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"
22 /* Forward declaration of methods */
23 static int whereLoopResize(sqlite3
*, WhereLoop
*, int);
25 /* Test variable that can be set to enable WHERE tracing */
26 #if defined(SQLITE_TEST) || defined(SQLITE_DEBUG)
27 /***/ int sqlite3WhereTrace
= 0;
32 ** Return the estimated number of output rows from a WHERE clause
34 LogEst
sqlite3WhereOutputRowCount(WhereInfo
*pWInfo
){
35 return pWInfo
->nRowOut
;
39 ** Return one of the WHERE_DISTINCT_xxxxx values to indicate how this
40 ** WHERE clause returns outputs for DISTINCT processing.
42 int sqlite3WhereIsDistinct(WhereInfo
*pWInfo
){
43 return pWInfo
->eDistinct
;
47 ** Return TRUE if the WHERE clause returns rows in ORDER BY order.
48 ** Return FALSE if the output needs to be sorted.
50 int sqlite3WhereIsOrdered(WhereInfo
*pWInfo
){
51 return pWInfo
->nOBSat
;
55 ** Return TRUE if the innermost loop of the WHERE clause implementation
56 ** returns rows in ORDER BY order for complete run of the inner loop.
58 ** Across multiple iterations of outer loops, the output rows need not be
59 ** sorted. As long as rows are sorted for just the innermost loop, this
60 ** routine can return TRUE.
62 int sqlite3WhereOrderedInnerLoop(WhereInfo
*pWInfo
){
63 return pWInfo
->bOrderedInnerLoop
;
67 ** Return the VDBE address or label to jump to in order to continue
68 ** immediately with the next row of a WHERE clause.
70 int sqlite3WhereContinueLabel(WhereInfo
*pWInfo
){
71 assert( pWInfo
->iContinue
!=0 );
72 return pWInfo
->iContinue
;
76 ** Return the VDBE address or label to jump to in order to break
77 ** out of a WHERE loop.
79 int sqlite3WhereBreakLabel(WhereInfo
*pWInfo
){
80 return pWInfo
->iBreak
;
84 ** Return ONEPASS_OFF (0) if an UPDATE or DELETE statement is unable to
85 ** operate directly on the rowis returned by a WHERE clause. Return
86 ** ONEPASS_SINGLE (1) if the statement can operation directly because only
87 ** a single row is to be changed. Return ONEPASS_MULTI (2) if the one-pass
88 ** optimization can be used on multiple
90 ** If the ONEPASS optimization is used (if this routine returns true)
91 ** then also write the indices of open cursors used by ONEPASS
92 ** into aiCur[0] and aiCur[1]. iaCur[0] gets the cursor of the data
93 ** table and iaCur[1] gets the cursor used by an auxiliary index.
94 ** Either value may be -1, indicating that cursor is not used.
95 ** Any cursors returned will have been opened for writing.
97 ** aiCur[0] and aiCur[1] both get -1 if the where-clause logic is
98 ** unable to use the ONEPASS optimization.
100 int sqlite3WhereOkOnePass(WhereInfo
*pWInfo
, int *aiCur
){
101 memcpy(aiCur
, pWInfo
->aiCurOnePass
, sizeof(int)*2);
102 #ifdef WHERETRACE_ENABLED
103 if( sqlite3WhereTrace
&& pWInfo
->eOnePass
!=ONEPASS_OFF
){
104 sqlite3DebugPrintf("%s cursors: %d %d\n",
105 pWInfo
->eOnePass
==ONEPASS_SINGLE
? "ONEPASS_SINGLE" : "ONEPASS_MULTI",
109 return pWInfo
->eOnePass
;
113 ** Move the content of pSrc into pDest
115 static void whereOrMove(WhereOrSet
*pDest
, WhereOrSet
*pSrc
){
117 memcpy(pDest
->a
, pSrc
->a
, pDest
->n
*sizeof(pDest
->a
[0]));
121 ** Try to insert a new prerequisite/cost entry into the WhereOrSet pSet.
123 ** The new entry might overwrite an existing entry, or it might be
124 ** appended, or it might be discarded. Do whatever is the right thing
125 ** so that pSet keeps the N_OR_COST best entries seen so far.
127 static int whereOrInsert(
128 WhereOrSet
*pSet
, /* The WhereOrSet to be updated */
129 Bitmask prereq
, /* Prerequisites of the new entry */
130 LogEst rRun
, /* Run-cost of the new entry */
131 LogEst nOut
/* Number of outputs for the new entry */
135 for(i
=pSet
->n
, p
=pSet
->a
; i
>0; i
--, p
++){
136 if( rRun
<=p
->rRun
&& (prereq
& p
->prereq
)==prereq
){
137 goto whereOrInsert_done
;
139 if( p
->rRun
<=rRun
&& (p
->prereq
& prereq
)==p
->prereq
){
143 if( pSet
->n
<N_OR_COST
){
144 p
= &pSet
->a
[pSet
->n
++];
148 for(i
=1; i
<pSet
->n
; i
++){
149 if( p
->rRun
>pSet
->a
[i
].rRun
) p
= pSet
->a
+ i
;
151 if( p
->rRun
<=rRun
) return 0;
156 if( p
->nOut
>nOut
) p
->nOut
= nOut
;
161 ** Return the bitmask for the given cursor number. Return 0 if
162 ** iCursor is not in the set.
164 Bitmask
sqlite3WhereGetMask(WhereMaskSet
*pMaskSet
, int iCursor
){
166 assert( pMaskSet
->n
<=(int)sizeof(Bitmask
)*8 );
167 for(i
=0; i
<pMaskSet
->n
; i
++){
168 if( pMaskSet
->ix
[i
]==iCursor
){
176 ** Create a new mask for cursor iCursor.
178 ** There is one cursor per table in the FROM clause. The number of
179 ** tables in the FROM clause is limited by a test early in the
180 ** sqlite3WhereBegin() routine. So we know that the pMaskSet->ix[]
181 ** array will never overflow.
183 static void createMask(WhereMaskSet
*pMaskSet
, int iCursor
){
184 assert( pMaskSet
->n
< ArraySize(pMaskSet
->ix
) );
185 pMaskSet
->ix
[pMaskSet
->n
++] = iCursor
;
189 ** Advance to the next WhereTerm that matches according to the criteria
190 ** established when the pScan object was initialized by whereScanInit().
191 ** Return NULL if there are no more matching WhereTerms.
193 static WhereTerm
*whereScanNext(WhereScan
*pScan
){
194 int iCur
; /* The cursor on the LHS of the term */
195 i16 iColumn
; /* The column on the LHS of the term. -1 for IPK */
196 Expr
*pX
; /* An expression being tested */
197 WhereClause
*pWC
; /* Shorthand for pScan->pWC */
198 WhereTerm
*pTerm
; /* The term being tested */
199 int k
= pScan
->k
; /* Where to start scanning */
201 assert( pScan
->iEquiv
<=pScan
->nEquiv
);
204 iColumn
= pScan
->aiColumn
[pScan
->iEquiv
-1];
205 iCur
= pScan
->aiCur
[pScan
->iEquiv
-1];
208 for(pTerm
=pWC
->a
+k
; k
<pWC
->nTerm
; k
++, pTerm
++){
209 if( pTerm
->leftCursor
==iCur
210 && pTerm
->u
.leftColumn
==iColumn
212 || sqlite3ExprCompareSkip(pTerm
->pExpr
->pLeft
,
213 pScan
->pIdxExpr
,iCur
)==0)
214 && (pScan
->iEquiv
<=1 || !ExprHasProperty(pTerm
->pExpr
, EP_FromJoin
))
216 if( (pTerm
->eOperator
& WO_EQUIV
)!=0
217 && pScan
->nEquiv
<ArraySize(pScan
->aiCur
)
218 && (pX
= sqlite3ExprSkipCollate(pTerm
->pExpr
->pRight
))->op
==TK_COLUMN
221 for(j
=0; j
<pScan
->nEquiv
; j
++){
222 if( pScan
->aiCur
[j
]==pX
->iTable
223 && pScan
->aiColumn
[j
]==pX
->iColumn
){
227 if( j
==pScan
->nEquiv
){
228 pScan
->aiCur
[j
] = pX
->iTable
;
229 pScan
->aiColumn
[j
] = pX
->iColumn
;
233 if( (pTerm
->eOperator
& pScan
->opMask
)!=0 ){
234 /* Verify the affinity and collating sequence match */
235 if( pScan
->zCollName
&& (pTerm
->eOperator
& WO_ISNULL
)==0 ){
237 Parse
*pParse
= pWC
->pWInfo
->pParse
;
239 if( !sqlite3IndexAffinityOk(pX
, pScan
->idxaff
) ){
243 pColl
= sqlite3BinaryCompareCollSeq(pParse
,
244 pX
->pLeft
, pX
->pRight
);
245 if( pColl
==0 ) pColl
= pParse
->db
->pDfltColl
;
246 if( sqlite3StrICmp(pColl
->zName
, pScan
->zCollName
) ){
250 if( (pTerm
->eOperator
& (WO_EQ
|WO_IS
))!=0
251 && (pX
= pTerm
->pExpr
->pRight
)->op
==TK_COLUMN
252 && pX
->iTable
==pScan
->aiCur
[0]
253 && pX
->iColumn
==pScan
->aiColumn
[0]
255 testcase( pTerm
->eOperator
& WO_IS
);
267 if( pScan
->iEquiv
>=pScan
->nEquiv
) break;
268 pWC
= pScan
->pOrigWC
;
276 ** Initialize a WHERE clause scanner object. Return a pointer to the
277 ** first match. Return NULL if there are no matches.
279 ** The scanner will be searching the WHERE clause pWC. It will look
280 ** for terms of the form "X <op> <expr>" where X is column iColumn of table
281 ** iCur. Or if pIdx!=0 then X is column iColumn of index pIdx. pIdx
282 ** must be one of the indexes of table iCur.
284 ** The <op> must be one of the operators described by opMask.
286 ** If the search is for X and the WHERE clause contains terms of the
287 ** form X=Y then this routine might also return terms of the form
288 ** "Y <op> <expr>". The number of levels of transitivity is limited,
289 ** but is enough to handle most commonly occurring SQL statements.
291 ** If X is not the INTEGER PRIMARY KEY then X must be compatible with
294 static WhereTerm
*whereScanInit(
295 WhereScan
*pScan
, /* The WhereScan object being initialized */
296 WhereClause
*pWC
, /* The WHERE clause to be scanned */
297 int iCur
, /* Cursor to scan for */
298 int iColumn
, /* Column to scan for */
299 u32 opMask
, /* Operator(s) to scan for */
300 Index
*pIdx
/* Must be compatible with this index */
302 pScan
->pOrigWC
= pWC
;
306 pScan
->zCollName
= 0;
309 iColumn
= pIdx
->aiColumn
[j
];
310 if( iColumn
==XN_EXPR
){
311 pScan
->pIdxExpr
= pIdx
->aColExpr
->a
[j
].pExpr
;
312 pScan
->zCollName
= pIdx
->azColl
[j
];
313 }else if( iColumn
==pIdx
->pTable
->iPKey
){
315 }else if( iColumn
>=0 ){
316 pScan
->idxaff
= pIdx
->pTable
->aCol
[iColumn
].affinity
;
317 pScan
->zCollName
= pIdx
->azColl
[j
];
319 }else if( iColumn
==XN_EXPR
){
322 pScan
->opMask
= opMask
;
324 pScan
->aiCur
[0] = iCur
;
325 pScan
->aiColumn
[0] = iColumn
;
328 return whereScanNext(pScan
);
332 ** Search for a term in the WHERE clause that is of the form "X <op> <expr>"
333 ** where X is a reference to the iColumn of table iCur or of index pIdx
334 ** if pIdx!=0 and <op> is one of the WO_xx operator codes specified by
335 ** the op parameter. Return a pointer to the term. Return 0 if not found.
337 ** If pIdx!=0 then it must be one of the indexes of table iCur.
338 ** Search for terms matching the iColumn-th column of pIdx
339 ** rather than the iColumn-th column of table iCur.
341 ** The term returned might by Y=<expr> if there is another constraint in
342 ** the WHERE clause that specifies that X=Y. Any such constraints will be
343 ** identified by the WO_EQUIV bit in the pTerm->eOperator field. The
344 ** aiCur[]/iaColumn[] arrays hold X and all its equivalents. There are 11
345 ** slots in aiCur[]/aiColumn[] so that means we can look for X plus up to 10
346 ** other equivalent values. Hence a search for X will return <expr> if X=A1
347 ** and A1=A2 and A2=A3 and ... and A9=A10 and A10=<expr>.
349 ** If there are multiple terms in the WHERE clause of the form "X <op> <expr>"
350 ** then try for the one with no dependencies on <expr> - in other words where
351 ** <expr> is a constant expression of some kind. Only return entries of
352 ** the form "X <op> Y" where Y is a column in another table if no terms of
353 ** the form "X <op> <const-expr>" exist. If no terms with a constant RHS
354 ** exist, try to return a term that does not use WO_EQUIV.
356 WhereTerm
*sqlite3WhereFindTerm(
357 WhereClause
*pWC
, /* The WHERE clause to be searched */
358 int iCur
, /* Cursor number of LHS */
359 int iColumn
, /* Column number of LHS */
360 Bitmask notReady
, /* RHS must not overlap with this mask */
361 u32 op
, /* Mask of WO_xx values describing operator */
362 Index
*pIdx
/* Must be compatible with this index, if not NULL */
364 WhereTerm
*pResult
= 0;
368 p
= whereScanInit(&scan
, pWC
, iCur
, iColumn
, op
, pIdx
);
371 if( (p
->prereqRight
& notReady
)==0 ){
372 if( p
->prereqRight
==0 && (p
->eOperator
&op
)!=0 ){
373 testcase( p
->eOperator
& WO_IS
);
376 if( pResult
==0 ) pResult
= p
;
378 p
= whereScanNext(&scan
);
384 ** This function searches pList for an entry that matches the iCol-th column
387 ** If such an expression is found, its index in pList->a[] is returned. If
388 ** no expression is found, -1 is returned.
390 static int findIndexCol(
391 Parse
*pParse
, /* Parse context */
392 ExprList
*pList
, /* Expression list to search */
393 int iBase
, /* Cursor for table associated with pIdx */
394 Index
*pIdx
, /* Index to match column of */
395 int iCol
/* Column of index to match */
398 const char *zColl
= pIdx
->azColl
[iCol
];
400 for(i
=0; i
<pList
->nExpr
; i
++){
401 Expr
*p
= sqlite3ExprSkipCollate(pList
->a
[i
].pExpr
);
403 && p
->iColumn
==pIdx
->aiColumn
[iCol
]
406 CollSeq
*pColl
= sqlite3ExprCollSeq(pParse
, pList
->a
[i
].pExpr
);
407 if( pColl
&& 0==sqlite3StrICmp(pColl
->zName
, zColl
) ){
417 ** Return TRUE if the iCol-th column of index pIdx is NOT NULL
419 static int indexColumnNotNull(Index
*pIdx
, int iCol
){
422 assert( iCol
>=0 && iCol
<pIdx
->nColumn
);
423 j
= pIdx
->aiColumn
[iCol
];
425 return pIdx
->pTable
->aCol
[j
].notNull
;
430 return 0; /* Assume an indexed expression can always yield a NULL */
436 ** Return true if the DISTINCT expression-list passed as the third argument
439 ** A DISTINCT list is redundant if any subset of the columns in the
440 ** DISTINCT list are collectively unique and individually non-null.
442 static int isDistinctRedundant(
443 Parse
*pParse
, /* Parsing context */
444 SrcList
*pTabList
, /* The FROM clause */
445 WhereClause
*pWC
, /* The WHERE clause */
446 ExprList
*pDistinct
/* The result set that needs to be DISTINCT */
453 /* If there is more than one table or sub-select in the FROM clause of
454 ** this query, then it will not be possible to show that the DISTINCT
455 ** clause is redundant. */
456 if( pTabList
->nSrc
!=1 ) return 0;
457 iBase
= pTabList
->a
[0].iCursor
;
458 pTab
= pTabList
->a
[0].pTab
;
460 /* If any of the expressions is an IPK column on table iBase, then return
461 ** true. Note: The (p->iTable==iBase) part of this test may be false if the
462 ** current SELECT is a correlated sub-query.
464 for(i
=0; i
<pDistinct
->nExpr
; i
++){
465 Expr
*p
= sqlite3ExprSkipCollate(pDistinct
->a
[i
].pExpr
);
466 if( p
->op
==TK_COLUMN
&& p
->iTable
==iBase
&& p
->iColumn
<0 ) return 1;
469 /* Loop through all indices on the table, checking each to see if it makes
470 ** the DISTINCT qualifier redundant. It does so if:
472 ** 1. The index is itself UNIQUE, and
474 ** 2. All of the columns in the index are either part of the pDistinct
475 ** list, or else the WHERE clause contains a term of the form "col=X",
476 ** where X is a constant value. The collation sequences of the
477 ** comparison and select-list expressions must match those of the index.
479 ** 3. All of those index columns for which the WHERE clause does not
480 ** contain a "col=X" term are subject to a NOT NULL constraint.
482 for(pIdx
=pTab
->pIndex
; pIdx
; pIdx
=pIdx
->pNext
){
483 if( !IsUniqueIndex(pIdx
) ) continue;
484 for(i
=0; i
<pIdx
->nKeyCol
; i
++){
485 if( 0==sqlite3WhereFindTerm(pWC
, iBase
, i
, ~(Bitmask
)0, WO_EQ
, pIdx
) ){
486 if( findIndexCol(pParse
, pDistinct
, iBase
, pIdx
, i
)<0 ) break;
487 if( indexColumnNotNull(pIdx
, i
)==0 ) break;
490 if( i
==pIdx
->nKeyCol
){
491 /* This index implies that the DISTINCT qualifier is redundant. */
501 ** Estimate the logarithm of the input value to base 2.
503 static LogEst
estLog(LogEst N
){
504 return N
<=10 ? 0 : sqlite3LogEst(N
) - 33;
508 ** Convert OP_Column opcodes to OP_Copy in previously generated code.
510 ** This routine runs over generated VDBE code and translates OP_Column
511 ** opcodes into OP_Copy when the table is being accessed via co-routine
512 ** instead of via table lookup.
514 ** If the bIncrRowid parameter is 0, then any OP_Rowid instructions on
515 ** cursor iTabCur are transformed into OP_Null. Or, if bIncrRowid is non-zero,
516 ** then each OP_Rowid is transformed into an instruction to increment the
517 ** value stored in its output register.
519 static void translateColumnToCopy(
520 Parse
*pParse
, /* Parsing context */
521 int iStart
, /* Translate from this opcode to the end */
522 int iTabCur
, /* OP_Column/OP_Rowid references to this table */
523 int iRegister
, /* The first column is in this register */
524 int bIncrRowid
/* If non-zero, transform OP_rowid to OP_AddImm(1) */
526 Vdbe
*v
= pParse
->pVdbe
;
527 VdbeOp
*pOp
= sqlite3VdbeGetOp(v
, iStart
);
528 int iEnd
= sqlite3VdbeCurrentAddr(v
);
529 if( pParse
->db
->mallocFailed
) return;
530 for(; iStart
<iEnd
; iStart
++, pOp
++){
531 if( pOp
->p1
!=iTabCur
) continue;
532 if( pOp
->opcode
==OP_Column
){
533 pOp
->opcode
= OP_Copy
;
534 pOp
->p1
= pOp
->p2
+ iRegister
;
537 }else if( pOp
->opcode
==OP_Rowid
){
539 /* Increment the value stored in the P2 operand of the OP_Rowid. */
540 pOp
->opcode
= OP_AddImm
;
544 pOp
->opcode
= OP_Null
;
553 ** Two routines for printing the content of an sqlite3_index_info
554 ** structure. Used for testing and debugging only. If neither
555 ** SQLITE_TEST or SQLITE_DEBUG are defined, then these routines
558 #if !defined(SQLITE_OMIT_VIRTUALTABLE) && defined(WHERETRACE_ENABLED)
559 static void TRACE_IDX_INPUTS(sqlite3_index_info
*p
){
561 if( !sqlite3WhereTrace
) return;
562 for(i
=0; i
<p
->nConstraint
; i
++){
563 sqlite3DebugPrintf(" constraint[%d]: col=%d termid=%d op=%d usabled=%d\n",
565 p
->aConstraint
[i
].iColumn
,
566 p
->aConstraint
[i
].iTermOffset
,
567 p
->aConstraint
[i
].op
,
568 p
->aConstraint
[i
].usable
);
570 for(i
=0; i
<p
->nOrderBy
; i
++){
571 sqlite3DebugPrintf(" orderby[%d]: col=%d desc=%d\n",
573 p
->aOrderBy
[i
].iColumn
,
574 p
->aOrderBy
[i
].desc
);
577 static void TRACE_IDX_OUTPUTS(sqlite3_index_info
*p
){
579 if( !sqlite3WhereTrace
) return;
580 for(i
=0; i
<p
->nConstraint
; i
++){
581 sqlite3DebugPrintf(" usage[%d]: argvIdx=%d omit=%d\n",
583 p
->aConstraintUsage
[i
].argvIndex
,
584 p
->aConstraintUsage
[i
].omit
);
586 sqlite3DebugPrintf(" idxNum=%d\n", p
->idxNum
);
587 sqlite3DebugPrintf(" idxStr=%s\n", p
->idxStr
);
588 sqlite3DebugPrintf(" orderByConsumed=%d\n", p
->orderByConsumed
);
589 sqlite3DebugPrintf(" estimatedCost=%g\n", p
->estimatedCost
);
590 sqlite3DebugPrintf(" estimatedRows=%lld\n", p
->estimatedRows
);
593 #define TRACE_IDX_INPUTS(A)
594 #define TRACE_IDX_OUTPUTS(A)
597 #ifndef SQLITE_OMIT_AUTOMATIC_INDEX
599 ** Return TRUE if the WHERE clause term pTerm is of a form where it
600 ** could be used with an index to access pSrc, assuming an appropriate
603 static int termCanDriveIndex(
604 WhereTerm
*pTerm
, /* WHERE clause term to check */
605 struct SrcList_item
*pSrc
, /* Table we are trying to access */
606 Bitmask notReady
/* Tables in outer loops of the join */
609 if( pTerm
->leftCursor
!=pSrc
->iCursor
) return 0;
610 if( (pTerm
->eOperator
& (WO_EQ
|WO_IS
))==0 ) return 0;
611 if( (pTerm
->prereqRight
& notReady
)!=0 ) return 0;
612 if( pTerm
->u
.leftColumn
<0 ) return 0;
613 aff
= pSrc
->pTab
->aCol
[pTerm
->u
.leftColumn
].affinity
;
614 if( !sqlite3IndexAffinityOk(pTerm
->pExpr
, aff
) ) return 0;
615 testcase( pTerm
->pExpr
->op
==TK_IS
);
621 #ifndef SQLITE_OMIT_AUTOMATIC_INDEX
623 ** Generate code to construct the Index object for an automatic index
624 ** and to set up the WhereLevel object pLevel so that the code generator
625 ** makes use of the automatic index.
627 static void constructAutomaticIndex(
628 Parse
*pParse
, /* The parsing context */
629 WhereClause
*pWC
, /* The WHERE clause */
630 struct SrcList_item
*pSrc
, /* The FROM clause term to get the next index */
631 Bitmask notReady
, /* Mask of cursors that are not available */
632 WhereLevel
*pLevel
/* Write new index here */
634 int nKeyCol
; /* Number of columns in the constructed index */
635 WhereTerm
*pTerm
; /* A single term of the WHERE clause */
636 WhereTerm
*pWCEnd
; /* End of pWC->a[] */
637 Index
*pIdx
; /* Object describing the transient index */
638 Vdbe
*v
; /* Prepared statement under construction */
639 int addrInit
; /* Address of the initialization bypass jump */
640 Table
*pTable
; /* The table being indexed */
641 int addrTop
; /* Top of the index fill loop */
642 int regRecord
; /* Register holding an index record */
643 int n
; /* Column counter */
644 int i
; /* Loop counter */
645 int mxBitCol
; /* Maximum column in pSrc->colUsed */
646 CollSeq
*pColl
; /* Collating sequence to on a column */
647 WhereLoop
*pLoop
; /* The Loop object */
648 char *zNotUsed
; /* Extra space on the end of pIdx */
649 Bitmask idxCols
; /* Bitmap of columns used for indexing */
650 Bitmask extraCols
; /* Bitmap of additional columns */
651 u8 sentWarning
= 0; /* True if a warnning has been issued */
652 Expr
*pPartial
= 0; /* Partial Index Expression */
653 int iContinue
= 0; /* Jump here to skip excluded rows */
654 struct SrcList_item
*pTabItem
; /* FROM clause term being indexed */
655 int addrCounter
= 0; /* Address where integer counter is initialized */
656 int regBase
; /* Array of registers where record is assembled */
658 /* Generate code to skip over the creation and initialization of the
659 ** transient index on 2nd and subsequent iterations of the loop. */
662 addrInit
= sqlite3VdbeAddOp0(v
, OP_Once
); VdbeCoverage(v
);
664 /* Count the number of columns that will be added to the index
665 ** and used to match WHERE clause constraints */
668 pWCEnd
= &pWC
->a
[pWC
->nTerm
];
669 pLoop
= pLevel
->pWLoop
;
671 for(pTerm
=pWC
->a
; pTerm
<pWCEnd
; pTerm
++){
672 Expr
*pExpr
= pTerm
->pExpr
;
673 assert( !ExprHasProperty(pExpr
, EP_FromJoin
) /* prereq always non-zero */
674 || pExpr
->iRightJoinTable
!=pSrc
->iCursor
/* for the right-hand */
675 || pLoop
->prereq
!=0 ); /* table of a LEFT JOIN */
677 && (pTerm
->wtFlags
& TERM_VIRTUAL
)==0
678 && !ExprHasProperty(pExpr
, EP_FromJoin
)
679 && sqlite3ExprIsTableConstant(pExpr
, pSrc
->iCursor
) ){
680 pPartial
= sqlite3ExprAnd(pParse
->db
, pPartial
,
681 sqlite3ExprDup(pParse
->db
, pExpr
, 0));
683 if( termCanDriveIndex(pTerm
, pSrc
, notReady
) ){
684 int iCol
= pTerm
->u
.leftColumn
;
685 Bitmask cMask
= iCol
>=BMS
? MASKBIT(BMS
-1) : MASKBIT(iCol
);
686 testcase( iCol
==BMS
);
687 testcase( iCol
==BMS
-1 );
689 sqlite3_log(SQLITE_WARNING_AUTOINDEX
,
690 "automatic index on %s(%s)", pTable
->zName
,
691 pTable
->aCol
[iCol
].zName
);
694 if( (idxCols
& cMask
)==0 ){
695 if( whereLoopResize(pParse
->db
, pLoop
, nKeyCol
+1) ){
696 goto end_auto_index_create
;
698 pLoop
->aLTerm
[nKeyCol
++] = pTerm
;
704 pLoop
->u
.btree
.nEq
= pLoop
->nLTerm
= nKeyCol
;
705 pLoop
->wsFlags
= WHERE_COLUMN_EQ
| WHERE_IDX_ONLY
| WHERE_INDEXED
708 /* Count the number of additional columns needed to create a
709 ** covering index. A "covering index" is an index that contains all
710 ** columns that are needed by the query. With a covering index, the
711 ** original table never needs to be accessed. Automatic indices must
712 ** be a covering index because the index will not be updated if the
713 ** original table changes and the index and table cannot both be used
714 ** if they go out of sync.
716 extraCols
= pSrc
->colUsed
& (~idxCols
| MASKBIT(BMS
-1));
717 mxBitCol
= MIN(BMS
-1,pTable
->nCol
);
718 testcase( pTable
->nCol
==BMS
-1 );
719 testcase( pTable
->nCol
==BMS
-2 );
720 for(i
=0; i
<mxBitCol
; i
++){
721 if( extraCols
& MASKBIT(i
) ) nKeyCol
++;
723 if( pSrc
->colUsed
& MASKBIT(BMS
-1) ){
724 nKeyCol
+= pTable
->nCol
- BMS
+ 1;
727 /* Construct the Index object to describe this index */
728 pIdx
= sqlite3AllocateIndexObject(pParse
->db
, nKeyCol
+1, 0, &zNotUsed
);
729 if( pIdx
==0 ) goto end_auto_index_create
;
730 pLoop
->u
.btree
.pIndex
= pIdx
;
731 pIdx
->zName
= "auto-index";
732 pIdx
->pTable
= pTable
;
735 for(pTerm
=pWC
->a
; pTerm
<pWCEnd
; pTerm
++){
736 if( termCanDriveIndex(pTerm
, pSrc
, notReady
) ){
737 int iCol
= pTerm
->u
.leftColumn
;
738 Bitmask cMask
= iCol
>=BMS
? MASKBIT(BMS
-1) : MASKBIT(iCol
);
739 testcase( iCol
==BMS
-1 );
740 testcase( iCol
==BMS
);
741 if( (idxCols
& cMask
)==0 ){
742 Expr
*pX
= pTerm
->pExpr
;
744 pIdx
->aiColumn
[n
] = pTerm
->u
.leftColumn
;
745 pColl
= sqlite3BinaryCompareCollSeq(pParse
, pX
->pLeft
, pX
->pRight
);
746 pIdx
->azColl
[n
] = pColl
? pColl
->zName
: sqlite3StrBINARY
;
751 assert( (u32
)n
==pLoop
->u
.btree
.nEq
);
753 /* Add additional columns needed to make the automatic index into
754 ** a covering index */
755 for(i
=0; i
<mxBitCol
; i
++){
756 if( extraCols
& MASKBIT(i
) ){
757 pIdx
->aiColumn
[n
] = i
;
758 pIdx
->azColl
[n
] = sqlite3StrBINARY
;
762 if( pSrc
->colUsed
& MASKBIT(BMS
-1) ){
763 for(i
=BMS
-1; i
<pTable
->nCol
; i
++){
764 pIdx
->aiColumn
[n
] = i
;
765 pIdx
->azColl
[n
] = sqlite3StrBINARY
;
769 assert( n
==nKeyCol
);
770 pIdx
->aiColumn
[n
] = XN_ROWID
;
771 pIdx
->azColl
[n
] = sqlite3StrBINARY
;
773 /* Create the automatic index */
774 assert( pLevel
->iIdxCur
>=0 );
775 pLevel
->iIdxCur
= pParse
->nTab
++;
776 sqlite3VdbeAddOp2(v
, OP_OpenAutoindex
, pLevel
->iIdxCur
, nKeyCol
+1);
777 sqlite3VdbeSetP4KeyInfo(pParse
, pIdx
);
778 VdbeComment((v
, "for %s", pTable
->zName
));
780 /* Fill the automatic index with content */
781 sqlite3ExprCachePush(pParse
);
782 pTabItem
= &pWC
->pWInfo
->pTabList
->a
[pLevel
->iFrom
];
783 if( pTabItem
->fg
.viaCoroutine
){
784 int regYield
= pTabItem
->regReturn
;
785 addrCounter
= sqlite3VdbeAddOp2(v
, OP_Integer
, 0, 0);
786 sqlite3VdbeAddOp3(v
, OP_InitCoroutine
, regYield
, 0, pTabItem
->addrFillSub
);
787 addrTop
= sqlite3VdbeAddOp1(v
, OP_Yield
, regYield
);
789 VdbeComment((v
, "next row of \"%s\"", pTabItem
->pTab
->zName
));
791 addrTop
= sqlite3VdbeAddOp1(v
, OP_Rewind
, pLevel
->iTabCur
); VdbeCoverage(v
);
794 iContinue
= sqlite3VdbeMakeLabel(v
);
795 sqlite3ExprIfFalse(pParse
, pPartial
, iContinue
, SQLITE_JUMPIFNULL
);
796 pLoop
->wsFlags
|= WHERE_PARTIALIDX
;
798 regRecord
= sqlite3GetTempReg(pParse
);
799 regBase
= sqlite3GenerateIndexKey(
800 pParse
, pIdx
, pLevel
->iTabCur
, regRecord
, 0, 0, 0, 0
802 sqlite3VdbeAddOp2(v
, OP_IdxInsert
, pLevel
->iIdxCur
, regRecord
);
803 sqlite3VdbeChangeP5(v
, OPFLAG_USESEEKRESULT
);
804 if( pPartial
) sqlite3VdbeResolveLabel(v
, iContinue
);
805 if( pTabItem
->fg
.viaCoroutine
){
806 sqlite3VdbeChangeP2(v
, addrCounter
, regBase
+n
);
807 testcase( pParse
->db
->mallocFailed
);
808 translateColumnToCopy(pParse
, addrTop
, pLevel
->iTabCur
,
809 pTabItem
->regResult
, 1);
810 sqlite3VdbeGoto(v
, addrTop
);
811 pTabItem
->fg
.viaCoroutine
= 0;
813 sqlite3VdbeAddOp2(v
, OP_Next
, pLevel
->iTabCur
, addrTop
+1); VdbeCoverage(v
);
815 sqlite3VdbeChangeP5(v
, SQLITE_STMTSTATUS_AUTOINDEX
);
816 sqlite3VdbeJumpHere(v
, addrTop
);
817 sqlite3ReleaseTempReg(pParse
, regRecord
);
818 sqlite3ExprCachePop(pParse
);
820 /* Jump here when skipping the initialization */
821 sqlite3VdbeJumpHere(v
, addrInit
);
823 end_auto_index_create
:
824 sqlite3ExprDelete(pParse
->db
, pPartial
);
826 #endif /* SQLITE_OMIT_AUTOMATIC_INDEX */
828 #ifndef SQLITE_OMIT_VIRTUALTABLE
830 ** Allocate and populate an sqlite3_index_info structure. It is the
831 ** responsibility of the caller to eventually release the structure
832 ** by passing the pointer returned by this function to sqlite3_free().
834 static sqlite3_index_info
*allocateIndexInfo(
837 Bitmask mUnusable
, /* Ignore terms with these prereqs */
838 struct SrcList_item
*pSrc
,
840 u16
*pmNoOmit
/* Mask of terms not to omit */
844 struct sqlite3_index_constraint
*pIdxCons
;
845 struct sqlite3_index_orderby
*pIdxOrderBy
;
846 struct sqlite3_index_constraint_usage
*pUsage
;
849 sqlite3_index_info
*pIdxInfo
;
852 /* Count the number of possible WHERE clause constraints referring
853 ** to this virtual table */
854 for(i
=nTerm
=0, pTerm
=pWC
->a
; i
<pWC
->nTerm
; i
++, pTerm
++){
855 if( pTerm
->leftCursor
!= pSrc
->iCursor
) continue;
856 if( pTerm
->prereqRight
& mUnusable
) continue;
857 assert( IsPowerOfTwo(pTerm
->eOperator
& ~WO_EQUIV
) );
858 testcase( pTerm
->eOperator
& WO_IN
);
859 testcase( pTerm
->eOperator
& WO_ISNULL
);
860 testcase( pTerm
->eOperator
& WO_IS
);
861 testcase( pTerm
->eOperator
& WO_ALL
);
862 if( (pTerm
->eOperator
& ~(WO_ISNULL
|WO_EQUIV
|WO_IS
))==0 ) continue;
863 if( pTerm
->wtFlags
& TERM_VNULL
) continue;
864 assert( pTerm
->u
.leftColumn
>=(-1) );
868 /* If the ORDER BY clause contains only columns in the current
869 ** virtual table then allocate space for the aOrderBy part of
870 ** the sqlite3_index_info structure.
874 int n
= pOrderBy
->nExpr
;
876 Expr
*pExpr
= pOrderBy
->a
[i
].pExpr
;
877 if( pExpr
->op
!=TK_COLUMN
|| pExpr
->iTable
!=pSrc
->iCursor
) break;
884 /* Allocate the sqlite3_index_info structure
886 pIdxInfo
= sqlite3DbMallocZero(pParse
->db
, sizeof(*pIdxInfo
)
887 + (sizeof(*pIdxCons
) + sizeof(*pUsage
))*nTerm
888 + sizeof(*pIdxOrderBy
)*nOrderBy
);
890 sqlite3ErrorMsg(pParse
, "out of memory");
894 /* Initialize the structure. The sqlite3_index_info structure contains
895 ** many fields that are declared "const" to prevent xBestIndex from
896 ** changing them. We have to do some funky casting in order to
897 ** initialize those fields.
899 pIdxCons
= (struct sqlite3_index_constraint
*)&pIdxInfo
[1];
900 pIdxOrderBy
= (struct sqlite3_index_orderby
*)&pIdxCons
[nTerm
];
901 pUsage
= (struct sqlite3_index_constraint_usage
*)&pIdxOrderBy
[nOrderBy
];
902 *(int*)&pIdxInfo
->nConstraint
= nTerm
;
903 *(int*)&pIdxInfo
->nOrderBy
= nOrderBy
;
904 *(struct sqlite3_index_constraint
**)&pIdxInfo
->aConstraint
= pIdxCons
;
905 *(struct sqlite3_index_orderby
**)&pIdxInfo
->aOrderBy
= pIdxOrderBy
;
906 *(struct sqlite3_index_constraint_usage
**)&pIdxInfo
->aConstraintUsage
=
909 for(i
=j
=0, pTerm
=pWC
->a
; i
<pWC
->nTerm
; i
++, pTerm
++){
911 if( pTerm
->leftCursor
!= pSrc
->iCursor
) continue;
912 if( pTerm
->prereqRight
& mUnusable
) continue;
913 assert( IsPowerOfTwo(pTerm
->eOperator
& ~WO_EQUIV
) );
914 testcase( pTerm
->eOperator
& WO_IN
);
915 testcase( pTerm
->eOperator
& WO_IS
);
916 testcase( pTerm
->eOperator
& WO_ISNULL
);
917 testcase( pTerm
->eOperator
& WO_ALL
);
918 if( (pTerm
->eOperator
& ~(WO_ISNULL
|WO_EQUIV
|WO_IS
))==0 ) continue;
919 if( pTerm
->wtFlags
& TERM_VNULL
) continue;
920 assert( pTerm
->u
.leftColumn
>=(-1) );
921 pIdxCons
[j
].iColumn
= pTerm
->u
.leftColumn
;
922 pIdxCons
[j
].iTermOffset
= i
;
923 op
= (u8
)pTerm
->eOperator
& WO_ALL
;
924 if( op
==WO_IN
) op
= WO_EQ
;
926 op
= pTerm
->eMatchOp
;
929 /* The direct assignment in the previous line is possible only because
930 ** the WO_ and SQLITE_INDEX_CONSTRAINT_ codes are identical. The
931 ** following asserts verify this fact. */
932 assert( WO_EQ
==SQLITE_INDEX_CONSTRAINT_EQ
);
933 assert( WO_LT
==SQLITE_INDEX_CONSTRAINT_LT
);
934 assert( WO_LE
==SQLITE_INDEX_CONSTRAINT_LE
);
935 assert( WO_GT
==SQLITE_INDEX_CONSTRAINT_GT
);
936 assert( WO_GE
==SQLITE_INDEX_CONSTRAINT_GE
);
937 assert( WO_MATCH
==SQLITE_INDEX_CONSTRAINT_MATCH
);
938 assert( pTerm
->eOperator
& (WO_IN
|WO_EQ
|WO_LT
|WO_LE
|WO_GT
|WO_GE
|WO_MATCH
) );
940 if( op
& (WO_LT
|WO_LE
|WO_GT
|WO_GE
)
941 && sqlite3ExprIsVector(pTerm
->pExpr
->pRight
)
943 if( i
<16 ) mNoOmit
|= (1 << i
);
944 if( op
==WO_LT
) pIdxCons
[j
].op
= WO_LE
;
945 if( op
==WO_GT
) pIdxCons
[j
].op
= WO_GE
;
950 for(i
=0; i
<nOrderBy
; i
++){
951 Expr
*pExpr
= pOrderBy
->a
[i
].pExpr
;
952 pIdxOrderBy
[i
].iColumn
= pExpr
->iColumn
;
953 pIdxOrderBy
[i
].desc
= pOrderBy
->a
[i
].sortOrder
;
961 ** The table object reference passed as the second argument to this function
962 ** must represent a virtual table. This function invokes the xBestIndex()
963 ** method of the virtual table with the sqlite3_index_info object that
964 ** comes in as the 3rd argument to this function.
966 ** If an error occurs, pParse is populated with an error message and a
967 ** non-zero value is returned. Otherwise, 0 is returned and the output
968 ** part of the sqlite3_index_info structure is left populated.
970 ** Whether or not an error is returned, it is the responsibility of the
971 ** caller to eventually free p->idxStr if p->needToFreeIdxStr indicates
972 ** that this is required.
974 static int vtabBestIndex(Parse
*pParse
, Table
*pTab
, sqlite3_index_info
*p
){
975 sqlite3_vtab
*pVtab
= sqlite3GetVTable(pParse
->db
, pTab
)->pVtab
;
979 rc
= pVtab
->pModule
->xBestIndex(pVtab
, p
);
980 TRACE_IDX_OUTPUTS(p
);
983 if( rc
==SQLITE_NOMEM
){
984 sqlite3OomFault(pParse
->db
);
985 }else if( !pVtab
->zErrMsg
){
986 sqlite3ErrorMsg(pParse
, "%s", sqlite3ErrStr(rc
));
988 sqlite3ErrorMsg(pParse
, "%s", pVtab
->zErrMsg
);
991 sqlite3_free(pVtab
->zErrMsg
);
995 /* This error is now caught by the caller.
996 ** Search for "xBestIndex malfunction" below */
997 for(i
=0; i
<p
->nConstraint
; i
++){
998 if( !p
->aConstraint
[i
].usable
&& p
->aConstraintUsage
[i
].argvIndex
>0 ){
999 sqlite3ErrorMsg(pParse
,
1000 "table %s: xBestIndex returned an invalid plan", pTab
->zName
);
1005 return pParse
->nErr
;
1007 #endif /* !defined(SQLITE_OMIT_VIRTUALTABLE) */
1009 #ifdef SQLITE_ENABLE_STAT3_OR_STAT4
1011 ** Estimate the location of a particular key among all keys in an
1012 ** index. Store the results in aStat as follows:
1014 ** aStat[0] Est. number of rows less than pRec
1015 ** aStat[1] Est. number of rows equal to pRec
1017 ** Return the index of the sample that is the smallest sample that
1018 ** is greater than or equal to pRec. Note that this index is not an index
1019 ** into the aSample[] array - it is an index into a virtual set of samples
1020 ** based on the contents of aSample[] and the number of fields in record
1023 static int whereKeyStats(
1024 Parse
*pParse
, /* Database connection */
1025 Index
*pIdx
, /* Index to consider domain of */
1026 UnpackedRecord
*pRec
, /* Vector of values to consider */
1027 int roundUp
, /* Round up if true. Round down if false */
1028 tRowcnt
*aStat
/* OUT: stats written here */
1030 IndexSample
*aSample
= pIdx
->aSample
;
1031 int iCol
; /* Index of required stats in anEq[] etc. */
1032 int i
; /* Index of first sample >= pRec */
1033 int iSample
; /* Smallest sample larger than or equal to pRec */
1034 int iMin
= 0; /* Smallest sample not yet tested */
1035 int iTest
; /* Next sample to test */
1036 int res
; /* Result of comparison operation */
1037 int nField
; /* Number of fields in pRec */
1038 tRowcnt iLower
= 0; /* anLt[] + anEq[] of largest sample pRec is > */
1040 #ifndef SQLITE_DEBUG
1041 UNUSED_PARAMETER( pParse
);
1044 assert( pIdx
->nSample
>0 );
1045 assert( pRec
->nField
>0 && pRec
->nField
<=pIdx
->nSampleCol
);
1047 /* Do a binary search to find the first sample greater than or equal
1048 ** to pRec. If pRec contains a single field, the set of samples to search
1049 ** is simply the aSample[] array. If the samples in aSample[] contain more
1050 ** than one fields, all fields following the first are ignored.
1052 ** If pRec contains N fields, where N is more than one, then as well as the
1053 ** samples in aSample[] (truncated to N fields), the search also has to
1054 ** consider prefixes of those samples. For example, if the set of samples
1057 ** aSample[0] = (a, 5)
1058 ** aSample[1] = (a, 10)
1059 ** aSample[2] = (b, 5)
1060 ** aSample[3] = (c, 100)
1061 ** aSample[4] = (c, 105)
1063 ** Then the search space should ideally be the samples above and the
1064 ** unique prefixes [a], [b] and [c]. But since that is hard to organize,
1065 ** the code actually searches this set:
1078 ** For each sample in the aSample[] array, N samples are present in the
1079 ** effective sample array. In the above, samples 0 and 1 are based on
1080 ** sample aSample[0]. Samples 2 and 3 on aSample[1] etc.
1082 ** Often, sample i of each block of N effective samples has (i+1) fields.
1083 ** Except, each sample may be extended to ensure that it is greater than or
1084 ** equal to the previous sample in the array. For example, in the above,
1085 ** sample 2 is the first sample of a block of N samples, so at first it
1086 ** appears that it should be 1 field in size. However, that would make it
1087 ** smaller than sample 1, so the binary search would not work. As a result,
1088 ** it is extended to two fields. The duplicates that this creates do not
1089 ** cause any problems.
1091 nField
= pRec
->nField
;
1093 iSample
= pIdx
->nSample
* nField
;
1095 int iSamp
; /* Index in aSample[] of test sample */
1096 int n
; /* Number of fields in test sample */
1098 iTest
= (iMin
+iSample
)/2;
1099 iSamp
= iTest
/ nField
;
1101 /* The proposed effective sample is a prefix of sample aSample[iSamp].
1102 ** Specifically, the shortest prefix of at least (1 + iTest%nField)
1103 ** fields that is greater than the previous effective sample. */
1104 for(n
=(iTest
% nField
) + 1; n
<nField
; n
++){
1105 if( aSample
[iSamp
-1].anLt
[n
-1]!=aSample
[iSamp
].anLt
[n
-1] ) break;
1112 res
= sqlite3VdbeRecordCompare(aSample
[iSamp
].n
, aSample
[iSamp
].p
, pRec
);
1114 iLower
= aSample
[iSamp
].anLt
[n
-1] + aSample
[iSamp
].anEq
[n
-1];
1116 }else if( res
==0 && n
<nField
){
1117 iLower
= aSample
[iSamp
].anLt
[n
-1];
1124 }while( res
&& iMin
<iSample
);
1125 i
= iSample
/ nField
;
1128 /* The following assert statements check that the binary search code
1129 ** above found the right answer. This block serves no purpose other
1130 ** than to invoke the asserts. */
1131 if( pParse
->db
->mallocFailed
==0 ){
1133 /* If (res==0) is true, then pRec must be equal to sample i. */
1134 assert( i
<pIdx
->nSample
);
1135 assert( iCol
==nField
-1 );
1136 pRec
->nField
= nField
;
1137 assert( 0==sqlite3VdbeRecordCompare(aSample
[i
].n
, aSample
[i
].p
, pRec
)
1138 || pParse
->db
->mallocFailed
1141 /* Unless i==pIdx->nSample, indicating that pRec is larger than
1142 ** all samples in the aSample[] array, pRec must be smaller than the
1143 ** (iCol+1) field prefix of sample i. */
1144 assert( i
<=pIdx
->nSample
&& i
>=0 );
1145 pRec
->nField
= iCol
+1;
1146 assert( i
==pIdx
->nSample
1147 || sqlite3VdbeRecordCompare(aSample
[i
].n
, aSample
[i
].p
, pRec
)>0
1148 || pParse
->db
->mallocFailed
);
1150 /* if i==0 and iCol==0, then record pRec is smaller than all samples
1151 ** in the aSample[] array. Otherwise, if (iCol>0) then pRec must
1152 ** be greater than or equal to the (iCol) field prefix of sample i.
1153 ** If (i>0), then pRec must also be greater than sample (i-1). */
1155 pRec
->nField
= iCol
;
1156 assert( sqlite3VdbeRecordCompare(aSample
[i
].n
, aSample
[i
].p
, pRec
)<=0
1157 || pParse
->db
->mallocFailed
);
1160 pRec
->nField
= nField
;
1161 assert( sqlite3VdbeRecordCompare(aSample
[i
-1].n
, aSample
[i
-1].p
, pRec
)<0
1162 || pParse
->db
->mallocFailed
);
1166 #endif /* ifdef SQLITE_DEBUG */
1169 /* Record pRec is equal to sample i */
1170 assert( iCol
==nField
-1 );
1171 aStat
[0] = aSample
[i
].anLt
[iCol
];
1172 aStat
[1] = aSample
[i
].anEq
[iCol
];
1174 /* At this point, the (iCol+1) field prefix of aSample[i] is the first
1175 ** sample that is greater than pRec. Or, if i==pIdx->nSample then pRec
1176 ** is larger than all samples in the array. */
1177 tRowcnt iUpper
, iGap
;
1178 if( i
>=pIdx
->nSample
){
1179 iUpper
= sqlite3LogEstToInt(pIdx
->aiRowLogEst
[0]);
1181 iUpper
= aSample
[i
].anLt
[iCol
];
1184 if( iLower
>=iUpper
){
1187 iGap
= iUpper
- iLower
;
1194 aStat
[0] = iLower
+ iGap
;
1195 aStat
[1] = pIdx
->aAvgEq
[nField
-1];
1198 /* Restore the pRec->nField value before returning. */
1199 pRec
->nField
= nField
;
1202 #endif /* SQLITE_ENABLE_STAT3_OR_STAT4 */
1205 ** If it is not NULL, pTerm is a term that provides an upper or lower
1206 ** bound on a range scan. Without considering pTerm, it is estimated
1207 ** that the scan will visit nNew rows. This function returns the number
1208 ** estimated to be visited after taking pTerm into account.
1210 ** If the user explicitly specified a likelihood() value for this term,
1211 ** then the return value is the likelihood multiplied by the number of
1212 ** input rows. Otherwise, this function assumes that an "IS NOT NULL" term
1213 ** has a likelihood of 0.50, and any other term a likelihood of 0.25.
1215 static LogEst
whereRangeAdjust(WhereTerm
*pTerm
, LogEst nNew
){
1218 if( pTerm
->truthProb
<=0 ){
1219 nRet
+= pTerm
->truthProb
;
1220 }else if( (pTerm
->wtFlags
& TERM_VNULL
)==0 ){
1221 nRet
-= 20; assert( 20==sqlite3LogEst(4) );
1228 #ifdef SQLITE_ENABLE_STAT3_OR_STAT4
1230 ** Return the affinity for a single column of an index.
1232 char sqlite3IndexColumnAffinity(sqlite3
*db
, Index
*pIdx
, int iCol
){
1233 assert( iCol
>=0 && iCol
<pIdx
->nColumn
);
1234 if( !pIdx
->zColAff
){
1235 if( sqlite3IndexAffinityStr(db
, pIdx
)==0 ) return SQLITE_AFF_BLOB
;
1237 return pIdx
->zColAff
[iCol
];
1242 #ifdef SQLITE_ENABLE_STAT3_OR_STAT4
1244 ** This function is called to estimate the number of rows visited by a
1245 ** range-scan on a skip-scan index. For example:
1247 ** CREATE INDEX i1 ON t1(a, b, c);
1248 ** SELECT * FROM t1 WHERE a=? AND c BETWEEN ? AND ?;
1250 ** Value pLoop->nOut is currently set to the estimated number of rows
1251 ** visited for scanning (a=? AND b=?). This function reduces that estimate
1252 ** by some factor to account for the (c BETWEEN ? AND ?) expression based
1253 ** on the stat4 data for the index. this scan will be peformed multiple
1254 ** times (once for each (a,b) combination that matches a=?) is dealt with
1257 ** It does this by scanning through all stat4 samples, comparing values
1258 ** extracted from pLower and pUpper with the corresponding column in each
1259 ** sample. If L and U are the number of samples found to be less than or
1260 ** equal to the values extracted from pLower and pUpper respectively, and
1261 ** N is the total number of samples, the pLoop->nOut value is adjusted
1264 ** nOut = nOut * ( min(U - L, 1) / N )
1266 ** If pLower is NULL, or a value cannot be extracted from the term, L is
1267 ** set to zero. If pUpper is NULL, or a value cannot be extracted from it,
1270 ** Normally, this function sets *pbDone to 1 before returning. However,
1271 ** if no value can be extracted from either pLower or pUpper (and so the
1272 ** estimate of the number of rows delivered remains unchanged), *pbDone
1275 ** If an error occurs, an SQLite error code is returned. Otherwise,
1278 static int whereRangeSkipScanEst(
1279 Parse
*pParse
, /* Parsing & code generating context */
1280 WhereTerm
*pLower
, /* Lower bound on the range. ex: "x>123" Might be NULL */
1281 WhereTerm
*pUpper
, /* Upper bound on the range. ex: "x<455" Might be NULL */
1282 WhereLoop
*pLoop
, /* Update the .nOut value of this loop */
1283 int *pbDone
/* Set to true if at least one expr. value extracted */
1285 Index
*p
= pLoop
->u
.btree
.pIndex
;
1286 int nEq
= pLoop
->u
.btree
.nEq
;
1287 sqlite3
*db
= pParse
->db
;
1289 int nUpper
= p
->nSample
+1;
1291 u8 aff
= sqlite3IndexColumnAffinity(db
, p
, nEq
);
1294 sqlite3_value
*p1
= 0; /* Value extracted from pLower */
1295 sqlite3_value
*p2
= 0; /* Value extracted from pUpper */
1296 sqlite3_value
*pVal
= 0; /* Value extracted from record */
1298 pColl
= sqlite3LocateCollSeq(pParse
, p
->azColl
[nEq
]);
1300 rc
= sqlite3Stat4ValueFromExpr(pParse
, pLower
->pExpr
->pRight
, aff
, &p1
);
1303 if( pUpper
&& rc
==SQLITE_OK
){
1304 rc
= sqlite3Stat4ValueFromExpr(pParse
, pUpper
->pExpr
->pRight
, aff
, &p2
);
1305 nUpper
= p2
? 0 : p
->nSample
;
1311 for(i
=0; rc
==SQLITE_OK
&& i
<p
->nSample
; i
++){
1312 rc
= sqlite3Stat4Column(db
, p
->aSample
[i
].p
, p
->aSample
[i
].n
, nEq
, &pVal
);
1313 if( rc
==SQLITE_OK
&& p1
){
1314 int res
= sqlite3MemCompare(p1
, pVal
, pColl
);
1315 if( res
>=0 ) nLower
++;
1317 if( rc
==SQLITE_OK
&& p2
){
1318 int res
= sqlite3MemCompare(p2
, pVal
, pColl
);
1319 if( res
>=0 ) nUpper
++;
1322 nDiff
= (nUpper
- nLower
);
1323 if( nDiff
<=0 ) nDiff
= 1;
1325 /* If there is both an upper and lower bound specified, and the
1326 ** comparisons indicate that they are close together, use the fallback
1327 ** method (assume that the scan visits 1/64 of the rows) for estimating
1328 ** the number of rows visited. Otherwise, estimate the number of rows
1329 ** using the method described in the header comment for this function. */
1330 if( nDiff
!=1 || pUpper
==0 || pLower
==0 ){
1331 int nAdjust
= (sqlite3LogEst(p
->nSample
) - sqlite3LogEst(nDiff
));
1332 pLoop
->nOut
-= nAdjust
;
1334 WHERETRACE(0x10, ("range skip-scan regions: %u..%u adjust=%d est=%d\n",
1335 nLower
, nUpper
, nAdjust
*-1, pLoop
->nOut
));
1339 assert( *pbDone
==0 );
1342 sqlite3ValueFree(p1
);
1343 sqlite3ValueFree(p2
);
1344 sqlite3ValueFree(pVal
);
1348 #endif /* SQLITE_ENABLE_STAT3_OR_STAT4 */
1351 ** This function is used to estimate the number of rows that will be visited
1352 ** by scanning an index for a range of values. The range may have an upper
1353 ** bound, a lower bound, or both. The WHERE clause terms that set the upper
1354 ** and lower bounds are represented by pLower and pUpper respectively. For
1355 ** example, assuming that index p is on t1(a):
1357 ** ... FROM t1 WHERE a > ? AND a < ? ...
1362 ** If either of the upper or lower bound is not present, then NULL is passed in
1363 ** place of the corresponding WhereTerm.
1365 ** The value in (pBuilder->pNew->u.btree.nEq) is the number of the index
1366 ** column subject to the range constraint. Or, equivalently, the number of
1367 ** equality constraints optimized by the proposed index scan. For example,
1368 ** assuming index p is on t1(a, b), and the SQL query is:
1370 ** ... FROM t1 WHERE a = ? AND b > ? AND b < ? ...
1372 ** then nEq is set to 1 (as the range restricted column, b, is the second
1373 ** left-most column of the index). Or, if the query is:
1375 ** ... FROM t1 WHERE a > ? AND a < ? ...
1377 ** then nEq is set to 0.
1379 ** When this function is called, *pnOut is set to the sqlite3LogEst() of the
1380 ** number of rows that the index scan is expected to visit without
1381 ** considering the range constraints. If nEq is 0, then *pnOut is the number of
1382 ** rows in the index. Assuming no error occurs, *pnOut is adjusted (reduced)
1383 ** to account for the range constraints pLower and pUpper.
1385 ** In the absence of sqlite_stat4 ANALYZE data, or if such data cannot be
1386 ** used, a single range inequality reduces the search space by a factor of 4.
1387 ** and a pair of constraints (x>? AND x<?) reduces the expected number of
1388 ** rows visited by a factor of 64.
1390 static int whereRangeScanEst(
1391 Parse
*pParse
, /* Parsing & code generating context */
1392 WhereLoopBuilder
*pBuilder
,
1393 WhereTerm
*pLower
, /* Lower bound on the range. ex: "x>123" Might be NULL */
1394 WhereTerm
*pUpper
, /* Upper bound on the range. ex: "x<455" Might be NULL */
1395 WhereLoop
*pLoop
/* Modify the .nOut and maybe .rRun fields */
1398 int nOut
= pLoop
->nOut
;
1401 #ifdef SQLITE_ENABLE_STAT3_OR_STAT4
1402 Index
*p
= pLoop
->u
.btree
.pIndex
;
1403 int nEq
= pLoop
->u
.btree
.nEq
;
1405 if( p
->nSample
>0 && nEq
<p
->nSampleCol
){
1406 if( nEq
==pBuilder
->nRecValid
){
1407 UnpackedRecord
*pRec
= pBuilder
->pRec
;
1409 int nBtm
= pLoop
->u
.btree
.nBtm
;
1410 int nTop
= pLoop
->u
.btree
.nTop
;
1412 /* Variable iLower will be set to the estimate of the number of rows in
1413 ** the index that are less than the lower bound of the range query. The
1414 ** lower bound being the concatenation of $P and $L, where $P is the
1415 ** key-prefix formed by the nEq values matched against the nEq left-most
1416 ** columns of the index, and $L is the value in pLower.
1418 ** Or, if pLower is NULL or $L cannot be extracted from it (because it
1419 ** is not a simple variable or literal value), the lower bound of the
1420 ** range is $P. Due to a quirk in the way whereKeyStats() works, even
1421 ** if $L is available, whereKeyStats() is called for both ($P) and
1422 ** ($P:$L) and the larger of the two returned values is used.
1424 ** Similarly, iUpper is to be set to the estimate of the number of rows
1425 ** less than the upper bound of the range query. Where the upper bound
1426 ** is either ($P) or ($P:$U). Again, even if $U is available, both values
1427 ** of iUpper are requested of whereKeyStats() and the smaller used.
1429 ** The number of rows between the two bounds is then just iUpper-iLower.
1431 tRowcnt iLower
; /* Rows less than the lower bound */
1432 tRowcnt iUpper
; /* Rows less than the upper bound */
1433 int iLwrIdx
= -2; /* aSample[] for the lower bound */
1434 int iUprIdx
= -1; /* aSample[] for the upper bound */
1437 testcase( pRec
->nField
!=pBuilder
->nRecValid
);
1438 pRec
->nField
= pBuilder
->nRecValid
;
1440 /* Determine iLower and iUpper using ($P) only. */
1443 iUpper
= p
->nRowEst0
;
1445 /* Note: this call could be optimized away - since the same values must
1446 ** have been requested when testing key $P in whereEqualScanEst(). */
1447 whereKeyStats(pParse
, p
, pRec
, 0, a
);
1449 iUpper
= a
[0] + a
[1];
1452 assert( pLower
==0 || (pLower
->eOperator
& (WO_GT
|WO_GE
))!=0 );
1453 assert( pUpper
==0 || (pUpper
->eOperator
& (WO_LT
|WO_LE
))!=0 );
1454 assert( p
->aSortOrder
!=0 );
1455 if( p
->aSortOrder
[nEq
] ){
1456 /* The roles of pLower and pUpper are swapped for a DESC index */
1457 SWAP(WhereTerm
*, pLower
, pUpper
);
1458 SWAP(int, nBtm
, nTop
);
1461 /* If possible, improve on the iLower estimate using ($P:$L). */
1463 int n
; /* Values extracted from pExpr */
1464 Expr
*pExpr
= pLower
->pExpr
->pRight
;
1465 rc
= sqlite3Stat4ProbeSetValue(pParse
, p
, &pRec
, pExpr
, nBtm
, nEq
, &n
);
1466 if( rc
==SQLITE_OK
&& n
){
1468 u16 mask
= WO_GT
|WO_LE
;
1469 if( sqlite3ExprVectorSize(pExpr
)>n
) mask
= (WO_LE
|WO_LT
);
1470 iLwrIdx
= whereKeyStats(pParse
, p
, pRec
, 0, a
);
1471 iNew
= a
[0] + ((pLower
->eOperator
& mask
) ? a
[1] : 0);
1472 if( iNew
>iLower
) iLower
= iNew
;
1478 /* If possible, improve on the iUpper estimate using ($P:$U). */
1480 int n
; /* Values extracted from pExpr */
1481 Expr
*pExpr
= pUpper
->pExpr
->pRight
;
1482 rc
= sqlite3Stat4ProbeSetValue(pParse
, p
, &pRec
, pExpr
, nTop
, nEq
, &n
);
1483 if( rc
==SQLITE_OK
&& n
){
1485 u16 mask
= WO_GT
|WO_LE
;
1486 if( sqlite3ExprVectorSize(pExpr
)>n
) mask
= (WO_LE
|WO_LT
);
1487 iUprIdx
= whereKeyStats(pParse
, p
, pRec
, 1, a
);
1488 iNew
= a
[0] + ((pUpper
->eOperator
& mask
) ? a
[1] : 0);
1489 if( iNew
<iUpper
) iUpper
= iNew
;
1495 pBuilder
->pRec
= pRec
;
1496 if( rc
==SQLITE_OK
){
1497 if( iUpper
>iLower
){
1498 nNew
= sqlite3LogEst(iUpper
- iLower
);
1499 /* TUNING: If both iUpper and iLower are derived from the same
1500 ** sample, then assume they are 4x more selective. This brings
1501 ** the estimated selectivity more in line with what it would be
1502 ** if estimated without the use of STAT3/4 tables. */
1503 if( iLwrIdx
==iUprIdx
) nNew
-= 20; assert( 20==sqlite3LogEst(4) );
1505 nNew
= 10; assert( 10==sqlite3LogEst(2) );
1510 WHERETRACE(0x10, ("STAT4 range scan: %u..%u est=%d\n",
1511 (u32
)iLower
, (u32
)iUpper
, nOut
));
1515 rc
= whereRangeSkipScanEst(pParse
, pLower
, pUpper
, pLoop
, &bDone
);
1516 if( bDone
) return rc
;
1520 UNUSED_PARAMETER(pParse
);
1521 UNUSED_PARAMETER(pBuilder
);
1522 assert( pLower
|| pUpper
);
1524 assert( pUpper
==0 || (pUpper
->wtFlags
& TERM_VNULL
)==0 );
1525 nNew
= whereRangeAdjust(pLower
, nOut
);
1526 nNew
= whereRangeAdjust(pUpper
, nNew
);
1528 /* TUNING: If there is both an upper and lower limit and neither limit
1529 ** has an application-defined likelihood(), assume the range is
1530 ** reduced by an additional 75%. This means that, by default, an open-ended
1531 ** range query (e.g. col > ?) is assumed to match 1/4 of the rows in the
1532 ** index. While a closed range (e.g. col BETWEEN ? AND ?) is estimated to
1533 ** match 1/64 of the index. */
1534 if( pLower
&& pLower
->truthProb
>0 && pUpper
&& pUpper
->truthProb
>0 ){
1538 nOut
-= (pLower
!=0) + (pUpper
!=0);
1539 if( nNew
<10 ) nNew
= 10;
1540 if( nNew
<nOut
) nOut
= nNew
;
1541 #if defined(WHERETRACE_ENABLED)
1542 if( pLoop
->nOut
>nOut
){
1543 WHERETRACE(0x10,("Range scan lowers nOut from %d to %d\n",
1544 pLoop
->nOut
, nOut
));
1547 pLoop
->nOut
= (LogEst
)nOut
;
1551 #ifdef SQLITE_ENABLE_STAT3_OR_STAT4
1553 ** Estimate the number of rows that will be returned based on
1554 ** an equality constraint x=VALUE and where that VALUE occurs in
1555 ** the histogram data. This only works when x is the left-most
1556 ** column of an index and sqlite_stat3 histogram data is available
1557 ** for that index. When pExpr==NULL that means the constraint is
1558 ** "x IS NULL" instead of "x=VALUE".
1560 ** Write the estimated row count into *pnRow and return SQLITE_OK.
1561 ** If unable to make an estimate, leave *pnRow unchanged and return
1564 ** This routine can fail if it is unable to load a collating sequence
1565 ** required for string comparison, or if unable to allocate memory
1566 ** for a UTF conversion required for comparison. The error is stored
1567 ** in the pParse structure.
1569 static int whereEqualScanEst(
1570 Parse
*pParse
, /* Parsing & code generating context */
1571 WhereLoopBuilder
*pBuilder
,
1572 Expr
*pExpr
, /* Expression for VALUE in the x=VALUE constraint */
1573 tRowcnt
*pnRow
/* Write the revised row estimate here */
1575 Index
*p
= pBuilder
->pNew
->u
.btree
.pIndex
;
1576 int nEq
= pBuilder
->pNew
->u
.btree
.nEq
;
1577 UnpackedRecord
*pRec
= pBuilder
->pRec
;
1578 int rc
; /* Subfunction return code */
1579 tRowcnt a
[2]; /* Statistics */
1583 assert( nEq
<=p
->nColumn
);
1584 assert( p
->aSample
!=0 );
1585 assert( p
->nSample
>0 );
1586 assert( pBuilder
->nRecValid
<nEq
);
1588 /* If values are not available for all fields of the index to the left
1589 ** of this one, no estimate can be made. Return SQLITE_NOTFOUND. */
1590 if( pBuilder
->nRecValid
<(nEq
-1) ){
1591 return SQLITE_NOTFOUND
;
1594 /* This is an optimization only. The call to sqlite3Stat4ProbeSetValue()
1595 ** below would return the same value. */
1596 if( nEq
>=p
->nColumn
){
1601 rc
= sqlite3Stat4ProbeSetValue(pParse
, p
, &pRec
, pExpr
, 1, nEq
-1, &bOk
);
1602 pBuilder
->pRec
= pRec
;
1603 if( rc
!=SQLITE_OK
) return rc
;
1604 if( bOk
==0 ) return SQLITE_NOTFOUND
;
1605 pBuilder
->nRecValid
= nEq
;
1607 whereKeyStats(pParse
, p
, pRec
, 0, a
);
1608 WHERETRACE(0x10,("equality scan regions %s(%d): %d\n",
1609 p
->zName
, nEq
-1, (int)a
[1]));
1614 #endif /* SQLITE_ENABLE_STAT3_OR_STAT4 */
1616 #ifdef SQLITE_ENABLE_STAT3_OR_STAT4
1618 ** Estimate the number of rows that will be returned based on
1619 ** an IN constraint where the right-hand side of the IN operator
1620 ** is a list of values. Example:
1622 ** WHERE x IN (1,2,3,4)
1624 ** Write the estimated row count into *pnRow and return SQLITE_OK.
1625 ** If unable to make an estimate, leave *pnRow unchanged and return
1628 ** This routine can fail if it is unable to load a collating sequence
1629 ** required for string comparison, or if unable to allocate memory
1630 ** for a UTF conversion required for comparison. The error is stored
1631 ** in the pParse structure.
1633 static int whereInScanEst(
1634 Parse
*pParse
, /* Parsing & code generating context */
1635 WhereLoopBuilder
*pBuilder
,
1636 ExprList
*pList
, /* The value list on the RHS of "x IN (v1,v2,v3,...)" */
1637 tRowcnt
*pnRow
/* Write the revised row estimate here */
1639 Index
*p
= pBuilder
->pNew
->u
.btree
.pIndex
;
1640 i64 nRow0
= sqlite3LogEstToInt(p
->aiRowLogEst
[0]);
1641 int nRecValid
= pBuilder
->nRecValid
;
1642 int rc
= SQLITE_OK
; /* Subfunction return code */
1643 tRowcnt nEst
; /* Number of rows for a single term */
1644 tRowcnt nRowEst
= 0; /* New estimate of the number of rows */
1645 int i
; /* Loop counter */
1647 assert( p
->aSample
!=0 );
1648 for(i
=0; rc
==SQLITE_OK
&& i
<pList
->nExpr
; i
++){
1650 rc
= whereEqualScanEst(pParse
, pBuilder
, pList
->a
[i
].pExpr
, &nEst
);
1652 pBuilder
->nRecValid
= nRecValid
;
1655 if( rc
==SQLITE_OK
){
1656 if( nRowEst
> nRow0
) nRowEst
= nRow0
;
1658 WHERETRACE(0x10,("IN row estimate: est=%d\n", nRowEst
));
1660 assert( pBuilder
->nRecValid
==nRecValid
);
1663 #endif /* SQLITE_ENABLE_STAT3_OR_STAT4 */
1666 #ifdef WHERETRACE_ENABLED
1668 ** Print the content of a WhereTerm object
1670 static void whereTermPrint(WhereTerm
*pTerm
, int iTerm
){
1672 sqlite3DebugPrintf("TERM-%-3d NULL\n", iTerm
);
1676 memcpy(zType
, "...", 4);
1677 if( pTerm
->wtFlags
& TERM_VIRTUAL
) zType
[0] = 'V';
1678 if( pTerm
->eOperator
& WO_EQUIV
) zType
[1] = 'E';
1679 if( ExprHasProperty(pTerm
->pExpr
, EP_FromJoin
) ) zType
[2] = 'L';
1680 if( pTerm
->eOperator
& WO_SINGLE
){
1681 sqlite3_snprintf(sizeof(zLeft
),zLeft
,"left={%d:%d}",
1682 pTerm
->leftCursor
, pTerm
->u
.leftColumn
);
1683 }else if( (pTerm
->eOperator
& WO_OR
)!=0 && pTerm
->u
.pOrInfo
!=0 ){
1684 sqlite3_snprintf(sizeof(zLeft
),zLeft
,"indexable=0x%lld",
1685 pTerm
->u
.pOrInfo
->indexable
);
1687 sqlite3_snprintf(sizeof(zLeft
),zLeft
,"left=%d", pTerm
->leftCursor
);
1690 "TERM-%-3d %p %s %-12s prob=%-3d op=0x%03x wtFlags=0x%04x",
1691 iTerm
, pTerm
, zType
, zLeft
, pTerm
->truthProb
,
1692 pTerm
->eOperator
, pTerm
->wtFlags
);
1693 if( pTerm
->iField
){
1694 sqlite3DebugPrintf(" iField=%d\n", pTerm
->iField
);
1696 sqlite3DebugPrintf("\n");
1698 sqlite3TreeViewExpr(0, pTerm
->pExpr
, 0);
1703 #ifdef WHERETRACE_ENABLED
1705 ** Show the complete content of a WhereClause
1707 void sqlite3WhereClausePrint(WhereClause
*pWC
){
1709 for(i
=0; i
<pWC
->nTerm
; i
++){
1710 whereTermPrint(&pWC
->a
[i
], i
);
1715 #ifdef WHERETRACE_ENABLED
1717 ** Print a WhereLoop object for debugging purposes
1719 static void whereLoopPrint(WhereLoop
*p
, WhereClause
*pWC
){
1720 WhereInfo
*pWInfo
= pWC
->pWInfo
;
1721 int nb
= 1+(pWInfo
->pTabList
->nSrc
+3)/4;
1722 struct SrcList_item
*pItem
= pWInfo
->pTabList
->a
+ p
->iTab
;
1723 Table
*pTab
= pItem
->pTab
;
1724 Bitmask mAll
= (((Bitmask
)1)<<(nb
*4)) - 1;
1725 sqlite3DebugPrintf("%c%2d.%0*llx.%0*llx", p
->cId
,
1726 p
->iTab
, nb
, p
->maskSelf
, nb
, p
->prereq
& mAll
);
1727 sqlite3DebugPrintf(" %12s",
1728 pItem
->zAlias
? pItem
->zAlias
: pTab
->zName
);
1729 if( (p
->wsFlags
& WHERE_VIRTUALTABLE
)==0 ){
1731 if( p
->u
.btree
.pIndex
&& (zName
= p
->u
.btree
.pIndex
->zName
)!=0 ){
1732 if( strncmp(zName
, "sqlite_autoindex_", 17)==0 ){
1733 int i
= sqlite3Strlen30(zName
) - 1;
1734 while( zName
[i
]!='_' ) i
--;
1737 sqlite3DebugPrintf(".%-16s %2d", zName
, p
->u
.btree
.nEq
);
1739 sqlite3DebugPrintf("%20s","");
1743 if( p
->u
.vtab
.idxStr
){
1744 z
= sqlite3_mprintf("(%d,\"%s\",%x)",
1745 p
->u
.vtab
.idxNum
, p
->u
.vtab
.idxStr
, p
->u
.vtab
.omitMask
);
1747 z
= sqlite3_mprintf("(%d,%x)", p
->u
.vtab
.idxNum
, p
->u
.vtab
.omitMask
);
1749 sqlite3DebugPrintf(" %-19s", z
);
1752 if( p
->wsFlags
& WHERE_SKIPSCAN
){
1753 sqlite3DebugPrintf(" f %05x %d-%d", p
->wsFlags
, p
->nLTerm
,p
->nSkip
);
1755 sqlite3DebugPrintf(" f %05x N %d", p
->wsFlags
, p
->nLTerm
);
1757 sqlite3DebugPrintf(" cost %d,%d,%d\n", p
->rSetup
, p
->rRun
, p
->nOut
);
1758 if( p
->nLTerm
&& (sqlite3WhereTrace
& 0x100)!=0 ){
1760 for(i
=0; i
<p
->nLTerm
; i
++){
1761 whereTermPrint(p
->aLTerm
[i
], i
);
1768 ** Convert bulk memory into a valid WhereLoop that can be passed
1769 ** to whereLoopClear harmlessly.
1771 static void whereLoopInit(WhereLoop
*p
){
1772 p
->aLTerm
= p
->aLTermSpace
;
1774 p
->nLSlot
= ArraySize(p
->aLTermSpace
);
1779 ** Clear the WhereLoop.u union. Leave WhereLoop.pLTerm intact.
1781 static void whereLoopClearUnion(sqlite3
*db
, WhereLoop
*p
){
1782 if( p
->wsFlags
& (WHERE_VIRTUALTABLE
|WHERE_AUTO_INDEX
) ){
1783 if( (p
->wsFlags
& WHERE_VIRTUALTABLE
)!=0 && p
->u
.vtab
.needFree
){
1784 sqlite3_free(p
->u
.vtab
.idxStr
);
1785 p
->u
.vtab
.needFree
= 0;
1786 p
->u
.vtab
.idxStr
= 0;
1787 }else if( (p
->wsFlags
& WHERE_AUTO_INDEX
)!=0 && p
->u
.btree
.pIndex
!=0 ){
1788 sqlite3DbFree(db
, p
->u
.btree
.pIndex
->zColAff
);
1789 sqlite3DbFreeNN(db
, p
->u
.btree
.pIndex
);
1790 p
->u
.btree
.pIndex
= 0;
1796 ** Deallocate internal memory used by a WhereLoop object
1798 static void whereLoopClear(sqlite3
*db
, WhereLoop
*p
){
1799 if( p
->aLTerm
!=p
->aLTermSpace
) sqlite3DbFreeNN(db
, p
->aLTerm
);
1800 whereLoopClearUnion(db
, p
);
1805 ** Increase the memory allocation for pLoop->aLTerm[] to be at least n.
1807 static int whereLoopResize(sqlite3
*db
, WhereLoop
*p
, int n
){
1809 if( p
->nLSlot
>=n
) return SQLITE_OK
;
1811 paNew
= sqlite3DbMallocRawNN(db
, sizeof(p
->aLTerm
[0])*n
);
1812 if( paNew
==0 ) return SQLITE_NOMEM_BKPT
;
1813 memcpy(paNew
, p
->aLTerm
, sizeof(p
->aLTerm
[0])*p
->nLSlot
);
1814 if( p
->aLTerm
!=p
->aLTermSpace
) sqlite3DbFreeNN(db
, p
->aLTerm
);
1821 ** Transfer content from the second pLoop into the first.
1823 static int whereLoopXfer(sqlite3
*db
, WhereLoop
*pTo
, WhereLoop
*pFrom
){
1824 whereLoopClearUnion(db
, pTo
);
1825 if( whereLoopResize(db
, pTo
, pFrom
->nLTerm
) ){
1826 memset(&pTo
->u
, 0, sizeof(pTo
->u
));
1827 return SQLITE_NOMEM_BKPT
;
1829 memcpy(pTo
, pFrom
, WHERE_LOOP_XFER_SZ
);
1830 memcpy(pTo
->aLTerm
, pFrom
->aLTerm
, pTo
->nLTerm
*sizeof(pTo
->aLTerm
[0]));
1831 if( pFrom
->wsFlags
& WHERE_VIRTUALTABLE
){
1832 pFrom
->u
.vtab
.needFree
= 0;
1833 }else if( (pFrom
->wsFlags
& WHERE_AUTO_INDEX
)!=0 ){
1834 pFrom
->u
.btree
.pIndex
= 0;
1840 ** Delete a WhereLoop object
1842 static void whereLoopDelete(sqlite3
*db
, WhereLoop
*p
){
1843 whereLoopClear(db
, p
);
1844 sqlite3DbFreeNN(db
, p
);
1848 ** Free a WhereInfo structure
1850 static void whereInfoFree(sqlite3
*db
, WhereInfo
*pWInfo
){
1851 if( ALWAYS(pWInfo
) ){
1853 for(i
=0; i
<pWInfo
->nLevel
; i
++){
1854 WhereLevel
*pLevel
= &pWInfo
->a
[i
];
1855 if( pLevel
->pWLoop
&& (pLevel
->pWLoop
->wsFlags
& WHERE_IN_ABLE
) ){
1856 sqlite3DbFree(db
, pLevel
->u
.in
.aInLoop
);
1859 sqlite3WhereClauseClear(&pWInfo
->sWC
);
1860 while( pWInfo
->pLoops
){
1861 WhereLoop
*p
= pWInfo
->pLoops
;
1862 pWInfo
->pLoops
= p
->pNextLoop
;
1863 whereLoopDelete(db
, p
);
1865 sqlite3DbFreeNN(db
, pWInfo
);
1870 ** Return TRUE if all of the following are true:
1872 ** (1) X has the same or lower cost that Y
1873 ** (2) X is a proper subset of Y
1874 ** (3) X skips at least as many columns as Y
1876 ** By "proper subset" we mean that X uses fewer WHERE clause terms
1877 ** than Y and that every WHERE clause term used by X is also used
1880 ** If X is a proper subset of Y then Y is a better choice and ought
1881 ** to have a lower cost. This routine returns TRUE when that cost
1882 ** relationship is inverted and needs to be adjusted. The third rule
1883 ** was added because if X uses skip-scan less than Y it still might
1884 ** deserve a lower cost even if it is a proper subset of Y.
1886 static int whereLoopCheaperProperSubset(
1887 const WhereLoop
*pX
, /* First WhereLoop to compare */
1888 const WhereLoop
*pY
/* Compare against this WhereLoop */
1891 if( pX
->nLTerm
-pX
->nSkip
>= pY
->nLTerm
-pY
->nSkip
){
1892 return 0; /* X is not a subset of Y */
1894 if( pY
->nSkip
> pX
->nSkip
) return 0;
1895 if( pX
->rRun
>= pY
->rRun
){
1896 if( pX
->rRun
> pY
->rRun
) return 0; /* X costs more than Y */
1897 if( pX
->nOut
> pY
->nOut
) return 0; /* X costs more than Y */
1899 for(i
=pX
->nLTerm
-1; i
>=0; i
--){
1900 if( pX
->aLTerm
[i
]==0 ) continue;
1901 for(j
=pY
->nLTerm
-1; j
>=0; j
--){
1902 if( pY
->aLTerm
[j
]==pX
->aLTerm
[i
] ) break;
1904 if( j
<0 ) return 0; /* X not a subset of Y since term X[i] not used by Y */
1906 return 1; /* All conditions meet */
1910 ** Try to adjust the cost of WhereLoop pTemplate upwards or downwards so
1913 ** (1) pTemplate costs less than any other WhereLoops that are a proper
1914 ** subset of pTemplate
1916 ** (2) pTemplate costs more than any other WhereLoops for which pTemplate
1917 ** is a proper subset.
1919 ** To say "WhereLoop X is a proper subset of Y" means that X uses fewer
1920 ** WHERE clause terms than Y and that every WHERE clause term used by X is
1923 static void whereLoopAdjustCost(const WhereLoop
*p
, WhereLoop
*pTemplate
){
1924 if( (pTemplate
->wsFlags
& WHERE_INDEXED
)==0 ) return;
1925 for(; p
; p
=p
->pNextLoop
){
1926 if( p
->iTab
!=pTemplate
->iTab
) continue;
1927 if( (p
->wsFlags
& WHERE_INDEXED
)==0 ) continue;
1928 if( whereLoopCheaperProperSubset(p
, pTemplate
) ){
1929 /* Adjust pTemplate cost downward so that it is cheaper than its
1931 WHERETRACE(0x80,("subset cost adjustment %d,%d to %d,%d\n",
1932 pTemplate
->rRun
, pTemplate
->nOut
, p
->rRun
, p
->nOut
-1));
1933 pTemplate
->rRun
= p
->rRun
;
1934 pTemplate
->nOut
= p
->nOut
- 1;
1935 }else if( whereLoopCheaperProperSubset(pTemplate
, p
) ){
1936 /* Adjust pTemplate cost upward so that it is costlier than p since
1937 ** pTemplate is a proper subset of p */
1938 WHERETRACE(0x80,("subset cost adjustment %d,%d to %d,%d\n",
1939 pTemplate
->rRun
, pTemplate
->nOut
, p
->rRun
, p
->nOut
+1));
1940 pTemplate
->rRun
= p
->rRun
;
1941 pTemplate
->nOut
= p
->nOut
+ 1;
1947 ** Search the list of WhereLoops in *ppPrev looking for one that can be
1948 ** replaced by pTemplate.
1950 ** Return NULL if pTemplate does not belong on the WhereLoop list.
1951 ** In other words if pTemplate ought to be dropped from further consideration.
1953 ** If pX is a WhereLoop that pTemplate can replace, then return the
1954 ** link that points to pX.
1956 ** If pTemplate cannot replace any existing element of the list but needs
1957 ** to be added to the list as a new entry, then return a pointer to the
1958 ** tail of the list.
1960 static WhereLoop
**whereLoopFindLesser(
1962 const WhereLoop
*pTemplate
1965 for(p
=(*ppPrev
); p
; ppPrev
=&p
->pNextLoop
, p
=*ppPrev
){
1966 if( p
->iTab
!=pTemplate
->iTab
|| p
->iSortIdx
!=pTemplate
->iSortIdx
){
1967 /* If either the iTab or iSortIdx values for two WhereLoop are different
1968 ** then those WhereLoops need to be considered separately. Neither is
1969 ** a candidate to replace the other. */
1972 /* In the current implementation, the rSetup value is either zero
1973 ** or the cost of building an automatic index (NlogN) and the NlogN
1974 ** is the same for compatible WhereLoops. */
1975 assert( p
->rSetup
==0 || pTemplate
->rSetup
==0
1976 || p
->rSetup
==pTemplate
->rSetup
);
1978 /* whereLoopAddBtree() always generates and inserts the automatic index
1979 ** case first. Hence compatible candidate WhereLoops never have a larger
1980 ** rSetup. Call this SETUP-INVARIANT */
1981 assert( p
->rSetup
>=pTemplate
->rSetup
);
1983 /* Any loop using an appliation-defined index (or PRIMARY KEY or
1984 ** UNIQUE constraint) with one or more == constraints is better
1985 ** than an automatic index. Unless it is a skip-scan. */
1986 if( (p
->wsFlags
& WHERE_AUTO_INDEX
)!=0
1987 && (pTemplate
->nSkip
)==0
1988 && (pTemplate
->wsFlags
& WHERE_INDEXED
)!=0
1989 && (pTemplate
->wsFlags
& WHERE_COLUMN_EQ
)!=0
1990 && (p
->prereq
& pTemplate
->prereq
)==pTemplate
->prereq
1995 /* If existing WhereLoop p is better than pTemplate, pTemplate can be
1996 ** discarded. WhereLoop p is better if:
1997 ** (1) p has no more dependencies than pTemplate, and
1998 ** (2) p has an equal or lower cost than pTemplate
2000 if( (p
->prereq
& pTemplate
->prereq
)==p
->prereq
/* (1) */
2001 && p
->rSetup
<=pTemplate
->rSetup
/* (2a) */
2002 && p
->rRun
<=pTemplate
->rRun
/* (2b) */
2003 && p
->nOut
<=pTemplate
->nOut
/* (2c) */
2005 return 0; /* Discard pTemplate */
2008 /* If pTemplate is always better than p, then cause p to be overwritten
2009 ** with pTemplate. pTemplate is better than p if:
2010 ** (1) pTemplate has no more dependences than p, and
2011 ** (2) pTemplate has an equal or lower cost than p.
2013 if( (p
->prereq
& pTemplate
->prereq
)==pTemplate
->prereq
/* (1) */
2014 && p
->rRun
>=pTemplate
->rRun
/* (2a) */
2015 && p
->nOut
>=pTemplate
->nOut
/* (2b) */
2017 assert( p
->rSetup
>=pTemplate
->rSetup
); /* SETUP-INVARIANT above */
2018 break; /* Cause p to be overwritten by pTemplate */
2025 ** Insert or replace a WhereLoop entry using the template supplied.
2027 ** An existing WhereLoop entry might be overwritten if the new template
2028 ** is better and has fewer dependencies. Or the template will be ignored
2029 ** and no insert will occur if an existing WhereLoop is faster and has
2030 ** fewer dependencies than the template. Otherwise a new WhereLoop is
2031 ** added based on the template.
2033 ** If pBuilder->pOrSet is not NULL then we care about only the
2034 ** prerequisites and rRun and nOut costs of the N best loops. That
2035 ** information is gathered in the pBuilder->pOrSet object. This special
2036 ** processing mode is used only for OR clause processing.
2038 ** When accumulating multiple loops (when pBuilder->pOrSet is NULL) we
2039 ** still might overwrite similar loops with the new template if the
2040 ** new template is better. Loops may be overwritten if the following
2041 ** conditions are met:
2043 ** (1) They have the same iTab.
2044 ** (2) They have the same iSortIdx.
2045 ** (3) The template has same or fewer dependencies than the current loop
2046 ** (4) The template has the same or lower cost than the current loop
2048 static int whereLoopInsert(WhereLoopBuilder
*pBuilder
, WhereLoop
*pTemplate
){
2049 WhereLoop
**ppPrev
, *p
;
2050 WhereInfo
*pWInfo
= pBuilder
->pWInfo
;
2051 sqlite3
*db
= pWInfo
->pParse
->db
;
2054 /* If pBuilder->pOrSet is defined, then only keep track of the costs
2057 if( pBuilder
->pOrSet
!=0 ){
2058 if( pTemplate
->nLTerm
){
2059 #if WHERETRACE_ENABLED
2060 u16 n
= pBuilder
->pOrSet
->n
;
2063 whereOrInsert(pBuilder
->pOrSet
, pTemplate
->prereq
, pTemplate
->rRun
,
2065 #if WHERETRACE_ENABLED /* 0x8 */
2066 if( sqlite3WhereTrace
& 0x8 ){
2067 sqlite3DebugPrintf(x
?" or-%d: ":" or-X: ", n
);
2068 whereLoopPrint(pTemplate
, pBuilder
->pWC
);
2075 /* Look for an existing WhereLoop to replace with pTemplate
2077 whereLoopAdjustCost(pWInfo
->pLoops
, pTemplate
);
2078 ppPrev
= whereLoopFindLesser(&pWInfo
->pLoops
, pTemplate
);
2081 /* There already exists a WhereLoop on the list that is better
2082 ** than pTemplate, so just ignore pTemplate */
2083 #if WHERETRACE_ENABLED /* 0x8 */
2084 if( sqlite3WhereTrace
& 0x8 ){
2085 sqlite3DebugPrintf(" skip: ");
2086 whereLoopPrint(pTemplate
, pBuilder
->pWC
);
2094 /* If we reach this point it means that either p[] should be overwritten
2095 ** with pTemplate[] if p[] exists, or if p==NULL then allocate a new
2096 ** WhereLoop and insert it.
2098 #if WHERETRACE_ENABLED /* 0x8 */
2099 if( sqlite3WhereTrace
& 0x8 ){
2101 sqlite3DebugPrintf("replace: ");
2102 whereLoopPrint(p
, pBuilder
->pWC
);
2103 sqlite3DebugPrintf(" with: ");
2105 sqlite3DebugPrintf(" add: ");
2107 whereLoopPrint(pTemplate
, pBuilder
->pWC
);
2111 /* Allocate a new WhereLoop to add to the end of the list */
2112 *ppPrev
= p
= sqlite3DbMallocRawNN(db
, sizeof(WhereLoop
));
2113 if( p
==0 ) return SQLITE_NOMEM_BKPT
;
2117 /* We will be overwriting WhereLoop p[]. But before we do, first
2118 ** go through the rest of the list and delete any other entries besides
2119 ** p[] that are also supplated by pTemplate */
2120 WhereLoop
**ppTail
= &p
->pNextLoop
;
2123 ppTail
= whereLoopFindLesser(ppTail
, pTemplate
);
2124 if( ppTail
==0 ) break;
2126 if( pToDel
==0 ) break;
2127 *ppTail
= pToDel
->pNextLoop
;
2128 #if WHERETRACE_ENABLED /* 0x8 */
2129 if( sqlite3WhereTrace
& 0x8 ){
2130 sqlite3DebugPrintf(" delete: ");
2131 whereLoopPrint(pToDel
, pBuilder
->pWC
);
2134 whereLoopDelete(db
, pToDel
);
2137 rc
= whereLoopXfer(db
, p
, pTemplate
);
2138 if( (p
->wsFlags
& WHERE_VIRTUALTABLE
)==0 ){
2139 Index
*pIndex
= p
->u
.btree
.pIndex
;
2140 if( pIndex
&& pIndex
->tnum
==0 ){
2141 p
->u
.btree
.pIndex
= 0;
2148 ** Adjust the WhereLoop.nOut value downward to account for terms of the
2149 ** WHERE clause that reference the loop but which are not used by an
2152 ** For every WHERE clause term that is not used by the index
2153 ** and which has a truth probability assigned by one of the likelihood(),
2154 ** likely(), or unlikely() SQL functions, reduce the estimated number
2155 ** of output rows by the probability specified.
2157 ** TUNING: For every WHERE clause term that is not used by the index
2158 ** and which does not have an assigned truth probability, heuristics
2159 ** described below are used to try to estimate the truth probability.
2160 ** TODO --> Perhaps this is something that could be improved by better
2161 ** table statistics.
2163 ** Heuristic 1: Estimate the truth probability as 93.75%. The 93.75%
2164 ** value corresponds to -1 in LogEst notation, so this means decrement
2165 ** the WhereLoop.nOut field for every such WHERE clause term.
2167 ** Heuristic 2: If there exists one or more WHERE clause terms of the
2168 ** form "x==EXPR" and EXPR is not a constant 0 or 1, then make sure the
2169 ** final output row estimate is no greater than 1/4 of the total number
2170 ** of rows in the table. In other words, assume that x==EXPR will filter
2171 ** out at least 3 out of 4 rows. If EXPR is -1 or 0 or 1, then maybe the
2172 ** "x" column is boolean or else -1 or 0 or 1 is a common default value
2173 ** on the "x" column and so in that case only cap the output row estimate
2174 ** at 1/2 instead of 1/4.
2176 static void whereLoopOutputAdjust(
2177 WhereClause
*pWC
, /* The WHERE clause */
2178 WhereLoop
*pLoop
, /* The loop to adjust downward */
2179 LogEst nRow
/* Number of rows in the entire table */
2181 WhereTerm
*pTerm
, *pX
;
2182 Bitmask notAllowed
= ~(pLoop
->prereq
|pLoop
->maskSelf
);
2184 LogEst iReduce
= 0; /* pLoop->nOut should not exceed nRow-iReduce */
2186 assert( (pLoop
->wsFlags
& WHERE_AUTO_INDEX
)==0 );
2187 for(i
=pWC
->nTerm
, pTerm
=pWC
->a
; i
>0; i
--, pTerm
++){
2188 if( (pTerm
->wtFlags
& TERM_VIRTUAL
)!=0 ) break;
2189 if( (pTerm
->prereqAll
& pLoop
->maskSelf
)==0 ) continue;
2190 if( (pTerm
->prereqAll
& notAllowed
)!=0 ) continue;
2191 for(j
=pLoop
->nLTerm
-1; j
>=0; j
--){
2192 pX
= pLoop
->aLTerm
[j
];
2193 if( pX
==0 ) continue;
2194 if( pX
==pTerm
) break;
2195 if( pX
->iParent
>=0 && (&pWC
->a
[pX
->iParent
])==pTerm
) break;
2198 if( pTerm
->truthProb
<=0 ){
2199 /* If a truth probability is specified using the likelihood() hints,
2200 ** then use the probability provided by the application. */
2201 pLoop
->nOut
+= pTerm
->truthProb
;
2203 /* In the absence of explicit truth probabilities, use heuristics to
2204 ** guess a reasonable truth probability. */
2206 if( pTerm
->eOperator
&(WO_EQ
|WO_IS
) ){
2207 Expr
*pRight
= pTerm
->pExpr
->pRight
;
2208 testcase( pTerm
->pExpr
->op
==TK_IS
);
2209 if( sqlite3ExprIsInteger(pRight
, &k
) && k
>=(-1) && k
<=1 ){
2214 if( iReduce
<k
) iReduce
= k
;
2219 if( pLoop
->nOut
> nRow
-iReduce
) pLoop
->nOut
= nRow
- iReduce
;
2223 ** Term pTerm is a vector range comparison operation. The first comparison
2224 ** in the vector can be optimized using column nEq of the index. This
2225 ** function returns the total number of vector elements that can be used
2226 ** as part of the range comparison.
2228 ** For example, if the query is:
2230 ** WHERE a = ? AND (b, c, d) > (?, ?, ?)
2234 ** CREATE INDEX ... ON (a, b, c, d, e)
2236 ** then this function would be invoked with nEq=1. The value returned in
2239 static int whereRangeVectorLen(
2240 Parse
*pParse
, /* Parsing context */
2241 int iCur
, /* Cursor open on pIdx */
2242 Index
*pIdx
, /* The index to be used for a inequality constraint */
2243 int nEq
, /* Number of prior equality constraints on same index */
2244 WhereTerm
*pTerm
/* The vector inequality constraint */
2246 int nCmp
= sqlite3ExprVectorSize(pTerm
->pExpr
->pLeft
);
2249 nCmp
= MIN(nCmp
, (pIdx
->nColumn
- nEq
));
2250 for(i
=1; i
<nCmp
; i
++){
2251 /* Test if comparison i of pTerm is compatible with column (i+nEq)
2252 ** of the index. If not, exit the loop. */
2253 char aff
; /* Comparison affinity */
2254 char idxaff
= 0; /* Indexed columns affinity */
2255 CollSeq
*pColl
; /* Comparison collation sequence */
2256 Expr
*pLhs
= pTerm
->pExpr
->pLeft
->x
.pList
->a
[i
].pExpr
;
2257 Expr
*pRhs
= pTerm
->pExpr
->pRight
;
2258 if( pRhs
->flags
& EP_xIsSelect
){
2259 pRhs
= pRhs
->x
.pSelect
->pEList
->a
[i
].pExpr
;
2261 pRhs
= pRhs
->x
.pList
->a
[i
].pExpr
;
2264 /* Check that the LHS of the comparison is a column reference to
2265 ** the right column of the right source table. And that the sort
2266 ** order of the index column is the same as the sort order of the
2267 ** leftmost index column. */
2268 if( pLhs
->op
!=TK_COLUMN
2269 || pLhs
->iTable
!=iCur
2270 || pLhs
->iColumn
!=pIdx
->aiColumn
[i
+nEq
]
2271 || pIdx
->aSortOrder
[i
+nEq
]!=pIdx
->aSortOrder
[nEq
]
2276 testcase( pLhs
->iColumn
==XN_ROWID
);
2277 aff
= sqlite3CompareAffinity(pRhs
, sqlite3ExprAffinity(pLhs
));
2278 idxaff
= sqlite3TableColumnAffinity(pIdx
->pTable
, pLhs
->iColumn
);
2279 if( aff
!=idxaff
) break;
2281 pColl
= sqlite3BinaryCompareCollSeq(pParse
, pLhs
, pRhs
);
2282 if( pColl
==0 ) break;
2283 if( sqlite3StrICmp(pColl
->zName
, pIdx
->azColl
[i
+nEq
]) ) break;
2289 ** Adjust the cost C by the costMult facter T. This only occurs if
2290 ** compiled with -DSQLITE_ENABLE_COSTMULT
2292 #ifdef SQLITE_ENABLE_COSTMULT
2293 # define ApplyCostMultiplier(C,T) C += T
2295 # define ApplyCostMultiplier(C,T)
2299 ** We have so far matched pBuilder->pNew->u.btree.nEq terms of the
2300 ** index pIndex. Try to match one more.
2302 ** When this function is called, pBuilder->pNew->nOut contains the
2303 ** number of rows expected to be visited by filtering using the nEq
2304 ** terms only. If it is modified, this value is restored before this
2305 ** function returns.
2307 ** If pProbe->tnum==0, that means pIndex is a fake index used for the
2308 ** INTEGER PRIMARY KEY.
2310 static int whereLoopAddBtreeIndex(
2311 WhereLoopBuilder
*pBuilder
, /* The WhereLoop factory */
2312 struct SrcList_item
*pSrc
, /* FROM clause term being analyzed */
2313 Index
*pProbe
, /* An index on pSrc */
2314 LogEst nInMul
/* log(Number of iterations due to IN) */
2316 WhereInfo
*pWInfo
= pBuilder
->pWInfo
; /* WHERE analyse context */
2317 Parse
*pParse
= pWInfo
->pParse
; /* Parsing context */
2318 sqlite3
*db
= pParse
->db
; /* Database connection malloc context */
2319 WhereLoop
*pNew
; /* Template WhereLoop under construction */
2320 WhereTerm
*pTerm
; /* A WhereTerm under consideration */
2321 int opMask
; /* Valid operators for constraints */
2322 WhereScan scan
; /* Iterator for WHERE terms */
2323 Bitmask saved_prereq
; /* Original value of pNew->prereq */
2324 u16 saved_nLTerm
; /* Original value of pNew->nLTerm */
2325 u16 saved_nEq
; /* Original value of pNew->u.btree.nEq */
2326 u16 saved_nBtm
; /* Original value of pNew->u.btree.nBtm */
2327 u16 saved_nTop
; /* Original value of pNew->u.btree.nTop */
2328 u16 saved_nSkip
; /* Original value of pNew->nSkip */
2329 u32 saved_wsFlags
; /* Original value of pNew->wsFlags */
2330 LogEst saved_nOut
; /* Original value of pNew->nOut */
2331 int rc
= SQLITE_OK
; /* Return code */
2332 LogEst rSize
; /* Number of rows in the table */
2333 LogEst rLogSize
; /* Logarithm of table size */
2334 WhereTerm
*pTop
= 0, *pBtm
= 0; /* Top and bottom range constraints */
2336 pNew
= pBuilder
->pNew
;
2337 if( db
->mallocFailed
) return SQLITE_NOMEM_BKPT
;
2338 WHERETRACE(0x800, ("BEGIN addBtreeIdx(%s), nEq=%d\n",
2339 pProbe
->zName
, pNew
->u
.btree
.nEq
));
2341 assert( (pNew
->wsFlags
& WHERE_VIRTUALTABLE
)==0 );
2342 assert( (pNew
->wsFlags
& WHERE_TOP_LIMIT
)==0 );
2343 if( pNew
->wsFlags
& WHERE_BTM_LIMIT
){
2344 opMask
= WO_LT
|WO_LE
;
2346 assert( pNew
->u
.btree
.nBtm
==0 );
2347 opMask
= WO_EQ
|WO_IN
|WO_GT
|WO_GE
|WO_LT
|WO_LE
|WO_ISNULL
|WO_IS
;
2349 if( pProbe
->bUnordered
) opMask
&= ~(WO_GT
|WO_GE
|WO_LT
|WO_LE
);
2351 assert( pNew
->u
.btree
.nEq
<pProbe
->nColumn
);
2353 saved_nEq
= pNew
->u
.btree
.nEq
;
2354 saved_nBtm
= pNew
->u
.btree
.nBtm
;
2355 saved_nTop
= pNew
->u
.btree
.nTop
;
2356 saved_nSkip
= pNew
->nSkip
;
2357 saved_nLTerm
= pNew
->nLTerm
;
2358 saved_wsFlags
= pNew
->wsFlags
;
2359 saved_prereq
= pNew
->prereq
;
2360 saved_nOut
= pNew
->nOut
;
2361 pTerm
= whereScanInit(&scan
, pBuilder
->pWC
, pSrc
->iCursor
, saved_nEq
,
2364 rSize
= pProbe
->aiRowLogEst
[0];
2365 rLogSize
= estLog(rSize
);
2366 for(; rc
==SQLITE_OK
&& pTerm
!=0; pTerm
= whereScanNext(&scan
)){
2367 u16 eOp
= pTerm
->eOperator
; /* Shorthand for pTerm->eOperator */
2369 LogEst nOutUnadjusted
; /* nOut before IN() and WHERE adjustments */
2371 #ifdef SQLITE_ENABLE_STAT3_OR_STAT4
2372 int nRecValid
= pBuilder
->nRecValid
;
2374 if( (eOp
==WO_ISNULL
|| (pTerm
->wtFlags
&TERM_VNULL
)!=0)
2375 && indexColumnNotNull(pProbe
, saved_nEq
)
2377 continue; /* ignore IS [NOT] NULL constraints on NOT NULL columns */
2379 if( pTerm
->prereqRight
& pNew
->maskSelf
) continue;
2381 /* Do not allow the upper bound of a LIKE optimization range constraint
2382 ** to mix with a lower range bound from some other source */
2383 if( pTerm
->wtFlags
& TERM_LIKEOPT
&& pTerm
->eOperator
==WO_LT
) continue;
2385 /* Do not allow IS constraints from the WHERE clause to be used by the
2386 ** right table of a LEFT JOIN. Only constraints in the ON clause are
2388 if( (pSrc
->fg
.jointype
& JT_LEFT
)!=0
2389 && !ExprHasProperty(pTerm
->pExpr
, EP_FromJoin
)
2390 && (eOp
& (WO_IS
|WO_ISNULL
))!=0
2392 testcase( eOp
& WO_IS
);
2393 testcase( eOp
& WO_ISNULL
);
2397 if( IsUniqueIndex(pProbe
) && saved_nEq
==pProbe
->nKeyCol
-1 ){
2398 pBuilder
->bldFlags
|= SQLITE_BLDF_UNIQUE
;
2400 pBuilder
->bldFlags
|= SQLITE_BLDF_INDEXED
;
2402 pNew
->wsFlags
= saved_wsFlags
;
2403 pNew
->u
.btree
.nEq
= saved_nEq
;
2404 pNew
->u
.btree
.nBtm
= saved_nBtm
;
2405 pNew
->u
.btree
.nTop
= saved_nTop
;
2406 pNew
->nLTerm
= saved_nLTerm
;
2407 if( whereLoopResize(db
, pNew
, pNew
->nLTerm
+1) ) break; /* OOM */
2408 pNew
->aLTerm
[pNew
->nLTerm
++] = pTerm
;
2409 pNew
->prereq
= (saved_prereq
| pTerm
->prereqRight
) & ~pNew
->maskSelf
;
2412 || (pNew
->wsFlags
& WHERE_COLUMN_NULL
)!=0
2413 || (pNew
->wsFlags
& WHERE_COLUMN_IN
)!=0
2414 || (pNew
->wsFlags
& WHERE_SKIPSCAN
)!=0
2418 Expr
*pExpr
= pTerm
->pExpr
;
2419 pNew
->wsFlags
|= WHERE_COLUMN_IN
;
2420 if( ExprHasProperty(pExpr
, EP_xIsSelect
) ){
2421 /* "x IN (SELECT ...)": TUNING: the SELECT returns 25 rows */
2423 nIn
= 46; assert( 46==sqlite3LogEst(25) );
2425 /* The expression may actually be of the form (x, y) IN (SELECT...).
2426 ** In this case there is a separate term for each of (x) and (y).
2427 ** However, the nIn multiplier should only be applied once, not once
2428 ** for each such term. The following loop checks that pTerm is the
2429 ** first such term in use, and sets nIn back to 0 if it is not. */
2430 for(i
=0; i
<pNew
->nLTerm
-1; i
++){
2431 if( pNew
->aLTerm
[i
] && pNew
->aLTerm
[i
]->pExpr
==pExpr
) nIn
= 0;
2433 }else if( ALWAYS(pExpr
->x
.pList
&& pExpr
->x
.pList
->nExpr
) ){
2434 /* "x IN (value, value, ...)" */
2435 nIn
= sqlite3LogEst(pExpr
->x
.pList
->nExpr
);
2436 assert( nIn
>0 ); /* RHS always has 2 or more terms... The parser
2437 ** changes "x IN (?)" into "x=?". */
2439 }else if( eOp
& (WO_EQ
|WO_IS
) ){
2440 int iCol
= pProbe
->aiColumn
[saved_nEq
];
2441 pNew
->wsFlags
|= WHERE_COLUMN_EQ
;
2442 assert( saved_nEq
==pNew
->u
.btree
.nEq
);
2444 || (iCol
>0 && nInMul
==0 && saved_nEq
==pProbe
->nKeyCol
-1)
2446 if( iCol
>=0 && pProbe
->uniqNotNull
==0 ){
2447 pNew
->wsFlags
|= WHERE_UNQ_WANTED
;
2449 pNew
->wsFlags
|= WHERE_ONEROW
;
2452 }else if( eOp
& WO_ISNULL
){
2453 pNew
->wsFlags
|= WHERE_COLUMN_NULL
;
2454 }else if( eOp
& (WO_GT
|WO_GE
) ){
2455 testcase( eOp
& WO_GT
);
2456 testcase( eOp
& WO_GE
);
2457 pNew
->wsFlags
|= WHERE_COLUMN_RANGE
|WHERE_BTM_LIMIT
;
2458 pNew
->u
.btree
.nBtm
= whereRangeVectorLen(
2459 pParse
, pSrc
->iCursor
, pProbe
, saved_nEq
, pTerm
2463 if( pTerm
->wtFlags
& TERM_LIKEOPT
){
2464 /* Range contraints that come from the LIKE optimization are
2465 ** always used in pairs. */
2467 assert( (pTop
-(pTerm
->pWC
->a
))<pTerm
->pWC
->nTerm
);
2468 assert( pTop
->wtFlags
& TERM_LIKEOPT
);
2469 assert( pTop
->eOperator
==WO_LT
);
2470 if( whereLoopResize(db
, pNew
, pNew
->nLTerm
+1) ) break; /* OOM */
2471 pNew
->aLTerm
[pNew
->nLTerm
++] = pTop
;
2472 pNew
->wsFlags
|= WHERE_TOP_LIMIT
;
2473 pNew
->u
.btree
.nTop
= 1;
2476 assert( eOp
& (WO_LT
|WO_LE
) );
2477 testcase( eOp
& WO_LT
);
2478 testcase( eOp
& WO_LE
);
2479 pNew
->wsFlags
|= WHERE_COLUMN_RANGE
|WHERE_TOP_LIMIT
;
2480 pNew
->u
.btree
.nTop
= whereRangeVectorLen(
2481 pParse
, pSrc
->iCursor
, pProbe
, saved_nEq
, pTerm
2484 pBtm
= (pNew
->wsFlags
& WHERE_BTM_LIMIT
)!=0 ?
2485 pNew
->aLTerm
[pNew
->nLTerm
-2] : 0;
2488 /* At this point pNew->nOut is set to the number of rows expected to
2489 ** be visited by the index scan before considering term pTerm, or the
2490 ** values of nIn and nInMul. In other words, assuming that all
2491 ** "x IN(...)" terms are replaced with "x = ?". This block updates
2492 ** the value of pNew->nOut to account for pTerm (but not nIn/nInMul). */
2493 assert( pNew
->nOut
==saved_nOut
);
2494 if( pNew
->wsFlags
& WHERE_COLUMN_RANGE
){
2495 /* Adjust nOut using stat3/stat4 data. Or, if there is no stat3/stat4
2496 ** data, using some other estimate. */
2497 whereRangeScanEst(pParse
, pBuilder
, pBtm
, pTop
, pNew
);
2499 int nEq
= ++pNew
->u
.btree
.nEq
;
2500 assert( eOp
& (WO_ISNULL
|WO_EQ
|WO_IN
|WO_IS
) );
2502 assert( pNew
->nOut
==saved_nOut
);
2503 if( pTerm
->truthProb
<=0 && pProbe
->aiColumn
[saved_nEq
]>=0 ){
2504 assert( (eOp
& WO_IN
) || nIn
==0 );
2505 testcase( eOp
& WO_IN
);
2506 pNew
->nOut
+= pTerm
->truthProb
;
2509 #ifdef SQLITE_ENABLE_STAT3_OR_STAT4
2513 && pNew
->u
.btree
.nEq
<=pProbe
->nSampleCol
2514 && ((eOp
& WO_IN
)==0 || !ExprHasProperty(pTerm
->pExpr
, EP_xIsSelect
))
2516 Expr
*pExpr
= pTerm
->pExpr
;
2517 if( (eOp
& (WO_EQ
|WO_ISNULL
|WO_IS
))!=0 ){
2518 testcase( eOp
& WO_EQ
);
2519 testcase( eOp
& WO_IS
);
2520 testcase( eOp
& WO_ISNULL
);
2521 rc
= whereEqualScanEst(pParse
, pBuilder
, pExpr
->pRight
, &nOut
);
2523 rc
= whereInScanEst(pParse
, pBuilder
, pExpr
->x
.pList
, &nOut
);
2525 if( rc
==SQLITE_NOTFOUND
) rc
= SQLITE_OK
;
2526 if( rc
!=SQLITE_OK
) break; /* Jump out of the pTerm loop */
2528 pNew
->nOut
= sqlite3LogEst(nOut
);
2529 if( pNew
->nOut
>saved_nOut
) pNew
->nOut
= saved_nOut
;
2536 pNew
->nOut
+= (pProbe
->aiRowLogEst
[nEq
] - pProbe
->aiRowLogEst
[nEq
-1]);
2537 if( eOp
& WO_ISNULL
){
2538 /* TUNING: If there is no likelihood() value, assume that a
2539 ** "col IS NULL" expression matches twice as many rows
2547 /* Set rCostIdx to the cost of visiting selected rows in index. Add
2548 ** it to pNew->rRun, which is currently set to the cost of the index
2549 ** seek only. Then, if this is a non-covering index, add the cost of
2550 ** visiting the rows in the main table. */
2551 rCostIdx
= pNew
->nOut
+ 1 + (15*pProbe
->szIdxRow
)/pSrc
->pTab
->szTabRow
;
2552 pNew
->rRun
= sqlite3LogEstAdd(rLogSize
, rCostIdx
);
2553 if( (pNew
->wsFlags
& (WHERE_IDX_ONLY
|WHERE_IPK
))==0 ){
2554 pNew
->rRun
= sqlite3LogEstAdd(pNew
->rRun
, pNew
->nOut
+ 16);
2556 ApplyCostMultiplier(pNew
->rRun
, pProbe
->pTable
->costMult
);
2558 nOutUnadjusted
= pNew
->nOut
;
2559 pNew
->rRun
+= nInMul
+ nIn
;
2560 pNew
->nOut
+= nInMul
+ nIn
;
2561 whereLoopOutputAdjust(pBuilder
->pWC
, pNew
, rSize
);
2562 rc
= whereLoopInsert(pBuilder
, pNew
);
2564 if( pNew
->wsFlags
& WHERE_COLUMN_RANGE
){
2565 pNew
->nOut
= saved_nOut
;
2567 pNew
->nOut
= nOutUnadjusted
;
2570 if( (pNew
->wsFlags
& WHERE_TOP_LIMIT
)==0
2571 && pNew
->u
.btree
.nEq
<pProbe
->nColumn
2573 whereLoopAddBtreeIndex(pBuilder
, pSrc
, pProbe
, nInMul
+nIn
);
2575 pNew
->nOut
= saved_nOut
;
2576 #ifdef SQLITE_ENABLE_STAT3_OR_STAT4
2577 pBuilder
->nRecValid
= nRecValid
;
2580 pNew
->prereq
= saved_prereq
;
2581 pNew
->u
.btree
.nEq
= saved_nEq
;
2582 pNew
->u
.btree
.nBtm
= saved_nBtm
;
2583 pNew
->u
.btree
.nTop
= saved_nTop
;
2584 pNew
->nSkip
= saved_nSkip
;
2585 pNew
->wsFlags
= saved_wsFlags
;
2586 pNew
->nOut
= saved_nOut
;
2587 pNew
->nLTerm
= saved_nLTerm
;
2589 /* Consider using a skip-scan if there are no WHERE clause constraints
2590 ** available for the left-most terms of the index, and if the average
2591 ** number of repeats in the left-most terms is at least 18.
2593 ** The magic number 18 is selected on the basis that scanning 17 rows
2594 ** is almost always quicker than an index seek (even though if the index
2595 ** contains fewer than 2^17 rows we assume otherwise in other parts of
2596 ** the code). And, even if it is not, it should not be too much slower.
2597 ** On the other hand, the extra seeks could end up being significantly
2598 ** more expensive. */
2599 assert( 42==sqlite3LogEst(18) );
2600 if( saved_nEq
==saved_nSkip
2601 && saved_nEq
+1<pProbe
->nKeyCol
2602 && pProbe
->noSkipScan
==0
2603 && pProbe
->aiRowLogEst
[saved_nEq
+1]>=42 /* TUNING: Minimum for skip-scan */
2604 && (rc
= whereLoopResize(db
, pNew
, pNew
->nLTerm
+1))==SQLITE_OK
2607 pNew
->u
.btree
.nEq
++;
2609 pNew
->aLTerm
[pNew
->nLTerm
++] = 0;
2610 pNew
->wsFlags
|= WHERE_SKIPSCAN
;
2611 nIter
= pProbe
->aiRowLogEst
[saved_nEq
] - pProbe
->aiRowLogEst
[saved_nEq
+1];
2612 pNew
->nOut
-= nIter
;
2613 /* TUNING: Because uncertainties in the estimates for skip-scan queries,
2614 ** add a 1.375 fudge factor to make skip-scan slightly less likely. */
2616 whereLoopAddBtreeIndex(pBuilder
, pSrc
, pProbe
, nIter
+ nInMul
);
2617 pNew
->nOut
= saved_nOut
;
2618 pNew
->u
.btree
.nEq
= saved_nEq
;
2619 pNew
->nSkip
= saved_nSkip
;
2620 pNew
->wsFlags
= saved_wsFlags
;
2623 WHERETRACE(0x800, ("END addBtreeIdx(%s), nEq=%d, rc=%d\n",
2624 pProbe
->zName
, saved_nEq
, rc
));
2629 ** Return True if it is possible that pIndex might be useful in
2630 ** implementing the ORDER BY clause in pBuilder.
2632 ** Return False if pBuilder does not contain an ORDER BY clause or
2633 ** if there is no way for pIndex to be useful in implementing that
2636 static int indexMightHelpWithOrderBy(
2637 WhereLoopBuilder
*pBuilder
,
2645 if( pIndex
->bUnordered
) return 0;
2646 if( (pOB
= pBuilder
->pWInfo
->pOrderBy
)==0 ) return 0;
2647 for(ii
=0; ii
<pOB
->nExpr
; ii
++){
2648 Expr
*pExpr
= sqlite3ExprSkipCollate(pOB
->a
[ii
].pExpr
);
2649 if( pExpr
->op
==TK_COLUMN
&& pExpr
->iTable
==iCursor
){
2650 if( pExpr
->iColumn
<0 ) return 1;
2651 for(jj
=0; jj
<pIndex
->nKeyCol
; jj
++){
2652 if( pExpr
->iColumn
==pIndex
->aiColumn
[jj
] ) return 1;
2654 }else if( (aColExpr
= pIndex
->aColExpr
)!=0 ){
2655 for(jj
=0; jj
<pIndex
->nKeyCol
; jj
++){
2656 if( pIndex
->aiColumn
[jj
]!=XN_EXPR
) continue;
2657 if( sqlite3ExprCompare(0, pExpr
,aColExpr
->a
[jj
].pExpr
,iCursor
)==0 ){
2667 ** Return a bitmask where 1s indicate that the corresponding column of
2668 ** the table is used by an index. Only the first 63 columns are considered.
2670 static Bitmask
columnsInIndex(Index
*pIdx
){
2673 for(j
=pIdx
->nColumn
-1; j
>=0; j
--){
2674 int x
= pIdx
->aiColumn
[j
];
2676 testcase( x
==BMS
-1 );
2677 testcase( x
==BMS
-2 );
2678 if( x
<BMS
-1 ) m
|= MASKBIT(x
);
2684 /* Check to see if a partial index with pPartIndexWhere can be used
2685 ** in the current query. Return true if it can be and false if not.
2687 static int whereUsablePartialIndex(int iTab
, WhereClause
*pWC
, Expr
*pWhere
){
2690 Parse
*pParse
= pWC
->pWInfo
->pParse
;
2691 while( pWhere
->op
==TK_AND
){
2692 if( !whereUsablePartialIndex(iTab
,pWC
,pWhere
->pLeft
) ) return 0;
2693 pWhere
= pWhere
->pRight
;
2695 if( pParse
->db
->flags
& SQLITE_EnableQPSG
) pParse
= 0;
2696 for(i
=0, pTerm
=pWC
->a
; i
<pWC
->nTerm
; i
++, pTerm
++){
2697 Expr
*pExpr
= pTerm
->pExpr
;
2698 if( (!ExprHasProperty(pExpr
, EP_FromJoin
) || pExpr
->iRightJoinTable
==iTab
)
2699 && sqlite3ExprImpliesExpr(pParse
, pExpr
, pWhere
, iTab
)
2708 ** Add all WhereLoop objects for a single table of the join where the table
2709 ** is identified by pBuilder->pNew->iTab. That table is guaranteed to be
2710 ** a b-tree table, not a virtual table.
2712 ** The costs (WhereLoop.rRun) of the b-tree loops added by this function
2713 ** are calculated as follows:
2715 ** For a full scan, assuming the table (or index) contains nRow rows:
2717 ** cost = nRow * 3.0 // full-table scan
2718 ** cost = nRow * K // scan of covering index
2719 ** cost = nRow * (K+3.0) // scan of non-covering index
2721 ** where K is a value between 1.1 and 3.0 set based on the relative
2722 ** estimated average size of the index and table records.
2724 ** For an index scan, where nVisit is the number of index rows visited
2725 ** by the scan, and nSeek is the number of seek operations required on
2726 ** the index b-tree:
2728 ** cost = nSeek * (log(nRow) + K * nVisit) // covering index
2729 ** cost = nSeek * (log(nRow) + (K+3.0) * nVisit) // non-covering index
2731 ** Normally, nSeek is 1. nSeek values greater than 1 come about if the
2732 ** WHERE clause includes "x IN (....)" terms used in place of "x=?". Or when
2733 ** implicit "x IN (SELECT x FROM tbl)" terms are added for skip-scans.
2735 ** The estimated values (nRow, nVisit, nSeek) often contain a large amount
2736 ** of uncertainty. For this reason, scoring is designed to pick plans that
2737 ** "do the least harm" if the estimates are inaccurate. For example, a
2738 ** log(nRow) factor is omitted from a non-covering index scan in order to
2739 ** bias the scoring in favor of using an index, since the worst-case
2740 ** performance of using an index is far better than the worst-case performance
2741 ** of a full table scan.
2743 static int whereLoopAddBtree(
2744 WhereLoopBuilder
*pBuilder
, /* WHERE clause information */
2745 Bitmask mPrereq
/* Extra prerequesites for using this table */
2747 WhereInfo
*pWInfo
; /* WHERE analysis context */
2748 Index
*pProbe
; /* An index we are evaluating */
2749 Index sPk
; /* A fake index object for the primary key */
2750 LogEst aiRowEstPk
[2]; /* The aiRowLogEst[] value for the sPk index */
2751 i16 aiColumnPk
= -1; /* The aColumn[] value for the sPk index */
2752 SrcList
*pTabList
; /* The FROM clause */
2753 struct SrcList_item
*pSrc
; /* The FROM clause btree term to add */
2754 WhereLoop
*pNew
; /* Template WhereLoop object */
2755 int rc
= SQLITE_OK
; /* Return code */
2756 int iSortIdx
= 1; /* Index number */
2757 int b
; /* A boolean value */
2758 LogEst rSize
; /* number of rows in the table */
2759 LogEst rLogSize
; /* Logarithm of the number of rows in the table */
2760 WhereClause
*pWC
; /* The parsed WHERE clause */
2761 Table
*pTab
; /* Table being queried */
2763 pNew
= pBuilder
->pNew
;
2764 pWInfo
= pBuilder
->pWInfo
;
2765 pTabList
= pWInfo
->pTabList
;
2766 pSrc
= pTabList
->a
+ pNew
->iTab
;
2768 pWC
= pBuilder
->pWC
;
2769 assert( !IsVirtual(pSrc
->pTab
) );
2771 if( pSrc
->pIBIndex
){
2772 /* An INDEXED BY clause specifies a particular index to use */
2773 pProbe
= pSrc
->pIBIndex
;
2774 }else if( !HasRowid(pTab
) ){
2775 pProbe
= pTab
->pIndex
;
2777 /* There is no INDEXED BY clause. Create a fake Index object in local
2778 ** variable sPk to represent the rowid primary key index. Make this
2779 ** fake index the first in a chain of Index objects with all of the real
2780 ** indices to follow */
2781 Index
*pFirst
; /* First of real indices on the table */
2782 memset(&sPk
, 0, sizeof(Index
));
2785 sPk
.aiColumn
= &aiColumnPk
;
2786 sPk
.aiRowLogEst
= aiRowEstPk
;
2787 sPk
.onError
= OE_Replace
;
2789 sPk
.szIdxRow
= pTab
->szTabRow
;
2790 aiRowEstPk
[0] = pTab
->nRowLogEst
;
2792 pFirst
= pSrc
->pTab
->pIndex
;
2793 if( pSrc
->fg
.notIndexed
==0 ){
2794 /* The real indices of the table are only considered if the
2795 ** NOT INDEXED qualifier is omitted from the FROM clause */
2800 rSize
= pTab
->nRowLogEst
;
2801 rLogSize
= estLog(rSize
);
2803 #ifndef SQLITE_OMIT_AUTOMATIC_INDEX
2804 /* Automatic indexes */
2805 if( !pBuilder
->pOrSet
/* Not part of an OR optimization */
2806 && (pWInfo
->wctrlFlags
& WHERE_OR_SUBCLAUSE
)==0
2807 && (pWInfo
->pParse
->db
->flags
& SQLITE_AutoIndex
)!=0
2808 && pSrc
->pIBIndex
==0 /* Has no INDEXED BY clause */
2809 && !pSrc
->fg
.notIndexed
/* Has no NOT INDEXED clause */
2810 && HasRowid(pTab
) /* Not WITHOUT ROWID table. (FIXME: Why not?) */
2811 && !pSrc
->fg
.isCorrelated
/* Not a correlated subquery */
2812 && !pSrc
->fg
.isRecursive
/* Not a recursive common table expression. */
2814 /* Generate auto-index WhereLoops */
2816 WhereTerm
*pWCEnd
= pWC
->a
+ pWC
->nTerm
;
2817 for(pTerm
=pWC
->a
; rc
==SQLITE_OK
&& pTerm
<pWCEnd
; pTerm
++){
2818 if( pTerm
->prereqRight
& pNew
->maskSelf
) continue;
2819 if( termCanDriveIndex(pTerm
, pSrc
, 0) ){
2820 pNew
->u
.btree
.nEq
= 1;
2822 pNew
->u
.btree
.pIndex
= 0;
2824 pNew
->aLTerm
[0] = pTerm
;
2825 /* TUNING: One-time cost for computing the automatic index is
2826 ** estimated to be X*N*log2(N) where N is the number of rows in
2827 ** the table being indexed and where X is 7 (LogEst=28) for normal
2828 ** tables or 1.375 (LogEst=4) for views and subqueries. The value
2829 ** of X is smaller for views and subqueries so that the query planner
2830 ** will be more aggressive about generating automatic indexes for
2831 ** those objects, since there is no opportunity to add schema
2832 ** indexes on subqueries and views. */
2833 pNew
->rSetup
= rLogSize
+ rSize
+ 4;
2834 if( pTab
->pSelect
==0 && (pTab
->tabFlags
& TF_Ephemeral
)==0 ){
2837 ApplyCostMultiplier(pNew
->rSetup
, pTab
->costMult
);
2838 if( pNew
->rSetup
<0 ) pNew
->rSetup
= 0;
2839 /* TUNING: Each index lookup yields 20 rows in the table. This
2840 ** is more than the usual guess of 10 rows, since we have no way
2841 ** of knowing how selective the index will ultimately be. It would
2842 ** not be unreasonable to make this value much larger. */
2843 pNew
->nOut
= 43; assert( 43==sqlite3LogEst(20) );
2844 pNew
->rRun
= sqlite3LogEstAdd(rLogSize
,pNew
->nOut
);
2845 pNew
->wsFlags
= WHERE_AUTO_INDEX
;
2846 pNew
->prereq
= mPrereq
| pTerm
->prereqRight
;
2847 rc
= whereLoopInsert(pBuilder
, pNew
);
2851 #endif /* SQLITE_OMIT_AUTOMATIC_INDEX */
2853 /* Loop over all indices
2855 for(; rc
==SQLITE_OK
&& pProbe
; pProbe
=pProbe
->pNext
, iSortIdx
++){
2856 if( pProbe
->pPartIdxWhere
!=0
2857 && !whereUsablePartialIndex(pSrc
->iCursor
, pWC
, pProbe
->pPartIdxWhere
) ){
2858 testcase( pNew
->iTab
!=pSrc
->iCursor
); /* See ticket [98d973b8f5] */
2859 continue; /* Partial index inappropriate for this query */
2861 rSize
= pProbe
->aiRowLogEst
[0];
2862 pNew
->u
.btree
.nEq
= 0;
2863 pNew
->u
.btree
.nBtm
= 0;
2864 pNew
->u
.btree
.nTop
= 0;
2869 pNew
->prereq
= mPrereq
;
2871 pNew
->u
.btree
.pIndex
= pProbe
;
2872 b
= indexMightHelpWithOrderBy(pBuilder
, pProbe
, pSrc
->iCursor
);
2873 /* The ONEPASS_DESIRED flags never occurs together with ORDER BY */
2874 assert( (pWInfo
->wctrlFlags
& WHERE_ONEPASS_DESIRED
)==0 || b
==0 );
2875 if( pProbe
->tnum
<=0 ){
2876 /* Integer primary key index */
2877 pNew
->wsFlags
= WHERE_IPK
;
2879 /* Full table scan */
2880 pNew
->iSortIdx
= b
? iSortIdx
: 0;
2881 /* TUNING: Cost of full table scan is (N*3.0). */
2882 pNew
->rRun
= rSize
+ 16;
2883 ApplyCostMultiplier(pNew
->rRun
, pTab
->costMult
);
2884 whereLoopOutputAdjust(pWC
, pNew
, rSize
);
2885 rc
= whereLoopInsert(pBuilder
, pNew
);
2890 if( pProbe
->isCovering
){
2891 pNew
->wsFlags
= WHERE_IDX_ONLY
| WHERE_INDEXED
;
2894 m
= pSrc
->colUsed
& ~columnsInIndex(pProbe
);
2895 pNew
->wsFlags
= (m
==0) ? (WHERE_IDX_ONLY
|WHERE_INDEXED
) : WHERE_INDEXED
;
2898 /* Full scan via index */
2901 || pProbe
->pPartIdxWhere
!=0
2903 && pProbe
->bUnordered
==0
2904 && (pProbe
->szIdxRow
<pTab
->szTabRow
)
2905 && (pWInfo
->wctrlFlags
& WHERE_ONEPASS_DESIRED
)==0
2906 && sqlite3GlobalConfig
.bUseCis
2907 && OptimizationEnabled(pWInfo
->pParse
->db
, SQLITE_CoverIdxScan
)
2910 pNew
->iSortIdx
= b
? iSortIdx
: 0;
2912 /* The cost of visiting the index rows is N*K, where K is
2913 ** between 1.1 and 3.0, depending on the relative sizes of the
2914 ** index and table rows. */
2915 pNew
->rRun
= rSize
+ 1 + (15*pProbe
->szIdxRow
)/pTab
->szTabRow
;
2917 /* If this is a non-covering index scan, add in the cost of
2918 ** doing table lookups. The cost will be 3x the number of
2919 ** lookups. Take into account WHERE clause terms that can be
2920 ** satisfied using just the index, and that do not require a
2922 LogEst nLookup
= rSize
+ 16; /* Base cost: N*3 */
2924 int iCur
= pSrc
->iCursor
;
2925 WhereClause
*pWC2
= &pWInfo
->sWC
;
2926 for(ii
=0; ii
<pWC2
->nTerm
; ii
++){
2927 WhereTerm
*pTerm
= &pWC2
->a
[ii
];
2928 if( !sqlite3ExprCoveredByIndex(pTerm
->pExpr
, iCur
, pProbe
) ){
2931 /* pTerm can be evaluated using just the index. So reduce
2932 ** the expected number of table lookups accordingly */
2933 if( pTerm
->truthProb
<=0 ){
2934 nLookup
+= pTerm
->truthProb
;
2937 if( pTerm
->eOperator
& (WO_EQ
|WO_IS
) ) nLookup
-= 19;
2941 pNew
->rRun
= sqlite3LogEstAdd(pNew
->rRun
, nLookup
);
2943 ApplyCostMultiplier(pNew
->rRun
, pTab
->costMult
);
2944 whereLoopOutputAdjust(pWC
, pNew
, rSize
);
2945 rc
= whereLoopInsert(pBuilder
, pNew
);
2951 pBuilder
->bldFlags
= 0;
2952 rc
= whereLoopAddBtreeIndex(pBuilder
, pSrc
, pProbe
, 0);
2953 if( pBuilder
->bldFlags
==SQLITE_BLDF_INDEXED
){
2954 /* If a non-unique index is used, or if a prefix of the key for
2955 ** unique index is used (making the index functionally non-unique)
2956 ** then the sqlite_stat1 data becomes important for scoring the
2958 pTab
->tabFlags
|= TF_StatsUsed
;
2960 #ifdef SQLITE_ENABLE_STAT3_OR_STAT4
2961 sqlite3Stat4ProbeFree(pBuilder
->pRec
);
2962 pBuilder
->nRecValid
= 0;
2966 /* If there was an INDEXED BY clause, then only that one index is
2968 if( pSrc
->pIBIndex
) break;
2973 #ifndef SQLITE_OMIT_VIRTUALTABLE
2976 ** Argument pIdxInfo is already populated with all constraints that may
2977 ** be used by the virtual table identified by pBuilder->pNew->iTab. This
2978 ** function marks a subset of those constraints usable, invokes the
2979 ** xBestIndex method and adds the returned plan to pBuilder.
2981 ** A constraint is marked usable if:
2983 ** * Argument mUsable indicates that its prerequisites are available, and
2985 ** * It is not one of the operators specified in the mExclude mask passed
2986 ** as the fourth argument (which in practice is either WO_IN or 0).
2988 ** Argument mPrereq is a mask of tables that must be scanned before the
2989 ** virtual table in question. These are added to the plans prerequisites
2990 ** before it is added to pBuilder.
2992 ** Output parameter *pbIn is set to true if the plan added to pBuilder
2993 ** uses one or more WO_IN terms, or false otherwise.
2995 static int whereLoopAddVirtualOne(
2996 WhereLoopBuilder
*pBuilder
,
2997 Bitmask mPrereq
, /* Mask of tables that must be used. */
2998 Bitmask mUsable
, /* Mask of usable tables */
2999 u16 mExclude
, /* Exclude terms using these operators */
3000 sqlite3_index_info
*pIdxInfo
, /* Populated object for xBestIndex */
3001 u16 mNoOmit
, /* Do not omit these constraints */
3002 int *pbIn
/* OUT: True if plan uses an IN(...) op */
3004 WhereClause
*pWC
= pBuilder
->pWC
;
3005 struct sqlite3_index_constraint
*pIdxCons
;
3006 struct sqlite3_index_constraint_usage
*pUsage
= pIdxInfo
->aConstraintUsage
;
3010 WhereLoop
*pNew
= pBuilder
->pNew
;
3011 Parse
*pParse
= pBuilder
->pWInfo
->pParse
;
3012 struct SrcList_item
*pSrc
= &pBuilder
->pWInfo
->pTabList
->a
[pNew
->iTab
];
3013 int nConstraint
= pIdxInfo
->nConstraint
;
3015 assert( (mUsable
& mPrereq
)==mPrereq
);
3017 pNew
->prereq
= mPrereq
;
3019 /* Set the usable flag on the subset of constraints identified by
3020 ** arguments mUsable and mExclude. */
3021 pIdxCons
= *(struct sqlite3_index_constraint
**)&pIdxInfo
->aConstraint
;
3022 for(i
=0; i
<nConstraint
; i
++, pIdxCons
++){
3023 WhereTerm
*pTerm
= &pWC
->a
[pIdxCons
->iTermOffset
];
3024 pIdxCons
->usable
= 0;
3025 if( (pTerm
->prereqRight
& mUsable
)==pTerm
->prereqRight
3026 && (pTerm
->eOperator
& mExclude
)==0
3028 pIdxCons
->usable
= 1;
3032 /* Initialize the output fields of the sqlite3_index_info structure */
3033 memset(pUsage
, 0, sizeof(pUsage
[0])*nConstraint
);
3034 assert( pIdxInfo
->needToFreeIdxStr
==0 );
3035 pIdxInfo
->idxStr
= 0;
3036 pIdxInfo
->idxNum
= 0;
3037 pIdxInfo
->orderByConsumed
= 0;
3038 pIdxInfo
->estimatedCost
= SQLITE_BIG_DBL
/ (double)2;
3039 pIdxInfo
->estimatedRows
= 25;
3040 pIdxInfo
->idxFlags
= 0;
3041 pIdxInfo
->colUsed
= (sqlite3_int64
)pSrc
->colUsed
;
3043 /* Invoke the virtual table xBestIndex() method */
3044 rc
= vtabBestIndex(pParse
, pSrc
->pTab
, pIdxInfo
);
3048 assert( pNew
->nLSlot
>=nConstraint
);
3049 for(i
=0; i
<nConstraint
; i
++) pNew
->aLTerm
[i
] = 0;
3050 pNew
->u
.vtab
.omitMask
= 0;
3051 pIdxCons
= *(struct sqlite3_index_constraint
**)&pIdxInfo
->aConstraint
;
3052 for(i
=0; i
<nConstraint
; i
++, pIdxCons
++){
3054 if( (iTerm
= pUsage
[i
].argvIndex
- 1)>=0 ){
3056 int j
= pIdxCons
->iTermOffset
;
3057 if( iTerm
>=nConstraint
3060 || pNew
->aLTerm
[iTerm
]!=0
3061 || pIdxCons
->usable
==0
3064 sqlite3ErrorMsg(pParse
,"%s.xBestIndex malfunction",pSrc
->pTab
->zName
);
3067 testcase( iTerm
==nConstraint
-1 );
3069 testcase( j
==pWC
->nTerm
-1 );
3071 pNew
->prereq
|= pTerm
->prereqRight
;
3072 assert( iTerm
<pNew
->nLSlot
);
3073 pNew
->aLTerm
[iTerm
] = pTerm
;
3074 if( iTerm
>mxTerm
) mxTerm
= iTerm
;
3075 testcase( iTerm
==15 );
3076 testcase( iTerm
==16 );
3077 if( iTerm
<16 && pUsage
[i
].omit
) pNew
->u
.vtab
.omitMask
|= 1<<iTerm
;
3078 if( (pTerm
->eOperator
& WO_IN
)!=0 ){
3079 /* A virtual table that is constrained by an IN clause may not
3080 ** consume the ORDER BY clause because (1) the order of IN terms
3081 ** is not necessarily related to the order of output terms and
3082 ** (2) Multiple outputs from a single IN value will not merge
3084 pIdxInfo
->orderByConsumed
= 0;
3085 pIdxInfo
->idxFlags
&= ~SQLITE_INDEX_SCAN_UNIQUE
;
3086 *pbIn
= 1; assert( (mExclude
& WO_IN
)==0 );
3090 pNew
->u
.vtab
.omitMask
&= ~mNoOmit
;
3092 pNew
->nLTerm
= mxTerm
+1;
3093 assert( pNew
->nLTerm
<=pNew
->nLSlot
);
3094 pNew
->u
.vtab
.idxNum
= pIdxInfo
->idxNum
;
3095 pNew
->u
.vtab
.needFree
= pIdxInfo
->needToFreeIdxStr
;
3096 pIdxInfo
->needToFreeIdxStr
= 0;
3097 pNew
->u
.vtab
.idxStr
= pIdxInfo
->idxStr
;
3098 pNew
->u
.vtab
.isOrdered
= (i8
)(pIdxInfo
->orderByConsumed
?
3099 pIdxInfo
->nOrderBy
: 0);
3101 pNew
->rRun
= sqlite3LogEstFromDouble(pIdxInfo
->estimatedCost
);
3102 pNew
->nOut
= sqlite3LogEst(pIdxInfo
->estimatedRows
);
3104 /* Set the WHERE_ONEROW flag if the xBestIndex() method indicated
3105 ** that the scan will visit at most one row. Clear it otherwise. */
3106 if( pIdxInfo
->idxFlags
& SQLITE_INDEX_SCAN_UNIQUE
){
3107 pNew
->wsFlags
|= WHERE_ONEROW
;
3109 pNew
->wsFlags
&= ~WHERE_ONEROW
;
3111 rc
= whereLoopInsert(pBuilder
, pNew
);
3112 if( pNew
->u
.vtab
.needFree
){
3113 sqlite3_free(pNew
->u
.vtab
.idxStr
);
3114 pNew
->u
.vtab
.needFree
= 0;
3116 WHERETRACE(0xffff, (" bIn=%d prereqIn=%04llx prereqOut=%04llx\n",
3117 *pbIn
, (sqlite3_uint64
)mPrereq
,
3118 (sqlite3_uint64
)(pNew
->prereq
& ~mPrereq
)));
3125 ** Add all WhereLoop objects for a table of the join identified by
3126 ** pBuilder->pNew->iTab. That table is guaranteed to be a virtual table.
3128 ** If there are no LEFT or CROSS JOIN joins in the query, both mPrereq and
3129 ** mUnusable are set to 0. Otherwise, mPrereq is a mask of all FROM clause
3130 ** entries that occur before the virtual table in the FROM clause and are
3131 ** separated from it by at least one LEFT or CROSS JOIN. Similarly, the
3132 ** mUnusable mask contains all FROM clause entries that occur after the
3133 ** virtual table and are separated from it by at least one LEFT or
3136 ** For example, if the query were:
3138 ** ... FROM t1, t2 LEFT JOIN t3, t4, vt CROSS JOIN t5, t6;
3140 ** then mPrereq corresponds to (t1, t2) and mUnusable to (t5, t6).
3142 ** All the tables in mPrereq must be scanned before the current virtual
3143 ** table. So any terms for which all prerequisites are satisfied by
3144 ** mPrereq may be specified as "usable" in all calls to xBestIndex.
3145 ** Conversely, all tables in mUnusable must be scanned after the current
3146 ** virtual table, so any terms for which the prerequisites overlap with
3147 ** mUnusable should always be configured as "not-usable" for xBestIndex.
3149 static int whereLoopAddVirtual(
3150 WhereLoopBuilder
*pBuilder
, /* WHERE clause information */
3151 Bitmask mPrereq
, /* Tables that must be scanned before this one */
3152 Bitmask mUnusable
/* Tables that must be scanned after this one */
3154 int rc
= SQLITE_OK
; /* Return code */
3155 WhereInfo
*pWInfo
; /* WHERE analysis context */
3156 Parse
*pParse
; /* The parsing context */
3157 WhereClause
*pWC
; /* The WHERE clause */
3158 struct SrcList_item
*pSrc
; /* The FROM clause term to search */
3159 sqlite3_index_info
*p
; /* Object to pass to xBestIndex() */
3160 int nConstraint
; /* Number of constraints in p */
3161 int bIn
; /* True if plan uses IN(...) operator */
3163 Bitmask mBest
; /* Tables used by best possible plan */
3166 assert( (mPrereq
& mUnusable
)==0 );
3167 pWInfo
= pBuilder
->pWInfo
;
3168 pParse
= pWInfo
->pParse
;
3169 pWC
= pBuilder
->pWC
;
3170 pNew
= pBuilder
->pNew
;
3171 pSrc
= &pWInfo
->pTabList
->a
[pNew
->iTab
];
3172 assert( IsVirtual(pSrc
->pTab
) );
3173 p
= allocateIndexInfo(pParse
, pWC
, mUnusable
, pSrc
, pBuilder
->pOrderBy
,
3175 if( p
==0 ) return SQLITE_NOMEM_BKPT
;
3177 pNew
->wsFlags
= WHERE_VIRTUALTABLE
;
3179 pNew
->u
.vtab
.needFree
= 0;
3180 nConstraint
= p
->nConstraint
;
3181 if( whereLoopResize(pParse
->db
, pNew
, nConstraint
) ){
3182 sqlite3DbFree(pParse
->db
, p
);
3183 return SQLITE_NOMEM_BKPT
;
3186 /* First call xBestIndex() with all constraints usable. */
3187 WHERETRACE(0x40, (" VirtualOne: all usable\n"));
3188 rc
= whereLoopAddVirtualOne(pBuilder
, mPrereq
, ALLBITS
, 0, p
, mNoOmit
, &bIn
);
3190 /* If the call to xBestIndex() with all terms enabled produced a plan
3191 ** that does not require any source tables (IOW: a plan with mBest==0),
3192 ** then there is no point in making any further calls to xBestIndex()
3193 ** since they will all return the same result (if the xBestIndex()
3194 ** implementation is sane). */
3195 if( rc
==SQLITE_OK
&& (mBest
= (pNew
->prereq
& ~mPrereq
))!=0 ){
3196 int seenZero
= 0; /* True if a plan with no prereqs seen */
3197 int seenZeroNoIN
= 0; /* Plan with no prereqs and no IN(...) seen */
3199 Bitmask mBestNoIn
= 0;
3201 /* If the plan produced by the earlier call uses an IN(...) term, call
3202 ** xBestIndex again, this time with IN(...) terms disabled. */
3204 WHERETRACE(0x40, (" VirtualOne: all usable w/o IN\n"));
3205 rc
= whereLoopAddVirtualOne(
3206 pBuilder
, mPrereq
, ALLBITS
, WO_IN
, p
, mNoOmit
, &bIn
);
3208 mBestNoIn
= pNew
->prereq
& ~mPrereq
;
3215 /* Call xBestIndex once for each distinct value of (prereqRight & ~mPrereq)
3216 ** in the set of terms that apply to the current virtual table. */
3217 while( rc
==SQLITE_OK
){
3219 Bitmask mNext
= ALLBITS
;
3221 for(i
=0; i
<nConstraint
; i
++){
3223 pWC
->a
[p
->aConstraint
[i
].iTermOffset
].prereqRight
& ~mPrereq
3225 if( mThis
>mPrev
&& mThis
<mNext
) mNext
= mThis
;
3228 if( mNext
==ALLBITS
) break;
3229 if( mNext
==mBest
|| mNext
==mBestNoIn
) continue;
3230 WHERETRACE(0x40, (" VirtualOne: mPrev=%04llx mNext=%04llx\n",
3231 (sqlite3_uint64
)mPrev
, (sqlite3_uint64
)mNext
));
3232 rc
= whereLoopAddVirtualOne(
3233 pBuilder
, mPrereq
, mNext
|mPrereq
, 0, p
, mNoOmit
, &bIn
);
3234 if( pNew
->prereq
==mPrereq
){
3236 if( bIn
==0 ) seenZeroNoIN
= 1;
3240 /* If the calls to xBestIndex() in the above loop did not find a plan
3241 ** that requires no source tables at all (i.e. one guaranteed to be
3242 ** usable), make a call here with all source tables disabled */
3243 if( rc
==SQLITE_OK
&& seenZero
==0 ){
3244 WHERETRACE(0x40, (" VirtualOne: all disabled\n"));
3245 rc
= whereLoopAddVirtualOne(
3246 pBuilder
, mPrereq
, mPrereq
, 0, p
, mNoOmit
, &bIn
);
3247 if( bIn
==0 ) seenZeroNoIN
= 1;
3250 /* If the calls to xBestIndex() have so far failed to find a plan
3251 ** that requires no source tables at all and does not use an IN(...)
3252 ** operator, make a final call to obtain one here. */
3253 if( rc
==SQLITE_OK
&& seenZeroNoIN
==0 ){
3254 WHERETRACE(0x40, (" VirtualOne: all disabled and w/o IN\n"));
3255 rc
= whereLoopAddVirtualOne(
3256 pBuilder
, mPrereq
, mPrereq
, WO_IN
, p
, mNoOmit
, &bIn
);
3260 if( p
->needToFreeIdxStr
) sqlite3_free(p
->idxStr
);
3261 sqlite3DbFreeNN(pParse
->db
, p
);
3264 #endif /* SQLITE_OMIT_VIRTUALTABLE */
3267 ** Add WhereLoop entries to handle OR terms. This works for either
3268 ** btrees or virtual tables.
3270 static int whereLoopAddOr(
3271 WhereLoopBuilder
*pBuilder
,
3275 WhereInfo
*pWInfo
= pBuilder
->pWInfo
;
3278 WhereTerm
*pTerm
, *pWCEnd
;
3282 WhereLoopBuilder sSubBuild
;
3283 WhereOrSet sSum
, sCur
;
3284 struct SrcList_item
*pItem
;
3286 pWC
= pBuilder
->pWC
;
3287 pWCEnd
= pWC
->a
+ pWC
->nTerm
;
3288 pNew
= pBuilder
->pNew
;
3289 memset(&sSum
, 0, sizeof(sSum
));
3290 pItem
= pWInfo
->pTabList
->a
+ pNew
->iTab
;
3291 iCur
= pItem
->iCursor
;
3293 for(pTerm
=pWC
->a
; pTerm
<pWCEnd
&& rc
==SQLITE_OK
; pTerm
++){
3294 if( (pTerm
->eOperator
& WO_OR
)!=0
3295 && (pTerm
->u
.pOrInfo
->indexable
& pNew
->maskSelf
)!=0
3297 WhereClause
* const pOrWC
= &pTerm
->u
.pOrInfo
->wc
;
3298 WhereTerm
* const pOrWCEnd
= &pOrWC
->a
[pOrWC
->nTerm
];
3303 sSubBuild
= *pBuilder
;
3304 sSubBuild
.pOrderBy
= 0;
3305 sSubBuild
.pOrSet
= &sCur
;
3307 WHERETRACE(0x200, ("Begin processing OR-clause %p\n", pTerm
));
3308 for(pOrTerm
=pOrWC
->a
; pOrTerm
<pOrWCEnd
; pOrTerm
++){
3309 if( (pOrTerm
->eOperator
& WO_AND
)!=0 ){
3310 sSubBuild
.pWC
= &pOrTerm
->u
.pAndInfo
->wc
;
3311 }else if( pOrTerm
->leftCursor
==iCur
){
3312 tempWC
.pWInfo
= pWC
->pWInfo
;
3313 tempWC
.pOuter
= pWC
;
3317 sSubBuild
.pWC
= &tempWC
;
3322 #ifdef WHERETRACE_ENABLED
3323 WHERETRACE(0x200, ("OR-term %d of %p has %d subterms:\n",
3324 (int)(pOrTerm
-pOrWC
->a
), pTerm
, sSubBuild
.pWC
->nTerm
));
3325 if( sqlite3WhereTrace
& 0x400 ){
3326 sqlite3WhereClausePrint(sSubBuild
.pWC
);
3329 #ifndef SQLITE_OMIT_VIRTUALTABLE
3330 if( IsVirtual(pItem
->pTab
) ){
3331 rc
= whereLoopAddVirtual(&sSubBuild
, mPrereq
, mUnusable
);
3335 rc
= whereLoopAddBtree(&sSubBuild
, mPrereq
);
3337 if( rc
==SQLITE_OK
){
3338 rc
= whereLoopAddOr(&sSubBuild
, mPrereq
, mUnusable
);
3340 assert( rc
==SQLITE_OK
|| sCur
.n
==0 );
3345 whereOrMove(&sSum
, &sCur
);
3349 whereOrMove(&sPrev
, &sSum
);
3351 for(i
=0; i
<sPrev
.n
; i
++){
3352 for(j
=0; j
<sCur
.n
; j
++){
3353 whereOrInsert(&sSum
, sPrev
.a
[i
].prereq
| sCur
.a
[j
].prereq
,
3354 sqlite3LogEstAdd(sPrev
.a
[i
].rRun
, sCur
.a
[j
].rRun
),
3355 sqlite3LogEstAdd(sPrev
.a
[i
].nOut
, sCur
.a
[j
].nOut
));
3361 pNew
->aLTerm
[0] = pTerm
;
3362 pNew
->wsFlags
= WHERE_MULTI_OR
;
3365 memset(&pNew
->u
, 0, sizeof(pNew
->u
));
3366 for(i
=0; rc
==SQLITE_OK
&& i
<sSum
.n
; i
++){
3367 /* TUNING: Currently sSum.a[i].rRun is set to the sum of the costs
3368 ** of all sub-scans required by the OR-scan. However, due to rounding
3369 ** errors, it may be that the cost of the OR-scan is equal to its
3370 ** most expensive sub-scan. Add the smallest possible penalty
3371 ** (equivalent to multiplying the cost by 1.07) to ensure that
3372 ** this does not happen. Otherwise, for WHERE clauses such as the
3373 ** following where there is an index on "y":
3375 ** WHERE likelihood(x=?, 0.99) OR y=?
3377 ** the planner may elect to "OR" together a full-table scan and an
3378 ** index lookup. And other similarly odd results. */
3379 pNew
->rRun
= sSum
.a
[i
].rRun
+ 1;
3380 pNew
->nOut
= sSum
.a
[i
].nOut
;
3381 pNew
->prereq
= sSum
.a
[i
].prereq
;
3382 rc
= whereLoopInsert(pBuilder
, pNew
);
3384 WHERETRACE(0x200, ("End processing OR-clause %p\n", pTerm
));
3391 ** Add all WhereLoop objects for all tables
3393 static int whereLoopAddAll(WhereLoopBuilder
*pBuilder
){
3394 WhereInfo
*pWInfo
= pBuilder
->pWInfo
;
3395 Bitmask mPrereq
= 0;
3398 SrcList
*pTabList
= pWInfo
->pTabList
;
3399 struct SrcList_item
*pItem
;
3400 struct SrcList_item
*pEnd
= &pTabList
->a
[pWInfo
->nLevel
];
3401 sqlite3
*db
= pWInfo
->pParse
->db
;
3404 u8 priorJointype
= 0;
3406 /* Loop over the tables in the join, from left to right */
3407 pNew
= pBuilder
->pNew
;
3408 whereLoopInit(pNew
);
3409 for(iTab
=0, pItem
=pTabList
->a
; pItem
<pEnd
; iTab
++, pItem
++){
3410 Bitmask mUnusable
= 0;
3412 pNew
->maskSelf
= sqlite3WhereGetMask(&pWInfo
->sMaskSet
, pItem
->iCursor
);
3413 if( ((pItem
->fg
.jointype
|priorJointype
) & (JT_LEFT
|JT_CROSS
))!=0 ){
3414 /* This condition is true when pItem is the FROM clause term on the
3415 ** right-hand-side of a LEFT or CROSS JOIN. */
3418 priorJointype
= pItem
->fg
.jointype
;
3419 #ifndef SQLITE_OMIT_VIRTUALTABLE
3420 if( IsVirtual(pItem
->pTab
) ){
3421 struct SrcList_item
*p
;
3422 for(p
=&pItem
[1]; p
<pEnd
; p
++){
3423 if( mUnusable
|| (p
->fg
.jointype
& (JT_LEFT
|JT_CROSS
)) ){
3424 mUnusable
|= sqlite3WhereGetMask(&pWInfo
->sMaskSet
, p
->iCursor
);
3427 rc
= whereLoopAddVirtual(pBuilder
, mPrereq
, mUnusable
);
3429 #endif /* SQLITE_OMIT_VIRTUALTABLE */
3431 rc
= whereLoopAddBtree(pBuilder
, mPrereq
);
3433 if( rc
==SQLITE_OK
){
3434 rc
= whereLoopAddOr(pBuilder
, mPrereq
, mUnusable
);
3436 mPrior
|= pNew
->maskSelf
;
3437 if( rc
|| db
->mallocFailed
) break;
3440 whereLoopClear(db
, pNew
);
3445 ** Examine a WherePath (with the addition of the extra WhereLoop of the 6th
3446 ** parameters) to see if it outputs rows in the requested ORDER BY
3447 ** (or GROUP BY) without requiring a separate sort operation. Return N:
3449 ** N>0: N terms of the ORDER BY clause are satisfied
3450 ** N==0: No terms of the ORDER BY clause are satisfied
3451 ** N<0: Unknown yet how many terms of ORDER BY might be satisfied.
3453 ** Note that processing for WHERE_GROUPBY and WHERE_DISTINCTBY is not as
3454 ** strict. With GROUP BY and DISTINCT the only requirement is that
3455 ** equivalent rows appear immediately adjacent to one another. GROUP BY
3456 ** and DISTINCT do not require rows to appear in any particular order as long
3457 ** as equivalent rows are grouped together. Thus for GROUP BY and DISTINCT
3458 ** the pOrderBy terms can be matched in any order. With ORDER BY, the
3459 ** pOrderBy terms must be matched in strict left-to-right order.
3461 static i8
wherePathSatisfiesOrderBy(
3462 WhereInfo
*pWInfo
, /* The WHERE clause */
3463 ExprList
*pOrderBy
, /* ORDER BY or GROUP BY or DISTINCT clause to check */
3464 WherePath
*pPath
, /* The WherePath to check */
3465 u16 wctrlFlags
, /* WHERE_GROUPBY or _DISTINCTBY or _ORDERBY_LIMIT */
3466 u16 nLoop
, /* Number of entries in pPath->aLoop[] */
3467 WhereLoop
*pLast
, /* Add this WhereLoop to the end of pPath->aLoop[] */
3468 Bitmask
*pRevMask
/* OUT: Mask of WhereLoops to run in reverse order */
3470 u8 revSet
; /* True if rev is known */
3471 u8 rev
; /* Composite sort order */
3472 u8 revIdx
; /* Index sort order */
3473 u8 isOrderDistinct
; /* All prior WhereLoops are order-distinct */
3474 u8 distinctColumns
; /* True if the loop has UNIQUE NOT NULL columns */
3475 u8 isMatch
; /* iColumn matches a term of the ORDER BY clause */
3476 u16 eqOpMask
; /* Allowed equality operators */
3477 u16 nKeyCol
; /* Number of key columns in pIndex */
3478 u16 nColumn
; /* Total number of ordered columns in the index */
3479 u16 nOrderBy
; /* Number terms in the ORDER BY clause */
3480 int iLoop
; /* Index of WhereLoop in pPath being processed */
3481 int i
, j
; /* Loop counters */
3482 int iCur
; /* Cursor number for current WhereLoop */
3483 int iColumn
; /* A column number within table iCur */
3484 WhereLoop
*pLoop
= 0; /* Current WhereLoop being processed. */
3485 WhereTerm
*pTerm
; /* A single term of the WHERE clause */
3486 Expr
*pOBExpr
; /* An expression from the ORDER BY clause */
3487 CollSeq
*pColl
; /* COLLATE function from an ORDER BY clause term */
3488 Index
*pIndex
; /* The index associated with pLoop */
3489 sqlite3
*db
= pWInfo
->pParse
->db
; /* Database connection */
3490 Bitmask obSat
= 0; /* Mask of ORDER BY terms satisfied so far */
3491 Bitmask obDone
; /* Mask of all ORDER BY terms */
3492 Bitmask orderDistinctMask
; /* Mask of all well-ordered loops */
3493 Bitmask ready
; /* Mask of inner loops */
3496 ** We say the WhereLoop is "one-row" if it generates no more than one
3497 ** row of output. A WhereLoop is one-row if all of the following are true:
3498 ** (a) All index columns match with WHERE_COLUMN_EQ.
3499 ** (b) The index is unique
3500 ** Any WhereLoop with an WHERE_COLUMN_EQ constraint on the rowid is one-row.
3501 ** Every one-row WhereLoop will have the WHERE_ONEROW bit set in wsFlags.
3503 ** We say the WhereLoop is "order-distinct" if the set of columns from
3504 ** that WhereLoop that are in the ORDER BY clause are different for every
3505 ** row of the WhereLoop. Every one-row WhereLoop is automatically
3506 ** order-distinct. A WhereLoop that has no columns in the ORDER BY clause
3507 ** is not order-distinct. To be order-distinct is not quite the same as being
3508 ** UNIQUE since a UNIQUE column or index can have multiple rows that
3509 ** are NULL and NULL values are equivalent for the purpose of order-distinct.
3510 ** To be order-distinct, the columns must be UNIQUE and NOT NULL.
3512 ** The rowid for a table is always UNIQUE and NOT NULL so whenever the
3513 ** rowid appears in the ORDER BY clause, the corresponding WhereLoop is
3514 ** automatically order-distinct.
3517 assert( pOrderBy
!=0 );
3518 if( nLoop
&& OptimizationDisabled(db
, SQLITE_OrderByIdxJoin
) ) return 0;
3520 nOrderBy
= pOrderBy
->nExpr
;
3521 testcase( nOrderBy
==BMS
-1 );
3522 if( nOrderBy
>BMS
-1 ) return 0; /* Cannot optimize overly large ORDER BYs */
3523 isOrderDistinct
= 1;
3524 obDone
= MASKBIT(nOrderBy
)-1;
3525 orderDistinctMask
= 0;
3527 eqOpMask
= WO_EQ
| WO_IS
| WO_ISNULL
;
3528 if( wctrlFlags
& WHERE_ORDERBY_LIMIT
) eqOpMask
|= WO_IN
;
3529 for(iLoop
=0; isOrderDistinct
&& obSat
<obDone
&& iLoop
<=nLoop
; iLoop
++){
3530 if( iLoop
>0 ) ready
|= pLoop
->maskSelf
;
3532 pLoop
= pPath
->aLoop
[iLoop
];
3533 if( wctrlFlags
& WHERE_ORDERBY_LIMIT
) continue;
3537 if( pLoop
->wsFlags
& WHERE_VIRTUALTABLE
){
3538 if( pLoop
->u
.vtab
.isOrdered
) obSat
= obDone
;
3541 pLoop
->u
.btree
.nIdxCol
= 0;
3543 iCur
= pWInfo
->pTabList
->a
[pLoop
->iTab
].iCursor
;
3545 /* Mark off any ORDER BY term X that is a column in the table of
3546 ** the current loop for which there is term in the WHERE
3547 ** clause of the form X IS NULL or X=? that reference only outer
3550 for(i
=0; i
<nOrderBy
; i
++){
3551 if( MASKBIT(i
) & obSat
) continue;
3552 pOBExpr
= sqlite3ExprSkipCollate(pOrderBy
->a
[i
].pExpr
);
3553 if( pOBExpr
->op
!=TK_COLUMN
) continue;
3554 if( pOBExpr
->iTable
!=iCur
) continue;
3555 pTerm
= sqlite3WhereFindTerm(&pWInfo
->sWC
, iCur
, pOBExpr
->iColumn
,
3556 ~ready
, eqOpMask
, 0);
3557 if( pTerm
==0 ) continue;
3558 if( pTerm
->eOperator
==WO_IN
){
3559 /* IN terms are only valid for sorting in the ORDER BY LIMIT
3560 ** optimization, and then only if they are actually used
3561 ** by the query plan */
3562 assert( wctrlFlags
& WHERE_ORDERBY_LIMIT
);
3563 for(j
=0; j
<pLoop
->nLTerm
&& pTerm
!=pLoop
->aLTerm
[j
]; j
++){}
3564 if( j
>=pLoop
->nLTerm
) continue;
3566 if( (pTerm
->eOperator
&(WO_EQ
|WO_IS
))!=0 && pOBExpr
->iColumn
>=0 ){
3567 const char *z1
, *z2
;
3568 pColl
= sqlite3ExprCollSeq(pWInfo
->pParse
, pOrderBy
->a
[i
].pExpr
);
3569 if( !pColl
) pColl
= db
->pDfltColl
;
3571 pColl
= sqlite3ExprCollSeq(pWInfo
->pParse
, pTerm
->pExpr
);
3572 if( !pColl
) pColl
= db
->pDfltColl
;
3574 if( sqlite3StrICmp(z1
, z2
)!=0 ) continue;
3575 testcase( pTerm
->pExpr
->op
==TK_IS
);
3577 obSat
|= MASKBIT(i
);
3580 if( (pLoop
->wsFlags
& WHERE_ONEROW
)==0 ){
3581 if( pLoop
->wsFlags
& WHERE_IPK
){
3585 }else if( (pIndex
= pLoop
->u
.btree
.pIndex
)==0 || pIndex
->bUnordered
){
3588 nKeyCol
= pIndex
->nKeyCol
;
3589 nColumn
= pIndex
->nColumn
;
3590 assert( nColumn
==nKeyCol
+1 || !HasRowid(pIndex
->pTable
) );
3591 assert( pIndex
->aiColumn
[nColumn
-1]==XN_ROWID
3592 || !HasRowid(pIndex
->pTable
));
3593 isOrderDistinct
= IsUniqueIndex(pIndex
);
3596 /* Loop through all columns of the index and deal with the ones
3597 ** that are not constrained by == or IN.
3600 distinctColumns
= 0;
3601 for(j
=0; j
<nColumn
; j
++){
3602 u8 bOnce
= 1; /* True to run the ORDER BY search loop */
3604 assert( j
>=pLoop
->u
.btree
.nEq
3605 || (pLoop
->aLTerm
[j
]==0)==(j
<pLoop
->nSkip
)
3607 if( j
<pLoop
->u
.btree
.nEq
&& j
>=pLoop
->nSkip
){
3608 u16 eOp
= pLoop
->aLTerm
[j
]->eOperator
;
3610 /* Skip over == and IS and ISNULL terms. (Also skip IN terms when
3611 ** doing WHERE_ORDERBY_LIMIT processing).
3613 ** If the current term is a column of an ((?,?) IN (SELECT...))
3614 ** expression for which the SELECT returns more than one column,
3615 ** check that it is the only column used by this loop. Otherwise,
3616 ** if it is one of two or more, none of the columns can be
3617 ** considered to match an ORDER BY term. */
3618 if( (eOp
& eqOpMask
)!=0 ){
3619 if( eOp
& WO_ISNULL
){
3620 testcase( isOrderDistinct
);
3621 isOrderDistinct
= 0;
3624 }else if( ALWAYS(eOp
& WO_IN
) ){
3625 /* ALWAYS() justification: eOp is an equality operator due to the
3626 ** j<pLoop->u.btree.nEq constraint above. Any equality other
3627 ** than WO_IN is captured by the previous "if". So this one
3628 ** always has to be WO_IN. */
3629 Expr
*pX
= pLoop
->aLTerm
[j
]->pExpr
;
3630 for(i
=j
+1; i
<pLoop
->u
.btree
.nEq
; i
++){
3631 if( pLoop
->aLTerm
[i
]->pExpr
==pX
){
3632 assert( (pLoop
->aLTerm
[i
]->eOperator
& WO_IN
) );
3640 /* Get the column number in the table (iColumn) and sort order
3641 ** (revIdx) for the j-th column of the index.
3644 iColumn
= pIndex
->aiColumn
[j
];
3645 revIdx
= pIndex
->aSortOrder
[j
];
3646 if( iColumn
==pIndex
->pTable
->iPKey
) iColumn
= -1;
3652 /* An unconstrained column that might be NULL means that this
3653 ** WhereLoop is not well-ordered
3657 && j
>=pLoop
->u
.btree
.nEq
3658 && pIndex
->pTable
->aCol
[iColumn
].notNull
==0
3660 isOrderDistinct
= 0;
3663 /* Find the ORDER BY term that corresponds to the j-th column
3664 ** of the index and mark that ORDER BY term off
3667 for(i
=0; bOnce
&& i
<nOrderBy
; i
++){
3668 if( MASKBIT(i
) & obSat
) continue;
3669 pOBExpr
= sqlite3ExprSkipCollate(pOrderBy
->a
[i
].pExpr
);
3670 testcase( wctrlFlags
& WHERE_GROUPBY
);
3671 testcase( wctrlFlags
& WHERE_DISTINCTBY
);
3672 if( (wctrlFlags
& (WHERE_GROUPBY
|WHERE_DISTINCTBY
))==0 ) bOnce
= 0;
3673 if( iColumn
>=(-1) ){
3674 if( pOBExpr
->op
!=TK_COLUMN
) continue;
3675 if( pOBExpr
->iTable
!=iCur
) continue;
3676 if( pOBExpr
->iColumn
!=iColumn
) continue;
3678 if( sqlite3ExprCompare(0,
3679 pOBExpr
,pIndex
->aColExpr
->a
[j
].pExpr
,iCur
) ){
3684 pColl
= sqlite3ExprCollSeq(pWInfo
->pParse
, pOrderBy
->a
[i
].pExpr
);
3685 if( !pColl
) pColl
= db
->pDfltColl
;
3686 if( sqlite3StrICmp(pColl
->zName
, pIndex
->azColl
[j
])!=0 ) continue;
3688 pLoop
->u
.btree
.nIdxCol
= j
+1;
3692 if( isMatch
&& (wctrlFlags
& WHERE_GROUPBY
)==0 ){
3693 /* Make sure the sort order is compatible in an ORDER BY clause.
3694 ** Sort order is irrelevant for a GROUP BY clause. */
3696 if( (rev
^ revIdx
)!=pOrderBy
->a
[i
].sortOrder
) isMatch
= 0;
3698 rev
= revIdx
^ pOrderBy
->a
[i
].sortOrder
;
3699 if( rev
) *pRevMask
|= MASKBIT(iLoop
);
3704 if( iColumn
==XN_ROWID
){
3705 testcase( distinctColumns
==0 );
3706 distinctColumns
= 1;
3708 obSat
|= MASKBIT(i
);
3710 /* No match found */
3711 if( j
==0 || j
<nKeyCol
){
3712 testcase( isOrderDistinct
!=0 );
3713 isOrderDistinct
= 0;
3717 } /* end Loop over all index columns */
3718 if( distinctColumns
){
3719 testcase( isOrderDistinct
==0 );
3720 isOrderDistinct
= 1;
3722 } /* end-if not one-row */
3724 /* Mark off any other ORDER BY terms that reference pLoop */
3725 if( isOrderDistinct
){
3726 orderDistinctMask
|= pLoop
->maskSelf
;
3727 for(i
=0; i
<nOrderBy
; i
++){
3730 if( MASKBIT(i
) & obSat
) continue;
3731 p
= pOrderBy
->a
[i
].pExpr
;
3732 mTerm
= sqlite3WhereExprUsage(&pWInfo
->sMaskSet
,p
);
3733 if( mTerm
==0 && !sqlite3ExprIsConstant(p
) ) continue;
3734 if( (mTerm
&~orderDistinctMask
)==0 ){
3735 obSat
|= MASKBIT(i
);
3739 } /* End the loop over all WhereLoops from outer-most down to inner-most */
3740 if( obSat
==obDone
) return (i8
)nOrderBy
;
3741 if( !isOrderDistinct
){
3742 for(i
=nOrderBy
-1; i
>0; i
--){
3743 Bitmask m
= MASKBIT(i
) - 1;
3744 if( (obSat
&m
)==m
) return i
;
3753 ** If the WHERE_GROUPBY flag is set in the mask passed to sqlite3WhereBegin(),
3754 ** the planner assumes that the specified pOrderBy list is actually a GROUP
3755 ** BY clause - and so any order that groups rows as required satisfies the
3758 ** Normally, in this case it is not possible for the caller to determine
3759 ** whether or not the rows are really being delivered in sorted order, or
3760 ** just in some other order that provides the required grouping. However,
3761 ** if the WHERE_SORTBYGROUP flag is also passed to sqlite3WhereBegin(), then
3762 ** this function may be called on the returned WhereInfo object. It returns
3763 ** true if the rows really will be sorted in the specified order, or false
3766 ** For example, assuming:
3768 ** CREATE INDEX i1 ON t1(x, Y);
3772 ** SELECT * FROM t1 GROUP BY x,y ORDER BY x,y; -- IsSorted()==1
3773 ** SELECT * FROM t1 GROUP BY y,x ORDER BY y,x; -- IsSorted()==0
3775 int sqlite3WhereIsSorted(WhereInfo
*pWInfo
){
3776 assert( pWInfo
->wctrlFlags
& WHERE_GROUPBY
);
3777 assert( pWInfo
->wctrlFlags
& WHERE_SORTBYGROUP
);
3778 return pWInfo
->sorted
;
3781 #ifdef WHERETRACE_ENABLED
3782 /* For debugging use only: */
3783 static const char *wherePathName(WherePath
*pPath
, int nLoop
, WhereLoop
*pLast
){
3784 static char zName
[65];
3786 for(i
=0; i
<nLoop
; i
++){ zName
[i
] = pPath
->aLoop
[i
]->cId
; }
3787 if( pLast
) zName
[i
++] = pLast
->cId
;
3794 ** Return the cost of sorting nRow rows, assuming that the keys have
3795 ** nOrderby columns and that the first nSorted columns are already in
3798 static LogEst
whereSortingCost(
3804 /* TUNING: Estimated cost of a full external sort, where N is
3805 ** the number of rows to sort is:
3807 ** cost = (3.0 * N * log(N)).
3809 ** Or, if the order-by clause has X terms but only the last Y
3810 ** terms are out of order, then block-sorting will reduce the
3813 ** cost = (3.0 * N * log(N)) * (Y/X)
3815 ** The (Y/X) term is implemented using stack variable rScale
3817 LogEst rScale
, rSortCost
;
3818 assert( nOrderBy
>0 && 66==sqlite3LogEst(100) );
3819 rScale
= sqlite3LogEst((nOrderBy
-nSorted
)*100/nOrderBy
) - 66;
3820 rSortCost
= nRow
+ rScale
+ 16;
3822 /* Multiple by log(M) where M is the number of output rows.
3823 ** Use the LIMIT for M if it is smaller */
3824 if( (pWInfo
->wctrlFlags
& WHERE_USE_LIMIT
)!=0 && pWInfo
->iLimit
<nRow
){
3825 nRow
= pWInfo
->iLimit
;
3827 rSortCost
+= estLog(nRow
);
3832 ** Given the list of WhereLoop objects at pWInfo->pLoops, this routine
3833 ** attempts to find the lowest cost path that visits each WhereLoop
3834 ** once. This path is then loaded into the pWInfo->a[].pWLoop fields.
3836 ** Assume that the total number of output rows that will need to be sorted
3837 ** will be nRowEst (in the 10*log2 representation). Or, ignore sorting
3838 ** costs if nRowEst==0.
3840 ** Return SQLITE_OK on success or SQLITE_NOMEM of a memory allocation
3843 static int wherePathSolver(WhereInfo
*pWInfo
, LogEst nRowEst
){
3844 int mxChoice
; /* Maximum number of simultaneous paths tracked */
3845 int nLoop
; /* Number of terms in the join */
3846 Parse
*pParse
; /* Parsing context */
3847 sqlite3
*db
; /* The database connection */
3848 int iLoop
; /* Loop counter over the terms of the join */
3849 int ii
, jj
; /* Loop counters */
3850 int mxI
= 0; /* Index of next entry to replace */
3851 int nOrderBy
; /* Number of ORDER BY clause terms */
3852 LogEst mxCost
= 0; /* Maximum cost of a set of paths */
3853 LogEst mxUnsorted
= 0; /* Maximum unsorted cost of a set of path */
3854 int nTo
, nFrom
; /* Number of valid entries in aTo[] and aFrom[] */
3855 WherePath
*aFrom
; /* All nFrom paths at the previous level */
3856 WherePath
*aTo
; /* The nTo best paths at the current level */
3857 WherePath
*pFrom
; /* An element of aFrom[] that we are working on */
3858 WherePath
*pTo
; /* An element of aTo[] that we are working on */
3859 WhereLoop
*pWLoop
; /* One of the WhereLoop objects */
3860 WhereLoop
**pX
; /* Used to divy up the pSpace memory */
3861 LogEst
*aSortCost
= 0; /* Sorting and partial sorting costs */
3862 char *pSpace
; /* Temporary memory used by this routine */
3863 int nSpace
; /* Bytes of space allocated at pSpace */
3865 pParse
= pWInfo
->pParse
;
3867 nLoop
= pWInfo
->nLevel
;
3868 /* TUNING: For simple queries, only the best path is tracked.
3869 ** For 2-way joins, the 5 best paths are followed.
3870 ** For joins of 3 or more tables, track the 10 best paths */
3871 mxChoice
= (nLoop
<=1) ? 1 : (nLoop
==2 ? 5 : 10);
3872 assert( nLoop
<=pWInfo
->pTabList
->nSrc
);
3873 WHERETRACE(0x002, ("---- begin solver. (nRowEst=%d)\n", nRowEst
));
3875 /* If nRowEst is zero and there is an ORDER BY clause, ignore it. In this
3876 ** case the purpose of this call is to estimate the number of rows returned
3877 ** by the overall query. Once this estimate has been obtained, the caller
3878 ** will invoke this function a second time, passing the estimate as the
3879 ** nRowEst parameter. */
3880 if( pWInfo
->pOrderBy
==0 || nRowEst
==0 ){
3883 nOrderBy
= pWInfo
->pOrderBy
->nExpr
;
3886 /* Allocate and initialize space for aTo, aFrom and aSortCost[] */
3887 nSpace
= (sizeof(WherePath
)+sizeof(WhereLoop
*)*nLoop
)*mxChoice
*2;
3888 nSpace
+= sizeof(LogEst
) * nOrderBy
;
3889 pSpace
= sqlite3DbMallocRawNN(db
, nSpace
);
3890 if( pSpace
==0 ) return SQLITE_NOMEM_BKPT
;
3891 aTo
= (WherePath
*)pSpace
;
3892 aFrom
= aTo
+mxChoice
;
3893 memset(aFrom
, 0, sizeof(aFrom
[0]));
3894 pX
= (WhereLoop
**)(aFrom
+mxChoice
);
3895 for(ii
=mxChoice
*2, pFrom
=aTo
; ii
>0; ii
--, pFrom
++, pX
+= nLoop
){
3899 /* If there is an ORDER BY clause and it is not being ignored, set up
3900 ** space for the aSortCost[] array. Each element of the aSortCost array
3901 ** is either zero - meaning it has not yet been initialized - or the
3902 ** cost of sorting nRowEst rows of data where the first X terms of
3903 ** the ORDER BY clause are already in order, where X is the array
3905 aSortCost
= (LogEst
*)pX
;
3906 memset(aSortCost
, 0, sizeof(LogEst
) * nOrderBy
);
3908 assert( aSortCost
==0 || &pSpace
[nSpace
]==(char*)&aSortCost
[nOrderBy
] );
3909 assert( aSortCost
!=0 || &pSpace
[nSpace
]==(char*)pX
);
3911 /* Seed the search with a single WherePath containing zero WhereLoops.
3913 ** TUNING: Do not let the number of iterations go above 28. If the cost
3914 ** of computing an automatic index is not paid back within the first 28
3915 ** rows, then do not use the automatic index. */
3916 aFrom
[0].nRow
= MIN(pParse
->nQueryLoop
, 48); assert( 48==sqlite3LogEst(28) );
3918 assert( aFrom
[0].isOrdered
==0 );
3920 /* If nLoop is zero, then there are no FROM terms in the query. Since
3921 ** in this case the query may return a maximum of one row, the results
3922 ** are already in the requested order. Set isOrdered to nOrderBy to
3923 ** indicate this. Or, if nLoop is greater than zero, set isOrdered to
3924 ** -1, indicating that the result set may or may not be ordered,
3925 ** depending on the loops added to the current plan. */
3926 aFrom
[0].isOrdered
= nLoop
>0 ? -1 : nOrderBy
;
3929 /* Compute successively longer WherePaths using the previous generation
3930 ** of WherePaths as the basis for the next. Keep track of the mxChoice
3931 ** best paths at each generation */
3932 for(iLoop
=0; iLoop
<nLoop
; iLoop
++){
3934 for(ii
=0, pFrom
=aFrom
; ii
<nFrom
; ii
++, pFrom
++){
3935 for(pWLoop
=pWInfo
->pLoops
; pWLoop
; pWLoop
=pWLoop
->pNextLoop
){
3936 LogEst nOut
; /* Rows visited by (pFrom+pWLoop) */
3937 LogEst rCost
; /* Cost of path (pFrom+pWLoop) */
3938 LogEst rUnsorted
; /* Unsorted cost of (pFrom+pWLoop) */
3939 i8 isOrdered
= pFrom
->isOrdered
; /* isOrdered for (pFrom+pWLoop) */
3940 Bitmask maskNew
; /* Mask of src visited by (..) */
3941 Bitmask revMask
= 0; /* Mask of rev-order loops for (..) */
3943 if( (pWLoop
->prereq
& ~pFrom
->maskLoop
)!=0 ) continue;
3944 if( (pWLoop
->maskSelf
& pFrom
->maskLoop
)!=0 ) continue;
3945 if( (pWLoop
->wsFlags
& WHERE_AUTO_INDEX
)!=0 && pFrom
->nRow
<10 ){
3946 /* Do not use an automatic index if the this loop is expected
3947 ** to run less than 2 times. */
3948 assert( 10==sqlite3LogEst(2) );
3951 /* At this point, pWLoop is a candidate to be the next loop.
3952 ** Compute its cost */
3953 rUnsorted
= sqlite3LogEstAdd(pWLoop
->rSetup
,pWLoop
->rRun
+ pFrom
->nRow
);
3954 rUnsorted
= sqlite3LogEstAdd(rUnsorted
, pFrom
->rUnsorted
);
3955 nOut
= pFrom
->nRow
+ pWLoop
->nOut
;
3956 maskNew
= pFrom
->maskLoop
| pWLoop
->maskSelf
;
3958 isOrdered
= wherePathSatisfiesOrderBy(pWInfo
,
3959 pWInfo
->pOrderBy
, pFrom
, pWInfo
->wctrlFlags
,
3960 iLoop
, pWLoop
, &revMask
);
3962 revMask
= pFrom
->revLoop
;
3964 if( isOrdered
>=0 && isOrdered
<nOrderBy
){
3965 if( aSortCost
[isOrdered
]==0 ){
3966 aSortCost
[isOrdered
] = whereSortingCost(
3967 pWInfo
, nRowEst
, nOrderBy
, isOrdered
3970 rCost
= sqlite3LogEstAdd(rUnsorted
, aSortCost
[isOrdered
]);
3973 ("---- sort cost=%-3d (%d/%d) increases cost %3d to %-3d\n",
3974 aSortCost
[isOrdered
], (nOrderBy
-isOrdered
), nOrderBy
,
3978 rUnsorted
-= 2; /* TUNING: Slight bias in favor of no-sort plans */
3981 /* Check to see if pWLoop should be added to the set of
3982 ** mxChoice best-so-far paths.
3984 ** First look for an existing path among best-so-far paths
3985 ** that covers the same set of loops and has the same isOrdered
3986 ** setting as the current path candidate.
3988 ** The term "((pTo->isOrdered^isOrdered)&0x80)==0" is equivalent
3989 ** to (pTo->isOrdered==(-1))==(isOrdered==(-1))" for the range
3990 ** of legal values for isOrdered, -1..64.
3992 for(jj
=0, pTo
=aTo
; jj
<nTo
; jj
++, pTo
++){
3993 if( pTo
->maskLoop
==maskNew
3994 && ((pTo
->isOrdered
^isOrdered
)&0x80)==0
3996 testcase( jj
==nTo
-1 );
4001 /* None of the existing best-so-far paths match the candidate. */
4003 && (rCost
>mxCost
|| (rCost
==mxCost
&& rUnsorted
>=mxUnsorted
))
4005 /* The current candidate is no better than any of the mxChoice
4006 ** paths currently in the best-so-far buffer. So discard
4007 ** this candidate as not viable. */
4008 #ifdef WHERETRACE_ENABLED /* 0x4 */
4009 if( sqlite3WhereTrace
&0x4 ){
4010 sqlite3DebugPrintf("Skip %s cost=%-3d,%3d,%3d order=%c\n",
4011 wherePathName(pFrom
, iLoop
, pWLoop
), rCost
, nOut
, rUnsorted
,
4012 isOrdered
>=0 ? isOrdered
+'0' : '?');
4017 /* If we reach this points it means that the new candidate path
4018 ** needs to be added to the set of best-so-far paths. */
4020 /* Increase the size of the aTo set by one */
4023 /* New path replaces the prior worst to keep count below mxChoice */
4027 #ifdef WHERETRACE_ENABLED /* 0x4 */
4028 if( sqlite3WhereTrace
&0x4 ){
4029 sqlite3DebugPrintf("New %s cost=%-3d,%3d,%3d order=%c\n",
4030 wherePathName(pFrom
, iLoop
, pWLoop
), rCost
, nOut
, rUnsorted
,
4031 isOrdered
>=0 ? isOrdered
+'0' : '?');
4035 /* Control reaches here if best-so-far path pTo=aTo[jj] covers the
4036 ** same set of loops and has the same isOrdered setting as the
4037 ** candidate path. Check to see if the candidate should replace
4038 ** pTo or if the candidate should be skipped.
4040 ** The conditional is an expanded vector comparison equivalent to:
4041 ** (pTo->rCost,pTo->nRow,pTo->rUnsorted) <= (rCost,nOut,rUnsorted)
4043 if( pTo
->rCost
<rCost
4044 || (pTo
->rCost
==rCost
4046 || (pTo
->nRow
==nOut
&& pTo
->rUnsorted
<=rUnsorted
)
4050 #ifdef WHERETRACE_ENABLED /* 0x4 */
4051 if( sqlite3WhereTrace
&0x4 ){
4053 "Skip %s cost=%-3d,%3d,%3d order=%c",
4054 wherePathName(pFrom
, iLoop
, pWLoop
), rCost
, nOut
, rUnsorted
,
4055 isOrdered
>=0 ? isOrdered
+'0' : '?');
4056 sqlite3DebugPrintf(" vs %s cost=%-3d,%3d,%3d order=%c\n",
4057 wherePathName(pTo
, iLoop
+1, 0), pTo
->rCost
, pTo
->nRow
,
4058 pTo
->rUnsorted
, pTo
->isOrdered
>=0 ? pTo
->isOrdered
+'0' : '?');
4061 /* Discard the candidate path from further consideration */
4062 testcase( pTo
->rCost
==rCost
);
4065 testcase( pTo
->rCost
==rCost
+1 );
4066 /* Control reaches here if the candidate path is better than the
4067 ** pTo path. Replace pTo with the candidate. */
4068 #ifdef WHERETRACE_ENABLED /* 0x4 */
4069 if( sqlite3WhereTrace
&0x4 ){
4071 "Update %s cost=%-3d,%3d,%3d order=%c",
4072 wherePathName(pFrom
, iLoop
, pWLoop
), rCost
, nOut
, rUnsorted
,
4073 isOrdered
>=0 ? isOrdered
+'0' : '?');
4074 sqlite3DebugPrintf(" was %s cost=%-3d,%3d,%3d order=%c\n",
4075 wherePathName(pTo
, iLoop
+1, 0), pTo
->rCost
, pTo
->nRow
,
4076 pTo
->rUnsorted
, pTo
->isOrdered
>=0 ? pTo
->isOrdered
+'0' : '?');
4080 /* pWLoop is a winner. Add it to the set of best so far */
4081 pTo
->maskLoop
= pFrom
->maskLoop
| pWLoop
->maskSelf
;
4082 pTo
->revLoop
= revMask
;
4085 pTo
->rUnsorted
= rUnsorted
;
4086 pTo
->isOrdered
= isOrdered
;
4087 memcpy(pTo
->aLoop
, pFrom
->aLoop
, sizeof(WhereLoop
*)*iLoop
);
4088 pTo
->aLoop
[iLoop
] = pWLoop
;
4089 if( nTo
>=mxChoice
){
4091 mxCost
= aTo
[0].rCost
;
4092 mxUnsorted
= aTo
[0].nRow
;
4093 for(jj
=1, pTo
=&aTo
[1]; jj
<mxChoice
; jj
++, pTo
++){
4094 if( pTo
->rCost
>mxCost
4095 || (pTo
->rCost
==mxCost
&& pTo
->rUnsorted
>mxUnsorted
)
4097 mxCost
= pTo
->rCost
;
4098 mxUnsorted
= pTo
->rUnsorted
;
4106 #ifdef WHERETRACE_ENABLED /* >=2 */
4107 if( sqlite3WhereTrace
& 0x02 ){
4108 sqlite3DebugPrintf("---- after round %d ----\n", iLoop
);
4109 for(ii
=0, pTo
=aTo
; ii
<nTo
; ii
++, pTo
++){
4110 sqlite3DebugPrintf(" %s cost=%-3d nrow=%-3d order=%c",
4111 wherePathName(pTo
, iLoop
+1, 0), pTo
->rCost
, pTo
->nRow
,
4112 pTo
->isOrdered
>=0 ? (pTo
->isOrdered
+'0') : '?');
4113 if( pTo
->isOrdered
>0 ){
4114 sqlite3DebugPrintf(" rev=0x%llx\n", pTo
->revLoop
);
4116 sqlite3DebugPrintf("\n");
4122 /* Swap the roles of aFrom and aTo for the next generation */
4130 sqlite3ErrorMsg(pParse
, "no query solution");
4131 sqlite3DbFreeNN(db
, pSpace
);
4132 return SQLITE_ERROR
;
4135 /* Find the lowest cost path. pFrom will be left pointing to that path */
4137 for(ii
=1; ii
<nFrom
; ii
++){
4138 if( pFrom
->rCost
>aFrom
[ii
].rCost
) pFrom
= &aFrom
[ii
];
4140 assert( pWInfo
->nLevel
==nLoop
);
4141 /* Load the lowest cost path into pWInfo */
4142 for(iLoop
=0; iLoop
<nLoop
; iLoop
++){
4143 WhereLevel
*pLevel
= pWInfo
->a
+ iLoop
;
4144 pLevel
->pWLoop
= pWLoop
= pFrom
->aLoop
[iLoop
];
4145 pLevel
->iFrom
= pWLoop
->iTab
;
4146 pLevel
->iTabCur
= pWInfo
->pTabList
->a
[pLevel
->iFrom
].iCursor
;
4148 if( (pWInfo
->wctrlFlags
& WHERE_WANT_DISTINCT
)!=0
4149 && (pWInfo
->wctrlFlags
& WHERE_DISTINCTBY
)==0
4150 && pWInfo
->eDistinct
==WHERE_DISTINCT_NOOP
4154 int rc
= wherePathSatisfiesOrderBy(pWInfo
, pWInfo
->pResultSet
, pFrom
,
4155 WHERE_DISTINCTBY
, nLoop
-1, pFrom
->aLoop
[nLoop
-1], ¬Used
);
4156 if( rc
==pWInfo
->pResultSet
->nExpr
){
4157 pWInfo
->eDistinct
= WHERE_DISTINCT_ORDERED
;
4160 if( pWInfo
->pOrderBy
){
4161 if( pWInfo
->wctrlFlags
& WHERE_DISTINCTBY
){
4162 if( pFrom
->isOrdered
==pWInfo
->pOrderBy
->nExpr
){
4163 pWInfo
->eDistinct
= WHERE_DISTINCT_ORDERED
;
4166 pWInfo
->nOBSat
= pFrom
->isOrdered
;
4167 pWInfo
->revMask
= pFrom
->revLoop
;
4168 if( pWInfo
->nOBSat
<=0 ){
4171 u32 wsFlags
= pFrom
->aLoop
[nLoop
-1]->wsFlags
;
4172 if( (wsFlags
& WHERE_ONEROW
)==0
4173 && (wsFlags
&(WHERE_IPK
|WHERE_COLUMN_IN
))!=(WHERE_IPK
|WHERE_COLUMN_IN
)
4176 int rc
= wherePathSatisfiesOrderBy(pWInfo
, pWInfo
->pOrderBy
, pFrom
,
4177 WHERE_ORDERBY_LIMIT
, nLoop
-1, pFrom
->aLoop
[nLoop
-1], &m
);
4178 testcase( wsFlags
& WHERE_IPK
);
4179 testcase( wsFlags
& WHERE_COLUMN_IN
);
4180 if( rc
==pWInfo
->pOrderBy
->nExpr
){
4181 pWInfo
->bOrderedInnerLoop
= 1;
4182 pWInfo
->revMask
= m
;
4188 if( (pWInfo
->wctrlFlags
& WHERE_SORTBYGROUP
)
4189 && pWInfo
->nOBSat
==pWInfo
->pOrderBy
->nExpr
&& nLoop
>0
4191 Bitmask revMask
= 0;
4192 int nOrder
= wherePathSatisfiesOrderBy(pWInfo
, pWInfo
->pOrderBy
,
4193 pFrom
, 0, nLoop
-1, pFrom
->aLoop
[nLoop
-1], &revMask
4195 assert( pWInfo
->sorted
==0 );
4196 if( nOrder
==pWInfo
->pOrderBy
->nExpr
){
4198 pWInfo
->revMask
= revMask
;
4204 pWInfo
->nRowOut
= pFrom
->nRow
;
4206 /* Free temporary memory and return success */
4207 sqlite3DbFreeNN(db
, pSpace
);
4212 ** Most queries use only a single table (they are not joins) and have
4213 ** simple == constraints against indexed fields. This routine attempts
4214 ** to plan those simple cases using much less ceremony than the
4215 ** general-purpose query planner, and thereby yield faster sqlite3_prepare()
4216 ** times for the common case.
4218 ** Return non-zero on success, if this query can be handled by this
4219 ** no-frills query planner. Return zero if this query needs the
4220 ** general-purpose query planner.
4222 static int whereShortCut(WhereLoopBuilder
*pBuilder
){
4224 struct SrcList_item
*pItem
;
4233 pWInfo
= pBuilder
->pWInfo
;
4234 if( pWInfo
->wctrlFlags
& WHERE_OR_SUBCLAUSE
) return 0;
4235 assert( pWInfo
->pTabList
->nSrc
>=1 );
4236 pItem
= pWInfo
->pTabList
->a
;
4238 if( IsVirtual(pTab
) ) return 0;
4239 if( pItem
->fg
.isIndexedBy
) return 0;
4240 iCur
= pItem
->iCursor
;
4242 pLoop
= pBuilder
->pNew
;
4245 pTerm
= sqlite3WhereFindTerm(pWC
, iCur
, -1, 0, WO_EQ
|WO_IS
, 0);
4247 testcase( pTerm
->eOperator
& WO_IS
);
4248 pLoop
->wsFlags
= WHERE_COLUMN_EQ
|WHERE_IPK
|WHERE_ONEROW
;
4249 pLoop
->aLTerm
[0] = pTerm
;
4251 pLoop
->u
.btree
.nEq
= 1;
4252 /* TUNING: Cost of a rowid lookup is 10 */
4253 pLoop
->rRun
= 33; /* 33==sqlite3LogEst(10) */
4255 for(pIdx
=pTab
->pIndex
; pIdx
; pIdx
=pIdx
->pNext
){
4257 assert( pLoop
->aLTermSpace
==pLoop
->aLTerm
);
4258 if( !IsUniqueIndex(pIdx
)
4259 || pIdx
->pPartIdxWhere
!=0
4260 || pIdx
->nKeyCol
>ArraySize(pLoop
->aLTermSpace
)
4262 opMask
= pIdx
->uniqNotNull
? (WO_EQ
|WO_IS
) : WO_EQ
;
4263 for(j
=0; j
<pIdx
->nKeyCol
; j
++){
4264 pTerm
= sqlite3WhereFindTerm(pWC
, iCur
, j
, 0, opMask
, pIdx
);
4265 if( pTerm
==0 ) break;
4266 testcase( pTerm
->eOperator
& WO_IS
);
4267 pLoop
->aLTerm
[j
] = pTerm
;
4269 if( j
!=pIdx
->nKeyCol
) continue;
4270 pLoop
->wsFlags
= WHERE_COLUMN_EQ
|WHERE_ONEROW
|WHERE_INDEXED
;
4271 if( pIdx
->isCovering
|| (pItem
->colUsed
& ~columnsInIndex(pIdx
))==0 ){
4272 pLoop
->wsFlags
|= WHERE_IDX_ONLY
;
4275 pLoop
->u
.btree
.nEq
= j
;
4276 pLoop
->u
.btree
.pIndex
= pIdx
;
4277 /* TUNING: Cost of a unique index lookup is 15 */
4278 pLoop
->rRun
= 39; /* 39==sqlite3LogEst(15) */
4282 if( pLoop
->wsFlags
){
4283 pLoop
->nOut
= (LogEst
)1;
4284 pWInfo
->a
[0].pWLoop
= pLoop
;
4285 assert( pWInfo
->sMaskSet
.n
==1 && iCur
==pWInfo
->sMaskSet
.ix
[0] );
4286 pLoop
->maskSelf
= 1; /* sqlite3WhereGetMask(&pWInfo->sMaskSet, iCur); */
4287 pWInfo
->a
[0].iTabCur
= iCur
;
4288 pWInfo
->nRowOut
= 1;
4289 if( pWInfo
->pOrderBy
) pWInfo
->nOBSat
= pWInfo
->pOrderBy
->nExpr
;
4290 if( pWInfo
->wctrlFlags
& WHERE_WANT_DISTINCT
){
4291 pWInfo
->eDistinct
= WHERE_DISTINCT_UNIQUE
;
4302 ** Helper function for exprIsDeterministic().
4304 static int exprNodeIsDeterministic(Walker
*pWalker
, Expr
*pExpr
){
4305 if( pExpr
->op
==TK_FUNCTION
&& ExprHasProperty(pExpr
, EP_ConstFunc
)==0 ){
4309 return WRC_Continue
;
4313 ** Return true if the expression contains no non-deterministic SQL
4314 ** functions. Do not consider non-deterministic SQL functions that are
4315 ** part of sub-select statements.
4317 static int exprIsDeterministic(Expr
*p
){
4319 memset(&w
, 0, sizeof(w
));
4321 w
.xExprCallback
= exprNodeIsDeterministic
;
4322 sqlite3WalkExpr(&w
, p
);
4327 ** Generate the beginning of the loop used for WHERE clause processing.
4328 ** The return value is a pointer to an opaque structure that contains
4329 ** information needed to terminate the loop. Later, the calling routine
4330 ** should invoke sqlite3WhereEnd() with the return value of this function
4331 ** in order to complete the WHERE clause processing.
4333 ** If an error occurs, this routine returns NULL.
4335 ** The basic idea is to do a nested loop, one loop for each table in
4336 ** the FROM clause of a select. (INSERT and UPDATE statements are the
4337 ** same as a SELECT with only a single table in the FROM clause.) For
4338 ** example, if the SQL is this:
4340 ** SELECT * FROM t1, t2, t3 WHERE ...;
4342 ** Then the code generated is conceptually like the following:
4344 ** foreach row1 in t1 do \ Code generated
4345 ** foreach row2 in t2 do |-- by sqlite3WhereBegin()
4346 ** foreach row3 in t3 do /
4348 ** end \ Code generated
4349 ** end |-- by sqlite3WhereEnd()
4352 ** Note that the loops might not be nested in the order in which they
4353 ** appear in the FROM clause if a different order is better able to make
4354 ** use of indices. Note also that when the IN operator appears in
4355 ** the WHERE clause, it might result in additional nested loops for
4356 ** scanning through all values on the right-hand side of the IN.
4358 ** There are Btree cursors associated with each table. t1 uses cursor
4359 ** number pTabList->a[0].iCursor. t2 uses the cursor pTabList->a[1].iCursor.
4360 ** And so forth. This routine generates code to open those VDBE cursors
4361 ** and sqlite3WhereEnd() generates the code to close them.
4363 ** The code that sqlite3WhereBegin() generates leaves the cursors named
4364 ** in pTabList pointing at their appropriate entries. The [...] code
4365 ** can use OP_Column and OP_Rowid opcodes on these cursors to extract
4366 ** data from the various tables of the loop.
4368 ** If the WHERE clause is empty, the foreach loops must each scan their
4369 ** entire tables. Thus a three-way join is an O(N^3) operation. But if
4370 ** the tables have indices and there are terms in the WHERE clause that
4371 ** refer to those indices, a complete table scan can be avoided and the
4372 ** code will run much faster. Most of the work of this routine is checking
4373 ** to see if there are indices that can be used to speed up the loop.
4375 ** Terms of the WHERE clause are also used to limit which rows actually
4376 ** make it to the "..." in the middle of the loop. After each "foreach",
4377 ** terms of the WHERE clause that use only terms in that loop and outer
4378 ** loops are evaluated and if false a jump is made around all subsequent
4379 ** inner loops (or around the "..." if the test occurs within the inner-
4384 ** An outer join of tables t1 and t2 is conceptally coded as follows:
4386 ** foreach row1 in t1 do
4388 ** foreach row2 in t2 do
4394 ** move the row2 cursor to a null row
4399 ** ORDER BY CLAUSE PROCESSING
4401 ** pOrderBy is a pointer to the ORDER BY clause (or the GROUP BY clause
4402 ** if the WHERE_GROUPBY flag is set in wctrlFlags) of a SELECT statement
4403 ** if there is one. If there is no ORDER BY clause or if this routine
4404 ** is called from an UPDATE or DELETE statement, then pOrderBy is NULL.
4406 ** The iIdxCur parameter is the cursor number of an index. If
4407 ** WHERE_OR_SUBCLAUSE is set, iIdxCur is the cursor number of an index
4408 ** to use for OR clause processing. The WHERE clause should use this
4409 ** specific cursor. If WHERE_ONEPASS_DESIRED is set, then iIdxCur is
4410 ** the first cursor in an array of cursors for all indices. iIdxCur should
4411 ** be used to compute the appropriate cursor depending on which index is
4414 WhereInfo
*sqlite3WhereBegin(
4415 Parse
*pParse
, /* The parser context */
4416 SrcList
*pTabList
, /* FROM clause: A list of all tables to be scanned */
4417 Expr
*pWhere
, /* The WHERE clause */
4418 ExprList
*pOrderBy
, /* An ORDER BY (or GROUP BY) clause, or NULL */
4419 ExprList
*pResultSet
, /* Query result set. Req'd for DISTINCT */
4420 u16 wctrlFlags
, /* The WHERE_* flags defined in sqliteInt.h */
4421 int iAuxArg
/* If WHERE_OR_SUBCLAUSE is set, index cursor number
4422 ** If WHERE_USE_LIMIT, then the limit amount */
4424 int nByteWInfo
; /* Num. bytes allocated for WhereInfo struct */
4425 int nTabList
; /* Number of elements in pTabList */
4426 WhereInfo
*pWInfo
; /* Will become the return value of this function */
4427 Vdbe
*v
= pParse
->pVdbe
; /* The virtual database engine */
4428 Bitmask notReady
; /* Cursors that are not yet positioned */
4429 WhereLoopBuilder sWLB
; /* The WhereLoop builder */
4430 WhereMaskSet
*pMaskSet
; /* The expression mask set */
4431 WhereLevel
*pLevel
; /* A single level in pWInfo->a[] */
4432 WhereLoop
*pLoop
; /* Pointer to a single WhereLoop object */
4433 int ii
; /* Loop counter */
4434 sqlite3
*db
; /* Database connection */
4435 int rc
; /* Return code */
4436 u8 bFordelete
= 0; /* OPFLAG_FORDELETE or zero, as appropriate */
4438 assert( (wctrlFlags
& WHERE_ONEPASS_MULTIROW
)==0 || (
4439 (wctrlFlags
& WHERE_ONEPASS_DESIRED
)!=0
4440 && (wctrlFlags
& WHERE_OR_SUBCLAUSE
)==0
4443 /* Only one of WHERE_OR_SUBCLAUSE or WHERE_USE_LIMIT */
4444 assert( (wctrlFlags
& WHERE_OR_SUBCLAUSE
)==0
4445 || (wctrlFlags
& WHERE_USE_LIMIT
)==0 );
4447 /* Variable initialization */
4449 memset(&sWLB
, 0, sizeof(sWLB
));
4451 /* An ORDER/GROUP BY clause of more than 63 terms cannot be optimized */
4452 testcase( pOrderBy
&& pOrderBy
->nExpr
==BMS
-1 );
4453 if( pOrderBy
&& pOrderBy
->nExpr
>=BMS
) pOrderBy
= 0;
4454 sWLB
.pOrderBy
= pOrderBy
;
4456 /* Disable the DISTINCT optimization if SQLITE_DistinctOpt is set via
4457 ** sqlite3_test_ctrl(SQLITE_TESTCTRL_OPTIMIZATIONS,...) */
4458 if( OptimizationDisabled(db
, SQLITE_DistinctOpt
) ){
4459 wctrlFlags
&= ~WHERE_WANT_DISTINCT
;
4462 /* The number of tables in the FROM clause is limited by the number of
4463 ** bits in a Bitmask
4465 testcase( pTabList
->nSrc
==BMS
);
4466 if( pTabList
->nSrc
>BMS
){
4467 sqlite3ErrorMsg(pParse
, "at most %d tables in a join", BMS
);
4471 /* This function normally generates a nested loop for all tables in
4472 ** pTabList. But if the WHERE_OR_SUBCLAUSE flag is set, then we should
4473 ** only generate code for the first table in pTabList and assume that
4474 ** any cursors associated with subsequent tables are uninitialized.
4476 nTabList
= (wctrlFlags
& WHERE_OR_SUBCLAUSE
) ? 1 : pTabList
->nSrc
;
4478 /* Allocate and initialize the WhereInfo structure that will become the
4479 ** return value. A single allocation is used to store the WhereInfo
4480 ** struct, the contents of WhereInfo.a[], the WhereClause structure
4481 ** and the WhereMaskSet structure. Since WhereClause contains an 8-byte
4482 ** field (type Bitmask) it must be aligned on an 8-byte boundary on
4483 ** some architectures. Hence the ROUND8() below.
4485 nByteWInfo
= ROUND8(sizeof(WhereInfo
)+(nTabList
-1)*sizeof(WhereLevel
));
4486 pWInfo
= sqlite3DbMallocRawNN(db
, nByteWInfo
+ sizeof(WhereLoop
));
4487 if( db
->mallocFailed
){
4488 sqlite3DbFree(db
, pWInfo
);
4490 goto whereBeginError
;
4492 pWInfo
->pParse
= pParse
;
4493 pWInfo
->pTabList
= pTabList
;
4494 pWInfo
->pOrderBy
= pOrderBy
;
4495 pWInfo
->pWhere
= pWhere
;
4496 pWInfo
->pResultSet
= pResultSet
;
4497 pWInfo
->aiCurOnePass
[0] = pWInfo
->aiCurOnePass
[1] = -1;
4498 pWInfo
->nLevel
= nTabList
;
4499 pWInfo
->iBreak
= pWInfo
->iContinue
= sqlite3VdbeMakeLabel(v
);
4500 pWInfo
->wctrlFlags
= wctrlFlags
;
4501 pWInfo
->iLimit
= iAuxArg
;
4502 pWInfo
->savedNQueryLoop
= pParse
->nQueryLoop
;
4503 memset(&pWInfo
->nOBSat
, 0,
4504 offsetof(WhereInfo
,sWC
) - offsetof(WhereInfo
,nOBSat
));
4505 memset(&pWInfo
->a
[0], 0, sizeof(WhereLoop
)+nTabList
*sizeof(WhereLevel
));
4506 assert( pWInfo
->eOnePass
==ONEPASS_OFF
); /* ONEPASS defaults to OFF */
4507 pMaskSet
= &pWInfo
->sMaskSet
;
4508 sWLB
.pWInfo
= pWInfo
;
4509 sWLB
.pWC
= &pWInfo
->sWC
;
4510 sWLB
.pNew
= (WhereLoop
*)(((char*)pWInfo
)+nByteWInfo
);
4511 assert( EIGHT_BYTE_ALIGNMENT(sWLB
.pNew
) );
4512 whereLoopInit(sWLB
.pNew
);
4514 sWLB
.pNew
->cId
= '*';
4517 /* Split the WHERE clause into separate subexpressions where each
4518 ** subexpression is separated by an AND operator.
4520 initMaskSet(pMaskSet
);
4521 sqlite3WhereClauseInit(&pWInfo
->sWC
, pWInfo
);
4522 sqlite3WhereSplit(&pWInfo
->sWC
, pWhere
, TK_AND
);
4524 /* Special case: No FROM clause
4527 if( pOrderBy
) pWInfo
->nOBSat
= pOrderBy
->nExpr
;
4528 if( wctrlFlags
& WHERE_WANT_DISTINCT
){
4529 pWInfo
->eDistinct
= WHERE_DISTINCT_UNIQUE
;
4533 /* Assign a bit from the bitmask to every term in the FROM clause.
4535 ** The N-th term of the FROM clause is assigned a bitmask of 1<<N.
4537 ** The rule of the previous sentence ensures thta if X is the bitmask for
4538 ** a table T, then X-1 is the bitmask for all other tables to the left of T.
4539 ** Knowing the bitmask for all tables to the left of a left join is
4540 ** important. Ticket #3015.
4542 ** Note that bitmasks are created for all pTabList->nSrc tables in
4543 ** pTabList, not just the first nTabList tables. nTabList is normally
4544 ** equal to pTabList->nSrc but might be shortened to 1 if the
4545 ** WHERE_OR_SUBCLAUSE flag is set.
4547 for(ii
=0; ii
<pTabList
->nSrc
; ii
++){
4548 createMask(pMaskSet
, pTabList
->a
[ii
].iCursor
);
4549 sqlite3WhereTabFuncArgs(pParse
, &pTabList
->a
[ii
], &pWInfo
->sWC
);
4554 for(ii
=0; ii
<pTabList
->nSrc
; ii
++){
4555 Bitmask m
= sqlite3WhereGetMask(pMaskSet
, pTabList
->a
[ii
].iCursor
);
4562 /* Analyze all of the subexpressions. */
4563 sqlite3WhereExprAnalyze(pTabList
, &pWInfo
->sWC
);
4564 if( db
->mallocFailed
) goto whereBeginError
;
4566 /* Special case: WHERE terms that do not refer to any tables in the join
4567 ** (constant expressions). Evaluate each such term, and jump over all the
4568 ** generated code if the result is not true.
4570 ** Do not do this if the expression contains non-deterministic functions
4571 ** that are not within a sub-select. This is not strictly required, but
4572 ** preserves SQLite's legacy behaviour in the following two cases:
4574 ** FROM ... WHERE random()>0; -- eval random() once per row
4575 ** FROM ... WHERE (SELECT random())>0; -- eval random() once overall
4577 for(ii
=0; ii
<sWLB
.pWC
->nTerm
; ii
++){
4578 WhereTerm
*pT
= &sWLB
.pWC
->a
[ii
];
4579 if( pT
->prereqAll
==0 && (nTabList
==0 || exprIsDeterministic(pT
->pExpr
)) ){
4580 sqlite3ExprIfFalse(pParse
, pT
->pExpr
, pWInfo
->iBreak
, SQLITE_JUMPIFNULL
);
4581 pT
->wtFlags
|= TERM_CODED
;
4585 if( wctrlFlags
& WHERE_WANT_DISTINCT
){
4586 if( isDistinctRedundant(pParse
, pTabList
, &pWInfo
->sWC
, pResultSet
) ){
4587 /* The DISTINCT marking is pointless. Ignore it. */
4588 pWInfo
->eDistinct
= WHERE_DISTINCT_UNIQUE
;
4589 }else if( pOrderBy
==0 ){
4590 /* Try to ORDER BY the result set to make distinct processing easier */
4591 pWInfo
->wctrlFlags
|= WHERE_DISTINCTBY
;
4592 pWInfo
->pOrderBy
= pResultSet
;
4596 /* Construct the WhereLoop objects */
4597 #if defined(WHERETRACE_ENABLED)
4598 if( sqlite3WhereTrace
& 0xffff ){
4599 sqlite3DebugPrintf("*** Optimizer Start *** (wctrlFlags: 0x%x",wctrlFlags
);
4600 if( wctrlFlags
& WHERE_USE_LIMIT
){
4601 sqlite3DebugPrintf(", limit: %d", iAuxArg
);
4603 sqlite3DebugPrintf(")\n");
4605 if( sqlite3WhereTrace
& 0x100 ){ /* Display all terms of the WHERE clause */
4606 sqlite3WhereClausePrint(sWLB
.pWC
);
4610 if( nTabList
!=1 || whereShortCut(&sWLB
)==0 ){
4611 rc
= whereLoopAddAll(&sWLB
);
4612 if( rc
) goto whereBeginError
;
4614 #ifdef WHERETRACE_ENABLED
4615 if( sqlite3WhereTrace
){ /* Display all of the WhereLoop objects */
4618 static const char zLabel
[] = "0123456789abcdefghijklmnopqrstuvwyxz"
4619 "ABCDEFGHIJKLMNOPQRSTUVWYXZ";
4620 for(p
=pWInfo
->pLoops
, i
=0; p
; p
=p
->pNextLoop
, i
++){
4621 p
->cId
= zLabel
[i
%(sizeof(zLabel
)-1)];
4622 whereLoopPrint(p
, sWLB
.pWC
);
4627 wherePathSolver(pWInfo
, 0);
4628 if( db
->mallocFailed
) goto whereBeginError
;
4629 if( pWInfo
->pOrderBy
){
4630 wherePathSolver(pWInfo
, pWInfo
->nRowOut
+1);
4631 if( db
->mallocFailed
) goto whereBeginError
;
4634 if( pWInfo
->pOrderBy
==0 && (db
->flags
& SQLITE_ReverseOrder
)!=0 ){
4635 pWInfo
->revMask
= ALLBITS
;
4637 if( pParse
->nErr
|| NEVER(db
->mallocFailed
) ){
4638 goto whereBeginError
;
4640 #ifdef WHERETRACE_ENABLED
4641 if( sqlite3WhereTrace
){
4642 sqlite3DebugPrintf("---- Solution nRow=%d", pWInfo
->nRowOut
);
4643 if( pWInfo
->nOBSat
>0 ){
4644 sqlite3DebugPrintf(" ORDERBY=%d,0x%llx", pWInfo
->nOBSat
, pWInfo
->revMask
);
4646 switch( pWInfo
->eDistinct
){
4647 case WHERE_DISTINCT_UNIQUE
: {
4648 sqlite3DebugPrintf(" DISTINCT=unique");
4651 case WHERE_DISTINCT_ORDERED
: {
4652 sqlite3DebugPrintf(" DISTINCT=ordered");
4655 case WHERE_DISTINCT_UNORDERED
: {
4656 sqlite3DebugPrintf(" DISTINCT=unordered");
4660 sqlite3DebugPrintf("\n");
4661 for(ii
=0; ii
<pWInfo
->nLevel
; ii
++){
4662 whereLoopPrint(pWInfo
->a
[ii
].pWLoop
, sWLB
.pWC
);
4666 /* Attempt to omit tables from the join that do not effect the result */
4667 if( pWInfo
->nLevel
>=2
4669 && OptimizationEnabled(db
, SQLITE_OmitNoopJoin
)
4671 Bitmask tabUsed
= sqlite3WhereExprListUsage(pMaskSet
, pResultSet
);
4672 if( sWLB
.pOrderBy
){
4673 tabUsed
|= sqlite3WhereExprListUsage(pMaskSet
, sWLB
.pOrderBy
);
4675 while( pWInfo
->nLevel
>=2 ){
4676 WhereTerm
*pTerm
, *pEnd
;
4677 pLoop
= pWInfo
->a
[pWInfo
->nLevel
-1].pWLoop
;
4678 if( (pWInfo
->pTabList
->a
[pLoop
->iTab
].fg
.jointype
& JT_LEFT
)==0 ) break;
4679 if( (wctrlFlags
& WHERE_WANT_DISTINCT
)==0
4680 && (pLoop
->wsFlags
& WHERE_ONEROW
)==0
4684 if( (tabUsed
& pLoop
->maskSelf
)!=0 ) break;
4685 pEnd
= sWLB
.pWC
->a
+ sWLB
.pWC
->nTerm
;
4686 for(pTerm
=sWLB
.pWC
->a
; pTerm
<pEnd
; pTerm
++){
4687 if( (pTerm
->prereqAll
& pLoop
->maskSelf
)!=0
4688 && !ExprHasProperty(pTerm
->pExpr
, EP_FromJoin
)
4693 if( pTerm
<pEnd
) break;
4694 WHERETRACE(0xffff, ("-> drop loop %c not used\n", pLoop
->cId
));
4699 WHERETRACE(0xffff,("*** Optimizer Finished ***\n"));
4700 pWInfo
->pParse
->nQueryLoop
+= pWInfo
->nRowOut
;
4702 /* If the caller is an UPDATE or DELETE statement that is requesting
4703 ** to use a one-pass algorithm, determine if this is appropriate.
4705 assert( (wctrlFlags
& WHERE_ONEPASS_DESIRED
)==0 || pWInfo
->nLevel
==1 );
4706 if( (wctrlFlags
& WHERE_ONEPASS_DESIRED
)!=0 ){
4707 int wsFlags
= pWInfo
->a
[0].pWLoop
->wsFlags
;
4708 int bOnerow
= (wsFlags
& WHERE_ONEROW
)!=0;
4710 || ((wctrlFlags
& WHERE_ONEPASS_MULTIROW
)!=0
4711 && 0==(wsFlags
& WHERE_VIRTUALTABLE
))
4713 pWInfo
->eOnePass
= bOnerow
? ONEPASS_SINGLE
: ONEPASS_MULTI
;
4714 if( HasRowid(pTabList
->a
[0].pTab
) && (wsFlags
& WHERE_IDX_ONLY
) ){
4715 if( wctrlFlags
& WHERE_ONEPASS_MULTIROW
){
4716 bFordelete
= OPFLAG_FORDELETE
;
4718 pWInfo
->a
[0].pWLoop
->wsFlags
= (wsFlags
& ~WHERE_IDX_ONLY
);
4723 /* Open all tables in the pTabList and any indices selected for
4724 ** searching those tables.
4726 for(ii
=0, pLevel
=pWInfo
->a
; ii
<nTabList
; ii
++, pLevel
++){
4727 Table
*pTab
; /* Table to open */
4728 int iDb
; /* Index of database containing table/index */
4729 struct SrcList_item
*pTabItem
;
4731 pTabItem
= &pTabList
->a
[pLevel
->iFrom
];
4732 pTab
= pTabItem
->pTab
;
4733 iDb
= sqlite3SchemaToIndex(db
, pTab
->pSchema
);
4734 pLoop
= pLevel
->pWLoop
;
4735 if( (pTab
->tabFlags
& TF_Ephemeral
)!=0 || pTab
->pSelect
){
4738 #ifndef SQLITE_OMIT_VIRTUALTABLE
4739 if( (pLoop
->wsFlags
& WHERE_VIRTUALTABLE
)!=0 ){
4740 const char *pVTab
= (const char *)sqlite3GetVTable(db
, pTab
);
4741 int iCur
= pTabItem
->iCursor
;
4742 sqlite3VdbeAddOp4(v
, OP_VOpen
, iCur
, 0, 0, pVTab
, P4_VTAB
);
4743 }else if( IsVirtual(pTab
) ){
4747 if( (pLoop
->wsFlags
& WHERE_IDX_ONLY
)==0
4748 && (wctrlFlags
& WHERE_OR_SUBCLAUSE
)==0 ){
4749 int op
= OP_OpenRead
;
4750 if( pWInfo
->eOnePass
!=ONEPASS_OFF
){
4752 pWInfo
->aiCurOnePass
[0] = pTabItem
->iCursor
;
4754 sqlite3OpenTable(pParse
, pTabItem
->iCursor
, iDb
, pTab
, op
);
4755 assert( pTabItem
->iCursor
==pLevel
->iTabCur
);
4756 testcase( pWInfo
->eOnePass
==ONEPASS_OFF
&& pTab
->nCol
==BMS
-1 );
4757 testcase( pWInfo
->eOnePass
==ONEPASS_OFF
&& pTab
->nCol
==BMS
);
4758 if( pWInfo
->eOnePass
==ONEPASS_OFF
&& pTab
->nCol
<BMS
&& HasRowid(pTab
) ){
4759 Bitmask b
= pTabItem
->colUsed
;
4761 for(; b
; b
=b
>>1, n
++){}
4762 sqlite3VdbeChangeP4(v
, -1, SQLITE_INT_TO_PTR(n
), P4_INT32
);
4763 assert( n
<=pTab
->nCol
);
4765 #ifdef SQLITE_ENABLE_CURSOR_HINTS
4766 if( pLoop
->u
.btree
.pIndex
!=0 ){
4767 sqlite3VdbeChangeP5(v
, OPFLAG_SEEKEQ
|bFordelete
);
4771 sqlite3VdbeChangeP5(v
, bFordelete
);
4773 #ifdef SQLITE_ENABLE_COLUMN_USED_MASK
4774 sqlite3VdbeAddOp4Dup8(v
, OP_ColumnsUsed
, pTabItem
->iCursor
, 0, 0,
4775 (const u8
*)&pTabItem
->colUsed
, P4_INT64
);
4778 sqlite3TableLock(pParse
, iDb
, pTab
->tnum
, 0, pTab
->zName
);
4780 if( pLoop
->wsFlags
& WHERE_INDEXED
){
4781 Index
*pIx
= pLoop
->u
.btree
.pIndex
;
4783 int op
= OP_OpenRead
;
4784 /* iAuxArg is always set if to a positive value if ONEPASS is possible */
4785 assert( iAuxArg
!=0 || (pWInfo
->wctrlFlags
& WHERE_ONEPASS_DESIRED
)==0 );
4786 if( !HasRowid(pTab
) && IsPrimaryKeyIndex(pIx
)
4787 && (wctrlFlags
& WHERE_OR_SUBCLAUSE
)!=0
4789 /* This is one term of an OR-optimization using the PRIMARY KEY of a
4790 ** WITHOUT ROWID table. No need for a separate index */
4791 iIndexCur
= pLevel
->iTabCur
;
4793 }else if( pWInfo
->eOnePass
!=ONEPASS_OFF
){
4794 Index
*pJ
= pTabItem
->pTab
->pIndex
;
4795 iIndexCur
= iAuxArg
;
4796 assert( wctrlFlags
& WHERE_ONEPASS_DESIRED
);
4797 while( ALWAYS(pJ
) && pJ
!=pIx
){
4802 pWInfo
->aiCurOnePass
[1] = iIndexCur
;
4803 }else if( iAuxArg
&& (wctrlFlags
& WHERE_OR_SUBCLAUSE
)!=0 ){
4804 iIndexCur
= iAuxArg
;
4807 iIndexCur
= pParse
->nTab
++;
4809 pLevel
->iIdxCur
= iIndexCur
;
4810 assert( pIx
->pSchema
==pTab
->pSchema
);
4811 assert( iIndexCur
>=0 );
4813 sqlite3VdbeAddOp3(v
, op
, iIndexCur
, pIx
->tnum
, iDb
);
4814 sqlite3VdbeSetP4KeyInfo(pParse
, pIx
);
4815 if( (pLoop
->wsFlags
& WHERE_CONSTRAINT
)!=0
4816 && (pLoop
->wsFlags
& (WHERE_COLUMN_RANGE
|WHERE_SKIPSCAN
))==0
4817 && (pWInfo
->wctrlFlags
&WHERE_ORDERBY_MIN
)==0
4818 && pWInfo
->eDistinct
!=WHERE_DISTINCT_ORDERED
4820 sqlite3VdbeChangeP5(v
, OPFLAG_SEEKEQ
); /* Hint to COMDB2 */
4822 VdbeComment((v
, "%s", pIx
->zName
));
4823 #ifdef SQLITE_ENABLE_COLUMN_USED_MASK
4827 for(ii
=0; ii
<pIx
->nColumn
; ii
++){
4828 jj
= pIx
->aiColumn
[ii
];
4829 if( jj
<0 ) continue;
4830 if( jj
>63 ) jj
= 63;
4831 if( (pTabItem
->colUsed
& MASKBIT(jj
))==0 ) continue;
4832 colUsed
|= ((u64
)1)<<(ii
<63 ? ii
: 63);
4834 sqlite3VdbeAddOp4Dup8(v
, OP_ColumnsUsed
, iIndexCur
, 0, 0,
4835 (u8
*)&colUsed
, P4_INT64
);
4837 #endif /* SQLITE_ENABLE_COLUMN_USED_MASK */
4840 if( iDb
>=0 ) sqlite3CodeVerifySchema(pParse
, iDb
);
4842 pWInfo
->iTop
= sqlite3VdbeCurrentAddr(v
);
4843 if( db
->mallocFailed
) goto whereBeginError
;
4845 /* Generate the code to do the search. Each iteration of the for
4846 ** loop below generates code for a single nested loop of the VM
4849 notReady
= ~(Bitmask
)0;
4850 for(ii
=0; ii
<nTabList
; ii
++){
4853 pLevel
= &pWInfo
->a
[ii
];
4854 wsFlags
= pLevel
->pWLoop
->wsFlags
;
4855 #ifndef SQLITE_OMIT_AUTOMATIC_INDEX
4856 if( (pLevel
->pWLoop
->wsFlags
& WHERE_AUTO_INDEX
)!=0 ){
4857 constructAutomaticIndex(pParse
, &pWInfo
->sWC
,
4858 &pTabList
->a
[pLevel
->iFrom
], notReady
, pLevel
);
4859 if( db
->mallocFailed
) goto whereBeginError
;
4862 addrExplain
= sqlite3WhereExplainOneScan(
4863 pParse
, pTabList
, pLevel
, ii
, pLevel
->iFrom
, wctrlFlags
4865 pLevel
->addrBody
= sqlite3VdbeCurrentAddr(v
);
4866 notReady
= sqlite3WhereCodeOneLoopStart(pWInfo
, ii
, notReady
);
4867 pWInfo
->iContinue
= pLevel
->addrCont
;
4868 if( (wsFlags
&WHERE_MULTI_OR
)==0 && (wctrlFlags
&WHERE_OR_SUBCLAUSE
)==0 ){
4869 sqlite3WhereAddScanStatus(v
, pTabList
, pLevel
, addrExplain
);
4874 VdbeModuleComment((v
, "Begin WHERE-core"));
4877 /* Jump here if malloc fails */
4880 pParse
->nQueryLoop
= pWInfo
->savedNQueryLoop
;
4881 whereInfoFree(db
, pWInfo
);
4887 ** Generate the end of the WHERE loop. See comments on
4888 ** sqlite3WhereBegin() for additional information.
4890 void sqlite3WhereEnd(WhereInfo
*pWInfo
){
4891 Parse
*pParse
= pWInfo
->pParse
;
4892 Vdbe
*v
= pParse
->pVdbe
;
4896 SrcList
*pTabList
= pWInfo
->pTabList
;
4897 sqlite3
*db
= pParse
->db
;
4899 /* Generate loop termination code.
4901 VdbeModuleComment((v
, "End WHERE-core"));
4902 sqlite3ExprCacheClear(pParse
);
4903 for(i
=pWInfo
->nLevel
-1; i
>=0; i
--){
4905 pLevel
= &pWInfo
->a
[i
];
4906 pLoop
= pLevel
->pWLoop
;
4907 if( pLevel
->op
!=OP_Noop
){
4908 #ifndef SQLITE_DISABLE_SKIPAHEAD_DISTINCT
4912 if( pWInfo
->eDistinct
==WHERE_DISTINCT_ORDERED
4913 && (pLoop
->wsFlags
& WHERE_INDEXED
)!=0
4914 && (pIdx
= pLoop
->u
.btree
.pIndex
)->hasStat1
4915 && (n
= pLoop
->u
.btree
.nIdxCol
)>0
4916 && pIdx
->aiRowLogEst
[n
]>=36
4918 int r1
= pParse
->nMem
+1;
4921 sqlite3VdbeAddOp3(v
, OP_Column
, pLevel
->iIdxCur
, j
, r1
+j
);
4923 pParse
->nMem
+= n
+1;
4924 op
= pLevel
->op
==OP_Prev
? OP_SeekLT
: OP_SeekGT
;
4925 addrSeek
= sqlite3VdbeAddOp4Int(v
, op
, pLevel
->iIdxCur
, 0, r1
, n
);
4926 VdbeCoverageIf(v
, op
==OP_SeekLT
);
4927 VdbeCoverageIf(v
, op
==OP_SeekGT
);
4928 sqlite3VdbeAddOp2(v
, OP_Goto
, 1, pLevel
->p2
);
4930 #endif /* SQLITE_DISABLE_SKIPAHEAD_DISTINCT */
4931 /* The common case: Advance to the next row */
4932 sqlite3VdbeResolveLabel(v
, pLevel
->addrCont
);
4933 sqlite3VdbeAddOp3(v
, pLevel
->op
, pLevel
->p1
, pLevel
->p2
, pLevel
->p3
);
4934 sqlite3VdbeChangeP5(v
, pLevel
->p5
);
4936 VdbeCoverageIf(v
, pLevel
->op
==OP_Next
);
4937 VdbeCoverageIf(v
, pLevel
->op
==OP_Prev
);
4938 VdbeCoverageIf(v
, pLevel
->op
==OP_VNext
);
4939 #ifndef SQLITE_DISABLE_SKIPAHEAD_DISTINCT
4940 if( addrSeek
) sqlite3VdbeJumpHere(v
, addrSeek
);
4943 sqlite3VdbeResolveLabel(v
, pLevel
->addrCont
);
4945 if( pLoop
->wsFlags
& WHERE_IN_ABLE
&& pLevel
->u
.in
.nIn
>0 ){
4948 sqlite3VdbeResolveLabel(v
, pLevel
->addrNxt
);
4949 for(j
=pLevel
->u
.in
.nIn
, pIn
=&pLevel
->u
.in
.aInLoop
[j
-1]; j
>0; j
--, pIn
--){
4950 sqlite3VdbeJumpHere(v
, pIn
->addrInTop
+1);
4951 if( pIn
->eEndLoopOp
!=OP_Noop
){
4952 sqlite3VdbeAddOp2(v
, pIn
->eEndLoopOp
, pIn
->iCur
, pIn
->addrInTop
);
4954 VdbeCoverageIf(v
, pIn
->eEndLoopOp
==OP_PrevIfOpen
);
4955 VdbeCoverageIf(v
, pIn
->eEndLoopOp
==OP_NextIfOpen
);
4957 sqlite3VdbeJumpHere(v
, pIn
->addrInTop
-1);
4960 sqlite3VdbeResolveLabel(v
, pLevel
->addrBrk
);
4961 if( pLevel
->addrSkip
){
4962 sqlite3VdbeGoto(v
, pLevel
->addrSkip
);
4963 VdbeComment((v
, "next skip-scan on %s", pLoop
->u
.btree
.pIndex
->zName
));
4964 sqlite3VdbeJumpHere(v
, pLevel
->addrSkip
);
4965 sqlite3VdbeJumpHere(v
, pLevel
->addrSkip
-2);
4967 #ifndef SQLITE_LIKE_DOESNT_MATCH_BLOBS
4968 if( pLevel
->addrLikeRep
){
4969 sqlite3VdbeAddOp2(v
, OP_DecrJumpZero
, (int)(pLevel
->iLikeRepCntr
>>1),
4970 pLevel
->addrLikeRep
);
4974 if( pLevel
->iLeftJoin
){
4975 int ws
= pLoop
->wsFlags
;
4976 addr
= sqlite3VdbeAddOp1(v
, OP_IfPos
, pLevel
->iLeftJoin
); VdbeCoverage(v
);
4977 assert( (ws
& WHERE_IDX_ONLY
)==0 || (ws
& WHERE_INDEXED
)!=0 );
4978 if( (ws
& WHERE_IDX_ONLY
)==0 ){
4979 sqlite3VdbeAddOp1(v
, OP_NullRow
, pTabList
->a
[i
].iCursor
);
4981 if( (ws
& WHERE_INDEXED
)
4982 || ((ws
& WHERE_MULTI_OR
) && pLevel
->u
.pCovidx
)
4984 sqlite3VdbeAddOp1(v
, OP_NullRow
, pLevel
->iIdxCur
);
4986 if( pLevel
->op
==OP_Return
){
4987 sqlite3VdbeAddOp2(v
, OP_Gosub
, pLevel
->p1
, pLevel
->addrFirst
);
4989 sqlite3VdbeGoto(v
, pLevel
->addrFirst
);
4991 sqlite3VdbeJumpHere(v
, addr
);
4993 VdbeModuleComment((v
, "End WHERE-loop%d: %s", i
,
4994 pWInfo
->pTabList
->a
[pLevel
->iFrom
].pTab
->zName
));
4997 /* The "break" point is here, just past the end of the outer loop.
5000 sqlite3VdbeResolveLabel(v
, pWInfo
->iBreak
);
5002 assert( pWInfo
->nLevel
<=pTabList
->nSrc
);
5003 for(i
=0, pLevel
=pWInfo
->a
; i
<pWInfo
->nLevel
; i
++, pLevel
++){
5007 struct SrcList_item
*pTabItem
= &pTabList
->a
[pLevel
->iFrom
];
5008 Table
*pTab
= pTabItem
->pTab
;
5010 pLoop
= pLevel
->pWLoop
;
5012 /* For a co-routine, change all OP_Column references to the table of
5013 ** the co-routine into OP_Copy of result contained in a register.
5014 ** OP_Rowid becomes OP_Null.
5016 if( pTabItem
->fg
.viaCoroutine
){
5017 testcase( pParse
->db
->mallocFailed
);
5018 translateColumnToCopy(pParse
, pLevel
->addrBody
, pLevel
->iTabCur
,
5019 pTabItem
->regResult
, 0);
5023 /* If this scan uses an index, make VDBE code substitutions to read data
5024 ** from the index instead of from the table where possible. In some cases
5025 ** this optimization prevents the table from ever being read, which can
5026 ** yield a significant performance boost.
5028 ** Calls to the code generator in between sqlite3WhereBegin and
5029 ** sqlite3WhereEnd will have created code that references the table
5030 ** directly. This loop scans all that code looking for opcodes
5031 ** that reference the table and converts them into opcodes that
5032 ** reference the index.
5034 if( pLoop
->wsFlags
& (WHERE_INDEXED
|WHERE_IDX_ONLY
) ){
5035 pIdx
= pLoop
->u
.btree
.pIndex
;
5036 }else if( pLoop
->wsFlags
& WHERE_MULTI_OR
){
5037 pIdx
= pLevel
->u
.pCovidx
;
5040 && (pWInfo
->eOnePass
==ONEPASS_OFF
|| !HasRowid(pIdx
->pTable
))
5041 && !db
->mallocFailed
5043 last
= sqlite3VdbeCurrentAddr(v
);
5044 k
= pLevel
->addrBody
;
5045 pOp
= sqlite3VdbeGetOp(v
, k
);
5046 for(; k
<last
; k
++, pOp
++){
5047 if( pOp
->p1
!=pLevel
->iTabCur
) continue;
5048 if( pOp
->opcode
==OP_Column
){
5050 assert( pIdx
->pTable
==pTab
);
5051 if( !HasRowid(pTab
) ){
5052 Index
*pPk
= sqlite3PrimaryKeyIndex(pTab
);
5053 x
= pPk
->aiColumn
[x
];
5056 x
= sqlite3ColumnOfIndex(pIdx
, x
);
5059 pOp
->p1
= pLevel
->iIdxCur
;
5061 assert( (pLoop
->wsFlags
& WHERE_IDX_ONLY
)==0 || x
>=0
5062 || pWInfo
->eOnePass
);
5063 }else if( pOp
->opcode
==OP_Rowid
){
5064 pOp
->p1
= pLevel
->iIdxCur
;
5065 pOp
->opcode
= OP_IdxRowid
;
5066 }else if( pOp
->opcode
==OP_IfNullRow
){
5067 pOp
->p1
= pLevel
->iIdxCur
;
5075 pParse
->nQueryLoop
= pWInfo
->savedNQueryLoop
;
5076 whereInfoFree(db
, pWInfo
);