
==saved_nSkip
2758 && saved_nEq
+1<pProbe
->nKeyCol
2759 && saved_nEq
==pNew
->nLTerm
2760 && pProbe
->noSkipScan
==0
2761 && pProbe
->hasStat1
!=0
2762 && OptimizationEnabled(db
, SQLITE_SkipScan
)
2763 && pProbe
->aiRowLogEst
[saved_nEq
+1]>=42 /* TUNING: Minimum for skip-scan */
2764 && (rc
= whereLoopResize(db
, pNew
, pNew
->nLTerm
+1))==SQLITE_OK
2767 pNew
->u
.btree
.nEq
++;
2769 pNew
->aLTerm
[pNew
->nLTerm
++] = 0;
2770 pNew
->wsFlags
|= WHERE_SKIPSCAN
;
2771 nIter
= pProbe
->aiRowLogEst
[saved_nEq
] - pProbe
->aiRowLogEst
[saved_nEq
+1];
2772 pNew
->nOut
-= nIter
;
2773 /* TUNING: Because uncertainties in the estimates for skip-scan queries,
2774 ** add a 1.375 fudge factor to make skip-scan slightly less likely. */
2776 whereLoopAddBtreeIndex(pBuilder
, pSrc
, pProbe
, nIter
+ nInMul
);
2777 pNew
->nOut
= saved_nOut
;
2778 pNew
->u
.btree
.nEq
= saved_nEq
;
2779 pNew
->nSkip
= saved_nSkip
;
2780 pNew
->wsFlags
= saved_wsFlags
;
2783 WHERETRACE(0x800, ("END %s.addBtreeIdx(%s), nEq=%d, rc=%d\n",
2784 pProbe
->pTable
->zName
, pProbe
->zName
, saved_nEq
, rc
));
2789 ** Return True if it is possible that pIndex might be useful in
2790 ** implementing the ORDER BY clause in pBuilder.
2792 ** Return False if pBuilder does not contain an ORDER BY clause or
2793 ** if there is no way for pIndex to be useful in implementing that
2796 static int indexMightHelpWithOrderBy(
2797 WhereLoopBuilder
*pBuilder
,
2805 if( pIndex
->bUnordered
) return 0;
2806 if( (pOB
= pBuilder
->pWInfo
->pOrderBy
)==0 ) return 0;
2807 for(ii
=0; ii
<pOB
->nExpr
; ii
++){
2808 Expr
*pExpr
= sqlite3ExprSkipCollateAndLikely(pOB
->a
[ii
].pExpr
);
2809 if( pExpr
->op
==TK_COLUMN
&& pExpr
->iTable
==iCursor
){
2810 if( pExpr
->iColumn
<0 ) return 1;
2811 for(jj
=0; jj
<pIndex
->nKeyCol
; jj
++){
2812 if( pExpr
->iColumn
==pIndex
->aiColumn
[jj
] ) return 1;
2814 }else if( (aColExpr
= pIndex
->aColExpr
)!=0 ){
2815 for(jj
=0; jj
<pIndex
->nKeyCol
; jj
++){
2816 if( pIndex
->aiColumn
[jj
]!=XN_EXPR
) continue;
2817 if( sqlite3ExprCompareSkip(pExpr
,aColExpr
->a
[jj
].pExpr
,iCursor
)==0 ){
2826 /* Check to see if a partial index with pPartIndexWhere can be used
2827 ** in the current query. Return true if it can be and false if not.
2829 static int whereUsablePartialIndex(
2830 int iTab
, /* The table for which we want an index */
2831 int isLeft
, /* True if iTab is the right table of a LEFT JOIN */
2832 WhereClause
*pWC
, /* The WHERE clause of the query */
2833 Expr
*pWhere
/* The WHERE clause from the partial index */
2837 Parse
*pParse
= pWC
->pWInfo
->pParse
;
2838 while( pWhere
->op
==TK_AND
){
2839 if( !whereUsablePartialIndex(iTab
,isLeft
,pWC
,pWhere
->pLeft
) ) return 0;
2840 pWhere
= pWhere
->pRight
;
2842 if( pParse
->db
->flags
& SQLITE_EnableQPSG
) pParse
= 0;
2843 for(i
=0, pTerm
=pWC
->a
; i
<pWC
->nTerm
; i
++, pTerm
++){
2845 pExpr
= pTerm
->pExpr
;
2846 if( (!ExprHasProperty(pExpr
, EP_FromJoin
) || pExpr
->iRightJoinTable
==iTab
)
2847 && (isLeft
==0 || ExprHasProperty(pExpr
, EP_FromJoin
))
2848 && sqlite3ExprImpliesExpr(pParse
, pExpr
, pWhere
, iTab
)
2857 ** Add all WhereLoop objects for a single table of the join where the table
2858 ** is identified by pBuilder->pNew->iTab. That table is guaranteed to be
2859 ** a b-tree table, not a virtual table.
2861 ** The costs (WhereLoop.rRun) of the b-tree loops added by this function
2862 ** are calculated as follows:
2864 ** For a full scan, assuming the table (or index) contains nRow rows:
2866 ** cost = nRow * 3.0 // full-table scan
2867 ** cost = nRow * K // scan of covering index
2868 ** cost = nRow * (K+3.0) // scan of non-covering index
2870 ** where K is a value between 1.1 and 3.0 set based on the relative
2871 ** estimated average size of the index and table records.
2873 ** For an index scan, where nVisit is the number of index rows visited
2874 ** by the scan, and nSeek is the number of seek operations required on
2875 ** the index b-tree:
2877 ** cost = nSeek * (log(nRow) + K * nVisit) // covering index
2878 ** cost = nSeek * (log(nRow) + (K+3.0) * nVisit) // non-covering index
2880 ** Normally, nSeek is 1. nSeek values greater than 1 come about if the
2881 ** WHERE clause includes "x IN (....)" terms used in place of "x=?". Or when
2882 ** implicit "x IN (SELECT x FROM tbl)" terms are added for skip-scans.
2884 ** The estimated values (nRow, nVisit, nSeek) often contain a large amount
2885 ** of uncertainty. For this reason, scoring is designed to pick plans that
2886 ** "do the least harm" if the estimates are inaccurate. For example, a
2887 ** log(nRow) factor is omitted from a non-covering index scan in order to
2888 ** bias the scoring in favor of using an index, since the worst-case
2889 ** performance of using an index is far better than the worst-case performance
2890 ** of a full table scan.
2892 static int whereLoopAddBtree(
2893 WhereLoopBuilder
*pBuilder
, /* WHERE clause information */
2894 Bitmask mPrereq
/* Extra prerequesites for using this table */
2896 WhereInfo
*pWInfo
; /* WHERE analysis context */
2897 Index
*pProbe
; /* An index we are evaluating */
2898 Index sPk
; /* A fake index object for the primary key */
2899 LogEst aiRowEstPk
[2]; /* The aiRowLogEst[] value for the sPk index */
2900 i16 aiColumnPk
= -1; /* The aColumn[] value for the sPk index */
2901 SrcList
*pTabList
; /* The FROM clause */
2902 struct SrcList_item
*pSrc
; /* The FROM clause btree term to add */
2903 WhereLoop
*pNew
; /* Template WhereLoop object */
2904 int rc
= SQLITE_OK
; /* Return code */
2905 int iSortIdx
= 1; /* Index number */
2906 int b
; /* A boolean value */
2907 LogEst rSize
; /* number of rows in the table */
2908 LogEst rLogSize
; /* Logarithm of the number of rows in the table */
2909 WhereClause
*pWC
; /* The parsed WHERE clause */
2910 Table
*pTab
; /* Table being queried */
2912 pNew
= pBuilder
->pNew
;
2913 pWInfo
= pBuilder
->pWInfo
;
2914 pTabList
= pWInfo
->pTabList
;
2915 pSrc
= pTabList
->a
+ pNew
->iTab
;
2917 pWC
= pBuilder
->pWC
;
2918 assert( !IsVirtual(pSrc
->pTab
) );
2920 if( pSrc
->pIBIndex
){
2921 /* An INDEXED BY clause specifies a particular index to use */
2922 pProbe
= pSrc
->pIBIndex
;
2923 }else if( !HasRowid(pTab
) ){
2924 pProbe
= pTab
->pIndex
;
2926 /* There is no INDEXED BY clause. Create a fake Index object in local
2927 ** variable sPk to represent the rowid primary key index. Make this
2928 ** fake index the first in a chain of Index objects with all of the real
2929 ** indices to follow */
2930 Index
*pFirst
; /* First of real indices on the table */
2931 memset(&sPk
, 0, sizeof(Index
));
2934 sPk
.aiColumn
= &aiColumnPk
;
2935 sPk
.aiRowLogEst
= aiRowEstPk
;
2936 sPk
.onError
= OE_Replace
;
2938 sPk
.szIdxRow
= pTab
->szTabRow
;
2939 sPk
.idxType
= SQLITE_IDXTYPE_IPK
;
2940 aiRowEstPk
[0] = pTab
->nRowLogEst
;
2942 pFirst
= pSrc
->pTab
->pIndex
;
2943 if( pSrc
->fg
.notIndexed
==0 ){
2944 /* The real indices of the table are only considered if the
2945 ** NOT INDEXED qualifier is omitted from the FROM clause */
2950 rSize
= pTab
->nRowLogEst
;
2951 rLogSize
= estLog(rSize
);
2953 #ifndef SQLITE_OMIT_AUTOMATIC_INDEX
2954 /* Automatic indexes */
2955 if( !pBuilder
->pOrSet
/* Not part of an OR optimization */
2956 && (pWInfo
->wctrlFlags
& WHERE_OR_SUBCLAUSE
)==0
2957 && (pWInfo
->pParse
->db
->flags
& SQLITE_AutoIndex
)!=0
2958 && pSrc
->pIBIndex
==0 /* Has no INDEXED BY clause */
2959 && !pSrc
->fg
.notIndexed
/* Has no NOT INDEXED clause */
2960 && HasRowid(pTab
) /* Not WITHOUT ROWID table. (FIXME: Why not?) */
2961 && !pSrc
->fg
.isCorrelated
/* Not a correlated subquery */
2962 && !pSrc
->fg
.isRecursive
/* Not a recursive common table expression. */
2964 /* Generate auto-index WhereLoops */
2966 WhereTerm
*pWCEnd
= pWC
->a
+ pWC
->nTerm
;
2967 for(pTerm
=pWC
->a
; rc
==SQLITE_OK
&& pTerm
<pWCEnd
; pTerm
++){
2968 if( pTerm
->prereqRight
& pNew
->maskSelf
) continue;
2969 if( termCanDriveIndex(pTerm
, pSrc
, 0) ){
2970 pNew
->u
.btree
.nEq
= 1;
2972 pNew
->u
.btree
.pIndex
= 0;
2974 pNew
->aLTerm
[0] = pTerm
;
2975 /* TUNING: One-time cost for computing the automatic index is
2976 ** estimated to be X*N*log2(N) where N is the number of rows in
2977 ** the table being indexed and where X is 7 (LogEst=28) for normal
2978 ** tables or 0.5 (LogEst=-10) for views and subqueries. The value
2979 ** of X is smaller for views and subqueries so that the query planner
2980 ** will be more aggressive about generating automatic indexes for
2981 ** those objects, since there is no opportunity to add schema
2982 ** indexes on subqueries and views. */
2983 pNew
->rSetup
= rLogSize
+ rSize
;
2984 if( pTab
->pSelect
==0 && (pTab
->tabFlags
& TF_Ephemeral
)==0 ){
2989 ApplyCostMultiplier(pNew
->rSetup
, pTab
->costMult
);
2990 if( pNew
->rSetup
<0 ) pNew
->rSetup
= 0;
2991 /* TUNING: Each index lookup yields 20 rows in the table. This
2992 ** is more than the usual guess of 10 rows, since we have no way
2993 ** of knowing how selective the index will ultimately be. It would
2994 ** not be unreasonable to make this value much larger. */
2995 pNew
->nOut
= 43; assert( 43==sqlite3LogEst(20) );
2996 pNew
->rRun
= sqlite3LogEstAdd(rLogSize
,pNew
->nOut
);
2997 pNew
->wsFlags
= WHERE_AUTO_INDEX
;
2998 pNew
->prereq
= mPrereq
| pTerm
->prereqRight
;
2999 rc
= whereLoopInsert(pBuilder
, pNew
);
3003 #endif /* SQLITE_OMIT_AUTOMATIC_INDEX */
3005 /* Loop over all indices. If there was an INDEXED BY clause, then only
3006 ** consider index pProbe. */
3007 for(; rc
==SQLITE_OK
&& pProbe
;
3008 pProbe
=(pSrc
->pIBIndex
? 0 : pProbe
->pNext
), iSortIdx
++
3010 int isLeft
= (pSrc
->fg
.jointype
& JT_OUTER
)!=0;
3011 if( pProbe
->pPartIdxWhere
!=0
3012 && !whereUsablePartialIndex(pSrc
->iCursor
, isLeft
, pWC
,
3013 pProbe
->pPartIdxWhere
)
3015 testcase( pNew
->iTab
!=pSrc
->iCursor
); /* See ticket [98d973b8f5] */
3016 continue; /* Partial index inappropriate for this query */
3018 if( pProbe
->bNoQuery
) continue;
3019 rSize
= pProbe
->aiRowLogEst
[0];
3020 pNew
->u
.btree
.nEq
= 0;
3021 pNew
->u
.btree
.nBtm
= 0;
3022 pNew
->u
.btree
.nTop
= 0;
3027 pNew
->prereq
= mPrereq
;
3029 pNew
->u
.btree
.pIndex
= pProbe
;
3030 b
= indexMightHelpWithOrderBy(pBuilder
, pProbe
, pSrc
->iCursor
);
3031 /* The ONEPASS_DESIRED flags never occurs together with ORDER BY */
3032 assert( (pWInfo
->wctrlFlags
& WHERE_ONEPASS_DESIRED
)==0 || b
==0 );
3033 if( pProbe
->idxType
==SQLITE_IDXTYPE_IPK
){
3034 /* Integer primary key index */
3035 pNew
->wsFlags
= WHERE_IPK
;
3037 /* Full table scan */
3038 pNew
->iSortIdx
= b
? iSortIdx
: 0;
3039 /* TUNING: Cost of full table scan is (N*3.0). */
3040 pNew
->rRun
= rSize
+ 16;
3041 ApplyCostMultiplier(pNew
->rRun
, pTab
->costMult
);
3042 whereLoopOutputAdjust(pWC
, pNew
, rSize
);
3043 rc
= whereLoopInsert(pBuilder
, pNew
);
3048 if( pProbe
->isCovering
){
3049 pNew
->wsFlags
= WHERE_IDX_ONLY
| WHERE_INDEXED
;
3052 m
= pSrc
->colUsed
& pProbe
->colNotIdxed
;
3053 pNew
->wsFlags
= (m
==0) ? (WHERE_IDX_ONLY
|WHERE_INDEXED
) : WHERE_INDEXED
;
3056 /* Full scan via index */
3059 || pProbe
->pPartIdxWhere
!=0
3061 && pProbe
->bUnordered
==0
3062 && (pProbe
->szIdxRow
<pTab
->szTabRow
)
3063 && (pWInfo
->wctrlFlags
& WHERE_ONEPASS_DESIRED
)==0
3064 && sqlite3GlobalConfig
.bUseCis
3065 && OptimizationEnabled(pWInfo
->pParse
->db
, SQLITE_CoverIdxScan
)
3068 pNew
->iSortIdx
= b
? iSortIdx
: 0;
3070 /* The cost of visiting the index rows is N*K, where K is
3071 ** between 1.1 and 3.0, depending on the relative sizes of the
3072 ** index and table rows. */
3073 pNew
->rRun
= rSize
+ 1 + (15*pProbe
->szIdxRow
)/pTab
->szTabRow
;
3075 /* If this is a non-covering index scan, add in the cost of
3076 ** doing table lookups. The cost will be 3x the number of
3077 ** lookups. Take into account WHERE clause terms that can be
3078 ** satisfied using just the index, and that do not require a
3080 LogEst nLookup
= rSize
+ 16; /* Base cost: N*3 */
3082 int iCur
= pSrc
->iCursor
;
3083 WhereClause
*pWC2
= &pWInfo
->sWC
;
3084 for(ii
=0; ii
<pWC2
->nTerm
; ii
++){
3085 WhereTerm
*pTerm
= &pWC2
->a
[ii
];
3086 if( !sqlite3ExprCoveredByIndex(pTerm
->pExpr
, iCur
, pProbe
) ){
3089 /* pTerm can be evaluated using just the index. So reduce
3090 ** the expected number of table lookups accordingly */
3091 if( pTerm
->truthProb
<=0 ){
3092 nLookup
+= pTerm
->truthProb
;
3095 if( pTerm
->eOperator
& (WO_EQ
|WO_IS
) ) nLookup
-= 19;
3099 pNew
->rRun
= sqlite3LogEstAdd(pNew
->rRun
, nLookup
);
3101 ApplyCostMultiplier(pNew
->rRun
, pTab
->costMult
);
3102 whereLoopOutputAdjust(pWC
, pNew
, rSize
);
3103 rc
= whereLoopInsert(pBuilder
, pNew
);
3109 pBuilder
->bldFlags1
= 0;
3110 rc
= whereLoopAddBtreeIndex(pBuilder
, pSrc
, pProbe
, 0);
3111 if( pBuilder
->bldFlags1
==SQLITE_BLDF1_INDEXED
){
3112 /* If a non-unique index is used, or if a prefix of the key for
3113 ** unique index is used (making the index functionally non-unique)
3114 ** then the sqlite_stat1 data becomes important for scoring the
3116 pTab
->tabFlags
|= TF_StatsUsed
;
3118 #ifdef SQLITE_ENABLE_STAT4
3119 sqlite3Stat4ProbeFree(pBuilder
->pRec
);
3120 pBuilder
->nRecValid
= 0;
3127 #ifndef SQLITE_OMIT_VIRTUALTABLE
3130 ** Argument pIdxInfo is already populated with all constraints that may
3131 ** be used by the virtual table identified by pBuilder->pNew->iTab. This
3132 ** function marks a subset of those constraints usable, invokes the
3133 ** xBestIndex method and adds the returned plan to pBuilder.
3135 ** A constraint is marked usable if:
3137 ** * Argument mUsable indicates that its prerequisites are available, and
3139 ** * It is not one of the operators specified in the mExclude mask passed
3140 ** as the fourth argument (which in practice is either WO_IN or 0).
3142 ** Argument mPrereq is a mask of tables that must be scanned before the
3143 ** virtual table in question. These are added to the plans prerequisites
3144 ** before it is added to pBuilder.
3146 ** Output parameter *pbIn is set to true if the plan added to pBuilder
3147 ** uses one or more WO_IN terms, or false otherwise.
3149 static int whereLoopAddVirtualOne(
3150 WhereLoopBuilder
*pBuilder
,
3151 Bitmask mPrereq
, /* Mask of tables that must be used. */
3152 Bitmask mUsable
, /* Mask of usable tables */
3153 u16 mExclude
, /* Exclude terms using these operators */
3154 sqlite3_index_info
*pIdxInfo
, /* Populated object for xBestIndex */
3155 u16 mNoOmit
, /* Do not omit these constraints */
3156 int *pbIn
/* OUT: True if plan uses an IN(...) op */
3158 WhereClause
*pWC
= pBuilder
->pWC
;
3159 struct sqlite3_index_constraint
*pIdxCons
;
3160 struct sqlite3_index_constraint_usage
*pUsage
= pIdxInfo
->aConstraintUsage
;
3164 WhereLoop
*pNew
= pBuilder
->pNew
;
3165 Parse
*pParse
= pBuilder
->pWInfo
->pParse
;
3166 struct SrcList_item
*pSrc
= &pBuilder
->pWInfo
->pTabList
->a
[pNew
->iTab
];
3167 int nConstraint
= pIdxInfo
->nConstraint
;
3169 assert( (mUsable
& mPrereq
)==mPrereq
);
3171 pNew
->prereq
= mPrereq
;
3173 /* Set the usable flag on the subset of constraints identified by
3174 ** arguments mUsable and mExclude. */
3175 pIdxCons
= *(struct sqlite3_index_constraint
**)&pIdxInfo
->aConstraint
;
3176 for(i
=0; i
<nConstraint
; i
++, pIdxCons
++){
3177 WhereTerm
*pTerm
= &pWC
->a
[pIdxCons
->iTermOffset
];
3178 pIdxCons
->usable
= 0;
3179 if( (pTerm
->prereqRight
& mUsable
)==pTerm
->prereqRight
3180 && (pTerm
->eOperator
& mExclude
)==0
3182 pIdxCons
->usable
= 1;
3186 /* Initialize the output fields of the sqlite3_index_info structure */
3187 memset(pUsage
, 0, sizeof(pUsage
[0])*nConstraint
);
3188 assert( pIdxInfo
->needToFreeIdxStr
==0 );
3189 pIdxInfo
->idxStr
= 0;
3190 pIdxInfo
->idxNum
= 0;
3191 pIdxInfo
->orderByConsumed
= 0;
3192 pIdxInfo
->estimatedCost
= SQLITE_BIG_DBL
/ (double)2;
3193 pIdxInfo
->estimatedRows
= 25;
3194 pIdxInfo
->idxFlags
= 0;
3195 pIdxInfo
->colUsed
= (sqlite3_int64
)pSrc
->colUsed
;
3197 /* Invoke the virtual table xBestIndex() method */
3198 rc
= vtabBestIndex(pParse
, pSrc
->pTab
, pIdxInfo
);
3200 if( rc
==SQLITE_CONSTRAINT
){
3201 /* If the xBestIndex method returns SQLITE_CONSTRAINT, that means
3202 ** that the particular combination of parameters provided is unusable.
3203 ** Make no entries in the loop table.
3205 WHERETRACE(0xffff, (" ^^^^--- non-viable plan rejected!\n"));
3212 assert( pNew
->nLSlot
>=nConstraint
);
3213 for(i
=0; i
<nConstraint
; i
++) pNew
->aLTerm
[i
] = 0;
3214 pNew
->u
.vtab
.omitMask
= 0;
3215 pIdxCons
= *(struct sqlite3_index_constraint
**)&pIdxInfo
->aConstraint
;
3216 for(i
=0; i
<nConstraint
; i
++, pIdxCons
++){
3218 if( (iTerm
= pUsage
[i
].argvIndex
- 1)>=0 ){
3220 int j
= pIdxCons
->iTermOffset
;
3221 if( iTerm
>=nConstraint
3224 || pNew
->aLTerm
[iTerm
]!=0
3225 || pIdxCons
->usable
==0
3227 sqlite3ErrorMsg(pParse
,"%s.xBestIndex malfunction",pSrc
->pTab
->zName
);
3228 testcase( pIdxInfo
->needToFreeIdxStr
);
3229 return SQLITE_ERROR
;
3231 testcase( iTerm
==nConstraint
-1 );
3233 testcase( j
==pWC
->nTerm
-1 );
3235 pNew
->prereq
|= pTerm
->prereqRight
;
3236 assert( iTerm
<pNew
->nLSlot
);
3237 pNew
->aLTerm
[iTerm
] = pTerm
;
3238 if( iTerm
>mxTerm
) mxTerm
= iTerm
;
3239 testcase( iTerm
==15 );
3240 testcase( iTerm
==16 );
3241 if( pUsage
[i
].omit
){
3242 if( i
<16 && ((1<<i
)&mNoOmit
)==0 ){
3243 testcase( i
!=iTerm
);
3244 pNew
->u
.vtab
.omitMask
|= 1<<iTerm
;
3246 testcase( i
!=iTerm
);
3249 if( (pTerm
->eOperator
& WO_IN
)!=0 ){
3250 /* A virtual table that is constrained by an IN clause may not
3251 ** consume the ORDER BY clause because (1) the order of IN terms
3252 ** is not necessarily related to the order of output terms and
3253 ** (2) Multiple outputs from a single IN value will not merge
3255 pIdxInfo
->orderByConsumed
= 0;
3256 pIdxInfo
->idxFlags
&= ~SQLITE_INDEX_SCAN_UNIQUE
;
3257 *pbIn
= 1; assert( (mExclude
& WO_IN
)==0 );
3262 pNew
->nLTerm
= mxTerm
+1;
3263 for(i
=0; i
<=mxTerm
; i
++){
3264 if( pNew
->aLTerm
[i
]==0 ){
3265 /* The non-zero argvIdx values must be contiguous. Raise an
3266 ** error if they are not */
3267 sqlite3ErrorMsg(pParse
,"%s.xBestIndex malfunction",pSrc
->pTab
->zName
);
3268 testcase( pIdxInfo
->needToFreeIdxStr
);
3269 return SQLITE_ERROR
;
3272 assert( pNew
->nLTerm
<=pNew
->nLSlot
);
3273 pNew
->u
.vtab
.idxNum
= pIdxInfo
->idxNum
;
3274 pNew
->u
.vtab
.needFree
= pIdxInfo
->needToFreeIdxStr
;
3275 pIdxInfo
->needToFreeIdxStr
= 0;
3276 pNew
->u
.vtab
.idxStr
= pIdxInfo
->idxStr
;
3277 pNew
->u
.vtab
.isOrdered
= (i8
)(pIdxInfo
->orderByConsumed
?
3278 pIdxInfo
->nOrderBy
: 0);
3280 pNew
->rRun
= sqlite3LogEstFromDouble(pIdxInfo
->estimatedCost
);
3281 pNew
->nOut
= sqlite3LogEst(pIdxInfo
->estimatedRows
);
3283 /* Set the WHERE_ONEROW flag if the xBestIndex() method indicated
3284 ** that the scan will visit at most one row. Clear it otherwise. */
3285 if( pIdxInfo
->idxFlags
& SQLITE_INDEX_SCAN_UNIQUE
){
3286 pNew
->wsFlags
|= WHERE_ONEROW
;
3288 pNew
->wsFlags
&= ~WHERE_ONEROW
;
3290 rc
= whereLoopInsert(pBuilder
, pNew
);
3291 if( pNew
->u
.vtab
.needFree
){
3292 sqlite3_free(pNew
->u
.vtab
.idxStr
);
3293 pNew
->u
.vtab
.needFree
= 0;
3295 WHERETRACE(0xffff, (" bIn=%d prereqIn=%04llx prereqOut=%04llx\n",
3296 *pbIn
, (sqlite3_uint64
)mPrereq
,
3297 (sqlite3_uint64
)(pNew
->prereq
& ~mPrereq
)));
3303 ** If this function is invoked from within an xBestIndex() callback, it
3304 ** returns a pointer to a buffer containing the name of the collation
3305 ** sequence associated with element iCons of the sqlite3_index_info.aConstraint
3306 ** array. Or, if iCons is out of range or there is no active xBestIndex
3307 ** call, return NULL.
3309 const char *sqlite3_vtab_collation(sqlite3_index_info
*pIdxInfo
, int iCons
){
3310 HiddenIndexInfo
*pHidden
= (HiddenIndexInfo
*)&pIdxInfo
[1];
3311 const char *zRet
= 0;
3312 if( iCons
>=0 && iCons
<pIdxInfo
->nConstraint
){
3314 int iTerm
= pIdxInfo
->aConstraint
[iCons
].iTermOffset
;
3315 Expr
*pX
= pHidden
->pWC
->a
[iTerm
].pExpr
;
3317 pC
= sqlite3ExprCompareCollSeq(pHidden
->pParse
, pX
);
3319 zRet
= (pC
? pC
->zName
: sqlite3StrBINARY
);
3325 ** Add all WhereLoop objects for a table of the join identified by
3326 ** pBuilder->pNew->iTab. That table is guaranteed to be a virtual table.
3328 ** If there are no LEFT or CROSS JOIN joins in the query, both mPrereq and
3329 ** mUnusable are set to 0. Otherwise, mPrereq is a mask of all FROM clause
3330 ** entries that occur before the virtual table in the FROM clause and are
3331 ** separated from it by at least one LEFT or CROSS JOIN. Similarly, the
3332 ** mUnusable mask contains all FROM clause entries that occur after the
3333 ** virtual table and are separated from it by at least one LEFT or
3336 ** For example, if the query were:
3338 ** ... FROM t1, t2 LEFT JOIN t3, t4, vt CROSS JOIN t5, t6;
3340 ** then mPrereq corresponds to (t1, t2) and mUnusable to (t5, t6).
3342 ** All the tables in mPrereq must be scanned before the current virtual
3343 ** table. So any terms for which all prerequisites are satisfied by
3344 ** mPrereq may be specified as "usable" in all calls to xBestIndex.
3345 ** Conversely, all tables in mUnusable must be scanned after the current
3346 ** virtual table, so any terms for which the prerequisites overlap with
3347 ** mUnusable should always be configured as "not-usable" for xBestIndex.
3349 static int whereLoopAddVirtual(
3350 WhereLoopBuilder
*pBuilder
, /* WHERE clause information */
3351 Bitmask mPrereq
, /* Tables that must be scanned before this one */
3352 Bitmask mUnusable
/* Tables that must be scanned after this one */
3354 int rc
= SQLITE_OK
; /* Return code */
3355 WhereInfo
*pWInfo
; /* WHERE analysis context */
3356 Parse
*pParse
; /* The parsing context */
3357 WhereClause
*pWC
; /* The WHERE clause */
3358 struct SrcList_item
*pSrc
; /* The FROM clause term to search */
3359 sqlite3_index_info
*p
; /* Object to pass to xBestIndex() */
3360 int nConstraint
; /* Number of constraints in p */
3361 int bIn
; /* True if plan uses IN(...) operator */
3363 Bitmask mBest
; /* Tables used by best possible plan */
3366 assert( (mPrereq
& mUnusable
)==0 );
3367 pWInfo
= pBuilder
->pWInfo
;
3368 pParse
= pWInfo
->pParse
;
3369 pWC
= pBuilder
->pWC
;
3370 pNew
= pBuilder
->pNew
;
3371 pSrc
= &pWInfo
->pTabList
->a
[pNew
->iTab
];
3372 assert( IsVirtual(pSrc
->pTab
) );
3373 p
= allocateIndexInfo(pParse
, pWC
, mUnusable
, pSrc
, pBuilder
->pOrderBy
,
3375 if( p
==0 ) return SQLITE_NOMEM_BKPT
;
3377 pNew
->wsFlags
= WHERE_VIRTUALTABLE
;
3379 pNew
->u
.vtab
.needFree
= 0;
3380 nConstraint
= p
->nConstraint
;
3381 if( whereLoopResize(pParse
->db
, pNew
, nConstraint
) ){
3382 sqlite3DbFree(pParse
->db
, p
);
3383 return SQLITE_NOMEM_BKPT
;
3386 /* First call xBestIndex() with all constraints usable. */
3387 WHERETRACE(0x800, ("BEGIN %s.addVirtual()\n", pSrc
->pTab
->zName
));
3388 WHERETRACE(0x40, (" VirtualOne: all usable\n"));
3389 rc
= whereLoopAddVirtualOne(pBuilder
, mPrereq
, ALLBITS
, 0, p
, mNoOmit
, &bIn
);
3391 /* If the call to xBestIndex() with all terms enabled produced a plan
3392 ** that does not require any source tables (IOW: a plan with mBest==0)
3393 ** and does not use an IN(...) operator, then there is no point in making
3394 ** any further calls to xBestIndex() since they will all return the same
3395 ** result (if the xBestIndex() implementation is sane). */
3396 if( rc
==SQLITE_OK
&& ((mBest
= (pNew
->prereq
& ~mPrereq
))!=0 || bIn
) ){
3397 int seenZero
= 0; /* True if a plan with no prereqs seen */
3398 int seenZeroNoIN
= 0; /* Plan with no prereqs and no IN(...) seen */
3400 Bitmask mBestNoIn
= 0;
3402 /* If the plan produced by the earlier call uses an IN(...) term, call
3403 ** xBestIndex again, this time with IN(...) terms disabled. */
3405 WHERETRACE(0x40, (" VirtualOne: all usable w/o IN\n"));
3406 rc
= whereLoopAddVirtualOne(
3407 pBuilder
, mPrereq
, ALLBITS
, WO_IN
, p
, mNoOmit
, &bIn
);
3409 mBestNoIn
= pNew
->prereq
& ~mPrereq
;
3416 /* Call xBestIndex once for each distinct value of (prereqRight & ~mPrereq)
3417 ** in the set of terms that apply to the current virtual table. */
3418 while( rc
==SQLITE_OK
){
3420 Bitmask mNext
= ALLBITS
;
3422 for(i
=0; i
<nConstraint
; i
++){
3424 pWC
->a
[p
->aConstraint
[i
].iTermOffset
].prereqRight
& ~mPrereq
3426 if( mThis
>mPrev
&& mThis
<mNext
) mNext
= mThis
;
3429 if( mNext
==ALLBITS
) break;
3430 if( mNext
==mBest
|| mNext
==mBestNoIn
) continue;
3431 WHERETRACE(0x40, (" VirtualOne: mPrev=%04llx mNext=%04llx\n",
3432 (sqlite3_uint64
)mPrev
, (sqlite3_uint64
)mNext
));
3433 rc
= whereLoopAddVirtualOne(
3434 pBuilder
, mPrereq
, mNext
|mPrereq
, 0, p
, mNoOmit
, &bIn
);
3435 if( pNew
->prereq
==mPrereq
){
3437 if( bIn
==0 ) seenZeroNoIN
= 1;
3441 /* If the calls to xBestIndex() in the above loop did not find a plan
3442 ** that requires no source tables at all (i.e. one guaranteed to be
3443 ** usable), make a call here with all source tables disabled */
3444 if( rc
==SQLITE_OK
&& seenZero
==0 ){
3445 WHERETRACE(0x40, (" VirtualOne: all disabled\n"));
3446 rc
= whereLoopAddVirtualOne(
3447 pBuilder
, mPrereq
, mPrereq
, 0, p
, mNoOmit
, &bIn
);
3448 if( bIn
==0 ) seenZeroNoIN
= 1;
3451 /* If the calls to xBestIndex() have so far failed to find a plan
3452 ** that requires no source tables at all and does not use an IN(...)
3453 ** operator, make a final call to obtain one here. */
3454 if( rc
==SQLITE_OK
&& seenZeroNoIN
==0 ){
3455 WHERETRACE(0x40, (" VirtualOne: all disabled and w/o IN\n"));
3456 rc
= whereLoopAddVirtualOne(
3457 pBuilder
, mPrereq
, mPrereq
, WO_IN
, p
, mNoOmit
, &bIn
);
3461 if( p
->needToFreeIdxStr
) sqlite3_free(p
->idxStr
);
3462 sqlite3DbFreeNN(pParse
->db
, p
);
3463 WHERETRACE(0x800, ("END %s.addVirtual(), rc=%d\n", pSrc
->pTab
->zName
, rc
));
3466 #endif /* SQLITE_OMIT_VIRTUALTABLE */
3469 ** Add WhereLoop entries to handle OR terms. This works for either
3470 ** btrees or virtual tables.
3472 static int whereLoopAddOr(
3473 WhereLoopBuilder
*pBuilder
,
3477 WhereInfo
*pWInfo
= pBuilder
->pWInfo
;
3480 WhereTerm
*pTerm
, *pWCEnd
;
3484 WhereLoopBuilder sSubBuild
;
3485 WhereOrSet sSum
, sCur
;
3486 struct SrcList_item
*pItem
;
3488 pWC
= pBuilder
->pWC
;
3489 pWCEnd
= pWC
->a
+ pWC
->nTerm
;
3490 pNew
= pBuilder
->pNew
;
3491 memset(&sSum
, 0, sizeof(sSum
));
3492 pItem
= pWInfo
->pTabList
->a
+ pNew
->iTab
;
3493 iCur
= pItem
->iCursor
;
3495 for(pTerm
=pWC
->a
; pTerm
<pWCEnd
&& rc
==SQLITE_OK
; pTerm
++){
3496 if( (pTerm
->eOperator
& WO_OR
)!=0
3497 && (pTerm
->u
.pOrInfo
->indexable
& pNew
->maskSelf
)!=0
3499 WhereClause
* const pOrWC
= &pTerm
->u
.pOrInfo
->wc
;
3500 WhereTerm
* const pOrWCEnd
= &pOrWC
->a
[pOrWC
->nTerm
];
3505 sSubBuild
= *pBuilder
;
3506 sSubBuild
.pOrderBy
= 0;
3507 sSubBuild
.pOrSet
= &sCur
;
3509 WHERETRACE(0x200, ("Begin processing OR-clause %p\n", pTerm
));
3510 for(pOrTerm
=pOrWC
->a
; pOrTerm
<pOrWCEnd
; pOrTerm
++){
3511 if( (pOrTerm
->eOperator
& WO_AND
)!=0 ){
3512 sSubBuild
.pWC
= &pOrTerm
->u
.pAndInfo
->wc
;
3513 }else if( pOrTerm
->leftCursor
==iCur
){
3514 tempWC
.pWInfo
= pWC
->pWInfo
;
3515 tempWC
.pOuter
= pWC
;
3519 sSubBuild
.pWC
= &tempWC
;
3524 #ifdef WHERETRACE_ENABLED
3525 WHERETRACE(0x200, ("OR-term %d of %p has %d subterms:\n",
3526 (int)(pOrTerm
-pOrWC
->a
), pTerm
, sSubBuild
.pWC
->nTerm
));
3527 if( sqlite3WhereTrace
& 0x400 ){
3528 sqlite3WhereClausePrint(sSubBuild
.pWC
);
3531 #ifndef SQLITE_OMIT_VIRTUALTABLE
3532 if( IsVirtual(pItem
->pTab
) ){
3533 rc
= whereLoopAddVirtual(&sSubBuild
, mPrereq
, mUnusable
);
3537 rc
= whereLoopAddBtree(&sSubBuild
, mPrereq
);
3539 if( rc
==SQLITE_OK
){
3540 rc
= whereLoopAddOr(&sSubBuild
, mPrereq
, mUnusable
);
3542 assert( rc
==SQLITE_OK
|| rc
==SQLITE_DONE
|| sCur
.n
==0 );
3543 testcase( rc
==SQLITE_DONE
);
3548 whereOrMove(&sSum
, &sCur
);
3552 whereOrMove(&sPrev
, &sSum
);
3554 for(i
=0; i
<sPrev
.n
; i
++){
3555 for(j
=0; j
<sCur
.n
; j
++){
3556 whereOrInsert(&sSum
, sPrev
.a
[i
].prereq
| sCur
.a
[j
].prereq
,
3557 sqlite3LogEstAdd(sPrev
.a
[i
].rRun
, sCur
.a
[j
].rRun
),
3558 sqlite3LogEstAdd(sPrev
.a
[i
].nOut
, sCur
.a
[j
].nOut
));
3564 pNew
->aLTerm
[0] = pTerm
;
3565 pNew
->wsFlags
= WHERE_MULTI_OR
;
3568 memset(&pNew
->u
, 0, sizeof(pNew
->u
));
3569 for(i
=0; rc
==SQLITE_OK
&& i
<sSum
.n
; i
++){
3570 /* TUNING: Currently sSum.a[i].rRun is set to the sum of the costs
3571 ** of all sub-scans required by the OR-scan. However, due to rounding
3572 ** errors, it may be that the cost of the OR-scan is equal to its
3573 ** most expensive sub-scan. Add the smallest possible penalty
3574 ** (equivalent to multiplying the cost by 1.07) to ensure that
3575 ** this does not happen. Otherwise, for WHERE clauses such as the
3576 ** following where there is an index on "y":
3578 ** WHERE likelihood(x=?, 0.99) OR y=?
3580 ** the planner may elect to "OR" together a full-table scan and an
3581 ** index lookup. And other similarly odd results. */
3582 pNew
->rRun
= sSum
.a
[i
].rRun
+ 1;
3583 pNew
->nOut
= sSum
.a
[i
].nOut
;
3584 pNew
->prereq
= sSum
.a
[i
].prereq
;
3585 rc
= whereLoopInsert(pBuilder
, pNew
);
3587 WHERETRACE(0x200, ("End processing OR-clause %p\n", pTerm
));
3594 ** Add all WhereLoop objects for all tables
3596 static int whereLoopAddAll(WhereLoopBuilder
*pBuilder
){
3597 WhereInfo
*pWInfo
= pBuilder
->pWInfo
;
3598 Bitmask mPrereq
= 0;
3601 SrcList
*pTabList
= pWInfo
->pTabList
;
3602 struct SrcList_item
*pItem
;
3603 struct SrcList_item
*pEnd
= &pTabList
->a
[pWInfo
->nLevel
];
3604 sqlite3
*db
= pWInfo
->pParse
->db
;
3607 u8 priorJointype
= 0;
3609 /* Loop over the tables in the join, from left to right */
3610 pNew
= pBuilder
->pNew
;
3611 whereLoopInit(pNew
);
3612 pBuilder
->iPlanLimit
= SQLITE_QUERY_PLANNER_LIMIT
;
3613 for(iTab
=0, pItem
=pTabList
->a
; pItem
<pEnd
; iTab
++, pItem
++){
3614 Bitmask mUnusable
= 0;
3616 pBuilder
->iPlanLimit
+= SQLITE_QUERY_PLANNER_LIMIT_INCR
;
3617 pNew
->maskSelf
= sqlite3WhereGetMask(&pWInfo
->sMaskSet
, pItem
->iCursor
);
3618 if( ((pItem
->fg
.jointype
|priorJointype
) & (JT_LEFT
|JT_CROSS
))!=0 ){
3619 /* This condition is true when pItem is the FROM clause term on the
3620 ** right-hand-side of a LEFT or CROSS JOIN. */
3623 priorJointype
= pItem
->fg
.jointype
;
3624 #ifndef SQLITE_OMIT_VIRTUALTABLE
3625 if( IsVirtual(pItem
->pTab
) ){
3626 struct SrcList_item
*p
;
3627 for(p
=&pItem
[1]; p
<pEnd
; p
++){
3628 if( mUnusable
|| (p
->fg
.jointype
& (JT_LEFT
|JT_CROSS
)) ){
3629 mUnusable
|= sqlite3WhereGetMask(&pWInfo
->sMaskSet
, p
->iCursor
);
3632 rc
= whereLoopAddVirtual(pBuilder
, mPrereq
, mUnusable
);
3634 #endif /* SQLITE_OMIT_VIRTUALTABLE */
3636 rc
= whereLoopAddBtree(pBuilder
, mPrereq
);
3638 if( rc
==SQLITE_OK
&& pBuilder
->pWC
->hasOr
){
3639 rc
= whereLoopAddOr(pBuilder
, mPrereq
, mUnusable
);
3641 mPrior
|= pNew
->maskSelf
;
3642 if( rc
|| db
->mallocFailed
){
3643 if( rc
==SQLITE_DONE
){
3644 /* We hit the query planner search limit set by iPlanLimit */
3645 sqlite3_log(SQLITE_WARNING
, "abbreviated query algorithm search");
3653 whereLoopClear(db
, pNew
);
3658 ** Examine a WherePath (with the addition of the extra WhereLoop of the 6th
3659 ** parameters) to see if it outputs rows in the requested ORDER BY
3660 ** (or GROUP BY) without requiring a separate sort operation. Return N:
3662 ** N>0: N terms of the ORDER BY clause are satisfied
3663 ** N==0: No terms of the ORDER BY clause are satisfied
3664 ** N<0: Unknown yet how many terms of ORDER BY might be satisfied.
3666 ** Note that processing for WHERE_GROUPBY and WHERE_DISTINCTBY is not as
3667 ** strict. With GROUP BY and DISTINCT the only requirement is that
3668 ** equivalent rows appear immediately adjacent to one another. GROUP BY
3669 ** and DISTINCT do not require rows to appear in any particular order as long
3670 ** as equivalent rows are grouped together. Thus for GROUP BY and DISTINCT
3671 ** the pOrderBy terms can be matched in any order. With ORDER BY, the
3672 ** pOrderBy terms must be matched in strict left-to-right order.
3674 static i8
wherePathSatisfiesOrderBy(
3675 WhereInfo
*pWInfo
, /* The WHERE clause */
3676 ExprList
*pOrderBy
, /* ORDER BY or GROUP BY or DISTINCT clause to check */
3677 WherePath
*pPath
, /* The WherePath to check */
3678 u16 wctrlFlags
, /* WHERE_GROUPBY or _DISTINCTBY or _ORDERBY_LIMIT */
3679 u16 nLoop
, /* Number of entries in pPath->aLoop[] */
3680 WhereLoop
*pLast
, /* Add this WhereLoop to the end of pPath->aLoop[] */
3681 Bitmask
*pRevMask
/* OUT: Mask of WhereLoops to run in reverse order */
3683 u8 revSet
; /* True if rev is known */
3684 u8 rev
; /* Composite sort order */
3685 u8 revIdx
; /* Index sort order */
3686 u8 isOrderDistinct
; /* All prior WhereLoops are order-distinct */
3687 u8 distinctColumns
; /* True if the loop has UNIQUE NOT NULL columns */
3688 u8 isMatch
; /* iColumn matches a term of the ORDER BY clause */
3689 u16 eqOpMask
; /* Allowed equality operators */
3690 u16 nKeyCol
; /* Number of key columns in pIndex */
3691 u16 nColumn
; /* Total number of ordered columns in the index */
3692 u16 nOrderBy
; /* Number terms in the ORDER BY clause */
3693 int iLoop
; /* Index of WhereLoop in pPath being processed */
3694 int i
, j
; /* Loop counters */
3695 int iCur
; /* Cursor number for current WhereLoop */
3696 int iColumn
; /* A column number within table iCur */
3697 WhereLoop
*pLoop
= 0; /* Current WhereLoop being processed. */
3698 WhereTerm
*pTerm
; /* A single term of the WHERE clause */
3699 Expr
*pOBExpr
; /* An expression from the ORDER BY clause */
3700 CollSeq
*pColl
; /* COLLATE function from an ORDER BY clause term */
3701 Index
*pIndex
; /* The index associated with pLoop */
3702 sqlite3
*db
= pWInfo
->pParse
->db
; /* Database connection */
3703 Bitmask obSat
= 0; /* Mask of ORDER BY terms satisfied so far */
3704 Bitmask obDone
; /* Mask of all ORDER BY terms */
3705 Bitmask orderDistinctMask
; /* Mask of all well-ordered loops */
3706 Bitmask ready
; /* Mask of inner loops */
3709 ** We say the WhereLoop is "one-row" if it generates no more than one
3710 ** row of output. A WhereLoop is one-row if all of the following are true:
3711 ** (a) All index columns match with WHERE_COLUMN_EQ.
3712 ** (b) The index is unique
3713 ** Any WhereLoop with an WHERE_COLUMN_EQ constraint on the rowid is one-row.
3714 ** Every one-row WhereLoop will have the WHERE_ONEROW bit set in wsFlags.
3716 ** We say the WhereLoop is "order-distinct" if the set of columns from
3717 ** that WhereLoop that are in the ORDER BY clause are different for every
3718 ** row of the WhereLoop. Every one-row WhereLoop is automatically
3719 ** order-distinct. A WhereLoop that has no columns in the ORDER BY clause
3720 ** is not order-distinct. To be order-distinct is not quite the same as being
3721 ** UNIQUE since a UNIQUE column or index can have multiple rows that
3722 ** are NULL and NULL values are equivalent for the purpose of order-distinct.
3723 ** To be order-distinct, the columns must be UNIQUE and NOT NULL.
3725 ** The rowid for a table is always UNIQUE and NOT NULL so whenever the
3726 ** rowid appears in the ORDER BY clause, the corresponding WhereLoop is
3727 ** automatically order-distinct.
3730 assert( pOrderBy
!=0 );
3731 if( nLoop
&& OptimizationDisabled(db
, SQLITE_OrderByIdxJoin
) ) return 0;
3733 nOrderBy
= pOrderBy
->nExpr
;
3734 testcase( nOrderBy
==BMS
-1 );
3735 if( nOrderBy
>BMS
-1 ) return 0; /* Cannot optimize overly large ORDER BYs */
3736 isOrderDistinct
= 1;
3737 obDone
= MASKBIT(nOrderBy
)-1;
3738 orderDistinctMask
= 0;
3740 eqOpMask
= WO_EQ
| WO_IS
| WO_ISNULL
;
3741 if( wctrlFlags
& WHERE_ORDERBY_LIMIT
) eqOpMask
|= WO_IN
;
3742 for(iLoop
=0; isOrderDistinct
&& obSat
<obDone
&& iLoop
<=nLoop
; iLoop
++){
3743 if( iLoop
>0 ) ready
|= pLoop
->maskSelf
;
3745 pLoop
= pPath
->aLoop
[iLoop
];
3746 if( wctrlFlags
& WHERE_ORDERBY_LIMIT
) continue;
3750 if( pLoop
->wsFlags
& WHERE_VIRTUALTABLE
){
3751 if( pLoop
->u
.vtab
.isOrdered
&& (wctrlFlags
& WHERE_DISTINCTBY
)==0 ){
3755 }else if( wctrlFlags
& WHERE_DISTINCTBY
){
3756 pLoop
->u
.btree
.nDistinctCol
= 0;
3758 iCur
= pWInfo
->pTabList
->a
[pLoop
->iTab
].iCursor
;
3760 /* Mark off any ORDER BY term X that is a column in the table of
3761 ** the current loop for which there is term in the WHERE
3762 ** clause of the form X IS NULL or X=? that reference only outer
3765 for(i
=0; i
<nOrderBy
; i
++){
3766 if( MASKBIT(i
) & obSat
) continue;
3767 pOBExpr
= sqlite3ExprSkipCollateAndLikely(pOrderBy
->a
[i
].pExpr
);
3768 if( pOBExpr
->op
!=TK_COLUMN
) continue;
3769 if( pOBExpr
->iTable
!=iCur
) continue;
3770 pTerm
= sqlite3WhereFindTerm(&pWInfo
->sWC
, iCur
, pOBExpr
->iColumn
,
3771 ~ready
, eqOpMask
, 0);
3772 if( pTerm
==0 ) continue;
3773 if( pTerm
->eOperator
==WO_IN
){
3774 /* IN terms are only valid for sorting in the ORDER BY LIMIT
3775 ** optimization, and then only if they are actually used
3776 ** by the query plan */
3777 assert( wctrlFlags
& WHERE_ORDERBY_LIMIT
);
3778 for(j
=0; j
<pLoop
->nLTerm
&& pTerm
!=pLoop
->aLTerm
[j
]; j
++){}
3779 if( j
>=pLoop
->nLTerm
) continue;
3781 if( (pTerm
->eOperator
&(WO_EQ
|WO_IS
))!=0 && pOBExpr
->iColumn
>=0 ){
3782 Parse
*pParse
= pWInfo
->pParse
;
3783 CollSeq
*pColl1
= sqlite3ExprNNCollSeq(pParse
, pOrderBy
->a
[i
].pExpr
);
3784 CollSeq
*pColl2
= sqlite3ExprCompareCollSeq(pParse
, pTerm
->pExpr
);
3786 if( pColl2
==0 || sqlite3StrICmp(pColl1
->zName
, pColl2
->zName
) ){
3789 testcase( pTerm
->pExpr
->op
==TK_IS
);
3791 obSat
|= MASKBIT(i
);
3794 if( (pLoop
->wsFlags
& WHERE_ONEROW
)==0 ){
3795 if( pLoop
->wsFlags
& WHERE_IPK
){
3799 }else if( (pIndex
= pLoop
->u
.btree
.pIndex
)==0 || pIndex
->bUnordered
){
3802 nKeyCol
= pIndex
->nKeyCol
;
3803 nColumn
= pIndex
->nColumn
;
3804 assert( nColumn
==nKeyCol
+1 || !HasRowid(pIndex
->pTable
) );
3805 assert( pIndex
->aiColumn
[nColumn
-1]==XN_ROWID
3806 || !HasRowid(pIndex
->pTable
));
3807 isOrderDistinct
= IsUniqueIndex(pIndex
)
3808 && (pLoop
->wsFlags
& WHERE_SKIPSCAN
)==0;
3811 /* Loop through all columns of the index and deal with the ones
3812 ** that are not constrained by == or IN.
3815 distinctColumns
= 0;
3816 for(j
=0; j
<nColumn
; j
++){
3817 u8 bOnce
= 1; /* True to run the ORDER BY search loop */
3819 assert( j
>=pLoop
->u
.btree
.nEq
3820 || (pLoop
->aLTerm
[j
]==0)==(j
<pLoop
->nSkip
)
3822 if( j
<pLoop
->u
.btree
.nEq
&& j
>=pLoop
->nSkip
){
3823 u16 eOp
= pLoop
->aLTerm
[j
]->eOperator
;
3825 /* Skip over == and IS and ISNULL terms. (Also skip IN terms when
3826 ** doing WHERE_ORDERBY_LIMIT processing). Except, IS and ISNULL
3827 ** terms imply that the index is not UNIQUE NOT NULL in which case
3828 ** the loop need to be marked as not order-distinct because it can
3829 ** have repeated NULL rows.
3831 ** If the current term is a column of an ((?,?) IN (SELECT...))
3832 ** expression for which the SELECT returns more than one column,
3833 ** check that it is the only column used by this loop. Otherwise,
3834 ** if it is one of two or more, none of the columns can be
3835 ** considered to match an ORDER BY term.
3837 if( (eOp
& eqOpMask
)!=0 ){
3838 if( eOp
& (WO_ISNULL
|WO_IS
) ){
3839 testcase( eOp
& WO_ISNULL
);
3840 testcase( eOp
& WO_IS
);
3841 testcase( isOrderDistinct
);
3842 isOrderDistinct
= 0;
3845 }else if( ALWAYS(eOp
& WO_IN
) ){
3846 /* ALWAYS() justification: eOp is an equality operator due to the
3847 ** j<pLoop->u.btree.nEq constraint above. Any equality other
3848 ** than WO_IN is captured by the previous "if". So this one
3849 ** always has to be WO_IN. */
3850 Expr
*pX
= pLoop
->aLTerm
[j
]->pExpr
;
3851 for(i
=j
+1; i
<pLoop
->u
.btree
.nEq
; i
++){
3852 if( pLoop
->aLTerm
[i
]->pExpr
==pX
){
3853 assert( (pLoop
->aLTerm
[i
]->eOperator
& WO_IN
) );
3861 /* Get the column number in the table (iColumn) and sort order
3862 ** (revIdx) for the j-th column of the index.
3865 iColumn
= pIndex
->aiColumn
[j
];
3866 revIdx
= pIndex
->aSortOrder
[j
] & KEYINFO_ORDER_DESC
;
3867 if( iColumn
==pIndex
->pTable
->iPKey
) iColumn
= XN_ROWID
;
3873 /* An unconstrained column that might be NULL means that this
3874 ** WhereLoop is not well-ordered
3878 && j
>=pLoop
->u
.btree
.nEq
3879 && pIndex
->pTable
->aCol
[iColumn
].notNull
==0
3881 isOrderDistinct
= 0;
3884 /* Find the ORDER BY term that corresponds to the j-th column
3885 ** of the index and mark that ORDER BY term off
3888 for(i
=0; bOnce
&& i
<nOrderBy
; i
++){
3889 if( MASKBIT(i
) & obSat
) continue;
3890 pOBExpr
= sqlite3ExprSkipCollateAndLikely(pOrderBy
->a
[i
].pExpr
);
3891 testcase( wctrlFlags
& WHERE_GROUPBY
);
3892 testcase( wctrlFlags
& WHERE_DISTINCTBY
);
3893 if( (wctrlFlags
& (WHERE_GROUPBY
|WHERE_DISTINCTBY
))==0 ) bOnce
= 0;
3894 if( iColumn
>=XN_ROWID
){
3895 if( pOBExpr
->op
!=TK_COLUMN
) continue;
3896 if( pOBExpr
->iTable
!=iCur
) continue;
3897 if( pOBExpr
->iColumn
!=iColumn
) continue;
3899 Expr
*pIdxExpr
= pIndex
->aColExpr
->a
[j
].pExpr
;
3900 if( sqlite3ExprCompareSkip(pOBExpr
, pIdxExpr
, iCur
) ){
3904 if( iColumn
!=XN_ROWID
){
3905 pColl
= sqlite3ExprNNCollSeq(pWInfo
->pParse
, pOrderBy
->a
[i
].pExpr
);
3906 if( sqlite3StrICmp(pColl
->zName
, pIndex
->azColl
[j
])!=0 ) continue;
3908 if( wctrlFlags
& WHERE_DISTINCTBY
){
3909 pLoop
->u
.btree
.nDistinctCol
= j
+1;
3914 if( isMatch
&& (wctrlFlags
& WHERE_GROUPBY
)==0 ){
3915 /* Make sure the sort order is compatible in an ORDER BY clause.
3916 ** Sort order is irrelevant for a GROUP BY clause. */
3918 if( (rev
^ revIdx
)!=(pOrderBy
->a
[i
].sortFlags
&KEYINFO_ORDER_DESC
) ){
3922 rev
= revIdx
^ (pOrderBy
->a
[i
].sortFlags
& KEYINFO_ORDER_DESC
);
3923 if( rev
) *pRevMask
|= MASKBIT(iLoop
);
3927 if( isMatch
&& (pOrderBy
->a
[i
].sortFlags
& KEYINFO_ORDER_BIGNULL
) ){
3928 if( j
==pLoop
->u
.btree
.nEq
){
3929 pLoop
->wsFlags
|= WHERE_BIGNULL_SORT
;
3935 if( iColumn
==XN_ROWID
){
3936 testcase( distinctColumns
==0 );
3937 distinctColumns
= 1;
3939 obSat
|= MASKBIT(i
);
3941 /* No match found */
3942 if( j
==0 || j
<nKeyCol
){
3943 testcase( isOrderDistinct
!=0 );
3944 isOrderDistinct
= 0;
3948 } /* end Loop over all index columns */
3949 if( distinctColumns
){
3950 testcase( isOrderDistinct
==0 );
3951 isOrderDistinct
= 1;
3953 } /* end-if not one-row */
3955 /* Mark off any other ORDER BY terms that reference pLoop */
3956 if( isOrderDistinct
){
3957 orderDistinctMask
|= pLoop
->maskSelf
;
3958 for(i
=0; i
<nOrderBy
; i
++){
3961 if( MASKBIT(i
) & obSat
) continue;
3962 p
= pOrderBy
->a
[i
].pExpr
;
3963 mTerm
= sqlite3WhereExprUsage(&pWInfo
->sMaskSet
,p
);
3964 if( mTerm
==0 && !sqlite3ExprIsConstant(p
) ) continue;
3965 if( (mTerm
&~orderDistinctMask
)==0 ){
3966 obSat
|= MASKBIT(i
);
3970 } /* End the loop over all WhereLoops from outer-most down to inner-most */
3971 if( obSat
==obDone
) return (i8
)nOrderBy
;
3972 if( !isOrderDistinct
){
3973 for(i
=nOrderBy
-1; i
>0; i
--){
3974 Bitmask m
= MASKBIT(i
) - 1;
3975 if( (obSat
&m
)==m
) return i
;
3984 ** If the WHERE_GROUPBY flag is set in the mask passed to sqlite3WhereBegin(),
3985 ** the planner assumes that the specified pOrderBy list is actually a GROUP
3986 ** BY clause - and so any order that groups rows as required satisfies the
3989 ** Normally, in this case it is not possible for the caller to determine
3990 ** whether or not the rows are really being delivered in sorted order, or
3991 ** just in some other order that provides the required grouping. However,
3992 ** if the WHERE_SORTBYGROUP flag is also passed to sqlite3WhereBegin(), then
3993 ** this function may be called on the returned WhereInfo object. It returns
3994 ** true if the rows really will be sorted in the specified order, or false
3997 ** For example, assuming:
3999 ** CREATE INDEX i1 ON t1(x, Y);
4003 ** SELECT * FROM t1 GROUP BY x,y ORDER BY x,y; -- IsSorted()==1
4004 ** SELECT * FROM t1 GROUP BY y,x ORDER BY y,x; -- IsSorted()==0
4006 int sqlite3WhereIsSorted(WhereInfo
*pWInfo
){
4007 assert( pWInfo
->wctrlFlags
& WHERE_GROUPBY
);
4008 assert( pWInfo
->wctrlFlags
& WHERE_SORTBYGROUP
);
4009 return pWInfo
->sorted
;
4012 #ifdef WHERETRACE_ENABLED
4013 /* For debugging use only: */
4014 static const char *wherePathName(WherePath
*pPath
, int nLoop
, WhereLoop
*pLast
){
4015 static char zName
[65];
4017 for(i
=0; i
<nLoop
; i
++){ zName
[i
] = pPath
->aLoop
[i
]->cId
; }
4018 if( pLast
) zName
[i
++] = pLast
->cId
;
4025 ** Return the cost of sorting nRow rows, assuming that the keys have
4026 ** nOrderby columns and that the first nSorted columns are already in
4029 static LogEst
whereSortingCost(
4035 /* TUNING: Estimated cost of a full external sort, where N is
4036 ** the number of rows to sort is:
4038 ** cost = (3.0 * N * log(N)).
4040 ** Or, if the order-by clause has X terms but only the last Y
4041 ** terms are out of order, then block-sorting will reduce the
4044 ** cost = (3.0 * N * log(N)) * (Y/X)
4046 ** The (Y/X) term is implemented using stack variable rScale
4048 LogEst rScale
, rSortCost
;
4049 assert( nOrderBy
>0 && 66==sqlite3LogEst(100) );
4050 rScale
= sqlite3LogEst((nOrderBy
-nSorted
)*100/nOrderBy
) - 66;
4051 rSortCost
= nRow
+ rScale
+ 16;
4053 /* Multiple by log(M) where M is the number of output rows.
4054 ** Use the LIMIT for M if it is smaller */
4055 if( (pWInfo
->wctrlFlags
& WHERE_USE_LIMIT
)!=0 && pWInfo
->iLimit
<nRow
){
4056 nRow
= pWInfo
->iLimit
;
4058 rSortCost
+= estLog(nRow
);
4063 ** Given the list of WhereLoop objects at pWInfo->pLoops, this routine
4064 ** attempts to find the lowest cost path that visits each WhereLoop
4065 ** once. This path is then loaded into the pWInfo->a[].pWLoop fields.
4067 ** Assume that the total number of output rows that will need to be sorted
4068 ** will be nRowEst (in the 10*log2 representation). Or, ignore sorting
4069 ** costs if nRowEst==0.
4071 ** Return SQLITE_OK on success or SQLITE_NOMEM of a memory allocation
4074 static int wherePathSolver(WhereInfo
*pWInfo
, LogEst nRowEst
){
4075 int mxChoice
; /* Maximum number of simultaneous paths tracked */
4076 int nLoop
; /* Number of terms in the join */
4077 Parse
*pParse
; /* Parsing context */
4078 sqlite3
*db
; /* The database connection */
4079 int iLoop
; /* Loop counter over the terms of the join */
4080 int ii
, jj
; /* Loop counters */
4081 int mxI
= 0; /* Index of next entry to replace */
4082 int nOrderBy
; /* Number of ORDER BY clause terms */
4083 LogEst mxCost
= 0; /* Maximum cost of a set of paths */
4084 LogEst mxUnsorted
= 0; /* Maximum unsorted cost of a set of path */
4085 int nTo
, nFrom
; /* Number of valid entries in aTo[] and aFrom[] */
4086 WherePath
*aFrom
; /* All nFrom paths at the previous level */
4087 WherePath
*aTo
; /* The nTo best paths at the current level */
4088 WherePath
*pFrom
; /* An element of aFrom[] that we are working on */
4089 WherePath
*pTo
; /* An element of aTo[] that we are working on */
4090 WhereLoop
*pWLoop
; /* One of the WhereLoop objects */
4091 WhereLoop
**pX
; /* Used to divy up the pSpace memory */
4092 LogEst
*aSortCost
= 0; /* Sorting and partial sorting costs */
4093 char *pSpace
; /* Temporary memory used by this routine */
4094 int nSpace
; /* Bytes of space allocated at pSpace */
4096 pParse
= pWInfo
->pParse
;
4098 nLoop
= pWInfo
->nLevel
;
4099 /* TUNING: For simple queries, only the best path is tracked.
4100 ** For 2-way joins, the 5 best paths are followed.
4101 ** For joins of 3 or more tables, track the 10 best paths */
4102 mxChoice
= (nLoop
<=1) ? 1 : (nLoop
==2 ? 5 : 10);
4103 assert( nLoop
<=pWInfo
->pTabList
->nSrc
);
4104 WHERETRACE(0x002, ("---- begin solver. (nRowEst=%d)\n", nRowEst
));
4106 /* If nRowEst is zero and there is an ORDER BY clause, ignore it. In this
4107 ** case the purpose of this call is to estimate the number of rows returned
4108 ** by the overall query. Once this estimate has been obtained, the caller
4109 ** will invoke this function a second time, passing the estimate as the
4110 ** nRowEst parameter. */
4111 if( pWInfo
->pOrderBy
==0 || nRowEst
==0 ){
4114 nOrderBy
= pWInfo
->pOrderBy
->nExpr
;
4117 /* Allocate and initialize space for aTo, aFrom and aSortCost[] */
4118 nSpace
= (sizeof(WherePath
)+sizeof(WhereLoop
*)*nLoop
)*mxChoice
*2;
4119 nSpace
+= sizeof(LogEst
) * nOrderBy
;
4120 pSpace
= sqlite3DbMallocRawNN(db
, nSpace
);
4121 if( pSpace
==0 ) return SQLITE_NOMEM_BKPT
;
4122 aTo
= (WherePath
*)pSpace
;
4123 aFrom
= aTo
+mxChoice
;
4124 memset(aFrom
, 0, sizeof(aFrom
[0]));
4125 pX
= (WhereLoop
**)(aFrom
+mxChoice
);
4126 for(ii
=mxChoice
*2, pFrom
=aTo
; ii
>0; ii
--, pFrom
++, pX
+= nLoop
){
4130 /* If there is an ORDER BY clause and it is not being ignored, set up
4131 ** space for the aSortCost[] array. Each element of the aSortCost array
4132 ** is either zero - meaning it has not yet been initialized - or the
4133 ** cost of sorting nRowEst rows of data where the first X terms of
4134 ** the ORDER BY clause are already in order, where X is the array
4136 aSortCost
= (LogEst
*)pX
;
4137 memset(aSortCost
, 0, sizeof(LogEst
) * nOrderBy
);
4139 assert( aSortCost
==0 || &pSpace
[nSpace
]==(char*)&aSortCost
[nOrderBy
] );
4140 assert( aSortCost
!=0 || &pSpace
[nSpace
]==(char*)pX
);
4142 /* Seed the search with a single WherePath containing zero WhereLoops.
4144 ** TUNING: Do not let the number of iterations go above 28. If the cost
4145 ** of computing an automatic index is not paid back within the first 28
4146 ** rows, then do not use the automatic index. */
4147 aFrom
[0].nRow
= MIN(pParse
->nQueryLoop
, 48); assert( 48==sqlite3LogEst(28) );
4149 assert( aFrom
[0].isOrdered
==0 );
4151 /* If nLoop is zero, then there are no FROM terms in the query. Since
4152 ** in this case the query may return a maximum of one row, the results
4153 ** are already in the requested order. Set isOrdered to nOrderBy to
4154 ** indicate this. Or, if nLoop is greater than zero, set isOrdered to
4155 ** -1, indicating that the result set may or may not be ordered,
4156 ** depending on the loops added to the current plan. */
4157 aFrom
[0].isOrdered
= nLoop
>0 ? -1 : nOrderBy
;
4160 /* Compute successively longer WherePaths using the previous generation
4161 ** of WherePaths as the basis for the next. Keep track of the mxChoice
4162 ** best paths at each generation */
4163 for(iLoop
=0; iLoop
<nLoop
; iLoop
++){
4165 for(ii
=0, pFrom
=aFrom
; ii
<nFrom
; ii
++, pFrom
++){
4166 for(pWLoop
=pWInfo
->pLoops
; pWLoop
; pWLoop
=pWLoop
->pNextLoop
){
4167 LogEst nOut
; /* Rows visited by (pFrom+pWLoop) */
4168 LogEst rCost
; /* Cost of path (pFrom+pWLoop) */
4169 LogEst rUnsorted
; /* Unsorted cost of (pFrom+pWLoop) */
4170 i8 isOrdered
= pFrom
->isOrdered
; /* isOrdered for (pFrom+pWLoop) */
4171 Bitmask maskNew
; /* Mask of src visited by (..) */
4172 Bitmask revMask
= 0; /* Mask of rev-order loops for (..) */
4174 if( (pWLoop
->prereq
& ~pFrom
->maskLoop
)!=0 ) continue;
4175 if( (pWLoop
->maskSelf
& pFrom
->maskLoop
)!=0 ) continue;
4176 if( (pWLoop
->wsFlags
& WHERE_AUTO_INDEX
)!=0 && pFrom
->nRow
<3 ){
4177 /* Do not use an automatic index if the this loop is expected
4178 ** to run less than 1.25 times. It is tempting to also exclude
4179 ** automatic index usage on an outer loop, but sometimes an automatic
4180 ** index is useful in the outer loop of a correlated subquery. */
4181 assert( 10==sqlite3LogEst(2) );
4185 /* At this point, pWLoop is a candidate to be the next loop.
4186 ** Compute its cost */
4187 rUnsorted
= sqlite3LogEstAdd(pWLoop
->rSetup
,pWLoop
->rRun
+ pFrom
->nRow
);
4188 rUnsorted
= sqlite3LogEstAdd(rUnsorted
, pFrom
->rUnsorted
);
4189 nOut
= pFrom
->nRow
+ pWLoop
->nOut
;
4190 maskNew
= pFrom
->maskLoop
| pWLoop
->maskSelf
;
4192 isOrdered
= wherePathSatisfiesOrderBy(pWInfo
,
4193 pWInfo
->pOrderBy
, pFrom
, pWInfo
->wctrlFlags
,
4194 iLoop
, pWLoop
, &revMask
);
4196 revMask
= pFrom
->revLoop
;
4198 if( isOrdered
>=0 && isOrdered
<nOrderBy
){
4199 if( aSortCost
[isOrdered
]==0 ){
4200 aSortCost
[isOrdered
] = whereSortingCost(
4201 pWInfo
, nRowEst
, nOrderBy
, isOrdered
4204 /* TUNING: Add a small extra penalty (5) to sorting as an
4205 ** extra encouragment to the query planner to select a plan
4206 ** where the rows emerge in the correct order without any sorting
4208 rCost
= sqlite3LogEstAdd(rUnsorted
, aSortCost
[isOrdered
]) + 5;
4211 ("---- sort cost=%-3d (%d/%d) increases cost %3d to %-3d\n",
4212 aSortCost
[isOrdered
], (nOrderBy
-isOrdered
), nOrderBy
,
4216 rUnsorted
-= 2; /* TUNING: Slight bias in favor of no-sort plans */
4219 /* Check to see if pWLoop should be added to the set of
4220 ** mxChoice best-so-far paths.
4222 ** First look for an existing path among best-so-far paths
4223 ** that covers the same set of loops and has the same isOrdered
4224 ** setting as the current path candidate.
4226 ** The term "((pTo->isOrdered^isOrdered)&0x80)==0" is equivalent
4227 ** to (pTo->isOrdered==(-1))==(isOrdered==(-1))" for the range
4228 ** of legal values for isOrdered, -1..64.
4230 for(jj
=0, pTo
=aTo
; jj
<nTo
; jj
++, pTo
++){
4231 if( pTo
->maskLoop
==maskNew
4232 && ((pTo
->isOrdered
^isOrdered
)&0x80)==0
4234 testcase( jj
==nTo
-1 );
4239 /* None of the existing best-so-far paths match the candidate. */
4241 && (rCost
>mxCost
|| (rCost
==mxCost
&& rUnsorted
>=mxUnsorted
))
4243 /* The current candidate is no better than any of the mxChoice
4244 ** paths currently in the best-so-far buffer. So discard
4245 ** this candidate as not viable. */
4246 #ifdef WHERETRACE_ENABLED /* 0x4 */
4247 if( sqlite3WhereTrace
&0x4 ){
4248 sqlite3DebugPrintf("Skip %s cost=%-3d,%3d,%3d order=%c\n",
4249 wherePathName(pFrom
, iLoop
, pWLoop
), rCost
, nOut
, rUnsorted
,
4250 isOrdered
>=0 ? isOrdered
+'0' : '?');
4255 /* If we reach this points it means that the new candidate path
4256 ** needs to be added to the set of best-so-far paths. */
4258 /* Increase the size of the aTo set by one */
4261 /* New path replaces the prior worst to keep count below mxChoice */
4265 #ifdef WHERETRACE_ENABLED /* 0x4 */
4266 if( sqlite3WhereTrace
&0x4 ){
4267 sqlite3DebugPrintf("New %s cost=%-3d,%3d,%3d order=%c\n",
4268 wherePathName(pFrom
, iLoop
, pWLoop
), rCost
, nOut
, rUnsorted
,
4269 isOrdered
>=0 ? isOrdered
+'0' : '?');
4273 /* Control reaches here if best-so-far path pTo=aTo[jj] covers the
4274 ** same set of loops and has the same isOrdered setting as the
4275 ** candidate path. Check to see if the candidate should replace
4276 ** pTo or if the candidate should be skipped.
4278 ** The conditional is an expanded vector comparison equivalent to:
4279 ** (pTo->rCost,pTo->nRow,pTo->rUnsorted) <= (rCost,nOut,rUnsorted)
4281 if( pTo
->rCost
<rCost
4282 || (pTo
->rCost
==rCost
4284 || (pTo
->nRow
==nOut
&& pTo
->rUnsorted
<=rUnsorted
)
4288 #ifdef WHERETRACE_ENABLED /* 0x4 */
4289 if( sqlite3WhereTrace
&0x4 ){
4291 "Skip %s cost=%-3d,%3d,%3d order=%c",
4292 wherePathName(pFrom
, iLoop
, pWLoop
), rCost
, nOut
, rUnsorted
,
4293 isOrdered
>=0 ? isOrdered
+'0' : '?');
4294 sqlite3DebugPrintf(" vs %s cost=%-3d,%3d,%3d order=%c\n",
4295 wherePathName(pTo
, iLoop
+1, 0), pTo
->rCost
, pTo
->nRow
,
4296 pTo
->rUnsorted
, pTo
->isOrdered
>=0 ? pTo
->isOrdered
+'0' : '?');
4299 /* Discard the candidate path from further consideration */
4300 testcase( pTo
->rCost
==rCost
);
4303 testcase( pTo
->rCost
==rCost
+1 );
4304 /* Control reaches here if the candidate path is better than the
4305 ** pTo path. Replace pTo with the candidate. */
4306 #ifdef WHERETRACE_ENABLED /* 0x4 */
4307 if( sqlite3WhereTrace
&0x4 ){
4309 "Update %s cost=%-3d,%3d,%3d order=%c",
4310 wherePathName(pFrom
, iLoop
, pWLoop
), rCost
, nOut
, rUnsorted
,
4311 isOrdered
>=0 ? isOrdered
+'0' : '?');
4312 sqlite3DebugPrintf(" was %s cost=%-3d,%3d,%3d order=%c\n",
4313 wherePathName(pTo
, iLoop
+1, 0), pTo
->rCost
, pTo
->nRow
,
4314 pTo
->rUnsorted
, pTo
->isOrdered
>=0 ? pTo
->isOrdered
+'0' : '?');
4318 /* pWLoop is a winner. Add it to the set of best so far */
4319 pTo
->maskLoop
= pFrom
->maskLoop
| pWLoop
->maskSelf
;
4320 pTo
->revLoop
= revMask
;
4323 pTo
->rUnsorted
= rUnsorted
;
4324 pTo
->isOrdered
= isOrdered
;
4325 memcpy(pTo
->aLoop
, pFrom
->aLoop
, sizeof(WhereLoop
*)*iLoop
);
4326 pTo
->aLoop
[iLoop
] = pWLoop
;
4327 if( nTo
>=mxChoice
){
4329 mxCost
= aTo
[0].rCost
;
4330 mxUnsorted
= aTo
[0].nRow
;
4331 for(jj
=1, pTo
=&aTo
[1]; jj
<mxChoice
; jj
++, pTo
++){
4332 if( pTo
->rCost
>mxCost
4333 || (pTo
->rCost
==mxCost
&& pTo
->rUnsorted
>mxUnsorted
)
4335 mxCost
= pTo
->rCost
;
4336 mxUnsorted
= pTo
->rUnsorted
;
4344 #ifdef WHERETRACE_ENABLED /* >=2 */
4345 if( sqlite3WhereTrace
& 0x02 ){
4346 sqlite3DebugPrintf("---- after round %d ----\n", iLoop
);
4347 for(ii
=0, pTo
=aTo
; ii
<nTo
; ii
++, pTo
++){
4348 sqlite3DebugPrintf(" %s cost=%-3d nrow=%-3d order=%c",
4349 wherePathName(pTo
, iLoop
+1, 0), pTo
->rCost
, pTo
->nRow
,
4350 pTo
->isOrdered
>=0 ? (pTo
->isOrdered
+'0') : '?');
4351 if( pTo
->isOrdered
>0 ){
4352 sqlite3DebugPrintf(" rev=0x%llx\n", pTo
->revLoop
);
4354 sqlite3DebugPrintf("\n");
4360 /* Swap the roles of aFrom and aTo for the next generation */
4368 sqlite3ErrorMsg(pParse
, "no query solution");
4369 sqlite3DbFreeNN(db
, pSpace
);
4370 return SQLITE_ERROR
;
4373 /* Find the lowest cost path. pFrom will be left pointing to that path */
4375 for(ii
=1; ii
<nFrom
; ii
++){
4376 if( pFrom
->rCost
>aFrom
[ii
].rCost
) pFrom
= &aFrom
[ii
];
4378 assert( pWInfo
->nLevel
==nLoop
);
4379 /* Load the lowest cost path into pWInfo */
4380 for(iLoop
=0; iLoop
<nLoop
; iLoop
++){
4381 WhereLevel
*pLevel
= pWInfo
->a
+ iLoop
;
4382 pLevel
->pWLoop
= pWLoop
= pFrom
->aLoop
[iLoop
];
4383 pLevel
->iFrom
= pWLoop
->iTab
;
4384 pLevel
->iTabCur
= pWInfo
->pTabList
->a
[pLevel
->iFrom
].iCursor
;
4386 if( (pWInfo
->wctrlFlags
& WHERE_WANT_DISTINCT
)!=0
4387 && (pWInfo
->wctrlFlags
& WHERE_DISTINCTBY
)==0
4388 && pWInfo
->eDistinct
==WHERE_DISTINCT_NOOP
4392 int rc
= wherePathSatisfiesOrderBy(pWInfo
, pWInfo
->pResultSet
, pFrom
,
4393 WHERE_DISTINCTBY
, nLoop
-1, pFrom
->aLoop
[nLoop
-1], ¬Used
);
4394 if( rc
==pWInfo
->pResultSet
->nExpr
){
4395 pWInfo
->eDistinct
= WHERE_DISTINCT_ORDERED
;
4398 pWInfo
->bOrderedInnerLoop
= 0;
4399 if( pWInfo
->pOrderBy
){
4400 if( pWInfo
->wctrlFlags
& WHERE_DISTINCTBY
){
4401 if( pFrom
->isOrdered
==pWInfo
->pOrderBy
->nExpr
){
4402 pWInfo
->eDistinct
= WHERE_DISTINCT_ORDERED
;
4405 pWInfo
->nOBSat
= pFrom
->isOrdered
;
4406 pWInfo
->revMask
= pFrom
->revLoop
;
4407 if( pWInfo
->nOBSat
<=0 ){
4410 u32 wsFlags
= pFrom
->aLoop
[nLoop
-1]->wsFlags
;
4411 if( (wsFlags
& WHERE_ONEROW
)==0
4412 && (wsFlags
&(WHERE_IPK
|WHERE_COLUMN_IN
))!=(WHERE_IPK
|WHERE_COLUMN_IN
)
4415 int rc
= wherePathSatisfiesOrderBy(pWInfo
, pWInfo
->pOrderBy
, pFrom
,
4416 WHERE_ORDERBY_LIMIT
, nLoop
-1, pFrom
->aLoop
[nLoop
-1], &m
);
4417 testcase( wsFlags
& WHERE_IPK
);
4418 testcase( wsFlags
& WHERE_COLUMN_IN
);
4419 if( rc
==pWInfo
->pOrderBy
->nExpr
){
4420 pWInfo
->bOrderedInnerLoop
= 1;
4421 pWInfo
->revMask
= m
;
4427 if( (pWInfo
->wctrlFlags
& WHERE_SORTBYGROUP
)
4428 && pWInfo
->nOBSat
==pWInfo
->pOrderBy
->nExpr
&& nLoop
>0
4430 Bitmask revMask
= 0;
4431 int nOrder
= wherePathSatisfiesOrderBy(pWInfo
, pWInfo
->pOrderBy
,
4432 pFrom
, 0, nLoop
-1, pFrom
->aLoop
[nLoop
-1], &revMask
4434 assert( pWInfo
->sorted
==0 );
4435 if( nOrder
==pWInfo
->pOrderBy
->nExpr
){
4437 pWInfo
->revMask
= revMask
;
4443 pWInfo
->nRowOut
= pFrom
->nRow
;
4445 /* Free temporary memory and return success */
4446 sqlite3DbFreeNN(db
, pSpace
);
4451 ** Most queries use only a single table (they are not joins) and have
4452 ** simple == constraints against indexed fields. This routine attempts
4453 ** to plan those simple cases using much less ceremony than the
4454 ** general-purpose query planner, and thereby yield faster sqlite3_prepare()
4455 ** times for the common case.
4457 ** Return non-zero on success, if this query can be handled by this
4458 ** no-frills query planner. Return zero if this query needs the
4459 ** general-purpose query planner.
4461 static int whereShortCut(WhereLoopBuilder
*pBuilder
){
4463 struct SrcList_item
*pItem
;
4472 pWInfo
= pBuilder
->pWInfo
;
4473 if( pWInfo
->wctrlFlags
& WHERE_OR_SUBCLAUSE
) return 0;
4474 assert( pWInfo
->pTabList
->nSrc
>=1 );
4475 pItem
= pWInfo
->pTabList
->a
;
4477 if( IsVirtual(pTab
) ) return 0;
4478 if( pItem
->fg
.isIndexedBy
) return 0;
4479 iCur
= pItem
->iCursor
;
4481 pLoop
= pBuilder
->pNew
;
4484 pTerm
= sqlite3WhereFindTerm(pWC
, iCur
, -1, 0, WO_EQ
|WO_IS
, 0);
4486 testcase( pTerm
->eOperator
& WO_IS
);
4487 pLoop
->wsFlags
= WHERE_COLUMN_EQ
|WHERE_IPK
|WHERE_ONEROW
;
4488 pLoop
->aLTerm
[0] = pTerm
;
4490 pLoop
->u
.btree
.nEq
= 1;
4491 /* TUNING: Cost of a rowid lookup is 10 */
4492 pLoop
->rRun
= 33; /* 33==sqlite3LogEst(10) */
4494 for(pIdx
=pTab
->pIndex
; pIdx
; pIdx
=pIdx
->pNext
){
4496 assert( pLoop
->aLTermSpace
==pLoop
->aLTerm
);
4497 if( !IsUniqueIndex(pIdx
)
4498 || pIdx
->pPartIdxWhere
!=0
4499 || pIdx
->nKeyCol
>ArraySize(pLoop
->aLTermSpace
)
4501 opMask
= pIdx
->uniqNotNull
? (WO_EQ
|WO_IS
) : WO_EQ
;
4502 for(j
=0; j
<pIdx
->nKeyCol
; j
++){
4503 pTerm
= sqlite3WhereFindTerm(pWC
, iCur
, j
, 0, opMask
, pIdx
);
4504 if( pTerm
==0 ) break;
4505 testcase( pTerm
->eOperator
& WO_IS
);
4506 pLoop
->aLTerm
[j
] = pTerm
;
4508 if( j
!=pIdx
->nKeyCol
) continue;
4509 pLoop
->wsFlags
= WHERE_COLUMN_EQ
|WHERE_ONEROW
|WHERE_INDEXED
;
4510 if( pIdx
->isCovering
|| (pItem
->colUsed
& pIdx
->colNotIdxed
)==0 ){
4511 pLoop
->wsFlags
|= WHERE_IDX_ONLY
;
4514 pLoop
->u
.btree
.nEq
= j
;
4515 pLoop
->u
.btree
.pIndex
= pIdx
;
4516 /* TUNING: Cost of a unique index lookup is 15 */
4517 pLoop
->rRun
= 39; /* 39==sqlite3LogEst(15) */
4521 if( pLoop
->wsFlags
){
4522 pLoop
->nOut
= (LogEst
)1;
4523 pWInfo
->a
[0].pWLoop
= pLoop
;
4524 assert( pWInfo
->sMaskSet
.n
==1 && iCur
==pWInfo
->sMaskSet
.ix
[0] );
4525 pLoop
->maskSelf
= 1; /* sqlite3WhereGetMask(&pWInfo->sMaskSet, iCur); */
4526 pWInfo
->a
[0].iTabCur
= iCur
;
4527 pWInfo
->nRowOut
= 1;
4528 if( pWInfo
->pOrderBy
) pWInfo
->nOBSat
= pWInfo
->pOrderBy
->nExpr
;
4529 if( pWInfo
->wctrlFlags
& WHERE_WANT_DISTINCT
){
4530 pWInfo
->eDistinct
= WHERE_DISTINCT_UNIQUE
;
4541 ** Helper function for exprIsDeterministic().
4543 static int exprNodeIsDeterministic(Walker
*pWalker
, Expr
*pExpr
){
4544 if( pExpr
->op
==TK_FUNCTION
&& ExprHasProperty(pExpr
, EP_ConstFunc
)==0 ){
4548 return WRC_Continue
;
4552 ** Return true if the expression contains no non-deterministic SQL
4553 ** functions. Do not consider non-deterministic SQL functions that are
4554 ** part of sub-select statements.
4556 static int exprIsDeterministic(Expr
*p
){
4558 memset(&w
, 0, sizeof(w
));
4560 w
.xExprCallback
= exprNodeIsDeterministic
;
4561 w
.xSelectCallback
= sqlite3SelectWalkFail
;
4562 sqlite3WalkExpr(&w
, p
);
4567 #ifdef WHERETRACE_ENABLED
4569 ** Display all WhereLoops in pWInfo
4571 static void showAllWhereLoops(WhereInfo
*pWInfo
, WhereClause
*pWC
){
4572 if( sqlite3WhereTrace
){ /* Display all of the WhereLoop objects */
4575 static const char zLabel
[] = "0123456789abcdefghijklmnopqrstuvwyxz"
4576 "ABCDEFGHIJKLMNOPQRSTUVWYXZ";
4577 for(p
=pWInfo
->pLoops
, i
=0; p
; p
=p
->pNextLoop
, i
++){
4578 p
->cId
= zLabel
[i
%(sizeof(zLabel
)-1)];
4579 sqlite3WhereLoopPrint(p
, pWC
);
4583 # define WHERETRACE_ALL_LOOPS(W,C) showAllWhereLoops(W,C)
4585 # define WHERETRACE_ALL_LOOPS(W,C)
4589 ** Generate the beginning of the loop used for WHERE clause processing.
4590 ** The return value is a pointer to an opaque structure that contains
4591 ** information needed to terminate the loop. Later, the calling routine
4592 ** should invoke sqlite3WhereEnd() with the return value of this function
4593 ** in order to complete the WHERE clause processing.
4595 ** If an error occurs, this routine returns NULL.
4597 ** The basic idea is to do a nested loop, one loop for each table in
4598 ** the FROM clause of a select. (INSERT and UPDATE statements are the
4599 ** same as a SELECT with only a single table in the FROM clause.) For
4600 ** example, if the SQL is this:
4602 ** SELECT * FROM t1, t2, t3 WHERE ...;
4604 ** Then the code generated is conceptually like the following:
4606 ** foreach row1 in t1 do \ Code generated
4607 ** foreach row2 in t2 do |-- by sqlite3WhereBegin()
4608 ** foreach row3 in t3 do /
4610 ** end \ Code generated
4611 ** end |-- by sqlite3WhereEnd()
4614 ** Note that the loops might not be nested in the order in which they
4615 ** appear in the FROM clause if a different order is better able to make
4616 ** use of indices. Note also that when the IN operator appears in
4617 ** the WHERE clause, it might result in additional nested loops for
4618 ** scanning through all values on the right-hand side of the IN.
4620 ** There are Btree cursors associated with each table. t1 uses cursor
4621 ** number pTabList->a[0].iCursor. t2 uses the cursor pTabList->a[1].iCursor.
4622 ** And so forth. This routine generates code to open those VDBE cursors
4623 ** and sqlite3WhereEnd() generates the code to close them.
4625 ** The code that sqlite3WhereBegin() generates leaves the cursors named
4626 ** in pTabList pointing at their appropriate entries. The [...] code
4627 ** can use OP_Column and OP_Rowid opcodes on these cursors to extract
4628 ** data from the various tables of the loop.
4630 ** If the WHERE clause is empty, the foreach loops must each scan their
4631 ** entire tables. Thus a three-way join is an O(N^3) operation. But if
4632 ** the tables have indices and there are terms in the WHERE clause that
4633 ** refer to those indices, a complete table scan can be avoided and the
4634 ** code will run much faster. Most of the work of this routine is checking
4635 ** to see if there are indices that can be used to speed up the loop.
4637 ** Terms of the WHERE clause are also used to limit which rows actually
4638 ** make it to the "..." in the middle of the loop. After each "foreach",
4639 ** terms of the WHERE clause that use only terms in that loop and outer
4640 ** loops are evaluated and if false a jump is made around all subsequent
4641 ** inner loops (or around the "..." if the test occurs within the inner-
4646 ** An outer join of tables t1 and t2 is conceptally coded as follows:
4648 ** foreach row1 in t1 do
4650 ** foreach row2 in t2 do
4656 ** move the row2 cursor to a null row
4661 ** ORDER BY CLAUSE PROCESSING
4663 ** pOrderBy is a pointer to the ORDER BY clause (or the GROUP BY clause
4664 ** if the WHERE_GROUPBY flag is set in wctrlFlags) of a SELECT statement
4665 ** if there is one. If there is no ORDER BY clause or if this routine
4666 ** is called from an UPDATE or DELETE statement, then pOrderBy is NULL.
4668 ** The iIdxCur parameter is the cursor number of an index. If
4669 ** WHERE_OR_SUBCLAUSE is set, iIdxCur is the cursor number of an index
4670 ** to use for OR clause processing. The WHERE clause should use this
4671 ** specific cursor. If WHERE_ONEPASS_DESIRED is set, then iIdxCur is
4672 ** the first cursor in an array of cursors for all indices. iIdxCur should
4673 ** be used to compute the appropriate cursor depending on which index is
4676 WhereInfo
*sqlite3WhereBegin(
4677 Parse
*pParse
, /* The parser context */
4678 SrcList
*pTabList
, /* FROM clause: A list of all tables to be scanned */
4679 Expr
*pWhere
, /* The WHERE clause */
4680 ExprList
*pOrderBy
, /* An ORDER BY (or GROUP BY) clause, or NULL */
4681 ExprList
*pResultSet
, /* Query result set. Req'd for DISTINCT */
4682 u16 wctrlFlags
, /* The WHERE_* flags defined in sqliteInt.h */
4683 int iAuxArg
/* If WHERE_OR_SUBCLAUSE is set, index cursor number
4684 ** If WHERE_USE_LIMIT, then the limit amount */
4686 int nByteWInfo
; /* Num. bytes allocated for WhereInfo struct */
4687 int nTabList
; /* Number of elements in pTabList */
4688 WhereInfo
*pWInfo
; /* Will become the return value of this function */
4689 Vdbe
*v
= pParse
->pVdbe
; /* The virtual database engine */
4690 Bitmask notReady
; /* Cursors that are not yet positioned */
4691 WhereLoopBuilder sWLB
; /* The WhereLoop builder */
4692 WhereMaskSet
*pMaskSet
; /* The expression mask set */
4693 WhereLevel
*pLevel
; /* A single level in pWInfo->a[] */
4694 WhereLoop
*pLoop
; /* Pointer to a single WhereLoop object */
4695 int ii
; /* Loop counter */
4696 sqlite3
*db
; /* Database connection */
4697 int rc
; /* Return code */
4698 u8 bFordelete
= 0; /* OPFLAG_FORDELETE or zero, as appropriate */
4700 assert( (wctrlFlags
& WHERE_ONEPASS_MULTIROW
)==0 || (
4701 (wctrlFlags
& WHERE_ONEPASS_DESIRED
)!=0
4702 && (wctrlFlags
& WHERE_OR_SUBCLAUSE
)==0
4705 /* Only one of WHERE_OR_SUBCLAUSE or WHERE_USE_LIMIT */
4706 assert( (wctrlFlags
& WHERE_OR_SUBCLAUSE
)==0
4707 || (wctrlFlags
& WHERE_USE_LIMIT
)==0 );
4709 /* Variable initialization */
4711 memset(&sWLB
, 0, sizeof(sWLB
));
4713 /* An ORDER/GROUP BY clause of more than 63 terms cannot be optimized */
4714 testcase( pOrderBy
&& pOrderBy
->nExpr
==BMS
-1 );
4715 if( pOrderBy
&& pOrderBy
->nExpr
>=BMS
) pOrderBy
= 0;
4716 sWLB
.pOrderBy
= pOrderBy
;
4718 /* Disable the DISTINCT optimization if SQLITE_DistinctOpt is set via
4719 ** sqlite3_test_ctrl(SQLITE_TESTCTRL_OPTIMIZATIONS,...) */
4720 if( OptimizationDisabled(db
, SQLITE_DistinctOpt
) ){
4721 wctrlFlags
&= ~WHERE_WANT_DISTINCT
;
4724 /* The number of tables in the FROM clause is limited by the number of
4725 ** bits in a Bitmask
4727 testcase( pTabList
->nSrc
==BMS
);
4728 if( pTabList
->nSrc
>BMS
){
4729 sqlite3ErrorMsg(pParse
, "at most %d tables in a join", BMS
);
4733 /* This function normally generates a nested loop for all tables in
4734 ** pTabList. But if the WHERE_OR_SUBCLAUSE flag is set, then we should
4735 ** only generate code for the first table in pTabList and assume that
4736 ** any cursors associated with subsequent tables are uninitialized.
4738 nTabList
= (wctrlFlags
& WHERE_OR_SUBCLAUSE
) ? 1 : pTabList
->nSrc
;
4740 /* Allocate and initialize the WhereInfo structure that will become the
4741 ** return value. A single allocation is used to store the WhereInfo
4742 ** struct, the contents of WhereInfo.a[], the WhereClause structure
4743 ** and the WhereMaskSet structure. Since WhereClause contains an 8-byte
4744 ** field (type Bitmask) it must be aligned on an 8-byte boundary on
4745 ** some architectures. Hence the ROUND8() below.
4747 nByteWInfo
= ROUND8(sizeof(WhereInfo
)+(nTabList
-1)*sizeof(WhereLevel
));
4748 pWInfo
= sqlite3DbMallocRawNN(db
, nByteWInfo
+ sizeof(WhereLoop
));
4749 if( db
->mallocFailed
){
4750 sqlite3DbFree(db
, pWInfo
);
4752 goto whereBeginError
;
4754 pWInfo
->pParse
= pParse
;
4755 pWInfo
->pTabList
= pTabList
;
4756 pWInfo
->pOrderBy
= pOrderBy
;
4757 pWInfo
->pWhere
= pWhere
;
4758 pWInfo
->pResultSet
= pResultSet
;
4759 pWInfo
->aiCurOnePass
[0] = pWInfo
->aiCurOnePass
[1] = -1;
4760 pWInfo
->nLevel
= nTabList
;
4761 pWInfo
->iBreak
= pWInfo
->iContinue
= sqlite3VdbeMakeLabel(pParse
);
4762 pWInfo
->wctrlFlags
= wctrlFlags
;
4763 pWInfo
->iLimit
= iAuxArg
;
4764 pWInfo
->savedNQueryLoop
= pParse
->nQueryLoop
;
4765 memset(&pWInfo
->nOBSat
, 0,
4766 offsetof(WhereInfo
,sWC
) - offsetof(WhereInfo
,nOBSat
));
4767 memset(&pWInfo
->a
[0], 0, sizeof(WhereLoop
)+nTabList
*sizeof(WhereLevel
));
4768 assert( pWInfo
->eOnePass
==ONEPASS_OFF
); /* ONEPASS defaults to OFF */
4769 pMaskSet
= &pWInfo
->sMaskSet
;
4770 sWLB
.pWInfo
= pWInfo
;
4771 sWLB
.pWC
= &pWInfo
->sWC
;
4772 sWLB
.pNew
= (WhereLoop
*)(((char*)pWInfo
)+nByteWInfo
);
4773 assert( EIGHT_BYTE_ALIGNMENT(sWLB
.pNew
) );
4774 whereLoopInit(sWLB
.pNew
);
4776 sWLB
.pNew
->cId
= '*';
4779 /* Split the WHERE clause into separate subexpressions where each
4780 ** subexpression is separated by an AND operator.
4782 initMaskSet(pMaskSet
);
4783 sqlite3WhereClauseInit(&pWInfo
->sWC
, pWInfo
);
4784 sqlite3WhereSplit(&pWInfo
->sWC
, pWhere
, TK_AND
);
4786 /* Special case: No FROM clause
4789 if( pOrderBy
) pWInfo
->nOBSat
= pOrderBy
->nExpr
;
4790 if( wctrlFlags
& WHERE_WANT_DISTINCT
){
4791 pWInfo
->eDistinct
= WHERE_DISTINCT_UNIQUE
;
4793 ExplainQueryPlan((pParse
, 0, "SCAN CONSTANT ROW"));
4795 /* Assign a bit from the bitmask to every term in the FROM clause.
4797 ** The N-th term of the FROM clause is assigned a bitmask of 1<<N.
4799 ** The rule of the previous sentence ensures thta if X is the bitmask for
4800 ** a table T, then X-1 is the bitmask for all other tables to the left of T.
4801 ** Knowing the bitmask for all tables to the left of a left join is
4802 ** important. Ticket #3015.
4804 ** Note that bitmasks are created for all pTabList->nSrc tables in
4805 ** pTabList, not just the first nTabList tables. nTabList is normally
4806 ** equal to pTabList->nSrc but might be shortened to 1 if the
4807 ** WHERE_OR_SUBCLAUSE flag is set.
4811 createMask(pMaskSet
, pTabList
->a
[ii
].iCursor
);
4812 sqlite3WhereTabFuncArgs(pParse
, &pTabList
->a
[ii
], &pWInfo
->sWC
);
4813 }while( (++ii
)<pTabList
->nSrc
);
4817 for(ii
=0; ii
<pTabList
->nSrc
; ii
++){
4818 Bitmask m
= sqlite3WhereGetMask(pMaskSet
, pTabList
->a
[ii
].iCursor
);
4826 /* Analyze all of the subexpressions. */
4827 sqlite3WhereExprAnalyze(pTabList
, &pWInfo
->sWC
);
4828 if( db
->mallocFailed
) goto whereBeginError
;
4830 /* Special case: WHERE terms that do not refer to any tables in the join
4831 ** (constant expressions). Evaluate each such term, and jump over all the
4832 ** generated code if the result is not true.
4834 ** Do not do this if the expression contains non-deterministic functions
4835 ** that are not within a sub-select. This is not strictly required, but
4836 ** preserves SQLite's legacy behaviour in the following two cases:
4838 ** FROM ... WHERE random()>0; -- eval random() once per row
4839 ** FROM ... WHERE (SELECT random())>0; -- eval random() once overall
4841 for(ii
=0; ii
<sWLB
.pWC
->nTerm
; ii
++){
4842 WhereTerm
*pT
= &sWLB
.pWC
->a
[ii
];
4843 if( pT
->wtFlags
& TERM_VIRTUAL
) continue;
4844 if( pT
->prereqAll
==0 && (nTabList
==0 || exprIsDeterministic(pT
->pExpr
)) ){
4845 sqlite3ExprIfFalse(pParse
, pT
->pExpr
, pWInfo
->iBreak
, SQLITE_JUMPIFNULL
);
4846 pT
->wtFlags
|= TERM_CODED
;
4850 if( wctrlFlags
& WHERE_WANT_DISTINCT
){
4851 if( isDistinctRedundant(pParse
, pTabList
, &pWInfo
->sWC
, pResultSet
) ){
4852 /* The DISTINCT marking is pointless. Ignore it. */
4853 pWInfo
->eDistinct
= WHERE_DISTINCT_UNIQUE
;
4854 }else if( pOrderBy
==0 ){
4855 /* Try to ORDER BY the result set to make distinct processing easier */
4856 pWInfo
->wctrlFlags
|= WHERE_DISTINCTBY
;
4857 pWInfo
->pOrderBy
= pResultSet
;
4861 /* Construct the WhereLoop objects */
4862 #if defined(WHERETRACE_ENABLED)
4863 if( sqlite3WhereTrace
& 0xffff ){
4864 sqlite3DebugPrintf("*** Optimizer Start *** (wctrlFlags: 0x%x",wctrlFlags
);
4865 if( wctrlFlags
& WHERE_USE_LIMIT
){
4866 sqlite3DebugPrintf(", limit: %d", iAuxArg
);
4868 sqlite3DebugPrintf(")\n");
4869 if( sqlite3WhereTrace
& 0x100 ){
4871 memset(&sSelect
, 0, sizeof(sSelect
));
4872 sSelect
.selFlags
= SF_WhereBegin
;
4873 sSelect
.pSrc
= pTabList
;
4874 sSelect
.pWhere
= pWhere
;
4875 sSelect
.pOrderBy
= pOrderBy
;
4876 sSelect
.pEList
= pResultSet
;
4877 sqlite3TreeViewSelect(0, &sSelect
, 0);
4880 if( sqlite3WhereTrace
& 0x100 ){ /* Display all terms of the WHERE clause */
4881 sqlite3DebugPrintf("---- WHERE clause at start of analysis:\n");
4882 sqlite3WhereClausePrint(sWLB
.pWC
);
4886 if( nTabList
!=1 || whereShortCut(&sWLB
)==0 ){
4887 rc
= whereLoopAddAll(&sWLB
);
4888 if( rc
) goto whereBeginError
;
4890 #ifdef SQLITE_ENABLE_STAT4
4891 /* If one or more WhereTerm.truthProb values were used in estimating
4892 ** loop parameters, but then those truthProb values were subsequently
4893 ** changed based on STAT4 information while computing subsequent loops,
4894 ** then we need to rerun the whole loop building process so that all
4895 ** loops will be built using the revised truthProb values. */
4896 if( sWLB
.bldFlags2
& SQLITE_BLDF2_2NDPASS
){
4897 WHERETRACE_ALL_LOOPS(pWInfo
, sWLB
.pWC
);
4899 ("**** Redo all loop computations due to"
4900 " TERM_HIGHTRUTH changes ****\n"));
4901 while( pWInfo
->pLoops
){
4902 WhereLoop
*p
= pWInfo
->pLoops
;
4903 pWInfo
->pLoops
= p
->pNextLoop
;
4904 whereLoopDelete(db
, p
);
4906 rc
= whereLoopAddAll(&sWLB
);
4907 if( rc
) goto whereBeginError
;
4910 WHERETRACE_ALL_LOOPS(pWInfo
, sWLB
.pWC
);
4912 wherePathSolver(pWInfo
, 0);
4913 if( db
->mallocFailed
) goto whereBeginError
;
4914 if( pWInfo
->pOrderBy
){
4915 wherePathSolver(pWInfo
, pWInfo
->nRowOut
+1);
4916 if( db
->mallocFailed
) goto whereBeginError
;
4919 if( pWInfo
->pOrderBy
==0 && (db
->flags
& SQLITE_ReverseOrder
)!=0 ){
4920 pWInfo
->revMask
= ALLBITS
;
4922 if( pParse
->nErr
|| NEVER(db
->mallocFailed
) ){
4923 goto whereBeginError
;
4925 #ifdef WHERETRACE_ENABLED
4926 if( sqlite3WhereTrace
){
4927 sqlite3DebugPrintf("---- Solution nRow=%d", pWInfo
->nRowOut
);
4928 if( pWInfo
->nOBSat
>0 ){
4929 sqlite3DebugPrintf(" ORDERBY=%d,0x%llx", pWInfo
->nOBSat
, pWInfo
->revMask
);
4931 switch( pWInfo
->eDistinct
){
4932 case WHERE_DISTINCT_UNIQUE
: {
4933 sqlite3DebugPrintf(" DISTINCT=unique");
4936 case WHERE_DISTINCT_ORDERED
: {
4937 sqlite3DebugPrintf(" DISTINCT=ordered");
4940 case WHERE_DISTINCT_UNORDERED
: {
4941 sqlite3DebugPrintf(" DISTINCT=unordered");
4945 sqlite3DebugPrintf("\n");
4946 for(ii
=0; ii
<pWInfo
->nLevel
; ii
++){
4947 sqlite3WhereLoopPrint(pWInfo
->a
[ii
].pWLoop
, sWLB
.pWC
);
4952 /* Attempt to omit tables from the join that do not affect the result.
4953 ** For a table to not affect the result, the following must be true:
4955 ** 1) The query must not be an aggregate.
4956 ** 2) The table must be the RHS of a LEFT JOIN.
4957 ** 3) Either the query must be DISTINCT, or else the ON or USING clause
4958 ** must contain a constraint that limits the scan of the table to
4959 ** at most a single row.
4960 ** 4) The table must not be referenced by any part of the query apart
4961 ** from its own USING or ON clause.
4963 ** For example, given:
4965 ** CREATE TABLE t1(ipk INTEGER PRIMARY KEY, v1);
4966 ** CREATE TABLE t2(ipk INTEGER PRIMARY KEY, v2);
4967 ** CREATE TABLE t3(ipk INTEGER PRIMARY KEY, v3);
4969 ** then table t2 can be omitted from the following:
4971 ** SELECT v1, v3 FROM t1
4972 ** LEFT JOIN t2 ON (t1.ipk=t2.ipk)
4973 ** LEFT JOIN t3 ON (t1.ipk=t3.ipk)
4977 ** SELECT DISTINCT v1, v3 FROM t1
4979 ** LEFT JOIN t3 ON (t1.ipk=t3.ipk)
4981 notReady
= ~(Bitmask
)0;
4982 if( pWInfo
->nLevel
>=2
4983 && pResultSet
!=0 /* guarantees condition (1) above */
4984 && OptimizationEnabled(db
, SQLITE_OmitNoopJoin
)
4987 Bitmask tabUsed
= sqlite3WhereExprListUsage(pMaskSet
, pResultSet
);
4988 if( sWLB
.pOrderBy
){
4989 tabUsed
|= sqlite3WhereExprListUsage(pMaskSet
, sWLB
.pOrderBy
);
4991 for(i
=pWInfo
->nLevel
-1; i
>=1; i
--){
4992 WhereTerm
*pTerm
, *pEnd
;
4993 struct SrcList_item
*pItem
;
4994 pLoop
= pWInfo
->a
[i
].pWLoop
;
4995 pItem
= &pWInfo
->pTabList
->a
[pLoop
->iTab
];
4996 if( (pItem
->fg
.jointype
& JT_LEFT
)==0 ) continue;
4997 if( (wctrlFlags
& WHERE_WANT_DISTINCT
)==0
4998 && (pLoop
->wsFlags
& WHERE_ONEROW
)==0
5002 if( (tabUsed
& pLoop
->maskSelf
)!=0 ) continue;
5003 pEnd
= sWLB
.pWC
->a
+ sWLB
.pWC
->nTerm
;
5004 for(pTerm
=sWLB
.pWC
->a
; pTerm
<pEnd
; pTerm
++){
5005 if( (pTerm
->prereqAll
& pLoop
->maskSelf
)!=0 ){
5006 if( !ExprHasProperty(pTerm
->pExpr
, EP_FromJoin
)
5007 || pTerm
->pExpr
->iRightJoinTable
!=pItem
->iCursor
5013 if( pTerm
<pEnd
) continue;
5014 WHERETRACE(0xffff, ("-> drop loop %c not used\n", pLoop
->cId
));
5015 notReady
&= ~pLoop
->maskSelf
;
5016 for(pTerm
=sWLB
.pWC
->a
; pTerm
<pEnd
; pTerm
++){
5017 if( (pTerm
->prereqAll
& pLoop
->maskSelf
)!=0 ){
5018 pTerm
->wtFlags
|= TERM_CODED
;
5021 if( i
!=pWInfo
->nLevel
-1 ){
5022 int nByte
= (pWInfo
->nLevel
-1-i
) * sizeof(WhereLevel
);
5023 memmove(&pWInfo
->a
[i
], &pWInfo
->a
[i
+1], nByte
);
5029 #if defined(WHERETRACE_ENABLED)
5030 if( sqlite3WhereTrace
& 0x100 ){ /* Display all terms of the WHERE clause */
5031 sqlite3DebugPrintf("---- WHERE clause at end of analysis:\n");
5032 sqlite3WhereClausePrint(sWLB
.pWC
);
5034 WHERETRACE(0xffff,("*** Optimizer Finished ***\n"));
5036 pWInfo
->pParse
->nQueryLoop
+= pWInfo
->nRowOut
;
5038 /* If the caller is an UPDATE or DELETE statement that is requesting
5039 ** to use a one-pass algorithm, determine if this is appropriate.
5041 ** A one-pass approach can be used if the caller has requested one
5042 ** and either (a) the scan visits at most one row or (b) each
5043 ** of the following are true:
5045 ** * the caller has indicated that a one-pass approach can be used
5046 ** with multiple rows (by setting WHERE_ONEPASS_MULTIROW), and
5047 ** * the table is not a virtual table, and
5048 ** * either the scan does not use the OR optimization or the caller
5049 ** is a DELETE operation (WHERE_DUPLICATES_OK is only specified
5052 ** The last qualification is because an UPDATE statement uses
5053 ** WhereInfo.aiCurOnePass[1] to determine whether or not it really can
5054 ** use a one-pass approach, and this is not set accurately for scans
5055 ** that use the OR optimization.
5057 assert( (wctrlFlags
& WHERE_ONEPASS_DESIRED
)==0 || pWInfo
->nLevel
==1 );
5058 if( (wctrlFlags
& WHERE_ONEPASS_DESIRED
)!=0 ){
5059 int wsFlags
= pWInfo
->a
[0].pWLoop
->wsFlags
;
5060 int bOnerow
= (wsFlags
& WHERE_ONEROW
)!=0;
5061 assert( !(wsFlags
& WHERE_VIRTUALTABLE
) || IsVirtual(pTabList
->a
[0].pTab
) );
5063 0!=(wctrlFlags
& WHERE_ONEPASS_MULTIROW
)
5064 && !IsVirtual(pTabList
->a
[0].pTab
)
5065 && (0==(wsFlags
& WHERE_MULTI_OR
) || (wctrlFlags
& WHERE_DUPLICATES_OK
))
5067 pWInfo
->eOnePass
= bOnerow
? ONEPASS_SINGLE
: ONEPASS_MULTI
;
5068 if( HasRowid(pTabList
->a
[0].pTab
) && (wsFlags
& WHERE_IDX_ONLY
) ){
5069 if( wctrlFlags
& WHERE_ONEPASS_MULTIROW
){
5070 bFordelete
= OPFLAG_FORDELETE
;
5072 pWInfo
->a
[0].pWLoop
->wsFlags
= (wsFlags
& ~WHERE_IDX_ONLY
);
5077 /* Open all tables in the pTabList and any indices selected for
5078 ** searching those tables.
5080 for(ii
=0, pLevel
=pWInfo
->a
; ii
<nTabList
; ii
++, pLevel
++){
5081 Table
*pTab
; /* Table to open */
5082 int iDb
; /* Index of database containing table/index */
5083 struct SrcList_item
*pTabItem
;
5085 pTabItem
= &pTabList
->a
[pLevel
->iFrom
];
5086 pTab
= pTabItem
->pTab
;
5087 iDb
= sqlite3SchemaToIndex(db
, pTab
->pSchema
);
5088 pLoop
= pLevel
->pWLoop
;
5089 if( (pTab
->tabFlags
& TF_Ephemeral
)!=0 || pTab
->pSelect
){
5092 #ifndef SQLITE_OMIT_VIRTUALTABLE
5093 if( (pLoop
->wsFlags
& WHERE_VIRTUALTABLE
)!=0 ){
5094 const char *pVTab
= (const char *)sqlite3GetVTable(db
, pTab
);
5095 int iCur
= pTabItem
->iCursor
;
5096 sqlite3VdbeAddOp4(v
, OP_VOpen
, iCur
, 0, 0, pVTab
, P4_VTAB
);
5097 }else if( IsVirtual(pTab
) ){
5101 if( (pLoop
->wsFlags
& WHERE_IDX_ONLY
)==0
5102 && (wctrlFlags
& WHERE_OR_SUBCLAUSE
)==0 ){
5103 int op
= OP_OpenRead
;
5104 if( pWInfo
->eOnePass
!=ONEPASS_OFF
){
5106 pWInfo
->aiCurOnePass
[0] = pTabItem
->iCursor
;
5108 sqlite3OpenTable(pParse
, pTabItem
->iCursor
, iDb
, pTab
, op
);
5109 assert( pTabItem
->iCursor
==pLevel
->iTabCur
);
5110 testcase( pWInfo
->eOnePass
==ONEPASS_OFF
&& pTab
->nCol
==BMS
-1 );
5111 testcase( pWInfo
->eOnePass
==ONEPASS_OFF
&& pTab
->nCol
==BMS
);
5112 if( pWInfo
->eOnePass
==ONEPASS_OFF
5114 && (pTab
->tabFlags
& (TF_HasGenerated
|TF_WithoutRowid
))==0
5116 /* If we know that only a prefix of the record will be used,
5117 ** it is advantageous to reduce the "column count" field in
5118 ** the P4 operand of the OP_OpenRead/Write opcode. */
5119 Bitmask b
= pTabItem
->colUsed
;
5121 for(; b
; b
=b
>>1, n
++){}
5122 sqlite3VdbeChangeP4(v
, -1, SQLITE_INT_TO_PTR(n
), P4_INT32
);
5123 assert( n
<=pTab
->nCol
);
5125 #ifdef SQLITE_ENABLE_CURSOR_HINTS
5126 if( pLoop
->u
.btree
.pIndex
!=0 ){
5127 sqlite3VdbeChangeP5(v
, OPFLAG_SEEKEQ
|bFordelete
);
5131 sqlite3VdbeChangeP5(v
, bFordelete
);
5133 #ifdef SQLITE_ENABLE_COLUMN_USED_MASK
5134 sqlite3VdbeAddOp4Dup8(v
, OP_ColumnsUsed
, pTabItem
->iCursor
, 0, 0,
5135 (const u8
*)&pTabItem
->colUsed
, P4_INT64
);
5138 sqlite3TableLock(pParse
, iDb
, pTab
->tnum
, 0, pTab
->zName
);
5140 if( pLoop
->wsFlags
& WHERE_INDEXED
){
5141 Index
*pIx
= pLoop
->u
.btree
.pIndex
;
5143 int op
= OP_OpenRead
;
5144 /* iAuxArg is always set to a positive value if ONEPASS is possible */
5145 assert( iAuxArg
!=0 || (pWInfo
->wctrlFlags
& WHERE_ONEPASS_DESIRED
)==0 );
5146 if( !HasRowid(pTab
) && IsPrimaryKeyIndex(pIx
)
5147 && (wctrlFlags
& WHERE_OR_SUBCLAUSE
)!=0
5149 /* This is one term of an OR-optimization using the PRIMARY KEY of a
5150 ** WITHOUT ROWID table. No need for a separate index */
5151 iIndexCur
= pLevel
->iTabCur
;
5153 }else if( pWInfo
->eOnePass
!=ONEPASS_OFF
){
5154 Index
*pJ
= pTabItem
->pTab
->pIndex
;
5155 iIndexCur
= iAuxArg
;
5156 assert( wctrlFlags
& WHERE_ONEPASS_DESIRED
);
5157 while( ALWAYS(pJ
) && pJ
!=pIx
){
5162 pWInfo
->aiCurOnePass
[1] = iIndexCur
;
5163 }else if( iAuxArg
&& (wctrlFlags
& WHERE_OR_SUBCLAUSE
)!=0 ){
5164 iIndexCur
= iAuxArg
;
5167 iIndexCur
= pParse
->nTab
++;
5169 pLevel
->iIdxCur
= iIndexCur
;
5170 assert( pIx
->pSchema
==pTab
->pSchema
);
5171 assert( iIndexCur
>=0 );
5173 sqlite3VdbeAddOp3(v
, op
, iIndexCur
, pIx
->tnum
, iDb
);
5174 sqlite3VdbeSetP4KeyInfo(pParse
, pIx
);
5175 if( (pLoop
->wsFlags
& WHERE_CONSTRAINT
)!=0
5176 && (pLoop
->wsFlags
& (WHERE_COLUMN_RANGE
|WHERE_SKIPSCAN
))==0
5177 && (pLoop
->wsFlags
& WHERE_BIGNULL_SORT
)==0
5178 && (pWInfo
->wctrlFlags
&WHERE_ORDERBY_MIN
)==0
5179 && pWInfo
->eDistinct
!=WHERE_DISTINCT_ORDERED
5181 sqlite3VdbeChangeP5(v
, OPFLAG_SEEKEQ
);
5183 VdbeComment((v
, "%s", pIx
->zName
));
5184 #ifdef SQLITE_ENABLE_COLUMN_USED_MASK
5188 for(ii
=0; ii
<pIx
->nColumn
; ii
++){
5189 jj
= pIx
->aiColumn
[ii
];
5190 if( jj
<0 ) continue;
5191 if( jj
>63 ) jj
= 63;
5192 if( (pTabItem
->colUsed
& MASKBIT(jj
))==0 ) continue;
5193 colUsed
|= ((u64
)1)<<(ii
<63 ? ii
: 63);
5195 sqlite3VdbeAddOp4Dup8(v
, OP_ColumnsUsed
, iIndexCur
, 0, 0,
5196 (u8
*)&colUsed
, P4_INT64
);
5198 #endif /* SQLITE_ENABLE_COLUMN_USED_MASK */
5201 if( iDb
>=0 ) sqlite3CodeVerifySchema(pParse
, iDb
);
5203 pWInfo
->iTop
= sqlite3VdbeCurrentAddr(v
);
5204 if( db
->mallocFailed
) goto whereBeginError
;
5206 /* Generate the code to do the search. Each iteration of the for
5207 ** loop below generates code for a single nested loop of the VM
5210 for(ii
=0; ii
<nTabList
; ii
++){
5213 pLevel
= &pWInfo
->a
[ii
];
5214 wsFlags
= pLevel
->pWLoop
->wsFlags
;
5215 #ifndef SQLITE_OMIT_AUTOMATIC_INDEX
5216 if( (pLevel
->pWLoop
->wsFlags
& WHERE_AUTO_INDEX
)!=0 ){
5217 constructAutomaticIndex(pParse
, &pWInfo
->sWC
,
5218 &pTabList
->a
[pLevel
->iFrom
], notReady
, pLevel
);
5219 if( db
->mallocFailed
) goto whereBeginError
;
5222 addrExplain
= sqlite3WhereExplainOneScan(
5223 pParse
, pTabList
, pLevel
, wctrlFlags
5225 pLevel
->addrBody
= sqlite3VdbeCurrentAddr(v
);
5226 notReady
= sqlite3WhereCodeOneLoopStart(pParse
,v
,pWInfo
,ii
,pLevel
,notReady
);
5227 pWInfo
->iContinue
= pLevel
->addrCont
;
5228 if( (wsFlags
&WHERE_MULTI_OR
)==0 && (wctrlFlags
&WHERE_OR_SUBCLAUSE
)==0 ){
5229 sqlite3WhereAddScanStatus(v
, pTabList
, pLevel
, addrExplain
);
5234 VdbeModuleComment((v
, "Begin WHERE-core"));
5237 /* Jump here if malloc fails */
5240 pParse
->nQueryLoop
= pWInfo
->savedNQueryLoop
;
5241 whereInfoFree(db
, pWInfo
);
5247 ** Part of sqlite3WhereEnd() will rewrite opcodes to reference the
5248 ** index rather than the main table. In SQLITE_DEBUG mode, we want
5249 ** to trace those changes if PRAGMA vdbe_addoptrace=on. This routine
5252 #ifndef SQLITE_DEBUG
5253 # define OpcodeRewriteTrace(D,K,P) /* no-op */
5255 # define OpcodeRewriteTrace(D,K,P) sqlite3WhereOpcodeRewriteTrace(D,K,P)
5256 static void sqlite3WhereOpcodeRewriteTrace(
5261 if( (db
->flags
& SQLITE_VdbeAddopTrace
)==0 ) return;
5262 sqlite3VdbePrintOp(0, pc
, pOp
);
5267 ** Generate the end of the WHERE loop. See comments on
5268 ** sqlite3WhereBegin() for additional information.
5270 void sqlite3WhereEnd(WhereInfo
*pWInfo
){
5271 Parse
*pParse
= pWInfo
->pParse
;
5272 Vdbe
*v
= pParse
->pVdbe
;
5276 SrcList
*pTabList
= pWInfo
->pTabList
;
5277 sqlite3
*db
= pParse
->db
;
5279 /* Generate loop termination code.
5281 VdbeModuleComment((v
, "End WHERE-core"));
5282 for(i
=pWInfo
->nLevel
-1; i
>=0; i
--){
5284 pLevel
= &pWInfo
->a
[i
];
5285 pLoop
= pLevel
->pWLoop
;
5286 if( pLevel
->op
!=OP_Noop
){
5287 #ifndef SQLITE_DISABLE_SKIPAHEAD_DISTINCT
5291 if( pWInfo
->eDistinct
==WHERE_DISTINCT_ORDERED
5292 && i
==pWInfo
->nLevel
-1 /* Ticket [ef9318757b152e3] 2017-10-21 */
5293 && (pLoop
->wsFlags
& WHERE_INDEXED
)!=0
5294 && (pIdx
= pLoop
->u
.btree
.pIndex
)->hasStat1
5295 && (n
= pLoop
->u
.btree
.nDistinctCol
)>0
5296 && pIdx
->aiRowLogEst
[n
]>=36
5298 int r1
= pParse
->nMem
+1;
5301 sqlite3VdbeAddOp3(v
, OP_Column
, pLevel
->iIdxCur
, j
, r1
+j
);
5303 pParse
->nMem
+= n
+1;
5304 op
= pLevel
->op
==OP_Prev
? OP_SeekLT
: OP_SeekGT
;
5305 addrSeek
= sqlite3VdbeAddOp4Int(v
, op
, pLevel
->iIdxCur
, 0, r1
, n
);
5306 VdbeCoverageIf(v
, op
==OP_SeekLT
);
5307 VdbeCoverageIf(v
, op
==OP_SeekGT
);
5308 sqlite3VdbeAddOp2(v
, OP_Goto
, 1, pLevel
->p2
);
5310 #endif /* SQLITE_DISABLE_SKIPAHEAD_DISTINCT */
5311 /* The common case: Advance to the next row */
5312 sqlite3VdbeResolveLabel(v
, pLevel
->addrCont
);
5313 sqlite3VdbeAddOp3(v
, pLevel
->op
, pLevel
->p1
, pLevel
->p2
, pLevel
->p3
);
5314 sqlite3VdbeChangeP5(v
, pLevel
->p5
);
5316 VdbeCoverageIf(v
, pLevel
->op
==OP_Next
);
5317 VdbeCoverageIf(v
, pLevel
->op
==OP_Prev
);
5318 VdbeCoverageIf(v
, pLevel
->op
==OP_VNext
);
5319 if( pLevel
->regBignull
){
5320 sqlite3VdbeResolveLabel(v
, pLevel
->addrBignull
);
5321 sqlite3VdbeAddOp2(v
, OP_DecrJumpZero
, pLevel
->regBignull
, pLevel
->p2
-1);
5324 #ifndef SQLITE_DISABLE_SKIPAHEAD_DISTINCT
5325 if( addrSeek
) sqlite3VdbeJumpHere(v
, addrSeek
);
5328 sqlite3VdbeResolveLabel(v
, pLevel
->addrCont
);
5330 if( pLoop
->wsFlags
& WHERE_IN_ABLE
&& pLevel
->u
.in
.nIn
>0 ){
5333 sqlite3VdbeResolveLabel(v
, pLevel
->addrNxt
);
5334 for(j
=pLevel
->u
.in
.nIn
, pIn
=&pLevel
->u
.in
.aInLoop
[j
-1]; j
>0; j
--, pIn
--){
5335 sqlite3VdbeJumpHere(v
, pIn
->addrInTop
+1);
5336 if( pIn
->eEndLoopOp
!=OP_Noop
){
5338 assert( pLoop
->wsFlags
& WHERE_IN_EARLYOUT
);
5339 if( pLevel
->iLeftJoin
){
5340 /* For LEFT JOIN queries, cursor pIn->iCur may not have been
5341 ** opened yet. This occurs for WHERE clauses such as
5342 ** "a = ? AND b IN (...)", where the index is on (a, b). If
5343 ** the RHS of the (a=?) is NULL, then the "b IN (...)" may
5344 ** never have been coded, but the body of the loop run to
5345 ** return the null-row. So, if the cursor is not open yet,
5346 ** jump over the OP_Next or OP_Prev instruction about to
5348 sqlite3VdbeAddOp2(v
, OP_IfNotOpen
, pIn
->iCur
,
5349 sqlite3VdbeCurrentAddr(v
) + 2 +
5350 ((pLoop
->wsFlags
& WHERE_VIRTUALTABLE
)==0)
5354 if( (pLoop
->wsFlags
& WHERE_VIRTUALTABLE
)==0 ){
5355 sqlite3VdbeAddOp4Int(v
, OP_IfNoHope
, pLevel
->iIdxCur
,
5356 sqlite3VdbeCurrentAddr(v
)+2,
5357 pIn
->iBase
, pIn
->nPrefix
);
5361 sqlite3VdbeAddOp2(v
, pIn
->eEndLoopOp
, pIn
->iCur
, pIn
->addrInTop
);
5363 VdbeCoverageIf(v
, pIn
->eEndLoopOp
==OP_Prev
);
5364 VdbeCoverageIf(v
, pIn
->eEndLoopOp
==OP_Next
);
5366 sqlite3VdbeJumpHere(v
, pIn
->addrInTop
-1);
5369 sqlite3VdbeResolveLabel(v
, pLevel
->addrBrk
);
5370 if( pLevel
->addrSkip
){
5371 sqlite3VdbeGoto(v
, pLevel
->addrSkip
);
5372 VdbeComment((v
, "next skip-scan on %s", pLoop
->u
.btree
.pIndex
->zName
));
5373 sqlite3VdbeJumpHere(v
, pLevel
->addrSkip
);
5374 sqlite3VdbeJumpHere(v
, pLevel
->addrSkip
-2);
5376 #ifndef SQLITE_LIKE_DOESNT_MATCH_BLOBS
5377 if( pLevel
->addrLikeRep
){
5378 sqlite3VdbeAddOp2(v
, OP_DecrJumpZero
, (int)(pLevel
->iLikeRepCntr
>>1),
5379 pLevel
->addrLikeRep
);
5383 if( pLevel
->iLeftJoin
){
5384 int ws
= pLoop
->wsFlags
;
5385 addr
= sqlite3VdbeAddOp1(v
, OP_IfPos
, pLevel
->iLeftJoin
); VdbeCoverage(v
);
5386 assert( (ws
& WHERE_IDX_ONLY
)==0 || (ws
& WHERE_INDEXED
)!=0 );
5387 if( (ws
& WHERE_IDX_ONLY
)==0 ){
5388 assert( pLevel
->iTabCur
==pTabList
->a
[pLevel
->iFrom
].iCursor
);
5389 sqlite3VdbeAddOp1(v
, OP_NullRow
, pLevel
->iTabCur
);
5391 if( (ws
& WHERE_INDEXED
)
5392 || ((ws
& WHERE_MULTI_OR
) && pLevel
->u
.pCovidx
)
5394 sqlite3VdbeAddOp1(v
, OP_NullRow
, pLevel
->iIdxCur
);
5396 if( pLevel
->op
==OP_Return
){
5397 sqlite3VdbeAddOp2(v
, OP_Gosub
, pLevel
->p1
, pLevel
->addrFirst
);
5399 sqlite3VdbeGoto(v
, pLevel
->addrFirst
);
5401 sqlite3VdbeJumpHere(v
, addr
);
5403 VdbeModuleComment((v
, "End WHERE-loop%d: %s", i
,
5404 pWInfo
->pTabList
->a
[pLevel
->iFrom
].pTab
->zName
));
5407 /* The "break" point is here, just past the end of the outer loop.
5410 sqlite3VdbeResolveLabel(v
, pWInfo
->iBreak
);
5412 assert( pWInfo
->nLevel
<=pTabList
->nSrc
);
5413 for(i
=0, pLevel
=pWInfo
->a
; i
<pWInfo
->nLevel
; i
++, pLevel
++){
5417 struct SrcList_item
*pTabItem
= &pTabList
->a
[pLevel
->iFrom
];
5418 Table
*pTab
= pTabItem
->pTab
;
5420 pLoop
= pLevel
->pWLoop
;
5422 /* For a co-routine, change all OP_Column references to the table of
5423 ** the co-routine into OP_Copy of result contained in a register.
5424 ** OP_Rowid becomes OP_Null.
5426 if( pTabItem
->fg
.viaCoroutine
){
5427 testcase( pParse
->db
->mallocFailed
);
5428 translateColumnToCopy(pParse
, pLevel
->addrBody
, pLevel
->iTabCur
,
5429 pTabItem
->regResult
, 0);
5433 #ifdef SQLITE_ENABLE_EARLY_CURSOR_CLOSE
5434 /* Close all of the cursors that were opened by sqlite3WhereBegin.
5435 ** Except, do not close cursors that will be reused by the OR optimization
5436 ** (WHERE_OR_SUBCLAUSE). And do not close the OP_OpenWrite cursors
5437 ** created for the ONEPASS optimization.
5439 if( (pTab
->tabFlags
& TF_Ephemeral
)==0
5441 && (pWInfo
->wctrlFlags
& WHERE_OR_SUBCLAUSE
)==0
5443 int ws
= pLoop
->wsFlags
;
5444 if( pWInfo
->eOnePass
==ONEPASS_OFF
&& (ws
& WHERE_IDX_ONLY
)==0 ){
5445 sqlite3VdbeAddOp1(v
, OP_Close
, pTabItem
->iCursor
);
5447 if( (ws
& WHERE_INDEXED
)!=0
5448 && (ws
& (WHERE_IPK
|WHERE_AUTO_INDEX
))==0
5449 && pLevel
->iIdxCur
!=pWInfo
->aiCurOnePass
[1]
5451 sqlite3VdbeAddOp1(v
, OP_Close
, pLevel
->iIdxCur
);
5456 /* If this scan uses an index, make VDBE code substitutions to read data
5457 ** from the index instead of from the table where possible. In some cases
5458 ** this optimization prevents the table from ever being read, which can
5459 ** yield a significant performance boost.
5461 ** Calls to the code generator in between sqlite3WhereBegin and
5462 ** sqlite3WhereEnd will have created code that references the table
5463 ** directly. This loop scans all that code looking for opcodes
5464 ** that reference the table and converts them into opcodes that
5465 ** reference the index.
5467 if( pLoop
->wsFlags
& (WHERE_INDEXED
|WHERE_IDX_ONLY
) ){
5468 pIdx
= pLoop
->u
.btree
.pIndex
;
5469 }else if( pLoop
->wsFlags
& WHERE_MULTI_OR
){
5470 pIdx
= pLevel
->u
.pCovidx
;
5473 && (pWInfo
->eOnePass
==ONEPASS_OFF
|| !HasRowid(pIdx
->pTable
))
5474 && !db
->mallocFailed
5476 last
= sqlite3VdbeCurrentAddr(v
);
5477 k
= pLevel
->addrBody
;
5479 if( db
->flags
& SQLITE_VdbeAddopTrace
){
5480 printf("TRANSLATE opcodes in range %d..%d\n", k
, last
-1);
5483 pOp
= sqlite3VdbeGetOp(v
, k
);
5484 for(; k
<last
; k
++, pOp
++){
5485 if( pOp
->p1
!=pLevel
->iTabCur
) continue;
5486 if( pOp
->opcode
==OP_Column
5487 #ifdef SQLITE_ENABLE_OFFSET_SQL_FUNC
5488 || pOp
->opcode
==OP_Offset
5492 assert( pIdx
->pTable
==pTab
);
5493 if( !HasRowid(pTab
) ){
5494 Index
*pPk
= sqlite3PrimaryKeyIndex(pTab
);
5495 x
= pPk
->aiColumn
[x
];
5498 testcase( x
!=sqlite3StorageColumnToTable(pTab
,x
) );
5499 x
= sqlite3StorageColumnToTable(pTab
,x
);
5501 x
= sqlite3TableColumnToIndex(pIdx
, x
);
5504 pOp
->p1
= pLevel
->iIdxCur
;
5505 OpcodeRewriteTrace(db
, k
, pOp
);
5507 assert( (pLoop
->wsFlags
& WHERE_IDX_ONLY
)==0 || x
>=0
5508 || pWInfo
->eOnePass
);
5509 }else if( pOp
->opcode
==OP_Rowid
){
5510 pOp
->p1
= pLevel
->iIdxCur
;
5511 pOp
->opcode
= OP_IdxRowid
;
5512 OpcodeRewriteTrace(db
, k
, pOp
);
5513 }else if( pOp
->opcode
==OP_IfNullRow
){
5514 pOp
->p1
= pLevel
->iIdxCur
;
5515 OpcodeRewriteTrace(db
, k
, pOp
);
5519 if( db
->flags
& SQLITE_VdbeAddopTrace
) printf("TRANSLATE complete\n");
5524 /* Undo all Expr node modifications */
5525 while( pWInfo
->pExprMods
){
5526 WhereExprMod
*p
= pWInfo
->pExprMods
;
5527 pWInfo
->pExprMods
= p
->pNext
;
5528 memcpy(p
->pExpr
, &p
->orig
, sizeof(p
->orig
));
5529 sqlite3DbFree(db
, p
);
5534 pParse
->nQueryLoop
= pWInfo
->savedNQueryLoop
;
5535 whereInfoFree(db
, pWInfo
);