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Diffstat (limited to 'src/where.c')
| -rw-r--r-- | src/where.c | 7030 |
1 files changed, 7030 insertions, 0 deletions
diff --git a/src/where.c b/src/where.c new file mode 100644 index 0000000..7781366 --- /dev/null +++ b/src/where.c @@ -0,0 +1,7030 @@ +/* +** 2001 September 15 +** +** The author disclaims copyright to this source code. In place of +** a legal notice, here is a blessing: +** +** May you do good and not evil. +** May you find forgiveness for yourself and forgive others. +** May you share freely, never taking more than you give. +** +************************************************************************* +** This module contains C code that generates VDBE code used to process +** the WHERE clause of SQL statements. This module is responsible for +** generating the code that loops through a table looking for applicable +** rows. Indices are selected and used to speed the search when doing +** so is applicable. Because this module is responsible for selecting +** indices, you might also think of this module as the "query optimizer". +*/ +#include "sqliteInt.h" +#include "whereInt.h" + +/* +** Extra information appended to the end of sqlite3_index_info but not +** visible to the xBestIndex function, at least not directly. The +** sqlite3_vtab_collation() interface knows how to reach it, however. +** +** This object is not an API and can be changed from one release to the +** next. As long as allocateIndexInfo() and sqlite3_vtab_collation() +** agree on the structure, all will be well. +*/ +typedef struct HiddenIndexInfo HiddenIndexInfo; +struct HiddenIndexInfo { + WhereClause *pWC; /* The Where clause being analyzed */ + Parse *pParse; /* The parsing context */ + int eDistinct; /* Value to return from sqlite3_vtab_distinct() */ + u32 mIn; /* Mask of terms that are <col> IN (...) */ + u32 mHandleIn; /* Terms that vtab will handle as <col> IN (...) */ + sqlite3_value *aRhs[1]; /* RHS values for constraints. MUST BE LAST + ** because extra space is allocated to hold up + ** to nTerm such values */ +}; + +/* Forward declaration of methods */ +static int whereLoopResize(sqlite3*, WhereLoop*, int); + +/* +** Return the estimated number of output rows from a WHERE clause +*/ +LogEst sqlite3WhereOutputRowCount(WhereInfo *pWInfo){ + return pWInfo->nRowOut; +} + +/* +** Return one of the WHERE_DISTINCT_xxxxx values to indicate how this +** WHERE clause returns outputs for DISTINCT processing. +*/ +int sqlite3WhereIsDistinct(WhereInfo *pWInfo){ + return pWInfo->eDistinct; +} + +/* +** Return the number of ORDER BY terms that are satisfied by the +** WHERE clause. A return of 0 means that the output must be +** completely sorted. A return equal to the number of ORDER BY +** terms means that no sorting is needed at all. A return that +** is positive but less than the number of ORDER BY terms means that +** block sorting is required. +*/ +int sqlite3WhereIsOrdered(WhereInfo *pWInfo){ + return pWInfo->nOBSat<0 ? 0 : pWInfo->nOBSat; +} + +/* +** In the ORDER BY LIMIT optimization, if the inner-most loop is known +** to emit rows in increasing order, and if the last row emitted by the +** inner-most loop did not fit within the sorter, then we can skip all +** subsequent rows for the current iteration of the inner loop (because they +** will not fit in the sorter either) and continue with the second inner +** loop - the loop immediately outside the inner-most. +** +** When a row does not fit in the sorter (because the sorter already +** holds LIMIT+OFFSET rows that are smaller), then a jump is made to the +** label returned by this function. +** +** If the ORDER BY LIMIT optimization applies, the jump destination should +** be the continuation for the second-inner-most loop. If the ORDER BY +** LIMIT optimization does not apply, then the jump destination should +** be the continuation for the inner-most loop. +** +** It is always safe for this routine to return the continuation of the +** inner-most loop, in the sense that a correct answer will result. +** Returning the continuation the second inner loop is an optimization +** that might make the code run a little faster, but should not change +** the final answer. +*/ +int sqlite3WhereOrderByLimitOptLabel(WhereInfo *pWInfo){ + WhereLevel *pInner; + if( !pWInfo->bOrderedInnerLoop ){ + /* The ORDER BY LIMIT optimization does not apply. Jump to the + ** continuation of the inner-most loop. */ + return pWInfo->iContinue; + } + pInner = &pWInfo->a[pWInfo->nLevel-1]; + assert( pInner->addrNxt!=0 ); + return pInner->pRJ ? pWInfo->iContinue : pInner->addrNxt; +} + +/* +** While generating code for the min/max optimization, after handling +** the aggregate-step call to min() or max(), check to see if any +** additional looping is required. If the output order is such that +** we are certain that the correct answer has already been found, then +** code an OP_Goto to by pass subsequent processing. +** +** Any extra OP_Goto that is coded here is an optimization. The +** correct answer should be obtained regardless. This OP_Goto just +** makes the answer appear faster. +*/ +void sqlite3WhereMinMaxOptEarlyOut(Vdbe *v, WhereInfo *pWInfo){ + WhereLevel *pInner; + int i; + if( !pWInfo->bOrderedInnerLoop ) return; + if( pWInfo->nOBSat==0 ) return; + for(i=pWInfo->nLevel-1; i>=0; i--){ + pInner = &pWInfo->a[i]; + if( (pInner->pWLoop->wsFlags & WHERE_COLUMN_IN)!=0 ){ + sqlite3VdbeGoto(v, pInner->addrNxt); + return; + } + } + sqlite3VdbeGoto(v, pWInfo->iBreak); +} + +/* +** Return the VDBE address or label to jump to in order to continue +** immediately with the next row of a WHERE clause. +*/ +int sqlite3WhereContinueLabel(WhereInfo *pWInfo){ + assert( pWInfo->iContinue!=0 ); + return pWInfo->iContinue; +} + +/* +** Return the VDBE address or label to jump to in order to break +** out of a WHERE loop. +*/ +int sqlite3WhereBreakLabel(WhereInfo *pWInfo){ + return pWInfo->iBreak; +} + +/* +** Return ONEPASS_OFF (0) if an UPDATE or DELETE statement is unable to +** operate directly on the rowids returned by a WHERE clause. Return +** ONEPASS_SINGLE (1) if the statement can operation directly because only +** a single row is to be changed. Return ONEPASS_MULTI (2) if the one-pass +** optimization can be used on multiple +** +** If the ONEPASS optimization is used (if this routine returns true) +** then also write the indices of open cursors used by ONEPASS +** into aiCur[0] and aiCur[1]. iaCur[0] gets the cursor of the data +** table and iaCur[1] gets the cursor used by an auxiliary index. +** Either value may be -1, indicating that cursor is not used. +** Any cursors returned will have been opened for writing. +** +** aiCur[0] and aiCur[1] both get -1 if the where-clause logic is +** unable to use the ONEPASS optimization. +*/ +int sqlite3WhereOkOnePass(WhereInfo *pWInfo, int *aiCur){ + memcpy(aiCur, pWInfo->aiCurOnePass, sizeof(int)*2); +#ifdef WHERETRACE_ENABLED + if( sqlite3WhereTrace && pWInfo->eOnePass!=ONEPASS_OFF ){ + sqlite3DebugPrintf("%s cursors: %d %d\n", + pWInfo->eOnePass==ONEPASS_SINGLE ? "ONEPASS_SINGLE" : "ONEPASS_MULTI", + aiCur[0], aiCur[1]); + } +#endif + return pWInfo->eOnePass; +} + +/* +** Return TRUE if the WHERE loop uses the OP_DeferredSeek opcode to move +** the data cursor to the row selected by the index cursor. +*/ +int sqlite3WhereUsesDeferredSeek(WhereInfo *pWInfo){ + return pWInfo->bDeferredSeek; +} + +/* +** Move the content of pSrc into pDest +*/ +static void whereOrMove(WhereOrSet *pDest, WhereOrSet *pSrc){ + pDest->n = pSrc->n; + memcpy(pDest->a, pSrc->a, pDest->n*sizeof(pDest->a[0])); +} + +/* +** Try to insert a new prerequisite/cost entry into the WhereOrSet pSet. +** +** The new entry might overwrite an existing entry, or it might be +** appended, or it might be discarded. Do whatever is the right thing +** so that pSet keeps the N_OR_COST best entries seen so far. +*/ +static int whereOrInsert( + WhereOrSet *pSet, /* The WhereOrSet to be updated */ + Bitmask prereq, /* Prerequisites of the new entry */ + LogEst rRun, /* Run-cost of the new entry */ + LogEst nOut /* Number of outputs for the new entry */ +){ + u16 i; + WhereOrCost *p; + for(i=pSet->n, p=pSet->a; i>0; i--, p++){ + if( rRun<=p->rRun && (prereq & p->prereq)==prereq ){ + goto whereOrInsert_done; + } + if( p->rRun<=rRun && (p->prereq & prereq)==p->prereq ){ + return 0; + } + } + if( pSet->n<N_OR_COST ){ + p = &pSet->a[pSet->n++]; + p->nOut = nOut; + }else{ + p = pSet->a; + for(i=1; i<pSet->n; i++){ + if( p->rRun>pSet->a[i].rRun ) p = pSet->a + i; + } + if( p->rRun<=rRun ) return 0; + } +whereOrInsert_done: + p->prereq = prereq; + p->rRun = rRun; + if( p->nOut>nOut ) p->nOut = nOut; + return 1; +} + +/* +** Return the bitmask for the given cursor number. Return 0 if +** iCursor is not in the set. +*/ +Bitmask sqlite3WhereGetMask(WhereMaskSet *pMaskSet, int iCursor){ + int i; + assert( pMaskSet->n<=(int)sizeof(Bitmask)*8 ); + assert( pMaskSet->n>0 || pMaskSet->ix[0]<0 ); + assert( iCursor>=-1 ); + if( pMaskSet->ix[0]==iCursor ){ + return 1; + } + for(i=1; i<pMaskSet->n; i++){ + if( pMaskSet->ix[i]==iCursor ){ + return MASKBIT(i); + } + } + return 0; +} + +/* Allocate memory that is automatically freed when pWInfo is freed. +*/ +void *sqlite3WhereMalloc(WhereInfo *pWInfo, u64 nByte){ + WhereMemBlock *pBlock; + pBlock = sqlite3DbMallocRawNN(pWInfo->pParse->db, nByte+sizeof(*pBlock)); + if( pBlock ){ + pBlock->pNext = pWInfo->pMemToFree; + pBlock->sz = nByte; + pWInfo->pMemToFree = pBlock; + pBlock++; + } + return (void*)pBlock; +} +void *sqlite3WhereRealloc(WhereInfo *pWInfo, void *pOld, u64 nByte){ + void *pNew = sqlite3WhereMalloc(pWInfo, nByte); + if( pNew && pOld ){ + WhereMemBlock *pOldBlk = (WhereMemBlock*)pOld; + pOldBlk--; + assert( pOldBlk->sz<nByte ); + memcpy(pNew, pOld, pOldBlk->sz); + } + return pNew; +} + +/* +** Create a new mask for cursor iCursor. +** +** There is one cursor per table in the FROM clause. The number of +** tables in the FROM clause is limited by a test early in the +** sqlite3WhereBegin() routine. So we know that the pMaskSet->ix[] +** array will never overflow. +*/ +static void createMask(WhereMaskSet *pMaskSet, int iCursor){ + assert( pMaskSet->n < ArraySize(pMaskSet->ix) ); + pMaskSet->ix[pMaskSet->n++] = iCursor; +} + +/* +** If the right-hand branch of the expression is a TK_COLUMN, then return +** a pointer to the right-hand branch. Otherwise, return NULL. +*/ +static Expr *whereRightSubexprIsColumn(Expr *p){ + p = sqlite3ExprSkipCollateAndLikely(p->pRight); + if( ALWAYS(p!=0) && p->op==TK_COLUMN && !ExprHasProperty(p, EP_FixedCol) ){ + return p; + } + return 0; +} + +/* +** Advance to the next WhereTerm that matches according to the criteria +** established when the pScan object was initialized by whereScanInit(). +** Return NULL if there are no more matching WhereTerms. +*/ +static WhereTerm *whereScanNext(WhereScan *pScan){ + int iCur; /* The cursor on the LHS of the term */ + i16 iColumn; /* The column on the LHS of the term. -1 for IPK */ + Expr *pX; /* An expression being tested */ + WhereClause *pWC; /* Shorthand for pScan->pWC */ + WhereTerm *pTerm; /* The term being tested */ + int k = pScan->k; /* Where to start scanning */ + + assert( pScan->iEquiv<=pScan->nEquiv ); + pWC = pScan->pWC; + while(1){ + iColumn = pScan->aiColumn[pScan->iEquiv-1]; + iCur = pScan->aiCur[pScan->iEquiv-1]; + assert( pWC!=0 ); + assert( iCur>=0 ); + do{ + for(pTerm=pWC->a+k; k<pWC->nTerm; k++, pTerm++){ + assert( (pTerm->eOperator & (WO_OR|WO_AND))==0 || pTerm->leftCursor<0 ); + if( pTerm->leftCursor==iCur + && pTerm->u.x.leftColumn==iColumn + && (iColumn!=XN_EXPR + || sqlite3ExprCompareSkip(pTerm->pExpr->pLeft, + pScan->pIdxExpr,iCur)==0) + && (pScan->iEquiv<=1 || !ExprHasProperty(pTerm->pExpr, EP_OuterON)) + ){ + if( (pTerm->eOperator & WO_EQUIV)!=0 + && pScan->nEquiv<ArraySize(pScan->aiCur) + && (pX = whereRightSubexprIsColumn(pTerm->pExpr))!=0 + ){ + int j; + for(j=0; j<pScan->nEquiv; j++){ + if( pScan->aiCur[j]==pX->iTable + && pScan->aiColumn[j]==pX->iColumn ){ + break; + } + } + if( j==pScan->nEquiv ){ + pScan->aiCur[j] = pX->iTable; + pScan->aiColumn[j] = pX->iColumn; + pScan->nEquiv++; + } + } + if( (pTerm->eOperator & pScan->opMask)!=0 ){ + /* Verify the affinity and collating sequence match */ + if( pScan->zCollName && (pTerm->eOperator & WO_ISNULL)==0 ){ + CollSeq *pColl; + Parse *pParse = pWC->pWInfo->pParse; + pX = pTerm->pExpr; + if( !sqlite3IndexAffinityOk(pX, pScan->idxaff) ){ + continue; + } + assert(pX->pLeft); + pColl = sqlite3ExprCompareCollSeq(pParse, pX); + if( pColl==0 ) pColl = pParse->db->pDfltColl; + if( sqlite3StrICmp(pColl->zName, pScan->zCollName) ){ + continue; + } + } + if( (pTerm->eOperator & (WO_EQ|WO_IS))!=0 + && (pX = pTerm->pExpr->pRight, ALWAYS(pX!=0)) + && pX->op==TK_COLUMN + && pX->iTable==pScan->aiCur[0] + && pX->iColumn==pScan->aiColumn[0] + ){ + testcase( pTerm->eOperator & WO_IS ); + continue; + } + pScan->pWC = pWC; + pScan->k = k+1; +#ifdef WHERETRACE_ENABLED + if( sqlite3WhereTrace & 0x20000 ){ + int ii; + sqlite3DebugPrintf("SCAN-TERM %p: nEquiv=%d", + pTerm, pScan->nEquiv); + for(ii=0; ii<pScan->nEquiv; ii++){ + sqlite3DebugPrintf(" {%d:%d}", + pScan->aiCur[ii], pScan->aiColumn[ii]); + } + sqlite3DebugPrintf("\n"); + } +#endif + return pTerm; + } + } + } + pWC = pWC->pOuter; + k = 0; + }while( pWC!=0 ); + if( pScan->iEquiv>=pScan->nEquiv ) break; + pWC = pScan->pOrigWC; + k = 0; + pScan->iEquiv++; + } + return 0; +} + +/* +** This is whereScanInit() for the case of an index on an expression. +** It is factored out into a separate tail-recursion subroutine so that +** the normal whereScanInit() routine, which is a high-runner, does not +** need to push registers onto the stack as part of its prologue. +*/ +static SQLITE_NOINLINE WhereTerm *whereScanInitIndexExpr(WhereScan *pScan){ + pScan->idxaff = sqlite3ExprAffinity(pScan->pIdxExpr); + return whereScanNext(pScan); +} + +/* +** Initialize a WHERE clause scanner object. Return a pointer to the +** first match. Return NULL if there are no matches. +** +** The scanner will be searching the WHERE clause pWC. It will look +** for terms of the form "X <op> <expr>" where X is column iColumn of table +** iCur. Or if pIdx!=0 then X is column iColumn of index pIdx. pIdx +** must be one of the indexes of table iCur. +** +** The <op> must be one of the operators described by opMask. +** +** If the search is for X and the WHERE clause contains terms of the +** form X=Y then this routine might also return terms of the form +** "Y <op> <expr>". The number of levels of transitivity is limited, +** but is enough to handle most commonly occurring SQL statements. +** +** If X is not the INTEGER PRIMARY KEY then X must be compatible with +** index pIdx. +*/ +static WhereTerm *whereScanInit( + WhereScan *pScan, /* The WhereScan object being initialized */ + WhereClause *pWC, /* The WHERE clause to be scanned */ + int iCur, /* Cursor to scan for */ + int iColumn, /* Column to scan for */ + u32 opMask, /* Operator(s) to scan for */ + Index *pIdx /* Must be compatible with this index */ +){ + pScan->pOrigWC = pWC; + pScan->pWC = pWC; + pScan->pIdxExpr = 0; + pScan->idxaff = 0; + pScan->zCollName = 0; + pScan->opMask = opMask; + pScan->k = 0; + pScan->aiCur[0] = iCur; + pScan->nEquiv = 1; + pScan->iEquiv = 1; + if( pIdx ){ + int j = iColumn; + iColumn = pIdx->aiColumn[j]; + if( iColumn==pIdx->pTable->iPKey ){ + iColumn = XN_ROWID; + }else if( iColumn>=0 ){ + pScan->idxaff = pIdx->pTable->aCol[iColumn].affinity; + pScan->zCollName = pIdx->azColl[j]; + }else if( iColumn==XN_EXPR ){ + pScan->pIdxExpr = pIdx->aColExpr->a[j].pExpr; + pScan->zCollName = pIdx->azColl[j]; + pScan->aiColumn[0] = XN_EXPR; + return whereScanInitIndexExpr(pScan); + } + }else if( iColumn==XN_EXPR ){ + return 0; + } + pScan->aiColumn[0] = iColumn; + return whereScanNext(pScan); +} + +/* +** Search for a term in the WHERE clause that is of the form "X <op> <expr>" +** where X is a reference to the iColumn of table iCur or of index pIdx +** if pIdx!=0 and <op> is one of the WO_xx operator codes specified by +** the op parameter. Return a pointer to the term. Return 0 if not found. +** +** If pIdx!=0 then it must be one of the indexes of table iCur. +** Search for terms matching the iColumn-th column of pIdx +** rather than the iColumn-th column of table iCur. +** +** The term returned might by Y=<expr> if there is another constraint in +** the WHERE clause that specifies that X=Y. Any such constraints will be +** identified by the WO_EQUIV bit in the pTerm->eOperator field. The +** aiCur[]/iaColumn[] arrays hold X and all its equivalents. There are 11 +** slots in aiCur[]/aiColumn[] so that means we can look for X plus up to 10 +** other equivalent values. Hence a search for X will return <expr> if X=A1 +** and A1=A2 and A2=A3 and ... and A9=A10 and A10=<expr>. +** +** If there are multiple terms in the WHERE clause of the form "X <op> <expr>" +** then try for the one with no dependencies on <expr> - in other words where +** <expr> is a constant expression of some kind. Only return entries of +** the form "X <op> Y" where Y is a column in another table if no terms of +** the form "X <op> <const-expr>" exist. If no terms with a constant RHS +** exist, try to return a term that does not use WO_EQUIV. +*/ +WhereTerm *sqlite3WhereFindTerm( + WhereClause *pWC, /* The WHERE clause to be searched */ + int iCur, /* Cursor number of LHS */ + int iColumn, /* Column number of LHS */ + Bitmask notReady, /* RHS must not overlap with this mask */ + u32 op, /* Mask of WO_xx values describing operator */ + Index *pIdx /* Must be compatible with this index, if not NULL */ +){ + WhereTerm *pResult = 0; + WhereTerm *p; + WhereScan scan; + + p = whereScanInit(&scan, pWC, iCur, iColumn, op, pIdx); + op &= WO_EQ|WO_IS; + while( p ){ + if( (p->prereqRight & notReady)==0 ){ + if( p->prereqRight==0 && (p->eOperator&op)!=0 ){ + testcase( p->eOperator & WO_IS ); + return p; + } + if( pResult==0 ) pResult = p; + } + p = whereScanNext(&scan); + } + return pResult; +} + +/* +** This function searches pList for an entry that matches the iCol-th column +** of index pIdx. +** +** If such an expression is found, its index in pList->a[] is returned. If +** no expression is found, -1 is returned. +*/ +static int findIndexCol( + Parse *pParse, /* Parse context */ + ExprList *pList, /* Expression list to search */ + int iBase, /* Cursor for table associated with pIdx */ + Index *pIdx, /* Index to match column of */ + int iCol /* Column of index to match */ +){ + int i; + const char *zColl = pIdx->azColl[iCol]; + + for(i=0; i<pList->nExpr; i++){ + Expr *p = sqlite3ExprSkipCollateAndLikely(pList->a[i].pExpr); + if( ALWAYS(p!=0) + && (p->op==TK_COLUMN || p->op==TK_AGG_COLUMN) + && p->iColumn==pIdx->aiColumn[iCol] + && p->iTable==iBase + ){ + CollSeq *pColl = sqlite3ExprNNCollSeq(pParse, pList->a[i].pExpr); + if( 0==sqlite3StrICmp(pColl->zName, zColl) ){ + return i; + } + } + } + + return -1; +} + +/* +** Return TRUE if the iCol-th column of index pIdx is NOT NULL +*/ +static int indexColumnNotNull(Index *pIdx, int iCol){ + int j; + assert( pIdx!=0 ); + assert( iCol>=0 && iCol<pIdx->nColumn ); + j = pIdx->aiColumn[iCol]; + if( j>=0 ){ + return pIdx->pTable->aCol[j].notNull; + }else if( j==(-1) ){ + return 1; + }else{ + assert( j==(-2) ); + return 0; /* Assume an indexed expression can always yield a NULL */ + + } +} + +/* +** Return true if the DISTINCT expression-list passed as the third argument +** is redundant. +** +** A DISTINCT list is redundant if any subset of the columns in the +** DISTINCT list are collectively unique and individually non-null. +*/ +static int isDistinctRedundant( + Parse *pParse, /* Parsing context */ + SrcList *pTabList, /* The FROM clause */ + WhereClause *pWC, /* The WHERE clause */ + ExprList *pDistinct /* The result set that needs to be DISTINCT */ +){ + Table *pTab; + Index *pIdx; + int i; + int iBase; + + /* If there is more than one table or sub-select in the FROM clause of + ** this query, then it will not be possible to show that the DISTINCT + ** clause is redundant. */ + if( pTabList->nSrc!=1 ) return 0; + iBase = pTabList->a[0].iCursor; + pTab = pTabList->a[0].pTab; + + /* If any of the expressions is an IPK column on table iBase, then return + ** true. Note: The (p->iTable==iBase) part of this test may be false if the + ** current SELECT is a correlated sub-query. + */ + for(i=0; i<pDistinct->nExpr; i++){ + Expr *p = sqlite3ExprSkipCollateAndLikely(pDistinct->a[i].pExpr); + if( NEVER(p==0) ) continue; + if( p->op!=TK_COLUMN && p->op!=TK_AGG_COLUMN ) continue; + if( p->iTable==iBase && p->iColumn<0 ) return 1; + } + + /* Loop through all indices on the table, checking each to see if it makes + ** the DISTINCT qualifier redundant. It does so if: + ** + ** 1. The index is itself UNIQUE, and + ** + ** 2. All of the columns in the index are either part of the pDistinct + ** list, or else the WHERE clause contains a term of the form "col=X", + ** where X is a constant value. The collation sequences of the + ** comparison and select-list expressions must match those of the index. + ** + ** 3. All of those index columns for which the WHERE clause does not + ** contain a "col=X" term are subject to a NOT NULL constraint. + */ + for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){ + if( !IsUniqueIndex(pIdx) ) continue; + if( pIdx->pPartIdxWhere ) continue; + for(i=0; i<pIdx->nKeyCol; i++){ + if( 0==sqlite3WhereFindTerm(pWC, iBase, i, ~(Bitmask)0, WO_EQ, pIdx) ){ + if( findIndexCol(pParse, pDistinct, iBase, pIdx, i)<0 ) break; + if( indexColumnNotNull(pIdx, i)==0 ) break; + } + } + if( i==pIdx->nKeyCol ){ + /* This index implies that the DISTINCT qualifier is redundant. */ + return 1; + } + } + + return 0; +} + + +/* +** Estimate the logarithm of the input value to base 2. +*/ +static LogEst estLog(LogEst N){ + return N<=10 ? 0 : sqlite3LogEst(N) - 33; +} + +/* +** Convert OP_Column opcodes to OP_Copy in previously generated code. +** +** This routine runs over generated VDBE code and translates OP_Column +** opcodes into OP_Copy when the table is being accessed via co-routine +** instead of via table lookup. +** +** If the iAutoidxCur is not zero, then any OP_Rowid instructions on +** cursor iTabCur are transformed into OP_Sequence opcode for the +** iAutoidxCur cursor, in order to generate unique rowids for the +** automatic index being generated. +*/ +static void translateColumnToCopy( + Parse *pParse, /* Parsing context */ + int iStart, /* Translate from this opcode to the end */ + int iTabCur, /* OP_Column/OP_Rowid references to this table */ + int iRegister, /* The first column is in this register */ + int iAutoidxCur /* If non-zero, cursor of autoindex being generated */ +){ + Vdbe *v = pParse->pVdbe; + VdbeOp *pOp = sqlite3VdbeGetOp(v, iStart); + int iEnd = sqlite3VdbeCurrentAddr(v); + if( pParse->db->mallocFailed ) return; + for(; iStart<iEnd; iStart++, pOp++){ + if( pOp->p1!=iTabCur ) continue; + if( pOp->opcode==OP_Column ){ +#ifdef SQLITE_DEBUG + if( pParse->db->flags & SQLITE_VdbeAddopTrace ){ + printf("TRANSLATE OP_Column to OP_Copy at %d\n", iStart); + } +#endif + pOp->opcode = OP_Copy; + pOp->p1 = pOp->p2 + iRegister; + pOp->p2 = pOp->p3; + pOp->p3 = 0; + pOp->p5 = 2; /* Cause the MEM_Subtype flag to be cleared */ + }else if( pOp->opcode==OP_Rowid ){ +#ifdef SQLITE_DEBUG + if( pParse->db->flags & SQLITE_VdbeAddopTrace ){ + printf("TRANSLATE OP_Rowid to OP_Sequence at %d\n", iStart); + } +#endif + pOp->opcode = OP_Sequence; + pOp->p1 = iAutoidxCur; +#ifdef SQLITE_ALLOW_ROWID_IN_VIEW + if( iAutoidxCur==0 ){ + pOp->opcode = OP_Null; + pOp->p3 = 0; + } +#endif + } + } +} + +/* +** Two routines for printing the content of an sqlite3_index_info +** structure. Used for testing and debugging only. If neither +** SQLITE_TEST or SQLITE_DEBUG are defined, then these routines +** are no-ops. +*/ +#if !defined(SQLITE_OMIT_VIRTUALTABLE) && defined(WHERETRACE_ENABLED) +static void whereTraceIndexInfoInputs(sqlite3_index_info *p){ + int i; + if( (sqlite3WhereTrace & 0x10)==0 ) return; + for(i=0; i<p->nConstraint; i++){ + sqlite3DebugPrintf( + " constraint[%d]: col=%d termid=%d op=%d usabled=%d collseq=%s\n", + i, + p->aConstraint[i].iColumn, + p->aConstraint[i].iTermOffset, + p->aConstraint[i].op, + p->aConstraint[i].usable, + sqlite3_vtab_collation(p,i)); + } + for(i=0; i<p->nOrderBy; i++){ + sqlite3DebugPrintf(" orderby[%d]: col=%d desc=%d\n", + i, + p->aOrderBy[i].iColumn, + p->aOrderBy[i].desc); + } +} +static void whereTraceIndexInfoOutputs(sqlite3_index_info *p){ + int i; + if( (sqlite3WhereTrace & 0x10)==0 ) return; + for(i=0; i<p->nConstraint; i++){ + sqlite3DebugPrintf(" usage[%d]: argvIdx=%d omit=%d\n", + i, + p->aConstraintUsage[i].argvIndex, + p->aConstraintUsage[i].omit); + } + sqlite3DebugPrintf(" idxNum=%d\n", p->idxNum); + sqlite3DebugPrintf(" idxStr=%s\n", p->idxStr); + sqlite3DebugPrintf(" orderByConsumed=%d\n", p->orderByConsumed); + sqlite3DebugPrintf(" estimatedCost=%g\n", p->estimatedCost); + sqlite3DebugPrintf(" estimatedRows=%lld\n", p->estimatedRows); +} +#else +#define whereTraceIndexInfoInputs(A) +#define whereTraceIndexInfoOutputs(A) +#endif + +/* +** We know that pSrc is an operand of an outer join. Return true if +** pTerm is a constraint that is compatible with that join. +** +** pTerm must be EP_OuterON if pSrc is the right operand of an +** outer join. pTerm can be either EP_OuterON or EP_InnerON if pSrc +** is the left operand of a RIGHT join. +** +** See https://sqlite.org/forum/forumpost/206d99a16dd9212f +** for an example of a WHERE clause constraints that may not be used on +** the right table of a RIGHT JOIN because the constraint implies a +** not-NULL condition on the left table of the RIGHT JOIN. +*/ +static int constraintCompatibleWithOuterJoin( + const WhereTerm *pTerm, /* WHERE clause term to check */ + const SrcItem *pSrc /* Table we are trying to access */ +){ + assert( (pSrc->fg.jointype&(JT_LEFT|JT_LTORJ|JT_RIGHT))!=0 ); /* By caller */ + testcase( (pSrc->fg.jointype & (JT_LEFT|JT_LTORJ|JT_RIGHT))==JT_LEFT ); + testcase( (pSrc->fg.jointype & (JT_LEFT|JT_LTORJ|JT_RIGHT))==JT_LTORJ ); + testcase( ExprHasProperty(pTerm->pExpr, EP_OuterON) ) + testcase( ExprHasProperty(pTerm->pExpr, EP_InnerON) ); + if( !ExprHasProperty(pTerm->pExpr, EP_OuterON|EP_InnerON) + || pTerm->pExpr->w.iJoin != pSrc->iCursor + ){ + return 0; + } + if( (pSrc->fg.jointype & (JT_LEFT|JT_RIGHT))!=0 + && ExprHasProperty(pTerm->pExpr, EP_InnerON) + ){ + return 0; + } + return 1; +} + + + +#ifndef SQLITE_OMIT_AUTOMATIC_INDEX +/* +** Return TRUE if the WHERE clause term pTerm is of a form where it +** could be used with an index to access pSrc, assuming an appropriate +** index existed. +*/ +static int termCanDriveIndex( + const WhereTerm *pTerm, /* WHERE clause term to check */ + const SrcItem *pSrc, /* Table we are trying to access */ + const Bitmask notReady /* Tables in outer loops of the join */ +){ + char aff; + if( pTerm->leftCursor!=pSrc->iCursor ) return 0; + if( (pTerm->eOperator & (WO_EQ|WO_IS))==0 ) return 0; + assert( (pSrc->fg.jointype & JT_RIGHT)==0 ); + if( (pSrc->fg.jointype & (JT_LEFT|JT_LTORJ|JT_RIGHT))!=0 + && !constraintCompatibleWithOuterJoin(pTerm,pSrc) + ){ + return 0; /* See https://sqlite.org/forum/forumpost/51e6959f61 */ + } + if( (pTerm->prereqRight & notReady)!=0 ) return 0; + assert( (pTerm->eOperator & (WO_OR|WO_AND))==0 ); + if( pTerm->u.x.leftColumn<0 ) return 0; + aff = pSrc->pTab->aCol[pTerm->u.x.leftColumn].affinity; + if( !sqlite3IndexAffinityOk(pTerm->pExpr, aff) ) return 0; + testcase( pTerm->pExpr->op==TK_IS ); + return 1; +} +#endif + + +#ifndef SQLITE_OMIT_AUTOMATIC_INDEX + +#ifdef SQLITE_ENABLE_STMT_SCANSTATUS +/* +** Argument pIdx represents an automatic index that the current statement +** will create and populate. Add an OP_Explain with text of the form: +** +** CREATE AUTOMATIC INDEX ON <table>(<cols>) [WHERE <expr>] +** +** This is only required if sqlite3_stmt_scanstatus() is enabled, to +** associate an SQLITE_SCANSTAT_NCYCLE and SQLITE_SCANSTAT_NLOOP +** values with. In order to avoid breaking legacy code and test cases, +** the OP_Explain is not added if this is an EXPLAIN QUERY PLAN command. +*/ +static void explainAutomaticIndex( + Parse *pParse, + Index *pIdx, /* Automatic index to explain */ + int bPartial, /* True if pIdx is a partial index */ + int *pAddrExplain /* OUT: Address of OP_Explain */ +){ + if( IS_STMT_SCANSTATUS(pParse->db) && pParse->explain!=2 ){ + Table *pTab = pIdx->pTable; + const char *zSep = ""; + char *zText = 0; + int ii = 0; + sqlite3_str *pStr = sqlite3_str_new(pParse->db); + sqlite3_str_appendf(pStr,"CREATE AUTOMATIC INDEX ON %s(", pTab->zName); + assert( pIdx->nColumn>1 ); + assert( pIdx->aiColumn[pIdx->nColumn-1]==XN_ROWID ); + for(ii=0; ii<(pIdx->nColumn-1); ii++){ + const char *zName = 0; + int iCol = pIdx->aiColumn[ii]; + + zName = pTab->aCol[iCol].zCnName; + sqlite3_str_appendf(pStr, "%s%s", zSep, zName); + zSep = ", "; + } + zText = sqlite3_str_finish(pStr); + if( zText==0 ){ + sqlite3OomFault(pParse->db); + }else{ + *pAddrExplain = sqlite3VdbeExplain( + pParse, 0, "%s)%s", zText, (bPartial ? " WHERE <expr>" : "") + ); + sqlite3_free(zText); + } + } +} +#else +# define explainAutomaticIndex(a,b,c,d) +#endif + +/* +** Generate code to construct the Index object for an automatic index +** and to set up the WhereLevel object pLevel so that the code generator +** makes use of the automatic index. +*/ +static SQLITE_NOINLINE void constructAutomaticIndex( + Parse *pParse, /* The parsing context */ + WhereClause *pWC, /* The WHERE clause */ + const Bitmask notReady, /* Mask of cursors that are not available */ + WhereLevel *pLevel /* Write new index here */ +){ + int nKeyCol; /* Number of columns in the constructed index */ + WhereTerm *pTerm; /* A single term of the WHERE clause */ + WhereTerm *pWCEnd; /* End of pWC->a[] */ + Index *pIdx; /* Object describing the transient index */ + Vdbe *v; /* Prepared statement under construction */ + int addrInit; /* Address of the initialization bypass jump */ + Table *pTable; /* The table being indexed */ + int addrTop; /* Top of the index fill loop */ + int regRecord; /* Register holding an index record */ + int n; /* Column counter */ + int i; /* Loop counter */ + int mxBitCol; /* Maximum column in pSrc->colUsed */ + CollSeq *pColl; /* Collating sequence to on a column */ + WhereLoop *pLoop; /* The Loop object */ + char *zNotUsed; /* Extra space on the end of pIdx */ + Bitmask idxCols; /* Bitmap of columns used for indexing */ + Bitmask extraCols; /* Bitmap of additional columns */ + u8 sentWarning = 0; /* True if a warning has been issued */ + u8 useBloomFilter = 0; /* True to also add a Bloom filter */ + Expr *pPartial = 0; /* Partial Index Expression */ + int iContinue = 0; /* Jump here to skip excluded rows */ + SrcList *pTabList; /* The complete FROM clause */ + SrcItem *pSrc; /* The FROM clause term to get the next index */ + int addrCounter = 0; /* Address where integer counter is initialized */ + int regBase; /* Array of registers where record is assembled */ +#ifdef SQLITE_ENABLE_STMT_SCANSTATUS + int addrExp = 0; /* Address of OP_Explain */ +#endif + + /* Generate code to skip over the creation and initialization of the + ** transient index on 2nd and subsequent iterations of the loop. */ + v = pParse->pVdbe; + assert( v!=0 ); + addrInit = sqlite3VdbeAddOp0(v, OP_Once); VdbeCoverage(v); + + /* Count the number of columns that will be added to the index + ** and used to match WHERE clause constraints */ + nKeyCol = 0; + pTabList = pWC->pWInfo->pTabList; + pSrc = &pTabList->a[pLevel->iFrom]; + pTable = pSrc->pTab; + pWCEnd = &pWC->a[pWC->nTerm]; + pLoop = pLevel->pWLoop; + idxCols = 0; + for(pTerm=pWC->a; pTerm<pWCEnd; pTerm++){ + Expr *pExpr = pTerm->pExpr; + /* Make the automatic index a partial index if there are terms in the + ** WHERE clause (or the ON clause of a LEFT join) that constrain which + ** rows of the target table (pSrc) that can be used. */ + if( (pTerm->wtFlags & TERM_VIRTUAL)==0 + && sqlite3ExprIsSingleTableConstraint(pExpr, pTabList, pLevel->iFrom) + ){ + pPartial = sqlite3ExprAnd(pParse, pPartial, + sqlite3ExprDup(pParse->db, pExpr, 0)); + } + if( termCanDriveIndex(pTerm, pSrc, notReady) ){ + int iCol; + Bitmask cMask; + assert( (pTerm->eOperator & (WO_OR|WO_AND))==0 ); + iCol = pTerm->u.x.leftColumn; + cMask = iCol>=BMS ? MASKBIT(BMS-1) : MASKBIT(iCol); + testcase( iCol==BMS ); + testcase( iCol==BMS-1 ); + if( !sentWarning ){ + sqlite3_log(SQLITE_WARNING_AUTOINDEX, + "automatic index on %s(%s)", pTable->zName, + pTable->aCol[iCol].zCnName); + sentWarning = 1; + } + if( (idxCols & cMask)==0 ){ + if( whereLoopResize(pParse->db, pLoop, nKeyCol+1) ){ + goto end_auto_index_create; + } + pLoop->aLTerm[nKeyCol++] = pTerm; + idxCols |= cMask; + } + } + } + assert( nKeyCol>0 || pParse->db->mallocFailed ); + pLoop->u.btree.nEq = pLoop->nLTerm = nKeyCol; + pLoop->wsFlags = WHERE_COLUMN_EQ | WHERE_IDX_ONLY | WHERE_INDEXED + | WHERE_AUTO_INDEX; + + /* Count the number of additional columns needed to create a + ** covering index. A "covering index" is an index that contains all + ** columns that are needed by the query. With a covering index, the + ** original table never needs to be accessed. Automatic indices must + ** be a covering index because the index will not be updated if the + ** original table changes and the index and table cannot both be used + ** if they go out of sync. + */ + if( IsView(pTable) ){ + extraCols = ALLBITS; + }else{ + extraCols = pSrc->colUsed & (~idxCols | MASKBIT(BMS-1)); + } + mxBitCol = MIN(BMS-1,pTable->nCol); + testcase( pTable->nCol==BMS-1 ); + testcase( pTable->nCol==BMS-2 ); + for(i=0; i<mxBitCol; i++){ + if( extraCols & MASKBIT(i) ) nKeyCol++; + } + if( pSrc->colUsed & MASKBIT(BMS-1) ){ + nKeyCol += pTable->nCol - BMS + 1; + } + + /* Construct the Index object to describe this index */ + pIdx = sqlite3AllocateIndexObject(pParse->db, nKeyCol+1, 0, &zNotUsed); + if( pIdx==0 ) goto end_auto_index_create; + pLoop->u.btree.pIndex = pIdx; + pIdx->zName = "auto-index"; + pIdx->pTable = pTable; + n = 0; + idxCols = 0; + for(pTerm=pWC->a; pTerm<pWCEnd; pTerm++){ + if( termCanDriveIndex(pTerm, pSrc, notReady) ){ + int iCol; + Bitmask cMask; + assert( (pTerm->eOperator & (WO_OR|WO_AND))==0 ); + iCol = pTerm->u.x.leftColumn; + cMask = iCol>=BMS ? MASKBIT(BMS-1) : MASKBIT(iCol); + testcase( iCol==BMS-1 ); + testcase( iCol==BMS ); + if( (idxCols & cMask)==0 ){ + Expr *pX = pTerm->pExpr; + idxCols |= cMask; + pIdx->aiColumn[n] = pTerm->u.x.leftColumn; + pColl = sqlite3ExprCompareCollSeq(pParse, pX); + assert( pColl!=0 || pParse->nErr>0 ); /* TH3 collate01.800 */ + pIdx->azColl[n] = pColl ? pColl->zName : sqlite3StrBINARY; + n++; + if( ALWAYS(pX->pLeft!=0) + && sqlite3ExprAffinity(pX->pLeft)!=SQLITE_AFF_TEXT + ){ + /* TUNING: only use a Bloom filter on an automatic index + ** if one or more key columns has the ability to hold numeric + ** values, since strings all have the same hash in the Bloom + ** filter implementation and hence a Bloom filter on a text column + ** is not usually helpful. */ + useBloomFilter = 1; + } + } + } + } + assert( (u32)n==pLoop->u.btree.nEq ); + + /* Add additional columns needed to make the automatic index into + ** a covering index */ + for(i=0; i<mxBitCol; i++){ + if( extraCols & MASKBIT(i) ){ + pIdx->aiColumn[n] = i; + pIdx->azColl[n] = sqlite3StrBINARY; + n++; + } + } + if( pSrc->colUsed & MASKBIT(BMS-1) ){ + for(i=BMS-1; i<pTable->nCol; i++){ + pIdx->aiColumn[n] = i; + pIdx->azColl[n] = sqlite3StrBINARY; + n++; + } + } + assert( n==nKeyCol ); + pIdx->aiColumn[n] = XN_ROWID; + pIdx->azColl[n] = sqlite3StrBINARY; + + /* Create the automatic index */ + explainAutomaticIndex(pParse, pIdx, pPartial!=0, &addrExp); + assert( pLevel->iIdxCur>=0 ); + pLevel->iIdxCur = pParse->nTab++; + sqlite3VdbeAddOp2(v, OP_OpenAutoindex, pLevel->iIdxCur, nKeyCol+1); + sqlite3VdbeSetP4KeyInfo(pParse, pIdx); + VdbeComment((v, "for %s", pTable->zName)); + if( OptimizationEnabled(pParse->db, SQLITE_BloomFilter) && useBloomFilter ){ + sqlite3WhereExplainBloomFilter(pParse, pWC->pWInfo, pLevel); + pLevel->regFilter = ++pParse->nMem; + sqlite3VdbeAddOp2(v, OP_Blob, 10000, pLevel->regFilter); + } + + /* Fill the automatic index with content */ + assert( pSrc == &pWC->pWInfo->pTabList->a[pLevel->iFrom] ); + if( pSrc->fg.viaCoroutine ){ + int regYield = pSrc->regReturn; + addrCounter = sqlite3VdbeAddOp2(v, OP_Integer, 0, 0); + sqlite3VdbeAddOp3(v, OP_InitCoroutine, regYield, 0, pSrc->addrFillSub); + addrTop = sqlite3VdbeAddOp1(v, OP_Yield, regYield); + VdbeCoverage(v); + VdbeComment((v, "next row of %s", pSrc->pTab->zName)); + }else{ + addrTop = sqlite3VdbeAddOp1(v, OP_Rewind, pLevel->iTabCur); VdbeCoverage(v); + } + if( pPartial ){ + iContinue = sqlite3VdbeMakeLabel(pParse); + sqlite3ExprIfFalse(pParse, pPartial, iContinue, SQLITE_JUMPIFNULL); + pLoop->wsFlags |= WHERE_PARTIALIDX; + } + regRecord = sqlite3GetTempReg(pParse); + regBase = sqlite3GenerateIndexKey( + pParse, pIdx, pLevel->iTabCur, regRecord, 0, 0, 0, 0 + ); + if( pLevel->regFilter ){ + sqlite3VdbeAddOp4Int(v, OP_FilterAdd, pLevel->regFilter, 0, + regBase, pLoop->u.btree.nEq); + } + sqlite3VdbeScanStatusCounters(v, addrExp, addrExp, sqlite3VdbeCurrentAddr(v)); + sqlite3VdbeAddOp2(v, OP_IdxInsert, pLevel->iIdxCur, regRecord); + sqlite3VdbeChangeP5(v, OPFLAG_USESEEKRESULT); + if( pPartial ) sqlite3VdbeResolveLabel(v, iContinue); + if( pSrc->fg.viaCoroutine ){ + sqlite3VdbeChangeP2(v, addrCounter, regBase+n); + testcase( pParse->db->mallocFailed ); + assert( pLevel->iIdxCur>0 ); + translateColumnToCopy(pParse, addrTop, pLevel->iTabCur, + pSrc->regResult, pLevel->iIdxCur); + sqlite3VdbeGoto(v, addrTop); + pSrc->fg.viaCoroutine = 0; + }else{ + sqlite3VdbeAddOp2(v, OP_Next, pLevel->iTabCur, addrTop+1); VdbeCoverage(v); + sqlite3VdbeChangeP5(v, SQLITE_STMTSTATUS_AUTOINDEX); + } + sqlite3VdbeJumpHere(v, addrTop); + sqlite3ReleaseTempReg(pParse, regRecord); + + /* Jump here when skipping the initialization */ + sqlite3VdbeJumpHere(v, addrInit); + sqlite3VdbeScanStatusRange(v, addrExp, addrExp, -1); + +end_auto_index_create: + sqlite3ExprDelete(pParse->db, pPartial); +} +#endif /* SQLITE_OMIT_AUTOMATIC_INDEX */ + +/* +** Generate bytecode that will initialize a Bloom filter that is appropriate +** for pLevel. +** +** If there are inner loops within pLevel that have the WHERE_BLOOMFILTER +** flag set, initialize a Bloomfilter for them as well. Except don't do +** this recursive initialization if the SQLITE_BloomPulldown optimization has +** been turned off. +** +** When the Bloom filter is initialized, the WHERE_BLOOMFILTER flag is cleared +** from the loop, but the regFilter value is set to a register that implements +** the Bloom filter. When regFilter is positive, the +** sqlite3WhereCodeOneLoopStart() will generate code to test the Bloom filter +** and skip the subsequence B-Tree seek if the Bloom filter indicates that +** no matching rows exist. +** +** This routine may only be called if it has previously been determined that +** the loop would benefit from a Bloom filter, and the WHERE_BLOOMFILTER bit +** is set. +*/ +static SQLITE_NOINLINE void sqlite3ConstructBloomFilter( + WhereInfo *pWInfo, /* The WHERE clause */ + int iLevel, /* Index in pWInfo->a[] that is pLevel */ + WhereLevel *pLevel, /* Make a Bloom filter for this FROM term */ + Bitmask notReady /* Loops that are not ready */ +){ + int addrOnce; /* Address of opening OP_Once */ + int addrTop; /* Address of OP_Rewind */ + int addrCont; /* Jump here to skip a row */ + const WhereTerm *pTerm; /* For looping over WHERE clause terms */ + const WhereTerm *pWCEnd; /* Last WHERE clause term */ + Parse *pParse = pWInfo->pParse; /* Parsing context */ + Vdbe *v = pParse->pVdbe; /* VDBE under construction */ + WhereLoop *pLoop = pLevel->pWLoop; /* The loop being coded */ + int iCur; /* Cursor for table getting the filter */ + IndexedExpr *saved_pIdxEpr; /* saved copy of Parse.pIdxEpr */ + IndexedExpr *saved_pIdxPartExpr; /* saved copy of Parse.pIdxPartExpr */ + + saved_pIdxEpr = pParse->pIdxEpr; + saved_pIdxPartExpr = pParse->pIdxPartExpr; + pParse->pIdxEpr = 0; + pParse->pIdxPartExpr = 0; + + assert( pLoop!=0 ); + assert( v!=0 ); + assert( pLoop->wsFlags & WHERE_BLOOMFILTER ); + assert( (pLoop->wsFlags & WHERE_IDX_ONLY)==0 ); + + addrOnce = sqlite3VdbeAddOp0(v, OP_Once); VdbeCoverage(v); + do{ + const SrcList *pTabList; + const SrcItem *pItem; + const Table *pTab; + u64 sz; + int iSrc; + sqlite3WhereExplainBloomFilter(pParse, pWInfo, pLevel); + addrCont = sqlite3VdbeMakeLabel(pParse); + iCur = pLevel->iTabCur; + pLevel->regFilter = ++pParse->nMem; + + /* The Bloom filter is a Blob held in a register. Initialize it + ** to zero-filled blob of at least 80K bits, but maybe more if the + ** estimated size of the table is larger. We could actually + ** measure the size of the table at run-time using OP_Count with + ** P3==1 and use that value to initialize the blob. But that makes + ** testing complicated. By basing the blob size on the value in the + ** sqlite_stat1 table, testing is much easier. + */ + pTabList = pWInfo->pTabList; + iSrc = pLevel->iFrom; + pItem = &pTabList->a[iSrc]; + assert( pItem!=0 ); + pTab = pItem->pTab; + assert( pTab!=0 ); + sz = sqlite3LogEstToInt(pTab->nRowLogEst); + if( sz<10000 ){ + sz = 10000; + }else if( sz>10000000 ){ + sz = 10000000; + } + sqlite3VdbeAddOp2(v, OP_Blob, (int)sz, pLevel->regFilter); + + addrTop = sqlite3VdbeAddOp1(v, OP_Rewind, iCur); VdbeCoverage(v); + pWCEnd = &pWInfo->sWC.a[pWInfo->sWC.nTerm]; + for(pTerm=pWInfo->sWC.a; pTerm<pWCEnd; pTerm++){ + Expr *pExpr = pTerm->pExpr; + if( (pTerm->wtFlags & TERM_VIRTUAL)==0 + && sqlite3ExprIsSingleTableConstraint(pExpr, pTabList, iSrc) + ){ + sqlite3ExprIfFalse(pParse, pTerm->pExpr, addrCont, SQLITE_JUMPIFNULL); + } + } + if( pLoop->wsFlags & WHERE_IPK ){ + int r1 = sqlite3GetTempReg(pParse); + sqlite3VdbeAddOp2(v, OP_Rowid, iCur, r1); + sqlite3VdbeAddOp4Int(v, OP_FilterAdd, pLevel->regFilter, 0, r1, 1); + sqlite3ReleaseTempReg(pParse, r1); + }else{ + Index *pIdx = pLoop->u.btree.pIndex; + int n = pLoop->u.btree.nEq; + int r1 = sqlite3GetTempRange(pParse, n); + int jj; + for(jj=0; jj<n; jj++){ + assert( pIdx->pTable==pItem->pTab ); + sqlite3ExprCodeLoadIndexColumn(pParse, pIdx, iCur, jj, r1+jj); + } + sqlite3VdbeAddOp4Int(v, OP_FilterAdd, pLevel->regFilter, 0, r1, n); + sqlite3ReleaseTempRange(pParse, r1, n); + } + sqlite3VdbeResolveLabel(v, addrCont); + sqlite3VdbeAddOp2(v, OP_Next, pLevel->iTabCur, addrTop+1); + VdbeCoverage(v); + sqlite3VdbeJumpHere(v, addrTop); + pLoop->wsFlags &= ~WHERE_BLOOMFILTER; + if( OptimizationDisabled(pParse->db, SQLITE_BloomPulldown) ) break; + while( ++iLevel < pWInfo->nLevel ){ + const SrcItem *pTabItem; + pLevel = &pWInfo->a[iLevel]; + pTabItem = &pWInfo->pTabList->a[pLevel->iFrom]; + if( pTabItem->fg.jointype & (JT_LEFT|JT_LTORJ) ) continue; + pLoop = pLevel->pWLoop; + if( NEVER(pLoop==0) ) continue; + if( pLoop->prereq & notReady ) continue; + if( (pLoop->wsFlags & (WHERE_BLOOMFILTER|WHERE_COLUMN_IN)) + ==WHERE_BLOOMFILTER + ){ + /* This is a candidate for bloom-filter pull-down (early evaluation). + ** The test that WHERE_COLUMN_IN is omitted is important, as we are + ** not able to do early evaluation of bloom filters that make use of + ** the IN operator */ + break; + } + } + }while( iLevel < pWInfo->nLevel ); + sqlite3VdbeJumpHere(v, addrOnce); + pParse->pIdxEpr = saved_pIdxEpr; + pParse->pIdxPartExpr = saved_pIdxPartExpr; +} + + +#ifndef SQLITE_OMIT_VIRTUALTABLE +/* +** Allocate and populate an sqlite3_index_info structure. It is the +** responsibility of the caller to eventually release the structure +** by passing the pointer returned by this function to freeIndexInfo(). +*/ +static sqlite3_index_info *allocateIndexInfo( + WhereInfo *pWInfo, /* The WHERE clause */ + WhereClause *pWC, /* The WHERE clause being analyzed */ + Bitmask mUnusable, /* Ignore terms with these prereqs */ + SrcItem *pSrc, /* The FROM clause term that is the vtab */ + u16 *pmNoOmit /* Mask of terms not to omit */ +){ + int i, j; + int nTerm; + Parse *pParse = pWInfo->pParse; + struct sqlite3_index_constraint *pIdxCons; + struct sqlite3_index_orderby *pIdxOrderBy; + struct sqlite3_index_constraint_usage *pUsage; + struct HiddenIndexInfo *pHidden; + WhereTerm *pTerm; + int nOrderBy; + sqlite3_index_info *pIdxInfo; + u16 mNoOmit = 0; + const Table *pTab; + int eDistinct = 0; + ExprList *pOrderBy = pWInfo->pOrderBy; + + assert( pSrc!=0 ); + pTab = pSrc->pTab; + assert( pTab!=0 ); + assert( IsVirtual(pTab) ); + + /* Find all WHERE clause constraints referring to this virtual table. + ** Mark each term with the TERM_OK flag. Set nTerm to the number of + ** terms found. + */ + for(i=nTerm=0, pTerm=pWC->a; i<pWC->nTerm; i++, pTerm++){ + pTerm->wtFlags &= ~TERM_OK; + if( pTerm->leftCursor != pSrc->iCursor ) continue; + if( pTerm->prereqRight & mUnusable ) continue; + assert( IsPowerOfTwo(pTerm->eOperator & ~WO_EQUIV) ); + testcase( pTerm->eOperator & WO_IN ); + testcase( pTerm->eOperator & WO_ISNULL ); + testcase( pTerm->eOperator & WO_IS ); + testcase( pTerm->eOperator & WO_ALL ); + if( (pTerm->eOperator & ~(WO_EQUIV))==0 ) continue; + if( pTerm->wtFlags & TERM_VNULL ) continue; + + assert( (pTerm->eOperator & (WO_OR|WO_AND))==0 ); + assert( pTerm->u.x.leftColumn>=XN_ROWID ); + assert( pTerm->u.x.leftColumn<pTab->nCol ); + if( (pSrc->fg.jointype & (JT_LEFT|JT_LTORJ|JT_RIGHT))!=0 + && !constraintCompatibleWithOuterJoin(pTerm,pSrc) + ){ + continue; + } + nTerm++; + pTerm->wtFlags |= TERM_OK; + } + + /* If the ORDER BY clause contains only columns in the current + ** virtual table then allocate space for the aOrderBy part of + ** the sqlite3_index_info structure. + */ + nOrderBy = 0; + if( pOrderBy ){ + int n = pOrderBy->nExpr; + for(i=0; i<n; i++){ + Expr *pExpr = pOrderBy->a[i].pExpr; + Expr *pE2; + + /* Skip over constant terms in the ORDER BY clause */ + if( sqlite3ExprIsConstant(pExpr) ){ + continue; + } + + /* Virtual tables are unable to deal with NULLS FIRST */ + if( pOrderBy->a[i].fg.sortFlags & KEYINFO_ORDER_BIGNULL ) break; + + /* First case - a direct column references without a COLLATE operator */ + if( pExpr->op==TK_COLUMN && pExpr->iTable==pSrc->iCursor ){ + assert( pExpr->iColumn>=XN_ROWID && pExpr->iColumn<pTab->nCol ); + continue; + } + + /* 2nd case - a column reference with a COLLATE operator. Only match + ** of the COLLATE operator matches the collation of the column. */ + if( pExpr->op==TK_COLLATE + && (pE2 = pExpr->pLeft)->op==TK_COLUMN + && pE2->iTable==pSrc->iCursor + ){ + const char *zColl; /* The collating sequence name */ + assert( !ExprHasProperty(pExpr, EP_IntValue) ); + assert( pExpr->u.zToken!=0 ); + assert( pE2->iColumn>=XN_ROWID && pE2->iColumn<pTab->nCol ); + pExpr->iColumn = pE2->iColumn; + if( pE2->iColumn<0 ) continue; /* Collseq does not matter for rowid */ + zColl = sqlite3ColumnColl(&pTab->aCol[pE2->iColumn]); + if( zColl==0 ) zColl = sqlite3StrBINARY; + if( sqlite3_stricmp(pExpr->u.zToken, zColl)==0 ) continue; + } + + /* No matches cause a break out of the loop */ + break; + } + if( i==n ){ + nOrderBy = n; + if( (pWInfo->wctrlFlags & WHERE_DISTINCTBY) ){ + eDistinct = 2 + ((pWInfo->wctrlFlags & WHERE_SORTBYGROUP)!=0); + }else if( pWInfo->wctrlFlags & WHERE_GROUPBY ){ + eDistinct = 1; + } + } + } + + /* Allocate the sqlite3_index_info structure + */ + pIdxInfo = sqlite3DbMallocZero(pParse->db, sizeof(*pIdxInfo) + + (sizeof(*pIdxCons) + sizeof(*pUsage))*nTerm + + sizeof(*pIdxOrderBy)*nOrderBy + sizeof(*pHidden) + + sizeof(sqlite3_value*)*nTerm ); + if( pIdxInfo==0 ){ + sqlite3ErrorMsg(pParse, "out of memory"); + return 0; + } + pHidden = (struct HiddenIndexInfo*)&pIdxInfo[1]; + pIdxCons = (struct sqlite3_index_constraint*)&pHidden->aRhs[nTerm]; + pIdxOrderBy = (struct sqlite3_index_orderby*)&pIdxCons[nTerm]; + pUsage = (struct sqlite3_index_constraint_usage*)&pIdxOrderBy[nOrderBy]; + pIdxInfo->aConstraint = pIdxCons; + pIdxInfo->aOrderBy = pIdxOrderBy; + pIdxInfo->aConstraintUsage = pUsage; + pHidden->pWC = pWC; + pHidden->pParse = pParse; + pHidden->eDistinct = eDistinct; + pHidden->mIn = 0; + for(i=j=0, pTerm=pWC->a; i<pWC->nTerm; i++, pTerm++){ + u16 op; + if( (pTerm->wtFlags & TERM_OK)==0 ) continue; + pIdxCons[j].iColumn = pTerm->u.x.leftColumn; + pIdxCons[j].iTermOffset = i; + op = pTerm->eOperator & WO_ALL; + if( op==WO_IN ){ + if( (pTerm->wtFlags & TERM_SLICE)==0 ){ + pHidden->mIn |= SMASKBIT32(j); + } + op = WO_EQ; + } + if( op==WO_AUX ){ + pIdxCons[j].op = pTerm->eMatchOp; + }else if( op & (WO_ISNULL|WO_IS) ){ + if( op==WO_ISNULL ){ + pIdxCons[j].op = SQLITE_INDEX_CONSTRAINT_ISNULL; + }else{ + pIdxCons[j].op = SQLITE_INDEX_CONSTRAINT_IS; + } + }else{ + pIdxCons[j].op = (u8)op; + /* The direct assignment in the previous line is possible only because + ** the WO_ and SQLITE_INDEX_CONSTRAINT_ codes are identical. The + ** following asserts verify this fact. */ + assert( WO_EQ==SQLITE_INDEX_CONSTRAINT_EQ ); + assert( WO_LT==SQLITE_INDEX_CONSTRAINT_LT ); + assert( WO_LE==SQLITE_INDEX_CONSTRAINT_LE ); + assert( WO_GT==SQLITE_INDEX_CONSTRAINT_GT ); + assert( WO_GE==SQLITE_INDEX_CONSTRAINT_GE ); + assert( pTerm->eOperator&(WO_IN|WO_EQ|WO_LT|WO_LE|WO_GT|WO_GE|WO_AUX) ); + + if( op & (WO_LT|WO_LE|WO_GT|WO_GE) + && sqlite3ExprIsVector(pTerm->pExpr->pRight) + ){ + testcase( j!=i ); + if( j<16 ) mNoOmit |= (1 << j); + if( op==WO_LT ) pIdxCons[j].op = WO_LE; + if( op==WO_GT ) pIdxCons[j].op = WO_GE; + } + } + + j++; + } + assert( j==nTerm ); + pIdxInfo->nConstraint = j; + for(i=j=0; i<nOrderBy; i++){ + Expr *pExpr = pOrderBy->a[i].pExpr; + if( sqlite3ExprIsConstant(pExpr) ) continue; + assert( pExpr->op==TK_COLUMN + || (pExpr->op==TK_COLLATE && pExpr->pLeft->op==TK_COLUMN + && pExpr->iColumn==pExpr->pLeft->iColumn) ); + pIdxOrderBy[j].iColumn = pExpr->iColumn; + pIdxOrderBy[j].desc = pOrderBy->a[i].fg.sortFlags & KEYINFO_ORDER_DESC; + j++; + } + pIdxInfo->nOrderBy = j; + + *pmNoOmit = mNoOmit; + return pIdxInfo; +} + +/* +** Free an sqlite3_index_info structure allocated by allocateIndexInfo() +** and possibly modified by xBestIndex methods. +*/ +static void freeIndexInfo(sqlite3 *db, sqlite3_index_info *pIdxInfo){ + HiddenIndexInfo *pHidden; + int i; + assert( pIdxInfo!=0 ); + pHidden = (HiddenIndexInfo*)&pIdxInfo[1]; + assert( pHidden->pParse!=0 ); + assert( pHidden->pParse->db==db ); + for(i=0; i<pIdxInfo->nConstraint; i++){ + sqlite3ValueFree(pHidden->aRhs[i]); /* IMP: R-14553-25174 */ + pHidden->aRhs[i] = 0; + } + sqlite3DbFree(db, pIdxInfo); +} + +/* +** The table object reference passed as the second argument to this function +** must represent a virtual table. This function invokes the xBestIndex() +** method of the virtual table with the sqlite3_index_info object that +** comes in as the 3rd argument to this function. +** +** If an error occurs, pParse is populated with an error message and an +** appropriate error code is returned. A return of SQLITE_CONSTRAINT from +** xBestIndex is not considered an error. SQLITE_CONSTRAINT indicates that +** the current configuration of "unusable" flags in sqlite3_index_info can +** not result in a valid plan. +** +** Whether or not an error is returned, it is the responsibility of the +** caller to eventually free p->idxStr if p->needToFreeIdxStr indicates +** that this is required. +*/ +static int vtabBestIndex(Parse *pParse, Table *pTab, sqlite3_index_info *p){ + sqlite3_vtab *pVtab = sqlite3GetVTable(pParse->db, pTab)->pVtab; + int rc; + + whereTraceIndexInfoInputs(p); + pParse->db->nSchemaLock++; + rc = pVtab->pModule->xBestIndex(pVtab, p); + pParse->db->nSchemaLock--; + whereTraceIndexInfoOutputs(p); + + if( rc!=SQLITE_OK && rc!=SQLITE_CONSTRAINT ){ + if( rc==SQLITE_NOMEM ){ + sqlite3OomFault(pParse->db); + }else if( !pVtab->zErrMsg ){ + sqlite3ErrorMsg(pParse, "%s", sqlite3ErrStr(rc)); + }else{ + sqlite3ErrorMsg(pParse, "%s", pVtab->zErrMsg); + } + } + if( pTab->u.vtab.p->bAllSchemas ){ + sqlite3VtabUsesAllSchemas(pParse); + } + sqlite3_free(pVtab->zErrMsg); + pVtab->zErrMsg = 0; + return rc; +} +#endif /* !defined(SQLITE_OMIT_VIRTUALTABLE) */ + +#ifdef SQLITE_ENABLE_STAT4 +/* +** Estimate the location of a particular key among all keys in an +** index. Store the results in aStat as follows: +** +** aStat[0] Est. number of rows less than pRec +** aStat[1] Est. number of rows equal to pRec +** +** Return the index of the sample that is the smallest sample that +** is greater than or equal to pRec. Note that this index is not an index +** into the aSample[] array - it is an index into a virtual set of samples +** based on the contents of aSample[] and the number of fields in record +** pRec. +*/ +static int whereKeyStats( + Parse *pParse, /* Database connection */ + Index *pIdx, /* Index to consider domain of */ + UnpackedRecord *pRec, /* Vector of values to consider */ + int roundUp, /* Round up if true. Round down if false */ + tRowcnt *aStat /* OUT: stats written here */ +){ + IndexSample *aSample = pIdx->aSample; + int iCol; /* Index of required stats in anEq[] etc. */ + int i; /* Index of first sample >= pRec */ + int iSample; /* Smallest sample larger than or equal to pRec */ + int iMin = 0; /* Smallest sample not yet tested */ + int iTest; /* Next sample to test */ + int res; /* Result of comparison operation */ + int nField; /* Number of fields in pRec */ + tRowcnt iLower = 0; /* anLt[] + anEq[] of largest sample pRec is > */ + +#ifndef SQLITE_DEBUG + UNUSED_PARAMETER( pParse ); +#endif + assert( pRec!=0 ); + assert( pIdx->nSample>0 ); + assert( pRec->nField>0 ); + + + /* Do a binary search to find the first sample greater than or equal + ** to pRec. If pRec contains a single field, the set of samples to search + ** is simply the aSample[] array. If the samples in aSample[] contain more + ** than one fields, all fields following the first are ignored. + ** + ** If pRec contains N fields, where N is more than one, then as well as the + ** samples in aSample[] (truncated to N fields), the search also has to + ** consider prefixes of those samples. For example, if the set of samples + ** in aSample is: + ** + ** aSample[0] = (a, 5) + ** aSample[1] = (a, 10) + ** aSample[2] = (b, 5) + ** aSample[3] = (c, 100) + ** aSample[4] = (c, 105) + ** + ** Then the search space should ideally be the samples above and the + ** unique prefixes [a], [b] and [c]. But since that is hard to organize, + ** the code actually searches this set: + ** + ** 0: (a) + ** 1: (a, 5) + ** 2: (a, 10) + ** 3: (a, 10) + ** 4: (b) + ** 5: (b, 5) + ** 6: (c) + ** 7: (c, 100) + ** 8: (c, 105) + ** 9: (c, 105) + ** + ** For each sample in the aSample[] array, N samples are present in the + ** effective sample array. In the above, samples 0 and 1 are based on + ** sample aSample[0]. Samples 2 and 3 on aSample[1] etc. + ** + ** Often, sample i of each block of N effective samples has (i+1) fields. + ** Except, each sample may be extended to ensure that it is greater than or + ** equal to the previous sample in the array. For example, in the above, + ** sample 2 is the first sample of a block of N samples, so at first it + ** appears that it should be 1 field in size. However, that would make it + ** smaller than sample 1, so the binary search would not work. As a result, + ** it is extended to two fields. The duplicates that this creates do not + ** cause any problems. + */ + if( !HasRowid(pIdx->pTable) && IsPrimaryKeyIndex(pIdx) ){ + nField = pIdx->nKeyCol; + }else{ + nField = pIdx->nColumn; + } + nField = MIN(pRec->nField, nField); + iCol = 0; + iSample = pIdx->nSample * nField; + do{ + int iSamp; /* Index in aSample[] of test sample */ + int n; /* Number of fields in test sample */ + + iTest = (iMin+iSample)/2; + iSamp = iTest / nField; + if( iSamp>0 ){ + /* The proposed effective sample is a prefix of sample aSample[iSamp]. + ** Specifically, the shortest prefix of at least (1 + iTest%nField) + ** fields that is greater than the previous effective sample. */ + for(n=(iTest % nField) + 1; n<nField; n++){ + if( aSample[iSamp-1].anLt[n-1]!=aSample[iSamp].anLt[n-1] ) break; + } + }else{ + n = iTest + 1; + } + + pRec->nField = n; + res = sqlite3VdbeRecordCompare(aSample[iSamp].n, aSample[iSamp].p, pRec); + if( res<0 ){ + iLower = aSample[iSamp].anLt[n-1] + aSample[iSamp].anEq[n-1]; + iMin = iTest+1; + }else if( res==0 && n<nField ){ + iLower = aSample[iSamp].anLt[n-1]; + iMin = iTest+1; + res = -1; + }else{ + iSample = iTest; + iCol = n-1; + } + }while( res && iMin<iSample ); + i = iSample / nField; + +#ifdef SQLITE_DEBUG + /* The following assert statements check that the binary search code + ** above found the right answer. This block serves no purpose other + ** than to invoke the asserts. */ + if( pParse->db->mallocFailed==0 ){ + if( res==0 ){ + /* If (res==0) is true, then pRec must be equal to sample i. */ + assert( i<pIdx->nSample ); + assert( iCol==nField-1 ); + pRec->nField = nField; + assert( 0==sqlite3VdbeRecordCompare(aSample[i].n, aSample[i].p, pRec) + || pParse->db->mallocFailed + ); + }else{ + /* Unless i==pIdx->nSample, indicating that pRec is larger than + ** all samples in the aSample[] array, pRec must be smaller than the + ** (iCol+1) field prefix of sample i. */ + assert( i<=pIdx->nSample && i>=0 ); + pRec->nField = iCol+1; + assert( i==pIdx->nSample + || sqlite3VdbeRecordCompare(aSample[i].n, aSample[i].p, pRec)>0 + || pParse->db->mallocFailed ); + + /* if i==0 and iCol==0, then record pRec is smaller than all samples + ** in the aSample[] array. Otherwise, if (iCol>0) then pRec must + ** be greater than or equal to the (iCol) field prefix of sample i. + ** If (i>0), then pRec must also be greater than sample (i-1). */ + if( iCol>0 ){ + pRec->nField = iCol; + assert( sqlite3VdbeRecordCompare(aSample[i].n, aSample[i].p, pRec)<=0 + || pParse->db->mallocFailed || CORRUPT_DB ); + } + if( i>0 ){ + pRec->nField = nField; + assert( sqlite3VdbeRecordCompare(aSample[i-1].n, aSample[i-1].p, pRec)<0 + || pParse->db->mallocFailed || CORRUPT_DB ); + } + } + } +#endif /* ifdef SQLITE_DEBUG */ + + if( res==0 ){ + /* Record pRec is equal to sample i */ + assert( iCol==nField-1 ); + aStat[0] = aSample[i].anLt[iCol]; + aStat[1] = aSample[i].anEq[iCol]; + }else{ + /* At this point, the (iCol+1) field prefix of aSample[i] is the first + ** sample that is greater than pRec. Or, if i==pIdx->nSample then pRec + ** is larger than all samples in the array. */ + tRowcnt iUpper, iGap; + if( i>=pIdx->nSample ){ + iUpper = pIdx->nRowEst0; + }else{ + iUpper = aSample[i].anLt[iCol]; + } + + if( iLower>=iUpper ){ + iGap = 0; + }else{ + iGap = iUpper - iLower; + } + if( roundUp ){ + iGap = (iGap*2)/3; + }else{ + iGap = iGap/3; + } + aStat[0] = iLower + iGap; + aStat[1] = pIdx->aAvgEq[nField-1]; + } + + /* Restore the pRec->nField value before returning. */ + pRec->nField = nField; + return i; +} +#endif /* SQLITE_ENABLE_STAT4 */ + +/* +** If it is not NULL, pTerm is a term that provides an upper or lower +** bound on a range scan. Without considering pTerm, it is estimated +** that the scan will visit nNew rows. This function returns the number +** estimated to be visited after taking pTerm into account. +** +** If the user explicitly specified a likelihood() value for this term, +** then the return value is the likelihood multiplied by the number of +** input rows. Otherwise, this function assumes that an "IS NOT NULL" term +** has a likelihood of 0.50, and any other term a likelihood of 0.25. +*/ +static LogEst whereRangeAdjust(WhereTerm *pTerm, LogEst nNew){ + LogEst nRet = nNew; + if( pTerm ){ + if( pTerm->truthProb<=0 ){ + nRet += pTerm->truthProb; + }else if( (pTerm->wtFlags & TERM_VNULL)==0 ){ + nRet -= 20; assert( 20==sqlite3LogEst(4) ); + } + } + return nRet; +} + + +#ifdef SQLITE_ENABLE_STAT4 +/* +** Return the affinity for a single column of an index. +*/ +char sqlite3IndexColumnAffinity(sqlite3 *db, Index *pIdx, int iCol){ + assert( iCol>=0 && iCol<pIdx->nColumn ); + if( !pIdx->zColAff ){ + if( sqlite3IndexAffinityStr(db, pIdx)==0 ) return SQLITE_AFF_BLOB; + } + assert( pIdx->zColAff[iCol]!=0 ); + return pIdx->zColAff[iCol]; +} +#endif + + +#ifdef SQLITE_ENABLE_STAT4 +/* +** This function is called to estimate the number of rows visited by a +** range-scan on a skip-scan index. For example: +** +** CREATE INDEX i1 ON t1(a, b, c); +** SELECT * FROM t1 WHERE a=? AND c BETWEEN ? AND ?; +** +** Value pLoop->nOut is currently set to the estimated number of rows +** visited for scanning (a=? AND b=?). This function reduces that estimate +** by some factor to account for the (c BETWEEN ? AND ?) expression based +** on the stat4 data for the index. this scan will be performed multiple +** times (once for each (a,b) combination that matches a=?) is dealt with +** by the caller. +** +** It does this by scanning through all stat4 samples, comparing values +** extracted from pLower and pUpper with the corresponding column in each +** sample. If L and U are the number of samples found to be less than or +** equal to the values extracted from pLower and pUpper respectively, and +** N is the total number of samples, the pLoop->nOut value is adjusted +** as follows: +** +** nOut = nOut * ( min(U - L, 1) / N ) +** +** If pLower is NULL, or a value cannot be extracted from the term, L is +** set to zero. If pUpper is NULL, or a value cannot be extracted from it, +** U is set to N. +** +** Normally, this function sets *pbDone to 1 before returning. However, +** if no value can be extracted from either pLower or pUpper (and so the +** estimate of the number of rows delivered remains unchanged), *pbDone +** is left as is. +** +** If an error occurs, an SQLite error code is returned. Otherwise, +** SQLITE_OK. +*/ +static int whereRangeSkipScanEst( + Parse *pParse, /* Parsing & code generating context */ + WhereTerm *pLower, /* Lower bound on the range. ex: "x>123" Might be NULL */ + WhereTerm *pUpper, /* Upper bound on the range. ex: "x<455" Might be NULL */ + WhereLoop *pLoop, /* Update the .nOut value of this loop */ + int *pbDone /* Set to true if at least one expr. value extracted */ +){ + Index *p = pLoop->u.btree.pIndex; + int nEq = pLoop->u.btree.nEq; + sqlite3 *db = pParse->db; + int nLower = -1; + int nUpper = p->nSample+1; + int rc = SQLITE_OK; + u8 aff = sqlite3IndexColumnAffinity(db, p, nEq); + CollSeq *pColl; + + sqlite3_value *p1 = 0; /* Value extracted from pLower */ + sqlite3_value *p2 = 0; /* Value extracted from pUpper */ + sqlite3_value *pVal = 0; /* Value extracted from record */ + + pColl = sqlite3LocateCollSeq(pParse, p->azColl[nEq]); + if( pLower ){ + rc = sqlite3Stat4ValueFromExpr(pParse, pLower->pExpr->pRight, aff, &p1); + nLower = 0; + } + if( pUpper && rc==SQLITE_OK ){ + rc = sqlite3Stat4ValueFromExpr(pParse, pUpper->pExpr->pRight, aff, &p2); + nUpper = p2 ? 0 : p->nSample; + } + + if( p1 || p2 ){ + int i; + int nDiff; + for(i=0; rc==SQLITE_OK && i<p->nSample; i++){ + rc = sqlite3Stat4Column(db, p->aSample[i].p, p->aSample[i].n, nEq, &pVal); + if( rc==SQLITE_OK && p1 ){ + int res = sqlite3MemCompare(p1, pVal, pColl); + if( res>=0 ) nLower++; + } + if( rc==SQLITE_OK && p2 ){ + int res = sqlite3MemCompare(p2, pVal, pColl); + if( res>=0 ) nUpper++; + } + } + nDiff = (nUpper - nLower); + if( nDiff<=0 ) nDiff = 1; + + /* If there is both an upper and lower bound specified, and the + ** comparisons indicate that they are close together, use the fallback + ** method (assume that the scan visits 1/64 of the rows) for estimating + ** the number of rows visited. Otherwise, estimate the number of rows + ** using the method described in the header comment for this function. */ + if( nDiff!=1 || pUpper==0 || pLower==0 ){ + int nAdjust = (sqlite3LogEst(p->nSample) - sqlite3LogEst(nDiff)); + pLoop->nOut -= nAdjust; + *pbDone = 1; + WHERETRACE(0x20, ("range skip-scan regions: %u..%u adjust=%d est=%d\n", + nLower, nUpper, nAdjust*-1, pLoop->nOut)); + } + + }else{ + assert( *pbDone==0 ); + } + + sqlite3ValueFree(p1); + sqlite3ValueFree(p2); + sqlite3ValueFree(pVal); + + return rc; +} +#endif /* SQLITE_ENABLE_STAT4 */ + +/* +** This function is used to estimate the number of rows that will be visited +** by scanning an index for a range of values. The range may have an upper +** bound, a lower bound, or both. The WHERE clause terms that set the upper +** and lower bounds are represented by pLower and pUpper respectively. For +** example, assuming that index p is on t1(a): +** +** ... FROM t1 WHERE a > ? AND a < ? ... +** |_____| |_____| +** | | +** pLower pUpper +** +** If either of the upper or lower bound is not present, then NULL is passed in +** place of the corresponding WhereTerm. +** +** The value in (pBuilder->pNew->u.btree.nEq) is the number of the index +** column subject to the range constraint. Or, equivalently, the number of +** equality constraints optimized by the proposed index scan. For example, +** assuming index p is on t1(a, b), and the SQL query is: +** +** ... FROM t1 WHERE a = ? AND b > ? AND b < ? ... +** +** then nEq is set to 1 (as the range restricted column, b, is the second +** left-most column of the index). Or, if the query is: +** +** ... FROM t1 WHERE a > ? AND a < ? ... +** +** then nEq is set to 0. +** +** When this function is called, *pnOut is set to the sqlite3LogEst() of the +** number of rows that the index scan is expected to visit without +** considering the range constraints. If nEq is 0, then *pnOut is the number of +** rows in the index. Assuming no error occurs, *pnOut is adjusted (reduced) +** to account for the range constraints pLower and pUpper. +** +** In the absence of sqlite_stat4 ANALYZE data, or if such data cannot be +** used, a single range inequality reduces the search space by a factor of 4. +** and a pair of constraints (x>? AND x<?) reduces the expected number of +** rows visited by a factor of 64. +*/ +static int whereRangeScanEst( + Parse *pParse, /* Parsing & code generating context */ + WhereLoopBuilder *pBuilder, + WhereTerm *pLower, /* Lower bound on the range. ex: "x>123" Might be NULL */ + WhereTerm *pUpper, /* Upper bound on the range. ex: "x<455" Might be NULL */ + WhereLoop *pLoop /* Modify the .nOut and maybe .rRun fields */ +){ + int rc = SQLITE_OK; + int nOut = pLoop->nOut; + LogEst nNew; + +#ifdef SQLITE_ENABLE_STAT4 + Index *p = pLoop->u.btree.pIndex; + int nEq = pLoop->u.btree.nEq; + + if( p->nSample>0 && ALWAYS(nEq<p->nSampleCol) + && OptimizationEnabled(pParse->db, SQLITE_Stat4) + ){ + if( nEq==pBuilder->nRecValid ){ + UnpackedRecord *pRec = pBuilder->pRec; + tRowcnt a[2]; + int nBtm = pLoop->u.btree.nBtm; + int nTop = pLoop->u.btree.nTop; + + /* Variable iLower will be set to the estimate of the number of rows in + ** the index that are less than the lower bound of the range query. The + ** lower bound being the concatenation of $P and $L, where $P is the + ** key-prefix formed by the nEq values matched against the nEq left-most + ** columns of the index, and $L is the value in pLower. + ** + ** Or, if pLower is NULL or $L cannot be extracted from it (because it + ** is not a simple variable or literal value), the lower bound of the + ** range is $P. Due to a quirk in the way whereKeyStats() works, even + ** if $L is available, whereKeyStats() is called for both ($P) and + ** ($P:$L) and the larger of the two returned values is used. + ** + ** Similarly, iUpper is to be set to the estimate of the number of rows + ** less than the upper bound of the range query. Where the upper bound + ** is either ($P) or ($P:$U). Again, even if $U is available, both values + ** of iUpper are requested of whereKeyStats() and the smaller used. + ** + ** The number of rows between the two bounds is then just iUpper-iLower. + */ + tRowcnt iLower; /* Rows less than the lower bound */ + tRowcnt iUpper; /* Rows less than the upper bound */ + int iLwrIdx = -2; /* aSample[] for the lower bound */ + int iUprIdx = -1; /* aSample[] for the upper bound */ + + if( pRec ){ + testcase( pRec->nField!=pBuilder->nRecValid ); + pRec->nField = pBuilder->nRecValid; + } + /* Determine iLower and iUpper using ($P) only. */ + if( nEq==0 ){ + iLower = 0; + iUpper = p->nRowEst0; + }else{ + /* Note: this call could be optimized away - since the same values must + ** have been requested when testing key $P in whereEqualScanEst(). */ + whereKeyStats(pParse, p, pRec, 0, a); + iLower = a[0]; + iUpper = a[0] + a[1]; + } + + assert( pLower==0 || (pLower->eOperator & (WO_GT|WO_GE))!=0 ); + assert( pUpper==0 || (pUpper->eOperator & (WO_LT|WO_LE))!=0 ); + assert( p->aSortOrder!=0 ); + if( p->aSortOrder[nEq] ){ + /* The roles of pLower and pUpper are swapped for a DESC index */ + SWAP(WhereTerm*, pLower, pUpper); + SWAP(int, nBtm, nTop); + } + + /* If possible, improve on the iLower estimate using ($P:$L). */ + if( pLower ){ + int n; /* Values extracted from pExpr */ + Expr *pExpr = pLower->pExpr->pRight; + rc = sqlite3Stat4ProbeSetValue(pParse, p, &pRec, pExpr, nBtm, nEq, &n); + if( rc==SQLITE_OK && n ){ + tRowcnt iNew; + u16 mask = WO_GT|WO_LE; + if( sqlite3ExprVectorSize(pExpr)>n ) mask = (WO_LE|WO_LT); + iLwrIdx = whereKeyStats(pParse, p, pRec, 0, a); + iNew = a[0] + ((pLower->eOperator & mask) ? a[1] : 0); + if( iNew>iLower ) iLower = iNew; + nOut--; + pLower = 0; + } + } + + /* If possible, improve on the iUpper estimate using ($P:$U). */ + if( pUpper ){ + int n; /* Values extracted from pExpr */ + Expr *pExpr = pUpper->pExpr->pRight; + rc = sqlite3Stat4ProbeSetValue(pParse, p, &pRec, pExpr, nTop, nEq, &n); + if( rc==SQLITE_OK && n ){ + tRowcnt iNew; + u16 mask = WO_GT|WO_LE; + if( sqlite3ExprVectorSize(pExpr)>n ) mask = (WO_LE|WO_LT); + iUprIdx = whereKeyStats(pParse, p, pRec, 1, a); + iNew = a[0] + ((pUpper->eOperator & mask) ? a[1] : 0); + if( iNew<iUpper ) iUpper = iNew; + nOut--; + pUpper = 0; + } + } + + pBuilder->pRec = pRec; + if( rc==SQLITE_OK ){ + if( iUpper>iLower ){ + nNew = sqlite3LogEst(iUpper - iLower); + /* TUNING: If both iUpper and iLower are derived from the same + ** sample, then assume they are 4x more selective. This brings + ** the estimated selectivity more in line with what it would be + ** if estimated without the use of STAT4 tables. */ + if( iLwrIdx==iUprIdx ){ nNew -= 20; } + assert( 20==sqlite3LogEst(4) ); + }else{ + nNew = 10; assert( 10==sqlite3LogEst(2) ); + } + if( nNew<nOut ){ + nOut = nNew; + } + WHERETRACE(0x20, ("STAT4 range scan: %u..%u est=%d\n", + (u32)iLower, (u32)iUpper, nOut)); + } + }else{ + int bDone = 0; + rc = whereRangeSkipScanEst(pParse, pLower, pUpper, pLoop, &bDone); + if( bDone ) return rc; + } + } +#else + UNUSED_PARAMETER(pParse); + UNUSED_PARAMETER(pBuilder); + assert( pLower || pUpper ); +#endif + assert( pUpper==0 || (pUpper->wtFlags & TERM_VNULL)==0 || pParse->nErr>0 ); + nNew = whereRangeAdjust(pLower, nOut); + nNew = whereRangeAdjust(pUpper, nNew); + + /* TUNING: If there is both an upper and lower limit and neither limit + ** has an application-defined likelihood(), assume the range is + ** reduced by an additional 75%. This means that, by default, an open-ended + ** range query (e.g. col > ?) is assumed to match 1/4 of the rows in the + ** index. While a closed range (e.g. col BETWEEN ? AND ?) is estimated to + ** match 1/64 of the index. */ + if( pLower && pLower->truthProb>0 && pUpper && pUpper->truthProb>0 ){ + nNew -= 20; + } + + nOut -= (pLower!=0) + (pUpper!=0); + if( nNew<10 ) nNew = 10; + if( nNew<nOut ) nOut = nNew; +#if defined(WHERETRACE_ENABLED) + if( pLoop->nOut>nOut ){ + WHERETRACE(0x20,("Range scan lowers nOut from %d to %d\n", + pLoop->nOut, nOut)); + } +#endif + pLoop->nOut = (LogEst)nOut; + return rc; +} + +#ifdef SQLITE_ENABLE_STAT4 +/* +** Estimate the number of rows that will be returned based on +** an equality constraint x=VALUE and where that VALUE occurs in +** the histogram data. This only works when x is the left-most +** column of an index and sqlite_stat4 histogram data is available +** for that index. When pExpr==NULL that means the constraint is +** "x IS NULL" instead of "x=VALUE". +** +** Write the estimated row count into *pnRow and return SQLITE_OK. +** If unable to make an estimate, leave *pnRow unchanged and return +** non-zero. +** +** This routine can fail if it is unable to load a collating sequence +** required for string comparison, or if unable to allocate memory +** for a UTF conversion required for comparison. The error is stored +** in the pParse structure. +*/ +static int whereEqualScanEst( + Parse *pParse, /* Parsing & code generating context */ + WhereLoopBuilder *pBuilder, + Expr *pExpr, /* Expression for VALUE in the x=VALUE constraint */ + tRowcnt *pnRow /* Write the revised row estimate here */ +){ + Index *p = pBuilder->pNew->u.btree.pIndex; + int nEq = pBuilder->pNew->u.btree.nEq; + UnpackedRecord *pRec = pBuilder->pRec; + int rc; /* Subfunction return code */ + tRowcnt a[2]; /* Statistics */ + int bOk; + + assert( nEq>=1 ); + assert( nEq<=p->nColumn ); + assert( p->aSample!=0 ); + assert( p->nSample>0 ); + assert( pBuilder->nRecValid<nEq ); + + /* If values are not available for all fields of the index to the left + ** of this one, no estimate can be made. Return SQLITE_NOTFOUND. */ + if( pBuilder->nRecValid<(nEq-1) ){ + return SQLITE_NOTFOUND; + } + + /* This is an optimization only. The call to sqlite3Stat4ProbeSetValue() + ** below would return the same value. */ + if( nEq>=p->nColumn ){ + *pnRow = 1; + return SQLITE_OK; + } + + rc = sqlite3Stat4ProbeSetValue(pParse, p, &pRec, pExpr, 1, nEq-1, &bOk); + pBuilder->pRec = pRec; + if( rc!=SQLITE_OK ) return rc; + if( bOk==0 ) return SQLITE_NOTFOUND; + pBuilder->nRecValid = nEq; + + whereKeyStats(pParse, p, pRec, 0, a); + WHERETRACE(0x20,("equality scan regions %s(%d): %d\n", + p->zName, nEq-1, (int)a[1])); + *pnRow = a[1]; + + return rc; +} +#endif /* SQLITE_ENABLE_STAT4 */ + +#ifdef SQLITE_ENABLE_STAT4 +/* +** Estimate the number of rows that will be returned based on +** an IN constraint where the right-hand side of the IN operator +** is a list of values. Example: +** +** WHERE x IN (1,2,3,4) +** +** Write the estimated row count into *pnRow and return SQLITE_OK. +** If unable to make an estimate, leave *pnRow unchanged and return +** non-zero. +** +** This routine can fail if it is unable to load a collating sequence +** required for string comparison, or if unable to allocate memory +** for a UTF conversion required for comparison. The error is stored +** in the pParse structure. +*/ +static int whereInScanEst( + Parse *pParse, /* Parsing & code generating context */ + WhereLoopBuilder *pBuilder, + ExprList *pList, /* The value list on the RHS of "x IN (v1,v2,v3,...)" */ + tRowcnt *pnRow /* Write the revised row estimate here */ +){ + Index *p = pBuilder->pNew->u.btree.pIndex; + i64 nRow0 = sqlite3LogEstToInt(p->aiRowLogEst[0]); + int nRecValid = pBuilder->nRecValid; + int rc = SQLITE_OK; /* Subfunction return code */ + tRowcnt nEst; /* Number of rows for a single term */ + tRowcnt nRowEst = 0; /* New estimate of the number of rows */ + int i; /* Loop counter */ + + assert( p->aSample!=0 ); + for(i=0; rc==SQLITE_OK && i<pList->nExpr; i++){ + nEst = nRow0; + rc = whereEqualScanEst(pParse, pBuilder, pList->a[i].pExpr, &nEst); + nRowEst += nEst; + pBuilder->nRecValid = nRecValid; + } + + if( rc==SQLITE_OK ){ + if( nRowEst > (tRowcnt)nRow0 ) nRowEst = nRow0; + *pnRow = nRowEst; + WHERETRACE(0x20,("IN row estimate: est=%d\n", nRowEst)); + } + assert( pBuilder->nRecValid==nRecValid ); + return rc; +} +#endif /* SQLITE_ENABLE_STAT4 */ + + +#ifdef WHERETRACE_ENABLED +/* +** Print the content of a WhereTerm object +*/ +void sqlite3WhereTermPrint(WhereTerm *pTerm, int iTerm){ + if( pTerm==0 ){ + sqlite3DebugPrintf("TERM-%-3d NULL\n", iTerm); + }else{ + char zType[8]; + char zLeft[50]; + memcpy(zType, "....", 5); + if( pTerm->wtFlags & TERM_VIRTUAL ) zType[0] = 'V'; + if( pTerm->eOperator & WO_EQUIV ) zType[1] = 'E'; + if( ExprHasProperty(pTerm->pExpr, EP_OuterON) ) zType[2] = 'L'; + if( pTerm->wtFlags & TERM_CODED ) zType[3] = 'C'; + if( pTerm->eOperator & WO_SINGLE ){ + assert( (pTerm->eOperator & (WO_OR|WO_AND))==0 ); + sqlite3_snprintf(sizeof(zLeft),zLeft,"left={%d:%d}", + pTerm->leftCursor, pTerm->u.x.leftColumn); + }else if( (pTerm->eOperator & WO_OR)!=0 && pTerm->u.pOrInfo!=0 ){ + sqlite3_snprintf(sizeof(zLeft),zLeft,"indexable=0x%llx", + pTerm->u.pOrInfo->indexable); + }else{ + sqlite3_snprintf(sizeof(zLeft),zLeft,"left=%d", pTerm->leftCursor); + } + sqlite3DebugPrintf( + "TERM-%-3d %p %s %-12s op=%03x wtFlags=%04x", + iTerm, pTerm, zType, zLeft, pTerm->eOperator, pTerm->wtFlags); + /* The 0x10000 .wheretrace flag causes extra information to be + ** shown about each Term */ + if( sqlite3WhereTrace & 0x10000 ){ + sqlite3DebugPrintf(" prob=%-3d prereq=%llx,%llx", + pTerm->truthProb, (u64)pTerm->prereqAll, (u64)pTerm->prereqRight); + } + if( (pTerm->eOperator & (WO_OR|WO_AND))==0 && pTerm->u.x.iField ){ + sqlite3DebugPrintf(" iField=%d", pTerm->u.x.iField); + } + if( pTerm->iParent>=0 ){ + sqlite3DebugPrintf(" iParent=%d", pTerm->iParent); + } + sqlite3DebugPrintf("\n"); + sqlite3TreeViewExpr(0, pTerm->pExpr, 0); + } +} +#endif + +#ifdef WHERETRACE_ENABLED +/* +** Show the complete content of a WhereClause +*/ +void sqlite3WhereClausePrint(WhereClause *pWC){ + int i; + for(i=0; i<pWC->nTerm; i++){ + sqlite3WhereTermPrint(&pWC->a[i], i); + } +} +#endif + +#ifdef WHERETRACE_ENABLED +/* +** Print a WhereLoop object for debugging purposes +** +** Format example: +** +** .--- Position in WHERE clause rSetup, rRun, nOut ---. +** | | +** | .--- selfMask nTerm ------. | +** | | | | +** | | .-- prereq Idx wsFlags----. | | +** | | | Name | | | +** | | | __|__ nEq ---. ___|__ | __|__ +** | / \ / \ / \ | / \ / \ / \ +** 1.002.001 t2.t2xy 2 f 010241 N 2 cost 0,56,31 +*/ +void sqlite3WhereLoopPrint(const WhereLoop *p, const WhereClause *pWC){ + if( pWC ){ + WhereInfo *pWInfo = pWC->pWInfo; + int nb = 1+(pWInfo->pTabList->nSrc+3)/4; + SrcItem *pItem = pWInfo->pTabList->a + p->iTab; + Table *pTab = pItem->pTab; + Bitmask mAll = (((Bitmask)1)<<(nb*4)) - 1; + sqlite3DebugPrintf("%c%2d.%0*llx.%0*llx", p->cId, + p->iTab, nb, p->maskSelf, nb, p->prereq & mAll); + sqlite3DebugPrintf(" %12s", + pItem->zAlias ? pItem->zAlias : pTab->zName); + }else{ + sqlite3DebugPrintf("%c%2d.%03llx.%03llx %c%d", + p->cId, p->iTab, p->maskSelf, p->prereq & 0xfff, p->cId, p->iTab); + } + if( (p->wsFlags & WHERE_VIRTUALTABLE)==0 ){ + const char *zName; + if( p->u.btree.pIndex && (zName = p->u.btree.pIndex->zName)!=0 ){ + if( strncmp(zName, "sqlite_autoindex_", 17)==0 ){ + int i = sqlite3Strlen30(zName) - 1; + while( zName[i]!='_' ) i--; + zName += i; + } + sqlite3DebugPrintf(".%-16s %2d", zName, p->u.btree.nEq); + }else{ + sqlite3DebugPrintf("%20s",""); + } + }else{ + char *z; + if( p->u.vtab.idxStr ){ + z = sqlite3_mprintf("(%d,\"%s\",%#x)", + p->u.vtab.idxNum, p->u.vtab.idxStr, p->u.vtab.omitMask); + }else{ + z = sqlite3_mprintf("(%d,%x)", p->u.vtab.idxNum, p->u.vtab.omitMask); + } + sqlite3DebugPrintf(" %-19s", z); + sqlite3_free(z); + } + if( p->wsFlags & WHERE_SKIPSCAN ){ + sqlite3DebugPrintf(" f %06x %d-%d", p->wsFlags, p->nLTerm,p->nSkip); + }else{ + sqlite3DebugPrintf(" f %06x N %d", p->wsFlags, p->nLTerm); + } + sqlite3DebugPrintf(" cost %d,%d,%d\n", p->rSetup, p->rRun, p->nOut); + if( p->nLTerm && (sqlite3WhereTrace & 0x4000)!=0 ){ + int i; + for(i=0; i<p->nLTerm; i++){ + sqlite3WhereTermPrint(p->aLTerm[i], i); + } + } +} +void sqlite3ShowWhereLoop(const WhereLoop *p){ + if( p ) sqlite3WhereLoopPrint(p, 0); +} +void sqlite3ShowWhereLoopList(const WhereLoop *p){ + while( p ){ + sqlite3ShowWhereLoop(p); + p = p->pNextLoop; + } +} +#endif + +/* +** Convert bulk memory into a valid WhereLoop that can be passed +** to whereLoopClear harmlessly. +*/ +static void whereLoopInit(WhereLoop *p){ + p->aLTerm = p->aLTermSpace; + p->nLTerm = 0; + p->nLSlot = ArraySize(p->aLTermSpace); + p->wsFlags = 0; +} + +/* +** Clear the WhereLoop.u union. Leave WhereLoop.pLTerm intact. +*/ +static void whereLoopClearUnion(sqlite3 *db, WhereLoop *p){ + if( p->wsFlags & (WHERE_VIRTUALTABLE|WHERE_AUTO_INDEX) ){ + if( (p->wsFlags & WHERE_VIRTUALTABLE)!=0 && p->u.vtab.needFree ){ + sqlite3_free(p->u.vtab.idxStr); + p->u.vtab.needFree = 0; + p->u.vtab.idxStr = 0; + }else if( (p->wsFlags & WHERE_AUTO_INDEX)!=0 && p->u.btree.pIndex!=0 ){ + sqlite3DbFree(db, p->u.btree.pIndex->zColAff); + sqlite3DbFreeNN(db, p->u.btree.pIndex); + p->u.btree.pIndex = 0; + } + } +} + +/* +** Deallocate internal memory used by a WhereLoop object. Leave the +** object in an initialized state, as if it had been newly allocated. +*/ +static void whereLoopClear(sqlite3 *db, WhereLoop *p){ + if( p->aLTerm!=p->aLTermSpace ){ + sqlite3DbFreeNN(db, p->aLTerm); + p->aLTerm = p->aLTermSpace; + p->nLSlot = ArraySize(p->aLTermSpace); + } + whereLoopClearUnion(db, p); + p->nLTerm = 0; + p->wsFlags = 0; +} + +/* +** Increase the memory allocation for pLoop->aLTerm[] to be at least n. +*/ +static int whereLoopResize(sqlite3 *db, WhereLoop *p, int n){ + WhereTerm **paNew; + if( p->nLSlot>=n ) return SQLITE_OK; + n = (n+7)&~7; + paNew = sqlite3DbMallocRawNN(db, sizeof(p->aLTerm[0])*n); + if( paNew==0 ) return SQLITE_NOMEM_BKPT; + memcpy(paNew, p->aLTerm, sizeof(p->aLTerm[0])*p->nLSlot); + if( p->aLTerm!=p->aLTermSpace ) sqlite3DbFreeNN(db, p->aLTerm); + p->aLTerm = paNew; + p->nLSlot = n; + return SQLITE_OK; +} + +/* +** Transfer content from the second pLoop into the first. +*/ +static int whereLoopXfer(sqlite3 *db, WhereLoop *pTo, WhereLoop *pFrom){ + whereLoopClearUnion(db, pTo); + if( pFrom->nLTerm > pTo->nLSlot + && whereLoopResize(db, pTo, pFrom->nLTerm) + ){ + memset(pTo, 0, WHERE_LOOP_XFER_SZ); + return SQLITE_NOMEM_BKPT; + } + memcpy(pTo, pFrom, WHERE_LOOP_XFER_SZ); + memcpy(pTo->aLTerm, pFrom->aLTerm, pTo->nLTerm*sizeof(pTo->aLTerm[0])); + if( pFrom->wsFlags & WHERE_VIRTUALTABLE ){ + pFrom->u.vtab.needFree = 0; + }else if( (pFrom->wsFlags & WHERE_AUTO_INDEX)!=0 ){ + pFrom->u.btree.pIndex = 0; + } + return SQLITE_OK; +} + +/* +** Delete a WhereLoop object +*/ +static void whereLoopDelete(sqlite3 *db, WhereLoop *p){ + assert( db!=0 ); + whereLoopClear(db, p); + sqlite3DbNNFreeNN(db, p); +} + +/* +** Free a WhereInfo structure +*/ +static void whereInfoFree(sqlite3 *db, WhereInfo *pWInfo){ + assert( pWInfo!=0 ); + assert( db!=0 ); + sqlite3WhereClauseClear(&pWInfo->sWC); + while( pWInfo->pLoops ){ + WhereLoop *p = pWInfo->pLoops; + pWInfo->pLoops = p->pNextLoop; + whereLoopDelete(db, p); + } + while( pWInfo->pMemToFree ){ + WhereMemBlock *pNext = pWInfo->pMemToFree->pNext; + sqlite3DbNNFreeNN(db, pWInfo->pMemToFree); + pWInfo->pMemToFree = pNext; + } + sqlite3DbNNFreeNN(db, pWInfo); +} + +/* +** Return TRUE if X is a proper subset of Y but is of equal or less cost. +** In other words, return true if all constraints of X are also part of Y +** and Y has additional constraints that might speed the search that X lacks +** but the cost of running X is not more than the cost of running Y. +** +** In other words, return true if the cost relationwship between X and Y +** is inverted and needs to be adjusted. +** +** Case 1: +** +** (1a) X and Y use the same index. +** (1b) X has fewer == terms than Y +** (1c) Neither X nor Y use skip-scan +** (1d) X does not have a a greater cost than Y +** +** Case 2: +** +** (2a) X has the same or lower cost, or returns the same or fewer rows, +** than Y. +** (2b) X uses fewer WHERE clause terms than Y +** (2c) Every WHERE clause term used by X is also used by Y +** (2d) X skips at least as many columns as Y +** (2e) If X is a covering index, than Y is too +*/ +static int whereLoopCheaperProperSubset( + const WhereLoop *pX, /* First WhereLoop to compare */ + const WhereLoop *pY /* Compare against this WhereLoop */ +){ + int i, j; + if( pX->rRun>pY->rRun && pX->nOut>pY->nOut ) return 0; /* (1d) and (2a) */ + assert( (pX->wsFlags & WHERE_VIRTUALTABLE)==0 ); + assert( (pY->wsFlags & WHERE_VIRTUALTABLE)==0 ); + if( pX->u.btree.nEq < pY->u.btree.nEq /* (1b) */ + && pX->u.btree.pIndex==pY->u.btree.pIndex /* (1a) */ + && pX->nSkip==0 && pY->nSkip==0 /* (1c) */ + ){ + return 1; /* Case 1 is true */ + } + if( pX->nLTerm-pX->nSkip >= pY->nLTerm-pY->nSkip ){ + return 0; /* (2b) */ + } + if( pY->nSkip > pX->nSkip ) return 0; /* (2d) */ + for(i=pX->nLTerm-1; i>=0; i--){ + if( pX->aLTerm[i]==0 ) continue; + for(j=pY->nLTerm-1; j>=0; j--){ + if( pY->aLTerm[j]==pX->aLTerm[i] ) break; + } + if( j<0 ) return 0; /* (2c) */ + } + if( (pX->wsFlags&WHERE_IDX_ONLY)!=0 + && (pY->wsFlags&WHERE_IDX_ONLY)==0 ){ + return 0; /* (2e) */ + } + return 1; /* Case 2 is true */ +} + +/* +** Try to adjust the cost and number of output rows of WhereLoop pTemplate +** upwards or downwards so that: +** +** (1) pTemplate costs less than any other WhereLoops that are a proper +** subset of pTemplate +** +** (2) pTemplate costs more than any other WhereLoops for which pTemplate +** is a proper subset. +** +** To say "WhereLoop X is a proper subset of Y" means that X uses fewer +** WHERE clause terms than Y and that every WHERE clause term used by X is +** also used by Y. +*/ +static void whereLoopAdjustCost(const WhereLoop *p, WhereLoop *pTemplate){ + if( (pTemplate->wsFlags & WHERE_INDEXED)==0 ) return; + for(; p; p=p->pNextLoop){ + if( p->iTab!=pTemplate->iTab ) continue; + if( (p->wsFlags & WHERE_INDEXED)==0 ) continue; + if( whereLoopCheaperProperSubset(p, pTemplate) ){ + /* Adjust pTemplate cost downward so that it is cheaper than its + ** subset p. */ + WHERETRACE(0x80,("subset cost adjustment %d,%d to %d,%d\n", + pTemplate->rRun, pTemplate->nOut, + MIN(p->rRun, pTemplate->rRun), + MIN(p->nOut - 1, pTemplate->nOut))); + pTemplate->rRun = MIN(p->rRun, pTemplate->rRun); + pTemplate->nOut = MIN(p->nOut - 1, pTemplate->nOut); + }else if( whereLoopCheaperProperSubset(pTemplate, p) ){ + /* Adjust pTemplate cost upward so that it is costlier than p since + ** pTemplate is a proper subset of p */ + WHERETRACE(0x80,("subset cost adjustment %d,%d to %d,%d\n", + pTemplate->rRun, pTemplate->nOut, + MAX(p->rRun, pTemplate->rRun), + MAX(p->nOut + 1, pTemplate->nOut))); + pTemplate->rRun = MAX(p->rRun, pTemplate->rRun); + pTemplate->nOut = MAX(p->nOut + 1, pTemplate->nOut); + } + } +} + +/* +** Search the list of WhereLoops in *ppPrev looking for one that can be +** replaced by pTemplate. +** +** Return NULL if pTemplate does not belong on the WhereLoop list. +** In other words if pTemplate ought to be dropped from further consideration. +** +** If pX is a WhereLoop that pTemplate can replace, then return the +** link that points to pX. +** +** If pTemplate cannot replace any existing element of the list but needs +** to be added to the list as a new entry, then return a pointer to the +** tail of the list. +*/ +static WhereLoop **whereLoopFindLesser( + WhereLoop **ppPrev, + const WhereLoop *pTemplate +){ + WhereLoop *p; + for(p=(*ppPrev); p; ppPrev=&p->pNextLoop, p=*ppPrev){ + if( p->iTab!=pTemplate->iTab || p->iSortIdx!=pTemplate->iSortIdx ){ + /* If either the iTab or iSortIdx values for two WhereLoop are different + ** then those WhereLoops need to be considered separately. Neither is + ** a candidate to replace the other. */ + continue; + } + /* In the current implementation, the rSetup value is either zero + ** or the cost of building an automatic index (NlogN) and the NlogN + ** is the same for compatible WhereLoops. */ + assert( p->rSetup==0 || pTemplate->rSetup==0 + || p->rSetup==pTemplate->rSetup ); + + /* whereLoopAddBtree() always generates and inserts the automatic index + ** case first. Hence compatible candidate WhereLoops never have a larger + ** rSetup. Call this SETUP-INVARIANT */ + assert( p->rSetup>=pTemplate->rSetup ); + + /* Any loop using an application-defined index (or PRIMARY KEY or + ** UNIQUE constraint) with one or more == constraints is better + ** than an automatic index. Unless it is a skip-scan. */ + if( (p->wsFlags & WHERE_AUTO_INDEX)!=0 + && (pTemplate->nSkip)==0 + && (pTemplate->wsFlags & WHERE_INDEXED)!=0 + && (pTemplate->wsFlags & WHERE_COLUMN_EQ)!=0 + && (p->prereq & pTemplate->prereq)==pTemplate->prereq + ){ + break; + } + + /* If existing WhereLoop p is better than pTemplate, pTemplate can be + ** discarded. WhereLoop p is better if: + ** (1) p has no more dependencies than pTemplate, and + ** (2) p has an equal or lower cost than pTemplate + */ + if( (p->prereq & pTemplate->prereq)==p->prereq /* (1) */ + && p->rSetup<=pTemplate->rSetup /* (2a) */ + && p->rRun<=pTemplate->rRun /* (2b) */ + && p->nOut<=pTemplate->nOut /* (2c) */ + ){ + return 0; /* Discard pTemplate */ + } + + /* If pTemplate is always better than p, then cause p to be overwritten + ** with pTemplate. pTemplate is better than p if: + ** (1) pTemplate has no more dependencies than p, and + ** (2) pTemplate has an equal or lower cost than p. + */ + if( (p->prereq & pTemplate->prereq)==pTemplate->prereq /* (1) */ + && p->rRun>=pTemplate->rRun /* (2a) */ + && p->nOut>=pTemplate->nOut /* (2b) */ + ){ + assert( p->rSetup>=pTemplate->rSetup ); /* SETUP-INVARIANT above */ + break; /* Cause p to be overwritten by pTemplate */ + } + } + return ppPrev; +} + +/* +** Insert or replace a WhereLoop entry using the template supplied. +** +** An existing WhereLoop entry might be overwritten if the new template +** is better and has fewer dependencies. Or the template will be ignored +** and no insert will occur if an existing WhereLoop is faster and has +** fewer dependencies than the template. Otherwise a new WhereLoop is +** added based on the template. +** +** If pBuilder->pOrSet is not NULL then we care about only the +** prerequisites and rRun and nOut costs of the N best loops. That +** information is gathered in the pBuilder->pOrSet object. This special +** processing mode is used only for OR clause processing. +** +** When accumulating multiple loops (when pBuilder->pOrSet is NULL) we +** still might overwrite similar loops with the new template if the +** new template is better. Loops may be overwritten if the following +** conditions are met: +** +** (1) They have the same iTab. +** (2) They have the same iSortIdx. +** (3) The template has same or fewer dependencies than the current loop +** (4) The template has the same or lower cost than the current loop +*/ +static int whereLoopInsert(WhereLoopBuilder *pBuilder, WhereLoop *pTemplate){ + WhereLoop **ppPrev, *p; + WhereInfo *pWInfo = pBuilder->pWInfo; + sqlite3 *db = pWInfo->pParse->db; + int rc; + + /* Stop the search once we hit the query planner search limit */ + if( pBuilder->iPlanLimit==0 ){ + WHERETRACE(0xffffffff,("=== query planner search limit reached ===\n")); + if( pBuilder->pOrSet ) pBuilder->pOrSet->n = 0; + return SQLITE_DONE; + } + pBuilder->iPlanLimit--; + + whereLoopAdjustCost(pWInfo->pLoops, pTemplate); + + /* If pBuilder->pOrSet is defined, then only keep track of the costs + ** and prereqs. + */ + if( pBuilder->pOrSet!=0 ){ + if( pTemplate->nLTerm ){ +#if WHERETRACE_ENABLED + u16 n = pBuilder->pOrSet->n; + int x = +#endif + whereOrInsert(pBuilder->pOrSet, pTemplate->prereq, pTemplate->rRun, + pTemplate->nOut); +#if WHERETRACE_ENABLED /* 0x8 */ + if( sqlite3WhereTrace & 0x8 ){ + sqlite3DebugPrintf(x?" or-%d: ":" or-X: ", n); + sqlite3WhereLoopPrint(pTemplate, pBuilder->pWC); + } +#endif + } + return SQLITE_OK; + } + + /* Look for an existing WhereLoop to replace with pTemplate + */ + ppPrev = whereLoopFindLesser(&pWInfo->pLoops, pTemplate); + + if( ppPrev==0 ){ + /* There already exists a WhereLoop on the list that is better + ** than pTemplate, so just ignore pTemplate */ +#if WHERETRACE_ENABLED /* 0x8 */ + if( sqlite3WhereTrace & 0x8 ){ + sqlite3DebugPrintf(" skip: "); + sqlite3WhereLoopPrint(pTemplate, pBuilder->pWC); + } +#endif + return SQLITE_OK; + }else{ + p = *ppPrev; + } + + /* If we reach this point it means that either p[] should be overwritten + ** with pTemplate[] if p[] exists, or if p==NULL then allocate a new + ** WhereLoop and insert it. + */ +#if WHERETRACE_ENABLED /* 0x8 */ + if( sqlite3WhereTrace & 0x8 ){ + if( p!=0 ){ + sqlite3DebugPrintf("replace: "); + sqlite3WhereLoopPrint(p, pBuilder->pWC); + sqlite3DebugPrintf(" with: "); + }else{ + sqlite3DebugPrintf(" add: "); + } + sqlite3WhereLoopPrint(pTemplate, pBuilder->pWC); + } +#endif + if( p==0 ){ + /* Allocate a new WhereLoop to add to the end of the list */ + *ppPrev = p = sqlite3DbMallocRawNN(db, sizeof(WhereLoop)); + if( p==0 ) return SQLITE_NOMEM_BKPT; + whereLoopInit(p); + p->pNextLoop = 0; + }else{ + /* We will be overwriting WhereLoop p[]. But before we do, first + ** go through the rest of the list and delete any other entries besides + ** p[] that are also supplanted by pTemplate */ + WhereLoop **ppTail = &p->pNextLoop; + WhereLoop *pToDel; + while( *ppTail ){ + ppTail = whereLoopFindLesser(ppTail, pTemplate); + if( ppTail==0 ) break; + pToDel = *ppTail; + if( pToDel==0 ) break; + *ppTail = pToDel->pNextLoop; +#if WHERETRACE_ENABLED /* 0x8 */ + if( sqlite3WhereTrace & 0x8 ){ + sqlite3DebugPrintf(" delete: "); + sqlite3WhereLoopPrint(pToDel, pBuilder->pWC); + } +#endif + whereLoopDelete(db, pToDel); + } + } + rc = whereLoopXfer(db, p, pTemplate); + if( (p->wsFlags & WHERE_VIRTUALTABLE)==0 ){ + Index *pIndex = p->u.btree.pIndex; + if( pIndex && pIndex->idxType==SQLITE_IDXTYPE_IPK ){ + p->u.btree.pIndex = 0; + } + } + return rc; +} + +/* +** Adjust the WhereLoop.nOut value downward to account for terms of the +** WHERE clause that reference the loop but which are not used by an +** index. +* +** For every WHERE clause term that is not used by the index +** and which has a truth probability assigned by one of the likelihood(), +** likely(), or unlikely() SQL functions, reduce the estimated number +** of output rows by the probability specified. +** +** TUNING: For every WHERE clause term that is not used by the index +** and which does not have an assigned truth probability, heuristics +** described below are used to try to estimate the truth probability. +** TODO --> Perhaps this is something that could be improved by better +** table statistics. +** +** Heuristic 1: Estimate the truth probability as 93.75%. The 93.75% +** value corresponds to -1 in LogEst notation, so this means decrement +** the WhereLoop.nOut field for every such WHERE clause term. +** +** Heuristic 2: If there exists one or more WHERE clause terms of the +** form "x==EXPR" and EXPR is not a constant 0 or 1, then make sure the +** final output row estimate is no greater than 1/4 of the total number +** of rows in the table. In other words, assume that x==EXPR will filter +** out at least 3 out of 4 rows. If EXPR is -1 or 0 or 1, then maybe the +** "x" column is boolean or else -1 or 0 or 1 is a common default value +** on the "x" column and so in that case only cap the output row estimate +** at 1/2 instead of 1/4. +*/ +static void whereLoopOutputAdjust( + WhereClause *pWC, /* The WHERE clause */ + WhereLoop *pLoop, /* The loop to adjust downward */ + LogEst nRow /* Number of rows in the entire table */ +){ + WhereTerm *pTerm, *pX; + Bitmask notAllowed = ~(pLoop->prereq|pLoop->maskSelf); + int i, j; + LogEst iReduce = 0; /* pLoop->nOut should not exceed nRow-iReduce */ + + assert( (pLoop->wsFlags & WHERE_AUTO_INDEX)==0 ); + for(i=pWC->nBase, pTerm=pWC->a; i>0; i--, pTerm++){ + assert( pTerm!=0 ); + if( (pTerm->prereqAll & notAllowed)!=0 ) continue; + if( (pTerm->prereqAll & pLoop->maskSelf)==0 ) continue; + if( (pTerm->wtFlags & TERM_VIRTUAL)!=0 ) continue; + for(j=pLoop->nLTerm-1; j>=0; j--){ + pX = pLoop->aLTerm[j]; + if( pX==0 ) continue; + if( pX==pTerm ) break; + if( pX->iParent>=0 && (&pWC->a[pX->iParent])==pTerm ) break; + } + if( j<0 ){ + sqlite3ProgressCheck(pWC->pWInfo->pParse); + if( pLoop->maskSelf==pTerm->prereqAll ){ + /* If there are extra terms in the WHERE clause not used by an index + ** that depend only on the table being scanned, and that will tend to + ** cause many rows to be omitted, then mark that table as + ** "self-culling". + ** + ** 2022-03-24: Self-culling only applies if either the extra terms + ** are straight comparison operators that are non-true with NULL + ** operand, or if the loop is not an OUTER JOIN. + */ + if( (pTerm->eOperator & 0x3f)!=0 + || (pWC->pWInfo->pTabList->a[pLoop->iTab].fg.jointype + & (JT_LEFT|JT_LTORJ))==0 + ){ + pLoop->wsFlags |= WHERE_SELFCULL; + } + } + if( pTerm->truthProb<=0 ){ + /* If a truth probability is specified using the likelihood() hints, + ** then use the probability provided by the application. */ + pLoop->nOut += pTerm->truthProb; + }else{ + /* In the absence of explicit truth probabilities, use heuristics to + ** guess a reasonable truth probability. */ + pLoop->nOut--; + if( (pTerm->eOperator&(WO_EQ|WO_IS))!=0 + && (pTerm->wtFlags & TERM_HIGHTRUTH)==0 /* tag-20200224-1 */ + ){ + Expr *pRight = pTerm->pExpr->pRight; + int k = 0; + testcase( pTerm->pExpr->op==TK_IS ); + if( sqlite3ExprIsInteger(pRight, &k) && k>=(-1) && k<=1 ){ + k = 10; + }else{ + k = 20; + } + if( iReduce<k ){ + pTerm->wtFlags |= TERM_HEURTRUTH; + iReduce = k; + } + } + } + } + } + if( pLoop->nOut > nRow-iReduce ){ + pLoop->nOut = nRow - iReduce; + } +} + +/* +** Term pTerm is a vector range comparison operation. The first comparison +** in the vector can be optimized using column nEq of the index. This +** function returns the total number of vector elements that can be used +** as part of the range comparison. +** +** For example, if the query is: +** +** WHERE a = ? AND (b, c, d) > (?, ?, ?) +** +** and the index: +** +** CREATE INDEX ... ON (a, b, c, d, e) +** +** then this function would be invoked with nEq=1. The value returned in +** this case is 3. +*/ +static int whereRangeVectorLen( + Parse *pParse, /* Parsing context */ + int iCur, /* Cursor open on pIdx */ + Index *pIdx, /* The index to be used for a inequality constraint */ + int nEq, /* Number of prior equality constraints on same index */ + WhereTerm *pTerm /* The vector inequality constraint */ +){ + int nCmp = sqlite3ExprVectorSize(pTerm->pExpr->pLeft); + int i; + + nCmp = MIN(nCmp, (pIdx->nColumn - nEq)); + for(i=1; i<nCmp; i++){ + /* Test if comparison i of pTerm is compatible with column (i+nEq) + ** of the index. If not, exit the loop. */ + char aff; /* Comparison affinity */ + char idxaff = 0; /* Indexed columns affinity */ + CollSeq *pColl; /* Comparison collation sequence */ + Expr *pLhs, *pRhs; + + assert( ExprUseXList(pTerm->pExpr->pLeft) ); + pLhs = pTerm->pExpr->pLeft->x.pList->a[i].pExpr; + pRhs = pTerm->pExpr->pRight; + if( ExprUseXSelect(pRhs) ){ + pRhs = pRhs->x.pSelect->pEList->a[i].pExpr; + }else{ + pRhs = pRhs->x.pList->a[i].pExpr; + } + + /* Check that the LHS of the comparison is a column reference to + ** the right column of the right source table. And that the sort + ** order of the index column is the same as the sort order of the + ** leftmost index column. */ + if( pLhs->op!=TK_COLUMN + || pLhs->iTable!=iCur + || pLhs->iColumn!=pIdx->aiColumn[i+nEq] + || pIdx->aSortOrder[i+nEq]!=pIdx->aSortOrder[nEq] + ){ + break; + } + + testcase( pLhs->iColumn==XN_ROWID ); + aff = sqlite3CompareAffinity(pRhs, sqlite3ExprAffinity(pLhs)); + idxaff = sqlite3TableColumnAffinity(pIdx->pTable, pLhs->iColumn); + if( aff!=idxaff ) break; + + pColl = sqlite3BinaryCompareCollSeq(pParse, pLhs, pRhs); + if( pColl==0 ) break; + if( sqlite3StrICmp(pColl->zName, pIdx->azColl[i+nEq]) ) break; + } + return i; +} + +/* +** Adjust the cost C by the costMult factor T. This only occurs if +** compiled with -DSQLITE_ENABLE_COSTMULT +*/ +#ifdef SQLITE_ENABLE_COSTMULT +# define ApplyCostMultiplier(C,T) C += T +#else +# define ApplyCostMultiplier(C,T) +#endif + +/* +** We have so far matched pBuilder->pNew->u.btree.nEq terms of the +** index pIndex. Try to match one more. +** +** When this function is called, pBuilder->pNew->nOut contains the +** number of rows expected to be visited by filtering using the nEq +** terms only. If it is modified, this value is restored before this +** function returns. +** +** If pProbe->idxType==SQLITE_IDXTYPE_IPK, that means pIndex is +** a fake index used for the INTEGER PRIMARY KEY. +*/ +static int whereLoopAddBtreeIndex( + WhereLoopBuilder *pBuilder, /* The WhereLoop factory */ + SrcItem *pSrc, /* FROM clause term being analyzed */ + Index *pProbe, /* An index on pSrc */ + LogEst nInMul /* log(Number of iterations due to IN) */ +){ + WhereInfo *pWInfo = pBuilder->pWInfo; /* WHERE analyze context */ + Parse *pParse = pWInfo->pParse; /* Parsing context */ + sqlite3 *db = pParse->db; /* Database connection malloc context */ + WhereLoop *pNew; /* Template WhereLoop under construction */ + WhereTerm *pTerm; /* A WhereTerm under consideration */ + int opMask; /* Valid operators for constraints */ + WhereScan scan; /* Iterator for WHERE terms */ + Bitmask saved_prereq; /* Original value of pNew->prereq */ + u16 saved_nLTerm; /* Original value of pNew->nLTerm */ + u16 saved_nEq; /* Original value of pNew->u.btree.nEq */ + u16 saved_nBtm; /* Original value of pNew->u.btree.nBtm */ + u16 saved_nTop; /* Original value of pNew->u.btree.nTop */ + u16 saved_nSkip; /* Original value of pNew->nSkip */ + u32 saved_wsFlags; /* Original value of pNew->wsFlags */ + LogEst saved_nOut; /* Original value of pNew->nOut */ + int rc = SQLITE_OK; /* Return code */ + LogEst rSize; /* Number of rows in the table */ + LogEst rLogSize; /* Logarithm of table size */ + WhereTerm *pTop = 0, *pBtm = 0; /* Top and bottom range constraints */ + + pNew = pBuilder->pNew; + assert( db->mallocFailed==0 || pParse->nErr>0 ); + if( pParse->nErr ){ + return pParse->rc; + } + WHERETRACE(0x800, ("BEGIN %s.addBtreeIdx(%s), nEq=%d, nSkip=%d, rRun=%d\n", + pProbe->pTable->zName,pProbe->zName, + pNew->u.btree.nEq, pNew->nSkip, pNew->rRun)); + + assert( (pNew->wsFlags & WHERE_VIRTUALTABLE)==0 ); + assert( (pNew->wsFlags & WHERE_TOP_LIMIT)==0 ); + if( pNew->wsFlags & WHERE_BTM_LIMIT ){ + opMask = WO_LT|WO_LE; + }else{ + assert( pNew->u.btree.nBtm==0 ); + opMask = WO_EQ|WO_IN|WO_GT|WO_GE|WO_LT|WO_LE|WO_ISNULL|WO_IS; + } + if( pProbe->bUnordered || pProbe->bLowQual ){ + if( pProbe->bUnordered ) opMask &= ~(WO_GT|WO_GE|WO_LT|WO_LE); + if( pProbe->bLowQual ) opMask &= ~(WO_EQ|WO_IN|WO_IS); + } + + assert( pNew->u.btree.nEq<pProbe->nColumn ); + assert( pNew->u.btree.nEq<pProbe->nKeyCol + || pProbe->idxType!=SQLITE_IDXTYPE_PRIMARYKEY ); + + saved_nEq = pNew->u.btree.nEq; + saved_nBtm = pNew->u.btree.nBtm; + saved_nTop = pNew->u.btree.nTop; + saved_nSkip = pNew->nSkip; + saved_nLTerm = pNew->nLTerm; + saved_wsFlags = pNew->wsFlags; + saved_prereq = pNew->prereq; + saved_nOut = pNew->nOut; + pTerm = whereScanInit(&scan, pBuilder->pWC, pSrc->iCursor, saved_nEq, + opMask, pProbe); + pNew->rSetup = 0; + rSize = pProbe->aiRowLogEst[0]; + rLogSize = estLog(rSize); + for(; rc==SQLITE_OK && pTerm!=0; pTerm = whereScanNext(&scan)){ + u16 eOp = pTerm->eOperator; /* Shorthand for pTerm->eOperator */ + LogEst rCostIdx; + LogEst nOutUnadjusted; /* nOut before IN() and WHERE adjustments */ + int nIn = 0; +#ifdef SQLITE_ENABLE_STAT4 + int nRecValid = pBuilder->nRecValid; +#endif + if( (eOp==WO_ISNULL || (pTerm->wtFlags&TERM_VNULL)!=0) + && indexColumnNotNull(pProbe, saved_nEq) + ){ + continue; /* ignore IS [NOT] NULL constraints on NOT NULL columns */ + } + if( pTerm->prereqRight & pNew->maskSelf ) continue; + + /* Do not allow the upper bound of a LIKE optimization range constraint + ** to mix with a lower range bound from some other source */ + if( pTerm->wtFlags & TERM_LIKEOPT && pTerm->eOperator==WO_LT ) continue; + + if( (pSrc->fg.jointype & (JT_LEFT|JT_LTORJ|JT_RIGHT))!=0 + && !constraintCompatibleWithOuterJoin(pTerm,pSrc) + ){ + continue; + } + if( IsUniqueIndex(pProbe) && saved_nEq==pProbe->nKeyCol-1 ){ + pBuilder->bldFlags1 |= SQLITE_BLDF1_UNIQUE; + }else{ + pBuilder->bldFlags1 |= SQLITE_BLDF1_INDEXED; + } + pNew->wsFlags = saved_wsFlags; + pNew->u.btree.nEq = saved_nEq; + pNew->u.btree.nBtm = saved_nBtm; + pNew->u.btree.nTop = saved_nTop; + pNew->nLTerm = saved_nLTerm; + if( pNew->nLTerm>=pNew->nLSlot + && whereLoopResize(db, pNew, pNew->nLTerm+1) + ){ + break; /* OOM while trying to enlarge the pNew->aLTerm array */ + } + pNew->aLTerm[pNew->nLTerm++] = pTerm; + pNew->prereq = (saved_prereq | pTerm->prereqRight) & ~pNew->maskSelf; + + assert( nInMul==0 + || (pNew->wsFlags & WHERE_COLUMN_NULL)!=0 + || (pNew->wsFlags & WHERE_COLUMN_IN)!=0 + || (pNew->wsFlags & WHERE_SKIPSCAN)!=0 + ); + + if( eOp & WO_IN ){ + Expr *pExpr = pTerm->pExpr; + if( ExprUseXSelect(pExpr) ){ + /* "x IN (SELECT ...)": TUNING: the SELECT returns 25 rows */ + int i; + nIn = 46; assert( 46==sqlite3LogEst(25) ); + + /* The expression may actually be of the form (x, y) IN (SELECT...). + ** In this case there is a separate term for each of (x) and (y). + ** However, the nIn multiplier should only be applied once, not once + ** for each such term. The following loop checks that pTerm is the + ** first such term in use, and sets nIn back to 0 if it is not. */ + for(i=0; i<pNew->nLTerm-1; i++){ + if( pNew->aLTerm[i] && pNew->aLTerm[i]->pExpr==pExpr ) nIn = 0; + } + }else if( ALWAYS(pExpr->x.pList && pExpr->x.pList->nExpr) ){ + /* "x IN (value, value, ...)" */ + nIn = sqlite3LogEst(pExpr->x.pList->nExpr); + } + if( pProbe->hasStat1 && rLogSize>=10 ){ + LogEst M, logK, x; + /* Let: + ** N = the total number of rows in the table + ** K = the number of entries on the RHS of the IN operator + ** M = the number of rows in the table that match terms to the + ** to the left in the same index. If the IN operator is on + ** the left-most index column, M==N. + ** + ** Given the definitions above, it is better to omit the IN operator + ** from the index lookup and instead do a scan of the M elements, + ** testing each scanned row against the IN operator separately, if: + ** + ** M*log(K) < K*log(N) + ** + ** Our estimates for M, K, and N might be inaccurate, so we build in + ** a safety margin of 2 (LogEst: 10) that favors using the IN operator + ** with the index, as using an index has better worst-case behavior. + ** If we do not have real sqlite_stat1 data, always prefer to use + ** the index. Do not bother with this optimization on very small + ** tables (less than 2 rows) as it is pointless in that case. + */ + M = pProbe->aiRowLogEst[saved_nEq]; + logK = estLog(nIn); + /* TUNING v----- 10 to bias toward indexed IN */ + x = M + logK + 10 - (nIn + rLogSize); + if( x>=0 ){ + WHERETRACE(0x40, + ("IN operator (N=%d M=%d logK=%d nIn=%d rLogSize=%d x=%d) " + "prefers indexed lookup\n", + saved_nEq, M, logK, nIn, rLogSize, x)); + }else if( nInMul<2 && OptimizationEnabled(db, SQLITE_SeekScan) ){ + WHERETRACE(0x40, + ("IN operator (N=%d M=%d logK=%d nIn=%d rLogSize=%d x=%d" + " nInMul=%d) prefers skip-scan\n", + saved_nEq, M, logK, nIn, rLogSize, x, nInMul)); + pNew->wsFlags |= WHERE_IN_SEEKSCAN; + }else{ + WHERETRACE(0x40, + ("IN operator (N=%d M=%d logK=%d nIn=%d rLogSize=%d x=%d" + " nInMul=%d) prefers normal scan\n", + saved_nEq, M, logK, nIn, rLogSize, x, nInMul)); + continue; + } + } + pNew->wsFlags |= WHERE_COLUMN_IN; + }else if( eOp & (WO_EQ|WO_IS) ){ + int iCol = pProbe->aiColumn[saved_nEq]; + pNew->wsFlags |= WHERE_COLUMN_EQ; + assert( saved_nEq==pNew->u.btree.nEq ); + if( iCol==XN_ROWID + || (iCol>=0 && nInMul==0 && saved_nEq==pProbe->nKeyCol-1) + ){ + if( iCol==XN_ROWID || pProbe->uniqNotNull + || (pProbe->nKeyCol==1 && pProbe->onError && eOp==WO_EQ) + ){ + pNew->wsFlags |= WHERE_ONEROW; + }else{ + pNew->wsFlags |= WHERE_UNQ_WANTED; + } + } + if( scan.iEquiv>1 ) pNew->wsFlags |= WHERE_TRANSCONS; + }else if( eOp & WO_ISNULL ){ + pNew->wsFlags |= WHERE_COLUMN_NULL; + }else{ + int nVecLen = whereRangeVectorLen( + pParse, pSrc->iCursor, pProbe, saved_nEq, pTerm + ); + if( eOp & (WO_GT|WO_GE) ){ + testcase( eOp & WO_GT ); + testcase( eOp & WO_GE ); + pNew->wsFlags |= WHERE_COLUMN_RANGE|WHERE_BTM_LIMIT; + pNew->u.btree.nBtm = nVecLen; + pBtm = pTerm; + pTop = 0; + if( pTerm->wtFlags & TERM_LIKEOPT ){ + /* Range constraints that come from the LIKE optimization are + ** always used in pairs. */ + pTop = &pTerm[1]; + assert( (pTop-(pTerm->pWC->a))<pTerm->pWC->nTerm ); + assert( pTop->wtFlags & TERM_LIKEOPT ); + assert( pTop->eOperator==WO_LT ); + if( whereLoopResize(db, pNew, pNew->nLTerm+1) ) break; /* OOM */ + pNew->aLTerm[pNew->nLTerm++] = pTop; + pNew->wsFlags |= WHERE_TOP_LIMIT; + pNew->u.btree.nTop = 1; + } + }else{ + assert( eOp & (WO_LT|WO_LE) ); + testcase( eOp & WO_LT ); + testcase( eOp & WO_LE ); + pNew->wsFlags |= WHERE_COLUMN_RANGE|WHERE_TOP_LIMIT; + pNew->u.btree.nTop = nVecLen; + pTop = pTerm; + pBtm = (pNew->wsFlags & WHERE_BTM_LIMIT)!=0 ? + pNew->aLTerm[pNew->nLTerm-2] : 0; + } + } + + /* At this point pNew->nOut is set to the number of rows expected to + ** be visited by the index scan before considering term pTerm, or the + ** values of nIn and nInMul. In other words, assuming that all + ** "x IN(...)" terms are replaced with "x = ?". This block updates + ** the value of pNew->nOut to account for pTerm (but not nIn/nInMul). */ + assert( pNew->nOut==saved_nOut ); + if( pNew->wsFlags & WHERE_COLUMN_RANGE ){ + /* Adjust nOut using stat4 data. Or, if there is no stat4 + ** data, using some other estimate. */ + whereRangeScanEst(pParse, pBuilder, pBtm, pTop, pNew); + }else{ + int nEq = ++pNew->u.btree.nEq; + assert( eOp & (WO_ISNULL|WO_EQ|WO_IN|WO_IS) ); + + assert( pNew->nOut==saved_nOut ); + if( pTerm->truthProb<=0 && pProbe->aiColumn[saved_nEq]>=0 ){ + assert( (eOp & WO_IN) || nIn==0 ); + testcase( eOp & WO_IN ); + pNew->nOut += pTerm->truthProb; + pNew->nOut -= nIn; + }else{ +#ifdef SQLITE_ENABLE_STAT4 + tRowcnt nOut = 0; + if( nInMul==0 + && pProbe->nSample + && ALWAYS(pNew->u.btree.nEq<=pProbe->nSampleCol) + && ((eOp & WO_IN)==0 || ExprUseXList(pTerm->pExpr)) + && OptimizationEnabled(db, SQLITE_Stat4) + ){ + Expr *pExpr = pTerm->pExpr; + if( (eOp & (WO_EQ|WO_ISNULL|WO_IS))!=0 ){ + testcase( eOp & WO_EQ ); + testcase( eOp & WO_IS ); + testcase( eOp & WO_ISNULL ); + rc = whereEqualScanEst(pParse, pBuilder, pExpr->pRight, &nOut); + }else{ + rc = whereInScanEst(pParse, pBuilder, pExpr->x.pList, &nOut); + } + if( rc==SQLITE_NOTFOUND ) rc = SQLITE_OK; + if( rc!=SQLITE_OK ) break; /* Jump out of the pTerm loop */ + if( nOut ){ + pNew->nOut = sqlite3LogEst(nOut); + if( nEq==1 + /* TUNING: Mark terms as "low selectivity" if they seem likely + ** to be true for half or more of the rows in the table. + ** See tag-202002240-1 */ + && pNew->nOut+10 > pProbe->aiRowLogEst[0] + ){ +#if WHERETRACE_ENABLED /* 0x01 */ + if( sqlite3WhereTrace & 0x20 ){ + sqlite3DebugPrintf( + "STAT4 determines term has low selectivity:\n"); + sqlite3WhereTermPrint(pTerm, 999); + } +#endif + pTerm->wtFlags |= TERM_HIGHTRUTH; + if( pTerm->wtFlags & TERM_HEURTRUTH ){ + /* If the term has previously been used with an assumption of + ** higher selectivity, then set the flag to rerun the + ** loop computations. */ + pBuilder->bldFlags2 |= SQLITE_BLDF2_2NDPASS; + } + } + if( pNew->nOut>saved_nOut ) pNew->nOut = saved_nOut; + pNew->nOut -= nIn; + } + } + if( nOut==0 ) +#endif + { + pNew->nOut += (pProbe->aiRowLogEst[nEq] - pProbe->aiRowLogEst[nEq-1]); + if( eOp & WO_ISNULL ){ + /* TUNING: If there is no likelihood() value, assume that a + ** "col IS NULL" expression matches twice as many rows + ** as (col=?). */ + pNew->nOut += 10; + } + } + } + } + + /* Set rCostIdx to the cost of visiting selected rows in index. Add + ** it to pNew->rRun, which is currently set to the cost of the index + ** seek only. Then, if this is a non-covering index, add the cost of + ** visiting the rows in the main table. */ + assert( pSrc->pTab->szTabRow>0 ); + if( pProbe->idxType==SQLITE_IDXTYPE_IPK ){ + /* The pProbe->szIdxRow is low for an IPK table since the interior + ** pages are small. Thus szIdxRow gives a good estimate of seek cost. + ** But the leaf pages are full-size, so pProbe->szIdxRow would badly + ** under-estimate the scanning cost. */ + rCostIdx = pNew->nOut + 16; + }else{ + rCostIdx = pNew->nOut + 1 + (15*pProbe->szIdxRow)/pSrc->pTab->szTabRow; + } + pNew->rRun = sqlite3LogEstAdd(rLogSize, rCostIdx); + if( (pNew->wsFlags & (WHERE_IDX_ONLY|WHERE_IPK|WHERE_EXPRIDX))==0 ){ + pNew->rRun = sqlite3LogEstAdd(pNew->rRun, pNew->nOut + 16); + } + ApplyCostMultiplier(pNew->rRun, pProbe->pTable->costMult); + + nOutUnadjusted = pNew->nOut; + pNew->rRun += nInMul + nIn; + pNew->nOut += nInMul + nIn; + whereLoopOutputAdjust(pBuilder->pWC, pNew, rSize); + rc = whereLoopInsert(pBuilder, pNew); + + if( pNew->wsFlags & WHERE_COLUMN_RANGE ){ + pNew->nOut = saved_nOut; + }else{ + pNew->nOut = nOutUnadjusted; + } + + if( (pNew->wsFlags & WHERE_TOP_LIMIT)==0 + && pNew->u.btree.nEq<pProbe->nColumn + && (pNew->u.btree.nEq<pProbe->nKeyCol || + pProbe->idxType!=SQLITE_IDXTYPE_PRIMARYKEY) + ){ + if( pNew->u.btree.nEq>3 ){ + sqlite3ProgressCheck(pParse); + } + whereLoopAddBtreeIndex(pBuilder, pSrc, pProbe, nInMul+nIn); + } + pNew->nOut = saved_nOut; +#ifdef SQLITE_ENABLE_STAT4 + pBuilder->nRecValid = nRecValid; +#endif + } + pNew->prereq = saved_prereq; + pNew->u.btree.nEq = saved_nEq; + pNew->u.btree.nBtm = saved_nBtm; + pNew->u.btree.nTop = saved_nTop; + pNew->nSkip = saved_nSkip; + pNew->wsFlags = saved_wsFlags; + pNew->nOut = saved_nOut; + pNew->nLTerm = saved_nLTerm; + + /* Consider using a skip-scan if there are no WHERE clause constraints + ** available for the left-most terms of the index, and if the average + ** number of repeats in the left-most terms is at least 18. + ** + ** The magic number 18 is selected on the basis that scanning 17 rows + ** is almost always quicker than an index seek (even though if the index + ** contains fewer than 2^17 rows we assume otherwise in other parts of + ** the code). And, even if it is not, it should not be too much slower. + ** On the other hand, the extra seeks could end up being significantly + ** more expensive. */ + assert( 42==sqlite3LogEst(18) ); + if( saved_nEq==saved_nSkip + && saved_nEq+1<pProbe->nKeyCol + && saved_nEq==pNew->nLTerm + && pProbe->noSkipScan==0 + && pProbe->hasStat1!=0 + && OptimizationEnabled(db, SQLITE_SkipScan) + && pProbe->aiRowLogEst[saved_nEq+1]>=42 /* TUNING: Minimum for skip-scan */ + && (rc = whereLoopResize(db, pNew, pNew->nLTerm+1))==SQLITE_OK + ){ + LogEst nIter; + pNew->u.btree.nEq++; + pNew->nSkip++; + pNew->aLTerm[pNew->nLTerm++] = 0; + pNew->wsFlags |= WHERE_SKIPSCAN; + nIter = pProbe->aiRowLogEst[saved_nEq] - pProbe->aiRowLogEst[saved_nEq+1]; + pNew->nOut -= nIter; + /* TUNING: Because uncertainties in the estimates for skip-scan queries, + ** add a 1.375 fudge factor to make skip-scan slightly less likely. */ + nIter += 5; + whereLoopAddBtreeIndex(pBuilder, pSrc, pProbe, nIter + nInMul); + pNew->nOut = saved_nOut; + pNew->u.btree.nEq = saved_nEq; + pNew->nSkip = saved_nSkip; + pNew->wsFlags = saved_wsFlags; + } + + WHERETRACE(0x800, ("END %s.addBtreeIdx(%s), nEq=%d, rc=%d\n", + pProbe->pTable->zName, pProbe->zName, saved_nEq, rc)); + return rc; +} + +/* +** Return True if it is possible that pIndex might be useful in +** implementing the ORDER BY clause in pBuilder. +** +** Return False if pBuilder does not contain an ORDER BY clause or +** if there is no way for pIndex to be useful in implementing that +** ORDER BY clause. +*/ +static int indexMightHelpWithOrderBy( + WhereLoopBuilder *pBuilder, + Index *pIndex, + int iCursor +){ + ExprList *pOB; + ExprList *aColExpr; + int ii, jj; + + if( pIndex->bUnordered ) return 0; + if( (pOB = pBuilder->pWInfo->pOrderBy)==0 ) return 0; + for(ii=0; ii<pOB->nExpr; ii++){ + Expr *pExpr = sqlite3ExprSkipCollateAndLikely(pOB->a[ii].pExpr); + if( NEVER(pExpr==0) ) continue; + if( pExpr->op==TK_COLUMN && pExpr->iTable==iCursor ){ + if( pExpr->iColumn<0 ) return 1; + for(jj=0; jj<pIndex->nKeyCol; jj++){ + if( pExpr->iColumn==pIndex->aiColumn[jj] ) return 1; + } + }else if( (aColExpr = pIndex->aColExpr)!=0 ){ + for(jj=0; jj<pIndex->nKeyCol; jj++){ + if( pIndex->aiColumn[jj]!=XN_EXPR ) continue; + if( sqlite3ExprCompareSkip(pExpr,aColExpr->a[jj].pExpr,iCursor)==0 ){ + return 1; + } + } + } + } + return 0; +} + +/* Check to see if a partial index with pPartIndexWhere can be used +** in the current query. Return true if it can be and false if not. +*/ +static int whereUsablePartialIndex( + int iTab, /* The table for which we want an index */ + u8 jointype, /* The JT_* flags on the join */ + WhereClause *pWC, /* The WHERE clause of the query */ + Expr *pWhere /* The WHERE clause from the partial index */ +){ + int i; + WhereTerm *pTerm; + Parse *pParse; + + if( jointype & JT_LTORJ ) return 0; + pParse = pWC->pWInfo->pParse; + while( pWhere->op==TK_AND ){ + if( !whereUsablePartialIndex(iTab,jointype,pWC,pWhere->pLeft) ) return 0; + pWhere = pWhere->pRight; + } + if( pParse->db->flags & SQLITE_EnableQPSG ) pParse = 0; + for(i=0, pTerm=pWC->a; i<pWC->nTerm; i++, pTerm++){ + Expr *pExpr; + pExpr = pTerm->pExpr; + if( (!ExprHasProperty(pExpr, EP_OuterON) || pExpr->w.iJoin==iTab) + && ((jointype & JT_OUTER)==0 || ExprHasProperty(pExpr, EP_OuterON)) + && sqlite3ExprImpliesExpr(pParse, pExpr, pWhere, iTab) + && (pTerm->wtFlags & TERM_VNULL)==0 + ){ + return 1; + } + } + return 0; +} + +/* +** pIdx is an index containing expressions. Check it see if any of the +** expressions in the index match the pExpr expression. +*/ +static int exprIsCoveredByIndex( + const Expr *pExpr, + const Index *pIdx, + int iTabCur +){ + int i; + for(i=0; i<pIdx->nColumn; i++){ + if( pIdx->aiColumn[i]==XN_EXPR + && sqlite3ExprCompare(0, pExpr, pIdx->aColExpr->a[i].pExpr, iTabCur)==0 + ){ + return 1; + } + } + return 0; +} + +/* +** Structure passed to the whereIsCoveringIndex Walker callback. +*/ +typedef struct CoveringIndexCheck CoveringIndexCheck; +struct CoveringIndexCheck { + Index *pIdx; /* The index */ + int iTabCur; /* Cursor number for the corresponding table */ + u8 bExpr; /* Uses an indexed expression */ + u8 bUnidx; /* Uses an unindexed column not within an indexed expr */ +}; + +/* +** Information passed in is pWalk->u.pCovIdxCk. Call it pCk. +** +** If the Expr node references the table with cursor pCk->iTabCur, then +** make sure that column is covered by the index pCk->pIdx. We know that +** all columns less than 63 (really BMS-1) are covered, so we don't need +** to check them. But we do need to check any column at 63 or greater. +** +** If the index does not cover the column, then set pWalk->eCode to +** non-zero and return WRC_Abort to stop the search. +** +** If this node does not disprove that the index can be a covering index, +** then just return WRC_Continue, to continue the search. +** +** If pCk->pIdx contains indexed expressions and one of those expressions +** matches pExpr, then prune the search. +*/ +static int whereIsCoveringIndexWalkCallback(Walker *pWalk, Expr *pExpr){ + int i; /* Loop counter */ + const Index *pIdx; /* The index of interest */ + const i16 *aiColumn; /* Columns contained in the index */ + u16 nColumn; /* Number of columns in the index */ + CoveringIndexCheck *pCk; /* Info about this search */ + + pCk = pWalk->u.pCovIdxCk; + pIdx = pCk->pIdx; + if( (pExpr->op==TK_COLUMN || pExpr->op==TK_AGG_COLUMN) ){ + /* if( pExpr->iColumn<(BMS-1) && pIdx->bHasExpr==0 ) return WRC_Continue;*/ + if( pExpr->iTable!=pCk->iTabCur ) return WRC_Continue; + pIdx = pWalk->u.pCovIdxCk->pIdx; + aiColumn = pIdx->aiColumn; + nColumn = pIdx->nColumn; + for(i=0; i<nColumn; i++){ + if( aiColumn[i]==pExpr->iColumn ) return WRC_Continue; + } + pCk->bUnidx = 1; + return WRC_Abort; + }else if( pIdx->bHasExpr + && exprIsCoveredByIndex(pExpr, pIdx, pWalk->u.pCovIdxCk->iTabCur) ){ + pCk->bExpr = 1; + return WRC_Prune; + } + return WRC_Continue; +} + + +/* +** pIdx is an index that covers all of the low-number columns used by +** pWInfo->pSelect (columns from 0 through 62) or an index that has +** expressions terms. Hence, we cannot determine whether or not it is +** a covering index by using the colUsed bitmasks. We have to do a search +** to see if the index is covering. This routine does that search. +** +** The return value is one of these: +** +** 0 The index is definitely not a covering index +** +** WHERE_IDX_ONLY The index is definitely a covering index +** +** WHERE_EXPRIDX The index is likely a covering index, but it is +** difficult to determine precisely because of the +** expressions that are indexed. Score it as a +** covering index, but still keep the main table open +** just in case we need it. +** +** This routine is an optimization. It is always safe to return zero. +** But returning one of the other two values when zero should have been +** returned can lead to incorrect bytecode and assertion faults. +*/ +static SQLITE_NOINLINE u32 whereIsCoveringIndex( + WhereInfo *pWInfo, /* The WHERE clause context */ + Index *pIdx, /* Index that is being tested */ + int iTabCur /* Cursor for the table being indexed */ +){ + int i, rc; + struct CoveringIndexCheck ck; + Walker w; + if( pWInfo->pSelect==0 ){ + /* We don't have access to the full query, so we cannot check to see + ** if pIdx is covering. Assume it is not. */ + return 0; + } + if( pIdx->bHasExpr==0 ){ + for(i=0; i<pIdx->nColumn; i++){ + if( pIdx->aiColumn[i]>=BMS-1 ) break; + } + if( i>=pIdx->nColumn ){ + /* pIdx does not index any columns greater than 62, but we know from + ** colMask that columns greater than 62 are used, so this is not a + ** covering index */ + return 0; + } + } + ck.pIdx = pIdx; + ck.iTabCur = iTabCur; + ck.bExpr = 0; + ck.bUnidx = 0; + memset(&w, 0, sizeof(w)); + w.xExprCallback = whereIsCoveringIndexWalkCallback; + w.xSelectCallback = sqlite3SelectWalkNoop; + w.u.pCovIdxCk = &ck; + sqlite3WalkSelect(&w, pWInfo->pSelect); + if( ck.bUnidx ){ + rc = 0; + }else if( ck.bExpr ){ + rc = WHERE_EXPRIDX; + }else{ + rc = WHERE_IDX_ONLY; + } + return rc; +} + +/* +** This is an sqlite3ParserAddCleanup() callback that is invoked to +** free the Parse->pIdxEpr list when the Parse object is destroyed. +*/ +static void whereIndexedExprCleanup(sqlite3 *db, void *pObject){ + IndexedExpr **pp = (IndexedExpr**)pObject; + while( *pp!=0 ){ + IndexedExpr *p = *pp; + *pp = p->pIENext; + sqlite3ExprDelete(db, p->pExpr); + sqlite3DbFreeNN(db, p); + } +} + +/* +** This function is called for a partial index - one with a WHERE clause - in +** two scenarios. In both cases, it determines whether or not the WHERE +** clause on the index implies that a column of the table may be safely +** replaced by a constant expression. For example, in the following +** SELECT: +** +** CREATE INDEX i1 ON t1(b, c) WHERE a=<expr>; +** SELECT a, b, c FROM t1 WHERE a=<expr> AND b=?; +** +** The "a" in the select-list may be replaced by <expr>, iff: +** +** (a) <expr> is a constant expression, and +** (b) The (a=<expr>) comparison uses the BINARY collation sequence, and +** (c) Column "a" has an affinity other than NONE or BLOB. +** +** If argument pItem is NULL, then pMask must not be NULL. In this case this +** function is being called as part of determining whether or not pIdx +** is a covering index. This function clears any bits in (*pMask) +** corresponding to columns that may be replaced by constants as described +** above. +** +** Otherwise, if pItem is not NULL, then this function is being called +** as part of coding a loop that uses index pIdx. In this case, add entries +** to the Parse.pIdxPartExpr list for each column that can be replaced +** by a constant. +*/ +static void wherePartIdxExpr( + Parse *pParse, /* Parse context */ + Index *pIdx, /* Partial index being processed */ + Expr *pPart, /* WHERE clause being processed */ + Bitmask *pMask, /* Mask to clear bits in */ + int iIdxCur, /* Cursor number for index */ + SrcItem *pItem /* The FROM clause entry for the table */ +){ + assert( pItem==0 || (pItem->fg.jointype & JT_RIGHT)==0 ); + assert( (pItem==0 || pMask==0) && (pMask!=0 || pItem!=0) ); + + if( pPart->op==TK_AND ){ + wherePartIdxExpr(pParse, pIdx, pPart->pRight, pMask, iIdxCur, pItem); + pPart = pPart->pLeft; + } + + if( (pPart->op==TK_EQ || pPart->op==TK_IS) ){ + Expr *pLeft = pPart->pLeft; + Expr *pRight = pPart->pRight; + u8 aff; + + if( pLeft->op!=TK_COLUMN ) return; + if( !sqlite3ExprIsConstant(pRight) ) return; + if( !sqlite3IsBinary(sqlite3ExprCompareCollSeq(pParse, pPart)) ) return; + if( pLeft->iColumn<0 ) return; + aff = pIdx->pTable->aCol[pLeft->iColumn].affinity; + if( aff>=SQLITE_AFF_TEXT ){ + if( pItem ){ + sqlite3 *db = pParse->db; + IndexedExpr *p = (IndexedExpr*)sqlite3DbMallocRaw(db, sizeof(*p)); + if( p ){ + int bNullRow = (pItem->fg.jointype&(JT_LEFT|JT_LTORJ))!=0; + p->pExpr = sqlite3ExprDup(db, pRight, 0); + p->iDataCur = pItem->iCursor; + p->iIdxCur = iIdxCur; + p->iIdxCol = pLeft->iColumn; + p->bMaybeNullRow = bNullRow; + p->pIENext = pParse->pIdxPartExpr; + p->aff = aff; + pParse->pIdxPartExpr = p; + if( p->pIENext==0 ){ + void *pArg = (void*)&pParse->pIdxPartExpr; + sqlite3ParserAddCleanup(pParse, whereIndexedExprCleanup, pArg); + } + } + }else if( pLeft->iColumn<(BMS-1) ){ + *pMask &= ~((Bitmask)1 << pLeft->iColumn); + } + } + } +} + + +/* +** Add all WhereLoop objects for a single table of the join where the table +** is identified by pBuilder->pNew->iTab. That table is guaranteed to be +** a b-tree table, not a virtual table. +** +** The costs (WhereLoop.rRun) of the b-tree loops added by this function +** are calculated as follows: +** +** For a full scan, assuming the table (or index) contains nRow rows: +** +** cost = nRow * 3.0 // full-table scan +** cost = nRow * K // scan of covering index +** cost = nRow * (K+3.0) // scan of non-covering index +** +** where K is a value between 1.1 and 3.0 set based on the relative +** estimated average size of the index and table records. +** +** For an index scan, where nVisit is the number of index rows visited +** by the scan, and nSeek is the number of seek operations required on +** the index b-tree: +** +** cost = nSeek * (log(nRow) + K * nVisit) // covering index +** cost = nSeek * (log(nRow) + (K+3.0) * nVisit) // non-covering index +** +** Normally, nSeek is 1. nSeek values greater than 1 come about if the +** WHERE clause includes "x IN (....)" terms used in place of "x=?". Or when +** implicit "x IN (SELECT x FROM tbl)" terms are added for skip-scans. +** +** The estimated values (nRow, nVisit, nSeek) often contain a large amount +** of uncertainty. For this reason, scoring is designed to pick plans that +** "do the least harm" if the estimates are inaccurate. For example, a +** log(nRow) factor is omitted from a non-covering index scan in order to +** bias the scoring in favor of using an index, since the worst-case +** performance of using an index is far better than the worst-case performance +** of a full table scan. +*/ +static int whereLoopAddBtree( + WhereLoopBuilder *pBuilder, /* WHERE clause information */ + Bitmask mPrereq /* Extra prerequisites for using this table */ +){ + WhereInfo *pWInfo; /* WHERE analysis context */ + Index *pProbe; /* An index we are evaluating */ + Index sPk; /* A fake index object for the primary key */ + LogEst aiRowEstPk[2]; /* The aiRowLogEst[] value for the sPk index */ + i16 aiColumnPk = -1; /* The aColumn[] value for the sPk index */ + SrcList *pTabList; /* The FROM clause */ + SrcItem *pSrc; /* The FROM clause btree term to add */ + WhereLoop *pNew; /* Template WhereLoop object */ + int rc = SQLITE_OK; /* Return code */ + int iSortIdx = 1; /* Index number */ + int b; /* A boolean value */ + LogEst rSize; /* number of rows in the table */ + WhereClause *pWC; /* The parsed WHERE clause */ + Table *pTab; /* Table being queried */ + + pNew = pBuilder->pNew; + pWInfo = pBuilder->pWInfo; + pTabList = pWInfo->pTabList; + pSrc = pTabList->a + pNew->iTab; + pTab = pSrc->pTab; + pWC = pBuilder->pWC; + assert( !IsVirtual(pSrc->pTab) ); + + if( pSrc->fg.isIndexedBy ){ + assert( pSrc->fg.isCte==0 ); + /* An INDEXED BY clause specifies a particular index to use */ + pProbe = pSrc->u2.pIBIndex; + }else if( !HasRowid(pTab) ){ + pProbe = pTab->pIndex; + }else{ + /* There is no INDEXED BY clause. Create a fake Index object in local + ** variable sPk to represent the rowid primary key index. Make this + ** fake index the first in a chain of Index objects with all of the real + ** indices to follow */ + Index *pFirst; /* First of real indices on the table */ + memset(&sPk, 0, sizeof(Index)); + sPk.nKeyCol = 1; + sPk.nColumn = 1; + sPk.aiColumn = &aiColumnPk; + sPk.aiRowLogEst = aiRowEstPk; + sPk.onError = OE_Replace; + sPk.pTable = pTab; + sPk.szIdxRow = 3; /* TUNING: Interior rows of IPK table are very small */ + sPk.idxType = SQLITE_IDXTYPE_IPK; + aiRowEstPk[0] = pTab->nRowLogEst; + aiRowEstPk[1] = 0; + pFirst = pSrc->pTab->pIndex; + if( pSrc->fg.notIndexed==0 ){ + /* The real indices of the table are only considered if the + ** NOT INDEXED qualifier is omitted from the FROM clause */ + sPk.pNext = pFirst; + } + pProbe = &sPk; + } + rSize = pTab->nRowLogEst; + +#ifndef SQLITE_OMIT_AUTOMATIC_INDEX + /* Automatic indexes */ + if( !pBuilder->pOrSet /* Not part of an OR optimization */ + && (pWInfo->wctrlFlags & (WHERE_RIGHT_JOIN|WHERE_OR_SUBCLAUSE))==0 + && (pWInfo->pParse->db->flags & SQLITE_AutoIndex)!=0 + && !pSrc->fg.isIndexedBy /* Has no INDEXED BY clause */ + && !pSrc->fg.notIndexed /* Has no NOT INDEXED clause */ + && HasRowid(pTab) /* Not WITHOUT ROWID table. (FIXME: Why not?) */ + && !pSrc->fg.isCorrelated /* Not a correlated subquery */ + && !pSrc->fg.isRecursive /* Not a recursive common table expression. */ + && (pSrc->fg.jointype & JT_RIGHT)==0 /* Not the right tab of a RIGHT JOIN */ + ){ + /* Generate auto-index WhereLoops */ + LogEst rLogSize; /* Logarithm of the number of rows in the table */ + WhereTerm *pTerm; + WhereTerm *pWCEnd = pWC->a + pWC->nTerm; + rLogSize = estLog(rSize); + for(pTerm=pWC->a; rc==SQLITE_OK && pTerm<pWCEnd; pTerm++){ + if( pTerm->prereqRight & pNew->maskSelf ) continue; + if( termCanDriveIndex(pTerm, pSrc, 0) ){ + pNew->u.btree.nEq = 1; + pNew->nSkip = 0; + pNew->u.btree.pIndex = 0; + pNew->nLTerm = 1; + pNew->aLTerm[0] = pTerm; + /* TUNING: One-time cost for computing the automatic index is + ** estimated to be X*N*log2(N) where N is the number of rows in + ** the table being indexed and where X is 7 (LogEst=28) for normal + ** tables or 0.5 (LogEst=-10) for views and subqueries. The value + ** of X is smaller for views and subqueries so that the query planner + ** will be more aggressive about generating automatic indexes for + ** those objects, since there is no opportunity to add schema + ** indexes on subqueries and views. */ + pNew->rSetup = rLogSize + rSize; + if( !IsView(pTab) && (pTab->tabFlags & TF_Ephemeral)==0 ){ + pNew->rSetup += 28; + }else{ + pNew->rSetup -= 25; /* Greatly reduced setup cost for auto indexes + ** on ephemeral materializations of views */ + } + ApplyCostMultiplier(pNew->rSetup, pTab->costMult); + if( pNew->rSetup<0 ) pNew->rSetup = 0; + /* TUNING: Each index lookup yields 20 rows in the table. This + ** is more than the usual guess of 10 rows, since we have no way + ** of knowing how selective the index will ultimately be. It would + ** not be unreasonable to make this value much larger. */ + pNew->nOut = 43; assert( 43==sqlite3LogEst(20) ); + pNew->rRun = sqlite3LogEstAdd(rLogSize,pNew->nOut); + pNew->wsFlags = WHERE_AUTO_INDEX; + pNew->prereq = mPrereq | pTerm->prereqRight; + rc = whereLoopInsert(pBuilder, pNew); + } + } + } +#endif /* SQLITE_OMIT_AUTOMATIC_INDEX */ + + /* Loop over all indices. If there was an INDEXED BY clause, then only + ** consider index pProbe. */ + for(; rc==SQLITE_OK && pProbe; + pProbe=(pSrc->fg.isIndexedBy ? 0 : pProbe->pNext), iSortIdx++ + ){ + if( pProbe->pPartIdxWhere!=0 + && !whereUsablePartialIndex(pSrc->iCursor, pSrc->fg.jointype, pWC, + pProbe->pPartIdxWhere) + ){ + testcase( pNew->iTab!=pSrc->iCursor ); /* See ticket [98d973b8f5] */ + continue; /* Partial index inappropriate for this query */ + } + if( pProbe->bNoQuery ) continue; + rSize = pProbe->aiRowLogEst[0]; + pNew->u.btree.nEq = 0; + pNew->u.btree.nBtm = 0; + pNew->u.btree.nTop = 0; + pNew->nSkip = 0; + pNew->nLTerm = 0; + pNew->iSortIdx = 0; + pNew->rSetup = 0; + pNew->prereq = mPrereq; + pNew->nOut = rSize; + pNew->u.btree.pIndex = pProbe; + b = indexMightHelpWithOrderBy(pBuilder, pProbe, pSrc->iCursor); + + /* The ONEPASS_DESIRED flags never occurs together with ORDER BY */ + assert( (pWInfo->wctrlFlags & WHERE_ONEPASS_DESIRED)==0 || b==0 ); + if( pProbe->idxType==SQLITE_IDXTYPE_IPK ){ + /* Integer primary key index */ + pNew->wsFlags = WHERE_IPK; + + /* Full table scan */ + pNew->iSortIdx = b ? iSortIdx : 0; + /* TUNING: Cost of full table scan is 3.0*N. The 3.0 factor is an + ** extra cost designed to discourage the use of full table scans, + ** since index lookups have better worst-case performance if our + ** stat guesses are wrong. Reduce the 3.0 penalty slightly + ** (to 2.75) if we have valid STAT4 information for the table. + ** At 2.75, a full table scan is preferred over using an index on + ** a column with just two distinct values where each value has about + ** an equal number of appearances. Without STAT4 data, we still want + ** to use an index in that case, since the constraint might be for + ** the scarcer of the two values, and in that case an index lookup is + ** better. + */ +#ifdef SQLITE_ENABLE_STAT4 + pNew->rRun = rSize + 16 - 2*((pTab->tabFlags & TF_HasStat4)!=0); +#else + pNew->rRun = rSize + 16; +#endif + ApplyCostMultiplier(pNew->rRun, pTab->costMult); + whereLoopOutputAdjust(pWC, pNew, rSize); + rc = whereLoopInsert(pBuilder, pNew); + pNew->nOut = rSize; + if( rc ) break; + }else{ + Bitmask m; + if( pProbe->isCovering ){ + m = 0; + pNew->wsFlags = WHERE_IDX_ONLY | WHERE_INDEXED; + }else{ + m = pSrc->colUsed & pProbe->colNotIdxed; + if( pProbe->pPartIdxWhere ){ + wherePartIdxExpr( + pWInfo->pParse, pProbe, pProbe->pPartIdxWhere, &m, 0, 0 + ); + } + pNew->wsFlags = WHERE_INDEXED; + if( m==TOPBIT || (pProbe->bHasExpr && !pProbe->bHasVCol && m!=0) ){ + u32 isCov = whereIsCoveringIndex(pWInfo, pProbe, pSrc->iCursor); + if( isCov==0 ){ + WHERETRACE(0x200, + ("-> %s is not a covering index" + " according to whereIsCoveringIndex()\n", pProbe->zName)); + assert( m!=0 ); + }else{ + m = 0; + pNew->wsFlags |= isCov; + if( isCov & WHERE_IDX_ONLY ){ + WHERETRACE(0x200, + ("-> %s is a covering expression index" + " according to whereIsCoveringIndex()\n", pProbe->zName)); + }else{ + assert( isCov==WHERE_EXPRIDX ); + WHERETRACE(0x200, + ("-> %s might be a covering expression index" + " according to whereIsCoveringIndex()\n", pProbe->zName)); + } + } + }else if( m==0 ){ + WHERETRACE(0x200, + ("-> %s a covering index according to bitmasks\n", + pProbe->zName, m==0 ? "is" : "is not")); + pNew->wsFlags = WHERE_IDX_ONLY | WHERE_INDEXED; + } + } + + /* Full scan via index */ + if( b + || !HasRowid(pTab) + || pProbe->pPartIdxWhere!=0 + || pSrc->fg.isIndexedBy + || ( m==0 + && pProbe->bUnordered==0 + && (pProbe->szIdxRow<pTab->szTabRow) + && (pWInfo->wctrlFlags & WHERE_ONEPASS_DESIRED)==0 + && sqlite3GlobalConfig.bUseCis + && OptimizationEnabled(pWInfo->pParse->db, SQLITE_CoverIdxScan) + ) + ){ + pNew->iSortIdx = b ? iSortIdx : 0; + + /* The cost of visiting the index rows is N*K, where K is + ** between 1.1 and 3.0, depending on the relative sizes of the + ** index and table rows. */ + pNew->rRun = rSize + 1 + (15*pProbe->szIdxRow)/pTab->szTabRow; + if( m!=0 ){ + /* If this is a non-covering index scan, add in the cost of + ** doing table lookups. The cost will be 3x the number of + ** lookups. Take into account WHERE clause terms that can be + ** satisfied using just the index, and that do not require a + ** table lookup. */ + LogEst nLookup = rSize + 16; /* Base cost: N*3 */ + int ii; + int iCur = pSrc->iCursor; + WhereClause *pWC2 = &pWInfo->sWC; + for(ii=0; ii<pWC2->nTerm; ii++){ + WhereTerm *pTerm = &pWC2->a[ii]; + if( !sqlite3ExprCoveredByIndex(pTerm->pExpr, iCur, pProbe) ){ + break; + } + /* pTerm can be evaluated using just the index. So reduce + ** the expected number of table lookups accordingly */ + if( pTerm->truthProb<=0 ){ + nLookup += pTerm->truthProb; + }else{ + nLookup--; + if( pTerm->eOperator & (WO_EQ|WO_IS) ) nLookup -= 19; + } + } + + pNew->rRun = sqlite3LogEstAdd(pNew->rRun, nLookup); + } + ApplyCostMultiplier(pNew->rRun, pTab->costMult); + whereLoopOutputAdjust(pWC, pNew, rSize); + if( (pSrc->fg.jointype & JT_RIGHT)!=0 && pProbe->aColExpr ){ + /* Do not do an SCAN of a index-on-expression in a RIGHT JOIN + ** because the cursor used to access the index might not be + ** positioned to the correct row during the right-join no-match + ** loop. */ + }else{ + rc = whereLoopInsert(pBuilder, pNew); + } + pNew->nOut = rSize; + if( rc ) break; + } + } + + pBuilder->bldFlags1 = 0; + rc = whereLoopAddBtreeIndex(pBuilder, pSrc, pProbe, 0); + if( pBuilder->bldFlags1==SQLITE_BLDF1_INDEXED ){ + /* If a non-unique index is used, or if a prefix of the key for + ** unique index is used (making the index functionally non-unique) + ** then the sqlite_stat1 data becomes important for scoring the + ** plan */ + pTab->tabFlags |= TF_StatsUsed; + } +#ifdef SQLITE_ENABLE_STAT4 + sqlite3Stat4ProbeFree(pBuilder->pRec); + pBuilder->nRecValid = 0; + pBuilder->pRec = 0; +#endif + } + return rc; +} + +#ifndef SQLITE_OMIT_VIRTUALTABLE + +/* +** Return true if pTerm is a virtual table LIMIT or OFFSET term. +*/ +static int isLimitTerm(WhereTerm *pTerm){ + assert( pTerm->eOperator==WO_AUX || pTerm->eMatchOp==0 ); + return pTerm->eMatchOp>=SQLITE_INDEX_CONSTRAINT_LIMIT + && pTerm->eMatchOp<=SQLITE_INDEX_CONSTRAINT_OFFSET; +} + +/* +** Argument pIdxInfo is already populated with all constraints that may +** be used by the virtual table identified by pBuilder->pNew->iTab. This +** function marks a subset of those constraints usable, invokes the +** xBestIndex method and adds the returned plan to pBuilder. +** +** A constraint is marked usable if: +** +** * Argument mUsable indicates that its prerequisites are available, and +** +** * It is not one of the operators specified in the mExclude mask passed +** as the fourth argument (which in practice is either WO_IN or 0). +** +** Argument mPrereq is a mask of tables that must be scanned before the +** virtual table in question. These are added to the plans prerequisites +** before it is added to pBuilder. +** +** Output parameter *pbIn is set to true if the plan added to pBuilder +** uses one or more WO_IN terms, or false otherwise. +*/ +static int whereLoopAddVirtualOne( + WhereLoopBuilder *pBuilder, + Bitmask mPrereq, /* Mask of tables that must be used. */ + Bitmask mUsable, /* Mask of usable tables */ + u16 mExclude, /* Exclude terms using these operators */ + sqlite3_index_info *pIdxInfo, /* Populated object for xBestIndex */ + u16 mNoOmit, /* Do not omit these constraints */ + int *pbIn, /* OUT: True if plan uses an IN(...) op */ + int *pbRetryLimit /* OUT: Retry without LIMIT/OFFSET */ +){ + WhereClause *pWC = pBuilder->pWC; + HiddenIndexInfo *pHidden = (HiddenIndexInfo*)&pIdxInfo[1]; + struct sqlite3_index_constraint *pIdxCons; + struct sqlite3_index_constraint_usage *pUsage = pIdxInfo->aConstraintUsage; + int i; + int mxTerm; + int rc = SQLITE_OK; + WhereLoop *pNew = pBuilder->pNew; + Parse *pParse = pBuilder->pWInfo->pParse; + SrcItem *pSrc = &pBuilder->pWInfo->pTabList->a[pNew->iTab]; + int nConstraint = pIdxInfo->nConstraint; + + assert( (mUsable & mPrereq)==mPrereq ); + *pbIn = 0; + pNew->prereq = mPrereq; + + /* Set the usable flag on the subset of constraints identified by + ** arguments mUsable and mExclude. */ + pIdxCons = *(struct sqlite3_index_constraint**)&pIdxInfo->aConstraint; + for(i=0; i<nConstraint; i++, pIdxCons++){ + WhereTerm *pTerm = &pWC->a[pIdxCons->iTermOffset]; + pIdxCons->usable = 0; + if( (pTerm->prereqRight & mUsable)==pTerm->prereqRight + && (pTerm->eOperator & mExclude)==0 + && (pbRetryLimit || !isLimitTerm(pTerm)) + ){ + pIdxCons->usable = 1; + } + } + + /* Initialize the output fields of the sqlite3_index_info structure */ + memset(pUsage, 0, sizeof(pUsage[0])*nConstraint); + assert( pIdxInfo->needToFreeIdxStr==0 ); + pIdxInfo->idxStr = 0; + pIdxInfo->idxNum = 0; + pIdxInfo->orderByConsumed = 0; + pIdxInfo->estimatedCost = SQLITE_BIG_DBL / (double)2; + pIdxInfo->estimatedRows = 25; + pIdxInfo->idxFlags = 0; + pIdxInfo->colUsed = (sqlite3_int64)pSrc->colUsed; + pHidden->mHandleIn = 0; + + /* Invoke the virtual table xBestIndex() method */ + rc = vtabBestIndex(pParse, pSrc->pTab, pIdxInfo); + if( rc ){ + if( rc==SQLITE_CONSTRAINT ){ + /* If the xBestIndex method returns SQLITE_CONSTRAINT, that means + ** that the particular combination of parameters provided is unusable. + ** Make no entries in the loop table. + */ + WHERETRACE(0xffffffff, (" ^^^^--- non-viable plan rejected!\n")); + return SQLITE_OK; + } + return rc; + } + + mxTerm = -1; + assert( pNew->nLSlot>=nConstraint ); + memset(pNew->aLTerm, 0, sizeof(pNew->aLTerm[0])*nConstraint ); + memset(&pNew->u.vtab, 0, sizeof(pNew->u.vtab)); + pIdxCons = *(struct sqlite3_index_constraint**)&pIdxInfo->aConstraint; + for(i=0; i<nConstraint; i++, pIdxCons++){ + int iTerm; + if( (iTerm = pUsage[i].argvIndex - 1)>=0 ){ + WhereTerm *pTerm; + int j = pIdxCons->iTermOffset; + if( iTerm>=nConstraint + || j<0 + || j>=pWC->nTerm + || pNew->aLTerm[iTerm]!=0 + || pIdxCons->usable==0 + ){ + sqlite3ErrorMsg(pParse,"%s.xBestIndex malfunction",pSrc->pTab->zName); + testcase( pIdxInfo->needToFreeIdxStr ); + return SQLITE_ERROR; + } + testcase( iTerm==nConstraint-1 ); + testcase( j==0 ); + testcase( j==pWC->nTerm-1 ); + pTerm = &pWC->a[j]; + pNew->prereq |= pTerm->prereqRight; + assert( iTerm<pNew->nLSlot ); + pNew->aLTerm[iTerm] = pTerm; + if( iTerm>mxTerm ) mxTerm = iTerm; + testcase( iTerm==15 ); + testcase( iTerm==16 ); + if( pUsage[i].omit ){ + if( i<16 && ((1<<i)&mNoOmit)==0 ){ + testcase( i!=iTerm ); + pNew->u.vtab.omitMask |= 1<<iTerm; + }else{ + testcase( i!=iTerm ); + } + if( pTerm->eMatchOp==SQLITE_INDEX_CONSTRAINT_OFFSET ){ + pNew->u.vtab.bOmitOffset = 1; + } + } + if( SMASKBIT32(i) & pHidden->mHandleIn ){ + pNew->u.vtab.mHandleIn |= MASKBIT32(iTerm); + }else if( (pTerm->eOperator & WO_IN)!=0 ){ + /* A virtual table that is constrained by an IN clause may not + ** consume the ORDER BY clause because (1) the order of IN terms + ** is not necessarily related to the order of output terms and + ** (2) Multiple outputs from a single IN value will not merge + ** together. */ + pIdxInfo->orderByConsumed = 0; + pIdxInfo->idxFlags &= ~SQLITE_INDEX_SCAN_UNIQUE; + *pbIn = 1; assert( (mExclude & WO_IN)==0 ); + } + + assert( pbRetryLimit || !isLimitTerm(pTerm) ); + if( isLimitTerm(pTerm) && *pbIn ){ + /* If there is an IN(...) term handled as an == (separate call to + ** xFilter for each value on the RHS of the IN) and a LIMIT or + ** OFFSET term handled as well, the plan is unusable. Set output + ** variable *pbRetryLimit to true to tell the caller to retry with + ** LIMIT and OFFSET disabled. */ + if( pIdxInfo->needToFreeIdxStr ){ + sqlite3_free(pIdxInfo->idxStr); + pIdxInfo->idxStr = 0; + pIdxInfo->needToFreeIdxStr = 0; + } + *pbRetryLimit = 1; + return SQLITE_OK; + } + } + } + + pNew->nLTerm = mxTerm+1; + for(i=0; i<=mxTerm; i++){ + if( pNew->aLTerm[i]==0 ){ + /* The non-zero argvIdx values must be contiguous. Raise an + ** error if they are not */ + sqlite3ErrorMsg(pParse,"%s.xBestIndex malfunction",pSrc->pTab->zName); + testcase( pIdxInfo->needToFreeIdxStr ); + return SQLITE_ERROR; + } + } + assert( pNew->nLTerm<=pNew->nLSlot ); + pNew->u.vtab.idxNum = pIdxInfo->idxNum; + pNew->u.vtab.needFree = pIdxInfo->needToFreeIdxStr; + pIdxInfo->needToFreeIdxStr = 0; + pNew->u.vtab.idxStr = pIdxInfo->idxStr; + pNew->u.vtab.isOrdered = (i8)(pIdxInfo->orderByConsumed ? + pIdxInfo->nOrderBy : 0); + pNew->rSetup = 0; + pNew->rRun = sqlite3LogEstFromDouble(pIdxInfo->estimatedCost); + pNew->nOut = sqlite3LogEst(pIdxInfo->estimatedRows); + + /* Set the WHERE_ONEROW flag if the xBestIndex() method indicated + ** that the scan will visit at most one row. Clear it otherwise. */ + if( pIdxInfo->idxFlags & SQLITE_INDEX_SCAN_UNIQUE ){ + pNew->wsFlags |= WHERE_ONEROW; + }else{ + pNew->wsFlags &= ~WHERE_ONEROW; + } + rc = whereLoopInsert(pBuilder, pNew); + if( pNew->u.vtab.needFree ){ + sqlite3_free(pNew->u.vtab.idxStr); + pNew->u.vtab.needFree = 0; + } + WHERETRACE(0xffffffff, (" bIn=%d prereqIn=%04llx prereqOut=%04llx\n", + *pbIn, (sqlite3_uint64)mPrereq, + (sqlite3_uint64)(pNew->prereq & ~mPrereq))); + + return rc; +} + +/* +** Return the collating sequence for a constraint passed into xBestIndex. +** +** pIdxInfo must be an sqlite3_index_info structure passed into xBestIndex. +** This routine depends on there being a HiddenIndexInfo structure immediately +** following the sqlite3_index_info structure. +** +** Return a pointer to the collation name: +** +** 1. If there is an explicit COLLATE operator on the constraint, return it. +** +** 2. Else, if the column has an alternative collation, return that. +** +** 3. Otherwise, return "BINARY". +*/ +const char *sqlite3_vtab_collation(sqlite3_index_info *pIdxInfo, int iCons){ + HiddenIndexInfo *pHidden = (HiddenIndexInfo*)&pIdxInfo[1]; + const char *zRet = 0; + if( iCons>=0 && iCons<pIdxInfo->nConstraint ){ + CollSeq *pC = 0; + int iTerm = pIdxInfo->aConstraint[iCons].iTermOffset; + Expr *pX = pHidden->pWC->a[iTerm].pExpr; + if( pX->pLeft ){ + pC = sqlite3ExprCompareCollSeq(pHidden->pParse, pX); + } + zRet = (pC ? pC->zName : sqlite3StrBINARY); + } + return zRet; +} + +/* +** Return true if constraint iCons is really an IN(...) constraint, or +** false otherwise. If iCons is an IN(...) constraint, set (if bHandle!=0) +** or clear (if bHandle==0) the flag to handle it using an iterator. +*/ +int sqlite3_vtab_in(sqlite3_index_info *pIdxInfo, int iCons, int bHandle){ + HiddenIndexInfo *pHidden = (HiddenIndexInfo*)&pIdxInfo[1]; + u32 m = SMASKBIT32(iCons); + if( m & pHidden->mIn ){ + if( bHandle==0 ){ + pHidden->mHandleIn &= ~m; + }else if( bHandle>0 ){ + pHidden->mHandleIn |= m; + } + return 1; + } + return 0; +} + +/* +** This interface is callable from within the xBestIndex callback only. +** +** If possible, set (*ppVal) to point to an object containing the value +** on the right-hand-side of constraint iCons. +*/ +int sqlite3_vtab_rhs_value( + sqlite3_index_info *pIdxInfo, /* Copy of first argument to xBestIndex */ + int iCons, /* Constraint for which RHS is wanted */ + sqlite3_value **ppVal /* Write value extracted here */ +){ + HiddenIndexInfo *pH = (HiddenIndexInfo*)&pIdxInfo[1]; + sqlite3_value *pVal = 0; + int rc = SQLITE_OK; + if( iCons<0 || iCons>=pIdxInfo->nConstraint ){ + rc = SQLITE_MISUSE_BKPT; /* EV: R-30545-25046 */ + }else{ + if( pH->aRhs[iCons]==0 ){ + WhereTerm *pTerm = &pH->pWC->a[pIdxInfo->aConstraint[iCons].iTermOffset]; + rc = sqlite3ValueFromExpr( + pH->pParse->db, pTerm->pExpr->pRight, ENC(pH->pParse->db), + SQLITE_AFF_BLOB, &pH->aRhs[iCons] + ); + testcase( rc!=SQLITE_OK ); + } + pVal = pH->aRhs[iCons]; + } + *ppVal = pVal; + + if( rc==SQLITE_OK && pVal==0 ){ /* IMP: R-19933-32160 */ + rc = SQLITE_NOTFOUND; /* IMP: R-36424-56542 */ + } + + return rc; +} + +/* +** Return true if ORDER BY clause may be handled as DISTINCT. +*/ +int sqlite3_vtab_distinct(sqlite3_index_info *pIdxInfo){ + HiddenIndexInfo *pHidden = (HiddenIndexInfo*)&pIdxInfo[1]; + assert( pHidden->eDistinct>=0 && pHidden->eDistinct<=3 ); + return pHidden->eDistinct; +} + +/* +** Cause the prepared statement that is associated with a call to +** xBestIndex to potentially use all schemas. If the statement being +** prepared is read-only, then just start read transactions on all +** schemas. But if this is a write operation, start writes on all +** schemas. +** +** This is used by the (built-in) sqlite_dbpage virtual table. +*/ +void sqlite3VtabUsesAllSchemas(Parse *pParse){ + int nDb = pParse->db->nDb; + int i; + for(i=0; i<nDb; i++){ + sqlite3CodeVerifySchema(pParse, i); + } + if( DbMaskNonZero(pParse->writeMask) ){ + for(i=0; i<nDb; i++){ + sqlite3BeginWriteOperation(pParse, 0, i); + } + } +} + +/* +** Add all WhereLoop objects for a table of the join identified by +** pBuilder->pNew->iTab. That table is guaranteed to be a virtual table. +** +** If there are no LEFT or CROSS JOIN joins in the query, both mPrereq and +** mUnusable are set to 0. Otherwise, mPrereq is a mask of all FROM clause +** entries that occur before the virtual table in the FROM clause and are +** separated from it by at least one LEFT or CROSS JOIN. Similarly, the +** mUnusable mask contains all FROM clause entries that occur after the +** virtual table and are separated from it by at least one LEFT or +** CROSS JOIN. +** +** For example, if the query were: +** +** ... FROM t1, t2 LEFT JOIN t3, t4, vt CROSS JOIN t5, t6; +** +** then mPrereq corresponds to (t1, t2) and mUnusable to (t5, t6). +** +** All the tables in mPrereq must be scanned before the current virtual +** table. So any terms for which all prerequisites are satisfied by +** mPrereq may be specified as "usable" in all calls to xBestIndex. +** Conversely, all tables in mUnusable must be scanned after the current +** virtual table, so any terms for which the prerequisites overlap with +** mUnusable should always be configured as "not-usable" for xBestIndex. +*/ +static int whereLoopAddVirtual( + WhereLoopBuilder *pBuilder, /* WHERE clause information */ + Bitmask mPrereq, /* Tables that must be scanned before this one */ + Bitmask mUnusable /* Tables that must be scanned after this one */ +){ + int rc = SQLITE_OK; /* Return code */ + WhereInfo *pWInfo; /* WHERE analysis context */ + Parse *pParse; /* The parsing context */ + WhereClause *pWC; /* The WHERE clause */ + SrcItem *pSrc; /* The FROM clause term to search */ + sqlite3_index_info *p; /* Object to pass to xBestIndex() */ + int nConstraint; /* Number of constraints in p */ + int bIn; /* True if plan uses IN(...) operator */ + WhereLoop *pNew; + Bitmask mBest; /* Tables used by best possible plan */ + u16 mNoOmit; + int bRetry = 0; /* True to retry with LIMIT/OFFSET disabled */ + + assert( (mPrereq & mUnusable)==0 ); + pWInfo = pBuilder->pWInfo; + pParse = pWInfo->pParse; + pWC = pBuilder->pWC; + pNew = pBuilder->pNew; + pSrc = &pWInfo->pTabList->a[pNew->iTab]; + assert( IsVirtual(pSrc->pTab) ); + p = allocateIndexInfo(pWInfo, pWC, mUnusable, pSrc, &mNoOmit); + if( p==0 ) return SQLITE_NOMEM_BKPT; + pNew->rSetup = 0; + pNew->wsFlags = WHERE_VIRTUALTABLE; + pNew->nLTerm = 0; + pNew->u.vtab.needFree = 0; + nConstraint = p->nConstraint; + if( whereLoopResize(pParse->db, pNew, nConstraint) ){ + freeIndexInfo(pParse->db, p); + return SQLITE_NOMEM_BKPT; + } + + /* First call xBestIndex() with all constraints usable. */ + WHERETRACE(0x800, ("BEGIN %s.addVirtual()\n", pSrc->pTab->zName)); + WHERETRACE(0x800, (" VirtualOne: all usable\n")); + rc = whereLoopAddVirtualOne( + pBuilder, mPrereq, ALLBITS, 0, p, mNoOmit, &bIn, &bRetry + ); + if( bRetry ){ + assert( rc==SQLITE_OK ); + rc = whereLoopAddVirtualOne( + pBuilder, mPrereq, ALLBITS, 0, p, mNoOmit, &bIn, 0 + ); + } + + /* If the call to xBestIndex() with all terms enabled produced a plan + ** that does not require any source tables (IOW: a plan with mBest==0) + ** and does not use an IN(...) operator, then there is no point in making + ** any further calls to xBestIndex() since they will all return the same + ** result (if the xBestIndex() implementation is sane). */ + if( rc==SQLITE_OK && ((mBest = (pNew->prereq & ~mPrereq))!=0 || bIn) ){ + int seenZero = 0; /* True if a plan with no prereqs seen */ + int seenZeroNoIN = 0; /* Plan with no prereqs and no IN(...) seen */ + Bitmask mPrev = 0; + Bitmask mBestNoIn = 0; + + /* If the plan produced by the earlier call uses an IN(...) term, call + ** xBestIndex again, this time with IN(...) terms disabled. */ + if( bIn ){ + WHERETRACE(0x800, (" VirtualOne: all usable w/o IN\n")); + rc = whereLoopAddVirtualOne( + pBuilder, mPrereq, ALLBITS, WO_IN, p, mNoOmit, &bIn, 0); + assert( bIn==0 ); + mBestNoIn = pNew->prereq & ~mPrereq; + if( mBestNoIn==0 ){ + seenZero = 1; + seenZeroNoIN = 1; + } + } + + /* Call xBestIndex once for each distinct value of (prereqRight & ~mPrereq) + ** in the set of terms that apply to the current virtual table. */ + while( rc==SQLITE_OK ){ + int i; + Bitmask mNext = ALLBITS; + assert( mNext>0 ); + for(i=0; i<nConstraint; i++){ + Bitmask mThis = ( + pWC->a[p->aConstraint[i].iTermOffset].prereqRight & ~mPrereq + ); + if( mThis>mPrev && mThis<mNext ) mNext = mThis; + } + mPrev = mNext; + if( mNext==ALLBITS ) break; + if( mNext==mBest || mNext==mBestNoIn ) continue; + WHERETRACE(0x800, (" VirtualOne: mPrev=%04llx mNext=%04llx\n", + (sqlite3_uint64)mPrev, (sqlite3_uint64)mNext)); + rc = whereLoopAddVirtualOne( + pBuilder, mPrereq, mNext|mPrereq, 0, p, mNoOmit, &bIn, 0); + if( pNew->prereq==mPrereq ){ + seenZero = 1; + if( bIn==0 ) seenZeroNoIN = 1; + } + } + + /* If the calls to xBestIndex() in the above loop did not find a plan + ** that requires no source tables at all (i.e. one guaranteed to be + ** usable), make a call here with all source tables disabled */ + if( rc==SQLITE_OK && seenZero==0 ){ + WHERETRACE(0x800, (" VirtualOne: all disabled\n")); + rc = whereLoopAddVirtualOne( + pBuilder, mPrereq, mPrereq, 0, p, mNoOmit, &bIn, 0); + if( bIn==0 ) seenZeroNoIN = 1; + } + + /* If the calls to xBestIndex() have so far failed to find a plan + ** that requires no source tables at all and does not use an IN(...) + ** operator, make a final call to obtain one here. */ + if( rc==SQLITE_OK && seenZeroNoIN==0 ){ + WHERETRACE(0x800, (" VirtualOne: all disabled and w/o IN\n")); + rc = whereLoopAddVirtualOne( + pBuilder, mPrereq, mPrereq, WO_IN, p, mNoOmit, &bIn, 0); + } + } + + if( p->needToFreeIdxStr ) sqlite3_free(p->idxStr); + freeIndexInfo(pParse->db, p); + WHERETRACE(0x800, ("END %s.addVirtual(), rc=%d\n", pSrc->pTab->zName, rc)); + return rc; +} +#endif /* SQLITE_OMIT_VIRTUALTABLE */ + +/* +** Add WhereLoop entries to handle OR terms. This works for either +** btrees or virtual tables. +*/ +static int whereLoopAddOr( + WhereLoopBuilder *pBuilder, + Bitmask mPrereq, + Bitmask mUnusable +){ + WhereInfo *pWInfo = pBuilder->pWInfo; + WhereClause *pWC; + WhereLoop *pNew; + WhereTerm *pTerm, *pWCEnd; + int rc = SQLITE_OK; + int iCur; + WhereClause tempWC; + WhereLoopBuilder sSubBuild; + WhereOrSet sSum, sCur; + SrcItem *pItem; + + pWC = pBuilder->pWC; + pWCEnd = pWC->a + pWC->nTerm; + pNew = pBuilder->pNew; + memset(&sSum, 0, sizeof(sSum)); + pItem = pWInfo->pTabList->a + pNew->iTab; + iCur = pItem->iCursor; + + /* The multi-index OR optimization does not work for RIGHT and FULL JOIN */ + if( pItem->fg.jointype & JT_RIGHT ) return SQLITE_OK; + + for(pTerm=pWC->a; pTerm<pWCEnd && rc==SQLITE_OK; pTerm++){ + if( (pTerm->eOperator & WO_OR)!=0 + && (pTerm->u.pOrInfo->indexable & pNew->maskSelf)!=0 + ){ + WhereClause * const pOrWC = &pTerm->u.pOrInfo->wc; + WhereTerm * const pOrWCEnd = &pOrWC->a[pOrWC->nTerm]; + WhereTerm *pOrTerm; + int once = 1; + int i, j; + + sSubBuild = *pBuilder; + sSubBuild.pOrSet = &sCur; + + WHERETRACE(0x400, ("Begin processing OR-clause %p\n", pTerm)); + for(pOrTerm=pOrWC->a; pOrTerm<pOrWCEnd; pOrTerm++){ + if( (pOrTerm->eOperator & WO_AND)!=0 ){ + sSubBuild.pWC = &pOrTerm->u.pAndInfo->wc; + }else if( pOrTerm->leftCursor==iCur ){ + tempWC.pWInfo = pWC->pWInfo; + tempWC.pOuter = pWC; + tempWC.op = TK_AND; + tempWC.nTerm = 1; + tempWC.nBase = 1; + tempWC.a = pOrTerm; + sSubBuild.pWC = &tempWC; + }else{ + continue; + } + sCur.n = 0; +#ifdef WHERETRACE_ENABLED + WHERETRACE(0x400, ("OR-term %d of %p has %d subterms:\n", + (int)(pOrTerm-pOrWC->a), pTerm, sSubBuild.pWC->nTerm)); + if( sqlite3WhereTrace & 0x20000 ){ + sqlite3WhereClausePrint(sSubBuild.pWC); + } +#endif +#ifndef SQLITE_OMIT_VIRTUALTABLE + if( IsVirtual(pItem->pTab) ){ + rc = whereLoopAddVirtual(&sSubBuild, mPrereq, mUnusable); + }else +#endif + { + rc = whereLoopAddBtree(&sSubBuild, mPrereq); + } + if( rc==SQLITE_OK ){ + rc = whereLoopAddOr(&sSubBuild, mPrereq, mUnusable); + } + testcase( rc==SQLITE_NOMEM && sCur.n>0 ); + testcase( rc==SQLITE_DONE ); + if( sCur.n==0 ){ + sSum.n = 0; + break; + }else if( once ){ + whereOrMove(&sSum, &sCur); + once = 0; + }else{ + WhereOrSet sPrev; + whereOrMove(&sPrev, &sSum); + sSum.n = 0; + for(i=0; i<sPrev.n; i++){ + for(j=0; j<sCur.n; j++){ + whereOrInsert(&sSum, sPrev.a[i].prereq | sCur.a[j].prereq, + sqlite3LogEstAdd(sPrev.a[i].rRun, sCur.a[j].rRun), + sqlite3LogEstAdd(sPrev.a[i].nOut, sCur.a[j].nOut)); + } + } + } + } + pNew->nLTerm = 1; + pNew->aLTerm[0] = pTerm; + pNew->wsFlags = WHERE_MULTI_OR; + pNew->rSetup = 0; + pNew->iSortIdx = 0; + memset(&pNew->u, 0, sizeof(pNew->u)); + for(i=0; rc==SQLITE_OK && i<sSum.n; i++){ + /* TUNING: Currently sSum.a[i].rRun is set to the sum of the costs + ** of all sub-scans required by the OR-scan. However, due to rounding + ** errors, it may be that the cost of the OR-scan is equal to its + ** most expensive sub-scan. Add the smallest possible penalty + ** (equivalent to multiplying the cost by 1.07) to ensure that + ** this does not happen. Otherwise, for WHERE clauses such as the + ** following where there is an index on "y": + ** + ** WHERE likelihood(x=?, 0.99) OR y=? + ** + ** the planner may elect to "OR" together a full-table scan and an + ** index lookup. And other similarly odd results. */ + pNew->rRun = sSum.a[i].rRun + 1; + pNew->nOut = sSum.a[i].nOut; + pNew->prereq = sSum.a[i].prereq; + rc = whereLoopInsert(pBuilder, pNew); + } + WHERETRACE(0x400, ("End processing OR-clause %p\n", pTerm)); + } + } + return rc; +} + +/* +** Add all WhereLoop objects for all tables +*/ +static int whereLoopAddAll(WhereLoopBuilder *pBuilder){ + WhereInfo *pWInfo = pBuilder->pWInfo; + Bitmask mPrereq = 0; + Bitmask mPrior = 0; + int iTab; + SrcList *pTabList = pWInfo->pTabList; + SrcItem *pItem; + SrcItem *pEnd = &pTabList->a[pWInfo->nLevel]; + sqlite3 *db = pWInfo->pParse->db; + int rc = SQLITE_OK; + int bFirstPastRJ = 0; + int hasRightJoin = 0; + WhereLoop *pNew; + + + /* Loop over the tables in the join, from left to right */ + pNew = pBuilder->pNew; + + /* Verify that pNew has already been initialized */ + assert( pNew->nLTerm==0 ); + assert( pNew->wsFlags==0 ); + assert( pNew->nLSlot>=ArraySize(pNew->aLTermSpace) ); + assert( pNew->aLTerm!=0 ); + + pBuilder->iPlanLimit = SQLITE_QUERY_PLANNER_LIMIT; + for(iTab=0, pItem=pTabList->a; pItem<pEnd; iTab++, pItem++){ + Bitmask mUnusable = 0; + pNew->iTab = iTab; + pBuilder->iPlanLimit += SQLITE_QUERY_PLANNER_LIMIT_INCR; + pNew->maskSelf = sqlite3WhereGetMask(&pWInfo->sMaskSet, pItem->iCursor); + if( bFirstPastRJ + || (pItem->fg.jointype & (JT_OUTER|JT_CROSS|JT_LTORJ))!=0 + ){ + /* Add prerequisites to prevent reordering of FROM clause terms + ** across CROSS joins and outer joins. The bFirstPastRJ boolean + ** prevents the right operand of a RIGHT JOIN from being swapped with + ** other elements even further to the right. + ** + ** The JT_LTORJ case and the hasRightJoin flag work together to + ** prevent FROM-clause terms from moving from the right side of + ** a LEFT JOIN over to the left side of that join if the LEFT JOIN + ** is itself on the left side of a RIGHT JOIN. + */ + if( pItem->fg.jointype & JT_LTORJ ) hasRightJoin = 1; + mPrereq |= mPrior; + bFirstPastRJ = (pItem->fg.jointype & JT_RIGHT)!=0; + }else if( !hasRightJoin ){ + mPrereq = 0; + } +#ifndef SQLITE_OMIT_VIRTUALTABLE + if( IsVirtual(pItem->pTab) ){ + SrcItem *p; + for(p=&pItem[1]; p<pEnd; p++){ + if( mUnusable || (p->fg.jointype & (JT_OUTER|JT_CROSS)) ){ + mUnusable |= sqlite3WhereGetMask(&pWInfo->sMaskSet, p->iCursor); + } + } + rc = whereLoopAddVirtual(pBuilder, mPrereq, mUnusable); + }else +#endif /* SQLITE_OMIT_VIRTUALTABLE */ + { + rc = whereLoopAddBtree(pBuilder, mPrereq); + } + if( rc==SQLITE_OK && pBuilder->pWC->hasOr ){ + rc = whereLoopAddOr(pBuilder, mPrereq, mUnusable); + } + mPrior |= pNew->maskSelf; + if( rc || db->mallocFailed ){ + if( rc==SQLITE_DONE ){ + /* We hit the query planner search limit set by iPlanLimit */ + sqlite3_log(SQLITE_WARNING, "abbreviated query algorithm search"); + rc = SQLITE_OK; + }else{ + break; + } + } + } + + whereLoopClear(db, pNew); + return rc; +} + +/* +** Examine a WherePath (with the addition of the extra WhereLoop of the 6th +** parameters) to see if it outputs rows in the requested ORDER BY +** (or GROUP BY) without requiring a separate sort operation. Return N: +** +** N>0: N terms of the ORDER BY clause are satisfied +** N==0: No terms of the ORDER BY clause are satisfied +** N<0: Unknown yet how many terms of ORDER BY might be satisfied. +** +** Note that processing for WHERE_GROUPBY and WHERE_DISTINCTBY is not as +** strict. With GROUP BY and DISTINCT the only requirement is that +** equivalent rows appear immediately adjacent to one another. GROUP BY +** and DISTINCT do not require rows to appear in any particular order as long +** as equivalent rows are grouped together. Thus for GROUP BY and DISTINCT +** the pOrderBy terms can be matched in any order. With ORDER BY, the +** pOrderBy terms must be matched in strict left-to-right order. +*/ +static i8 wherePathSatisfiesOrderBy( + WhereInfo *pWInfo, /* The WHERE clause */ + ExprList *pOrderBy, /* ORDER BY or GROUP BY or DISTINCT clause to check */ + WherePath *pPath, /* The WherePath to check */ + u16 wctrlFlags, /* WHERE_GROUPBY or _DISTINCTBY or _ORDERBY_LIMIT */ + u16 nLoop, /* Number of entries in pPath->aLoop[] */ + WhereLoop *pLast, /* Add this WhereLoop to the end of pPath->aLoop[] */ + Bitmask *pRevMask /* OUT: Mask of WhereLoops to run in reverse order */ +){ + u8 revSet; /* True if rev is known */ + u8 rev; /* Composite sort order */ + u8 revIdx; /* Index sort order */ + u8 isOrderDistinct; /* All prior WhereLoops are order-distinct */ + u8 distinctColumns; /* True if the loop has UNIQUE NOT NULL columns */ + u8 isMatch; /* iColumn matches a term of the ORDER BY clause */ + u16 eqOpMask; /* Allowed equality operators */ + u16 nKeyCol; /* Number of key columns in pIndex */ + u16 nColumn; /* Total number of ordered columns in the index */ + u16 nOrderBy; /* Number terms in the ORDER BY clause */ + int iLoop; /* Index of WhereLoop in pPath being processed */ + int i, j; /* Loop counters */ + int iCur; /* Cursor number for current WhereLoop */ + int iColumn; /* A column number within table iCur */ + WhereLoop *pLoop = 0; /* Current WhereLoop being processed. */ + WhereTerm *pTerm; /* A single term of the WHERE clause */ + Expr *pOBExpr; /* An expression from the ORDER BY clause */ + CollSeq *pColl; /* COLLATE function from an ORDER BY clause term */ + Index *pIndex; /* The index associated with pLoop */ + sqlite3 *db = pWInfo->pParse->db; /* Database connection */ + Bitmask obSat = 0; /* Mask of ORDER BY terms satisfied so far */ + Bitmask obDone; /* Mask of all ORDER BY terms */ + Bitmask orderDistinctMask; /* Mask of all well-ordered loops */ + Bitmask ready; /* Mask of inner loops */ + + /* + ** We say the WhereLoop is "one-row" if it generates no more than one + ** row of output. A WhereLoop is one-row if all of the following are true: + ** (a) All index columns match with WHERE_COLUMN_EQ. + ** (b) The index is unique + ** Any WhereLoop with an WHERE_COLUMN_EQ constraint on the rowid is one-row. + ** Every one-row WhereLoop will have the WHERE_ONEROW bit set in wsFlags. + ** + ** We say the WhereLoop is "order-distinct" if the set of columns from + ** that WhereLoop that are in the ORDER BY clause are different for every + ** row of the WhereLoop. Every one-row WhereLoop is automatically + ** order-distinct. A WhereLoop that has no columns in the ORDER BY clause + ** is not order-distinct. To be order-distinct is not quite the same as being + ** UNIQUE since a UNIQUE column or index can have multiple rows that + ** are NULL and NULL values are equivalent for the purpose of order-distinct. + ** To be order-distinct, the columns must be UNIQUE and NOT NULL. + ** + ** The rowid for a table is always UNIQUE and NOT NULL so whenever the + ** rowid appears in the ORDER BY clause, the corresponding WhereLoop is + ** automatically order-distinct. + */ + + assert( pOrderBy!=0 ); + if( nLoop && OptimizationDisabled(db, SQLITE_OrderByIdxJoin) ) return 0; + + nOrderBy = pOrderBy->nExpr; + testcase( nOrderBy==BMS-1 ); + if( nOrderBy>BMS-1 ) return 0; /* Cannot optimize overly large ORDER BYs */ + isOrderDistinct = 1; + obDone = MASKBIT(nOrderBy)-1; + orderDistinctMask = 0; + ready = 0; + eqOpMask = WO_EQ | WO_IS | WO_ISNULL; + if( wctrlFlags & (WHERE_ORDERBY_LIMIT|WHERE_ORDERBY_MAX|WHERE_ORDERBY_MIN) ){ + eqOpMask |= WO_IN; + } + for(iLoop=0; isOrderDistinct && obSat<obDone && iLoop<=nLoop; iLoop++){ + if( iLoop>0 ) ready |= pLoop->maskSelf; + if( iLoop<nLoop ){ + pLoop = pPath->aLoop[iLoop]; + if( wctrlFlags & WHERE_ORDERBY_LIMIT ) continue; + }else{ + pLoop = pLast; + } + if( pLoop->wsFlags & WHERE_VIRTUALTABLE ){ + if( pLoop->u.vtab.isOrdered + && ((wctrlFlags&(WHERE_DISTINCTBY|WHERE_SORTBYGROUP))!=WHERE_DISTINCTBY) + ){ + obSat = obDone; + } + break; + }else if( wctrlFlags & WHERE_DISTINCTBY ){ + pLoop->u.btree.nDistinctCol = 0; + } + iCur = pWInfo->pTabList->a[pLoop->iTab].iCursor; + + /* Mark off any ORDER BY term X that is a column in the table of + ** the current loop for which there is term in the WHERE + ** clause of the form X IS NULL or X=? that reference only outer + ** loops. + */ + for(i=0; i<nOrderBy; i++){ + if( MASKBIT(i) & obSat ) continue; + pOBExpr = sqlite3ExprSkipCollateAndLikely(pOrderBy->a[i].pExpr); + if( NEVER(pOBExpr==0) ) continue; + if( pOBExpr->op!=TK_COLUMN && pOBExpr->op!=TK_AGG_COLUMN ) continue; + if( pOBExpr->iTable!=iCur ) continue; + pTerm = sqlite3WhereFindTerm(&pWInfo->sWC, iCur, pOBExpr->iColumn, + ~ready, eqOpMask, 0); + if( pTerm==0 ) continue; + if( pTerm->eOperator==WO_IN ){ + /* IN terms are only valid for sorting in the ORDER BY LIMIT + ** optimization, and then only if they are actually used + ** by the query plan */ + assert( wctrlFlags & + (WHERE_ORDERBY_LIMIT|WHERE_ORDERBY_MIN|WHERE_ORDERBY_MAX) ); + for(j=0; j<pLoop->nLTerm && pTerm!=pLoop->aLTerm[j]; j++){} + if( j>=pLoop->nLTerm ) continue; + } + if( (pTerm->eOperator&(WO_EQ|WO_IS))!=0 && pOBExpr->iColumn>=0 ){ + Parse *pParse = pWInfo->pParse; + CollSeq *pColl1 = sqlite3ExprNNCollSeq(pParse, pOrderBy->a[i].pExpr); + CollSeq *pColl2 = sqlite3ExprCompareCollSeq(pParse, pTerm->pExpr); + assert( pColl1 ); + if( pColl2==0 || sqlite3StrICmp(pColl1->zName, pColl2->zName) ){ + continue; + } + testcase( pTerm->pExpr->op==TK_IS ); + } + obSat |= MASKBIT(i); + } + + if( (pLoop->wsFlags & WHERE_ONEROW)==0 ){ + if( pLoop->wsFlags & WHERE_IPK ){ + pIndex = 0; + nKeyCol = 0; + nColumn = 1; + }else if( (pIndex = pLoop->u.btree.pIndex)==0 || pIndex->bUnordered ){ + return 0; + }else{ + nKeyCol = pIndex->nKeyCol; + nColumn = pIndex->nColumn; + assert( nColumn==nKeyCol+1 || !HasRowid(pIndex->pTable) ); + assert( pIndex->aiColumn[nColumn-1]==XN_ROWID + || !HasRowid(pIndex->pTable)); + /* All relevant terms of the index must also be non-NULL in order + ** for isOrderDistinct to be true. So the isOrderDistint value + ** computed here might be a false positive. Corrections will be + ** made at tag-20210426-1 below */ + isOrderDistinct = IsUniqueIndex(pIndex) + && (pLoop->wsFlags & WHERE_SKIPSCAN)==0; + } + + /* Loop through all columns of the index and deal with the ones + ** that are not constrained by == or IN. + */ + rev = revSet = 0; + distinctColumns = 0; + for(j=0; j<nColumn; j++){ + u8 bOnce = 1; /* True to run the ORDER BY search loop */ + + assert( j>=pLoop->u.btree.nEq + || (pLoop->aLTerm[j]==0)==(j<pLoop->nSkip) + ); + if( j<pLoop->u.btree.nEq && j>=pLoop->nSkip ){ + u16 eOp = pLoop->aLTerm[j]->eOperator; + + /* Skip over == and IS and ISNULL terms. (Also skip IN terms when + ** doing WHERE_ORDERBY_LIMIT processing). Except, IS and ISNULL + ** terms imply that the index is not UNIQUE NOT NULL in which case + ** the loop need to be marked as not order-distinct because it can + ** have repeated NULL rows. + ** + ** If the current term is a column of an ((?,?) IN (SELECT...)) + ** expression for which the SELECT returns more than one column, + ** check that it is the only column used by this loop. Otherwise, + ** if it is one of two or more, none of the columns can be + ** considered to match an ORDER BY term. + */ + if( (eOp & eqOpMask)!=0 ){ + if( eOp & (WO_ISNULL|WO_IS) ){ + testcase( eOp & WO_ISNULL ); + testcase( eOp & WO_IS ); + testcase( isOrderDistinct ); + isOrderDistinct = 0; + } + continue; + }else if( ALWAYS(eOp & WO_IN) ){ + /* ALWAYS() justification: eOp is an equality operator due to the + ** j<pLoop->u.btree.nEq constraint above. Any equality other + ** than WO_IN is captured by the previous "if". So this one + ** always has to be WO_IN. */ + Expr *pX = pLoop->aLTerm[j]->pExpr; + for(i=j+1; i<pLoop->u.btree.nEq; i++){ + if( pLoop->aLTerm[i]->pExpr==pX ){ + assert( (pLoop->aLTerm[i]->eOperator & WO_IN) ); + bOnce = 0; + break; + } + } + } + } + + /* Get the column number in the table (iColumn) and sort order + ** (revIdx) for the j-th column of the index. + */ + if( pIndex ){ + iColumn = pIndex->aiColumn[j]; + revIdx = pIndex->aSortOrder[j] & KEYINFO_ORDER_DESC; + if( iColumn==pIndex->pTable->iPKey ) iColumn = XN_ROWID; + }else{ + iColumn = XN_ROWID; + revIdx = 0; + } + + /* An unconstrained column that might be NULL means that this + ** WhereLoop is not well-ordered. tag-20210426-1 + */ + if( isOrderDistinct ){ + if( iColumn>=0 + && j>=pLoop->u.btree.nEq + && pIndex->pTable->aCol[iColumn].notNull==0 + ){ + isOrderDistinct = 0; + } + if( iColumn==XN_EXPR ){ + isOrderDistinct = 0; + } + } + + /* Find the ORDER BY term that corresponds to the j-th column + ** of the index and mark that ORDER BY term off + */ + isMatch = 0; + for(i=0; bOnce && i<nOrderBy; i++){ + if( MASKBIT(i) & obSat ) continue; + pOBExpr = sqlite3ExprSkipCollateAndLikely(pOrderBy->a[i].pExpr); + testcase( wctrlFlags & WHERE_GROUPBY ); + testcase( wctrlFlags & WHERE_DISTINCTBY ); + if( NEVER(pOBExpr==0) ) continue; + if( (wctrlFlags & (WHERE_GROUPBY|WHERE_DISTINCTBY))==0 ) bOnce = 0; + if( iColumn>=XN_ROWID ){ + if( pOBExpr->op!=TK_COLUMN && pOBExpr->op!=TK_AGG_COLUMN ) continue; + if( pOBExpr->iTable!=iCur ) continue; + if( pOBExpr->iColumn!=iColumn ) continue; + }else{ + Expr *pIxExpr = pIndex->aColExpr->a[j].pExpr; + if( sqlite3ExprCompareSkip(pOBExpr, pIxExpr, iCur) ){ + continue; + } + } + if( iColumn!=XN_ROWID ){ + pColl = sqlite3ExprNNCollSeq(pWInfo->pParse, pOrderBy->a[i].pExpr); + if( sqlite3StrICmp(pColl->zName, pIndex->azColl[j])!=0 ) continue; + } + if( wctrlFlags & WHERE_DISTINCTBY ){ + pLoop->u.btree.nDistinctCol = j+1; + } + isMatch = 1; + break; + } + if( isMatch && (wctrlFlags & WHERE_GROUPBY)==0 ){ + /* Make sure the sort order is compatible in an ORDER BY clause. + ** Sort order is irrelevant for a GROUP BY clause. */ + if( revSet ){ + if( (rev ^ revIdx) + != (pOrderBy->a[i].fg.sortFlags&KEYINFO_ORDER_DESC) + ){ + isMatch = 0; + } + }else{ + rev = revIdx ^ (pOrderBy->a[i].fg.sortFlags & KEYINFO_ORDER_DESC); + if( rev ) *pRevMask |= MASKBIT(iLoop); + revSet = 1; + } + } + if( isMatch && (pOrderBy->a[i].fg.sortFlags & KEYINFO_ORDER_BIGNULL) ){ + if( j==pLoop->u.btree.nEq ){ + pLoop->wsFlags |= WHERE_BIGNULL_SORT; + }else{ + isMatch = 0; + } + } + if( isMatch ){ + if( iColumn==XN_ROWID ){ + testcase( distinctColumns==0 ); + distinctColumns = 1; + } + obSat |= MASKBIT(i); + }else{ + /* No match found */ + if( j==0 || j<nKeyCol ){ + testcase( isOrderDistinct!=0 ); + isOrderDistinct = 0; + } + break; + } + } /* end Loop over all index columns */ + if( distinctColumns ){ + testcase( isOrderDistinct==0 ); + isOrderDistinct = 1; + } + } /* end-if not one-row */ + + /* Mark off any other ORDER BY terms that reference pLoop */ + if( isOrderDistinct ){ + orderDistinctMask |= pLoop->maskSelf; + for(i=0; i<nOrderBy; i++){ + Expr *p; + Bitmask mTerm; + if( MASKBIT(i) & obSat ) continue; + p = pOrderBy->a[i].pExpr; + mTerm = sqlite3WhereExprUsage(&pWInfo->sMaskSet,p); + if( mTerm==0 && !sqlite3ExprIsConstant(p) ) continue; + if( (mTerm&~orderDistinctMask)==0 ){ + obSat |= MASKBIT(i); + } + } + } + } /* End the loop over all WhereLoops from outer-most down to inner-most */ + if( obSat==obDone ) return (i8)nOrderBy; + if( !isOrderDistinct ){ + for(i=nOrderBy-1; i>0; i--){ + Bitmask m = ALWAYS(i<BMS) ? MASKBIT(i) - 1 : 0; + if( (obSat&m)==m ) return i; + } + return 0; + } + return -1; +} + + +/* +** If the WHERE_GROUPBY flag is set in the mask passed to sqlite3WhereBegin(), +** the planner assumes that the specified pOrderBy list is actually a GROUP +** BY clause - and so any order that groups rows as required satisfies the +** request. +** +** Normally, in this case it is not possible for the caller to determine +** whether or not the rows are really being delivered in sorted order, or +** just in some other order that provides the required grouping. However, +** if the WHERE_SORTBYGROUP flag is also passed to sqlite3WhereBegin(), then +** this function may be called on the returned WhereInfo object. It returns +** true if the rows really will be sorted in the specified order, or false +** otherwise. +** +** For example, assuming: +** +** CREATE INDEX i1 ON t1(x, Y); +** +** then +** +** SELECT * FROM t1 GROUP BY x,y ORDER BY x,y; -- IsSorted()==1 +** SELECT * FROM t1 GROUP BY y,x ORDER BY y,x; -- IsSorted()==0 +*/ +int sqlite3WhereIsSorted(WhereInfo *pWInfo){ + assert( pWInfo->wctrlFlags & (WHERE_GROUPBY|WHERE_DISTINCTBY) ); + assert( pWInfo->wctrlFlags & WHERE_SORTBYGROUP ); + return pWInfo->sorted; +} + +#ifdef WHERETRACE_ENABLED +/* For debugging use only: */ +static const char *wherePathName(WherePath *pPath, int nLoop, WhereLoop *pLast){ + static char zName[65]; + int i; + for(i=0; i<nLoop; i++){ zName[i] = pPath->aLoop[i]->cId; } + if( pLast ) zName[i++] = pLast->cId; + zName[i] = 0; + return zName; +} +#endif + +/* +** Return the cost of sorting nRow rows, assuming that the keys have +** nOrderby columns and that the first nSorted columns are already in +** order. +*/ +static LogEst whereSortingCost( + WhereInfo *pWInfo, /* Query planning context */ + LogEst nRow, /* Estimated number of rows to sort */ + int nOrderBy, /* Number of ORDER BY clause terms */ + int nSorted /* Number of initial ORDER BY terms naturally in order */ +){ + /* Estimated cost of a full external sort, where N is + ** the number of rows to sort is: + ** + ** cost = (K * N * log(N)). + ** + ** Or, if the order-by clause has X terms but only the last Y + ** terms are out of order, then block-sorting will reduce the + ** sorting cost to: + ** + ** cost = (K * N * log(N)) * (Y/X) + ** + ** The constant K is at least 2.0 but will be larger if there are a + ** large number of columns to be sorted, as the sorting time is + ** proportional to the amount of content to be sorted. The algorithm + ** does not currently distinguish between fat columns (BLOBs and TEXTs) + ** and skinny columns (INTs). It just uses the number of columns as + ** an approximation for the row width. + ** + ** And extra factor of 2.0 or 3.0 is added to the sorting cost if the sort + ** is built using OP_IdxInsert and OP_Sort rather than with OP_SorterInsert. + */ + LogEst rSortCost, nCol; + assert( pWInfo->pSelect!=0 ); + assert( pWInfo->pSelect->pEList!=0 ); + /* TUNING: sorting cost proportional to the number of output columns: */ + nCol = sqlite3LogEst((pWInfo->pSelect->pEList->nExpr+59)/30); + rSortCost = nRow + nCol; + if( nSorted>0 ){ + /* Scale the result by (Y/X) */ + rSortCost += sqlite3LogEst((nOrderBy-nSorted)*100/nOrderBy) - 66; + } + + /* Multiple by log(M) where M is the number of output rows. + ** Use the LIMIT for M if it is smaller. Or if this sort is for + ** a DISTINCT operator, M will be the number of distinct output + ** rows, so fudge it downwards a bit. + */ + if( (pWInfo->wctrlFlags & WHERE_USE_LIMIT)!=0 ){ + rSortCost += 10; /* TUNING: Extra 2.0x if using LIMIT */ + if( nSorted!=0 ){ + rSortCost += 6; /* TUNING: Extra 1.5x if also using partial sort */ + } + if( pWInfo->iLimit<nRow ){ + nRow = pWInfo->iLimit; + } + }else if( (pWInfo->wctrlFlags & WHERE_WANT_DISTINCT) ){ + /* TUNING: In the sort for a DISTINCT operator, assume that the DISTINCT + ** reduces the number of output rows by a factor of 2 */ + if( nRow>10 ){ nRow -= 10; assert( 10==sqlite3LogEst(2) ); } + } + rSortCost += estLog(nRow); + return rSortCost; +} + +/* +** Given the list of WhereLoop objects at pWInfo->pLoops, this routine +** attempts to find the lowest cost path that visits each WhereLoop +** once. This path is then loaded into the pWInfo->a[].pWLoop fields. +** +** Assume that the total number of output rows that will need to be sorted +** will be nRowEst (in the 10*log2 representation). Or, ignore sorting +** costs if nRowEst==0. +** +** Return SQLITE_OK on success or SQLITE_NOMEM of a memory allocation +** error occurs. +*/ +static int wherePathSolver(WhereInfo *pWInfo, LogEst nRowEst){ + int mxChoice; /* Maximum number of simultaneous paths tracked */ + int nLoop; /* Number of terms in the join */ + Parse *pParse; /* Parsing context */ + int iLoop; /* Loop counter over the terms of the join */ + int ii, jj; /* Loop counters */ + int mxI = 0; /* Index of next entry to replace */ + int nOrderBy; /* Number of ORDER BY clause terms */ + LogEst mxCost = 0; /* Maximum cost of a set of paths */ + LogEst mxUnsorted = 0; /* Maximum unsorted cost of a set of path */ + int nTo, nFrom; /* Number of valid entries in aTo[] and aFrom[] */ + WherePath *aFrom; /* All nFrom paths at the previous level */ + WherePath *aTo; /* The nTo best paths at the current level */ + WherePath *pFrom; /* An element of aFrom[] that we are working on */ + WherePath *pTo; /* An element of aTo[] that we are working on */ + WhereLoop *pWLoop; /* One of the WhereLoop objects */ + WhereLoop **pX; /* Used to divy up the pSpace memory */ + LogEst *aSortCost = 0; /* Sorting and partial sorting costs */ + char *pSpace; /* Temporary memory used by this routine */ + int nSpace; /* Bytes of space allocated at pSpace */ + + pParse = pWInfo->pParse; + nLoop = pWInfo->nLevel; + /* TUNING: For simple queries, only the best path is tracked. + ** For 2-way joins, the 5 best paths are followed. + ** For joins of 3 or more tables, track the 10 best paths */ + mxChoice = (nLoop<=1) ? 1 : (nLoop==2 ? 5 : 10); + assert( nLoop<=pWInfo->pTabList->nSrc ); + WHERETRACE(0x002, ("---- begin solver. (nRowEst=%d, nQueryLoop=%d)\n", + nRowEst, pParse->nQueryLoop)); + + /* If nRowEst is zero and there is an ORDER BY clause, ignore it. In this + ** case the purpose of this call is to estimate the number of rows returned + ** by the overall query. Once this estimate has been obtained, the caller + ** will invoke this function a second time, passing the estimate as the + ** nRowEst parameter. */ + if( pWInfo->pOrderBy==0 || nRowEst==0 ){ + nOrderBy = 0; + }else{ + nOrderBy = pWInfo->pOrderBy->nExpr; + } + + /* Allocate and initialize space for aTo, aFrom and aSortCost[] */ + nSpace = (sizeof(WherePath)+sizeof(WhereLoop*)*nLoop)*mxChoice*2; + nSpace += sizeof(LogEst) * nOrderBy; + pSpace = sqlite3StackAllocRawNN(pParse->db, nSpace); + if( pSpace==0 ) return SQLITE_NOMEM_BKPT; + aTo = (WherePath*)pSpace; + aFrom = aTo+mxChoice; + memset(aFrom, 0, sizeof(aFrom[0])); + pX = (WhereLoop**)(aFrom+mxChoice); + for(ii=mxChoice*2, pFrom=aTo; ii>0; ii--, pFrom++, pX += nLoop){ + pFrom->aLoop = pX; + } + if( nOrderBy ){ + /* If there is an ORDER BY clause and it is not being ignored, set up + ** space for the aSortCost[] array. Each element of the aSortCost array + ** is either zero - meaning it has not yet been initialized - or the + ** cost of sorting nRowEst rows of data where the first X terms of + ** the ORDER BY clause are already in order, where X is the array + ** index. */ + aSortCost = (LogEst*)pX; + memset(aSortCost, 0, sizeof(LogEst) * nOrderBy); + } + assert( aSortCost==0 || &pSpace[nSpace]==(char*)&aSortCost[nOrderBy] ); + assert( aSortCost!=0 || &pSpace[nSpace]==(char*)pX ); + + /* Seed the search with a single WherePath containing zero WhereLoops. + ** + ** TUNING: Do not let the number of iterations go above 28. If the cost + ** of computing an automatic index is not paid back within the first 28 + ** rows, then do not use the automatic index. */ + aFrom[0].nRow = MIN(pParse->nQueryLoop, 48); assert( 48==sqlite3LogEst(28) ); + nFrom = 1; + assert( aFrom[0].isOrdered==0 ); + if( nOrderBy ){ + /* If nLoop is zero, then there are no FROM terms in the query. Since + ** in this case the query may return a maximum of one row, the results + ** are already in the requested order. Set isOrdered to nOrderBy to + ** indicate this. Or, if nLoop is greater than zero, set isOrdered to + ** -1, indicating that the result set may or may not be ordered, + ** depending on the loops added to the current plan. */ + aFrom[0].isOrdered = nLoop>0 ? -1 : nOrderBy; + } + + /* Compute successively longer WherePaths using the previous generation + ** of WherePaths as the basis for the next. Keep track of the mxChoice + ** best paths at each generation */ + for(iLoop=0; iLoop<nLoop; iLoop++){ + nTo = 0; + for(ii=0, pFrom=aFrom; ii<nFrom; ii++, pFrom++){ + for(pWLoop=pWInfo->pLoops; pWLoop; pWLoop=pWLoop->pNextLoop){ + LogEst nOut; /* Rows visited by (pFrom+pWLoop) */ + LogEst rCost; /* Cost of path (pFrom+pWLoop) */ + LogEst rUnsorted; /* Unsorted cost of (pFrom+pWLoop) */ + i8 isOrdered; /* isOrdered for (pFrom+pWLoop) */ + Bitmask maskNew; /* Mask of src visited by (..) */ + Bitmask revMask; /* Mask of rev-order loops for (..) */ + + if( (pWLoop->prereq & ~pFrom->maskLoop)!=0 ) continue; + if( (pWLoop->maskSelf & pFrom->maskLoop)!=0 ) continue; + if( (pWLoop->wsFlags & WHERE_AUTO_INDEX)!=0 && pFrom->nRow<3 ){ + /* Do not use an automatic index if the this loop is expected + ** to run less than 1.25 times. It is tempting to also exclude + ** automatic index usage on an outer loop, but sometimes an automatic + ** index is useful in the outer loop of a correlated subquery. */ + assert( 10==sqlite3LogEst(2) ); + continue; + } + + /* At this point, pWLoop is a candidate to be the next loop. + ** Compute its cost */ + rUnsorted = sqlite3LogEstAdd(pWLoop->rSetup,pWLoop->rRun + pFrom->nRow); + rUnsorted = sqlite3LogEstAdd(rUnsorted, pFrom->rUnsorted); + nOut = pFrom->nRow + pWLoop->nOut; + maskNew = pFrom->maskLoop | pWLoop->maskSelf; + isOrdered = pFrom->isOrdered; + if( isOrdered<0 ){ + revMask = 0; + isOrdered = wherePathSatisfiesOrderBy(pWInfo, + pWInfo->pOrderBy, pFrom, pWInfo->wctrlFlags, + iLoop, pWLoop, &revMask); + }else{ + revMask = pFrom->revLoop; + } + if( isOrdered>=0 && isOrdered<nOrderBy ){ + if( aSortCost[isOrdered]==0 ){ + aSortCost[isOrdered] = whereSortingCost( + pWInfo, nRowEst, nOrderBy, isOrdered + ); + } + /* TUNING: Add a small extra penalty (3) to sorting as an + ** extra encouragement to the query planner to select a plan + ** where the rows emerge in the correct order without any sorting + ** required. */ + rCost = sqlite3LogEstAdd(rUnsorted, aSortCost[isOrdered]) + 3; + + WHERETRACE(0x002, + ("---- sort cost=%-3d (%d/%d) increases cost %3d to %-3d\n", + aSortCost[isOrdered], (nOrderBy-isOrdered), nOrderBy, + rUnsorted, rCost)); + }else{ + rCost = rUnsorted; + rUnsorted -= 2; /* TUNING: Slight bias in favor of no-sort plans */ + } + + /* Check to see if pWLoop should be added to the set of + ** mxChoice best-so-far paths. + ** + ** First look for an existing path among best-so-far paths + ** that covers the same set of loops and has the same isOrdered + ** setting as the current path candidate. + ** + ** The term "((pTo->isOrdered^isOrdered)&0x80)==0" is equivalent + ** to (pTo->isOrdered==(-1))==(isOrdered==(-1))" for the range + ** of legal values for isOrdered, -1..64. + */ + for(jj=0, pTo=aTo; jj<nTo; jj++, pTo++){ + if( pTo->maskLoop==maskNew + && ((pTo->isOrdered^isOrdered)&0x80)==0 + ){ + testcase( jj==nTo-1 ); + break; + } + } + if( jj>=nTo ){ + /* None of the existing best-so-far paths match the candidate. */ + if( nTo>=mxChoice + && (rCost>mxCost || (rCost==mxCost && rUnsorted>=mxUnsorted)) + ){ + /* The current candidate is no better than any of the mxChoice + ** paths currently in the best-so-far buffer. So discard + ** this candidate as not viable. */ +#ifdef WHERETRACE_ENABLED /* 0x4 */ + if( sqlite3WhereTrace&0x4 ){ + sqlite3DebugPrintf("Skip %s cost=%-3d,%3d,%3d order=%c\n", + wherePathName(pFrom, iLoop, pWLoop), rCost, nOut, rUnsorted, + isOrdered>=0 ? isOrdered+'0' : '?'); + } +#endif + continue; + } + /* If we reach this points it means that the new candidate path + ** needs to be added to the set of best-so-far paths. */ + if( nTo<mxChoice ){ + /* Increase the size of the aTo set by one */ + jj = nTo++; + }else{ + /* New path replaces the prior worst to keep count below mxChoice */ + jj = mxI; + } + pTo = &aTo[jj]; +#ifdef WHERETRACE_ENABLED /* 0x4 */ + if( sqlite3WhereTrace&0x4 ){ + sqlite3DebugPrintf("New %s cost=%-3d,%3d,%3d order=%c\n", + wherePathName(pFrom, iLoop, pWLoop), rCost, nOut, rUnsorted, + isOrdered>=0 ? isOrdered+'0' : '?'); + } +#endif + }else{ + /* Control reaches here if best-so-far path pTo=aTo[jj] covers the + ** same set of loops and has the same isOrdered setting as the + ** candidate path. Check to see if the candidate should replace + ** pTo or if the candidate should be skipped. + ** + ** The conditional is an expanded vector comparison equivalent to: + ** (pTo->rCost,pTo->nRow,pTo->rUnsorted) <= (rCost,nOut,rUnsorted) + */ + if( pTo->rCost<rCost + || (pTo->rCost==rCost + && (pTo->nRow<nOut + || (pTo->nRow==nOut && pTo->rUnsorted<=rUnsorted) + ) + ) + ){ +#ifdef WHERETRACE_ENABLED /* 0x4 */ + if( sqlite3WhereTrace&0x4 ){ + sqlite3DebugPrintf( + "Skip %s cost=%-3d,%3d,%3d order=%c", + wherePathName(pFrom, iLoop, pWLoop), rCost, nOut, rUnsorted, + isOrdered>=0 ? isOrdered+'0' : '?'); + sqlite3DebugPrintf(" vs %s cost=%-3d,%3d,%3d order=%c\n", + wherePathName(pTo, iLoop+1, 0), pTo->rCost, pTo->nRow, + pTo->rUnsorted, pTo->isOrdered>=0 ? pTo->isOrdered+'0' : '?'); + } +#endif + /* Discard the candidate path from further consideration */ + testcase( pTo->rCost==rCost ); + continue; + } + testcase( pTo->rCost==rCost+1 ); + /* Control reaches here if the candidate path is better than the + ** pTo path. Replace pTo with the candidate. */ +#ifdef WHERETRACE_ENABLED /* 0x4 */ + if( sqlite3WhereTrace&0x4 ){ + sqlite3DebugPrintf( + "Update %s cost=%-3d,%3d,%3d order=%c", + wherePathName(pFrom, iLoop, pWLoop), rCost, nOut, rUnsorted, + isOrdered>=0 ? isOrdered+'0' : '?'); + sqlite3DebugPrintf(" was %s cost=%-3d,%3d,%3d order=%c\n", + wherePathName(pTo, iLoop+1, 0), pTo->rCost, pTo->nRow, + pTo->rUnsorted, pTo->isOrdered>=0 ? pTo->isOrdered+'0' : '?'); + } +#endif + } + /* pWLoop is a winner. Add it to the set of best so far */ + pTo->maskLoop = pFrom->maskLoop | pWLoop->maskSelf; + pTo->revLoop = revMask; + pTo->nRow = nOut; + pTo->rCost = rCost; + pTo->rUnsorted = rUnsorted; + pTo->isOrdered = isOrdered; + memcpy(pTo->aLoop, pFrom->aLoop, sizeof(WhereLoop*)*iLoop); + pTo->aLoop[iLoop] = pWLoop; + if( nTo>=mxChoice ){ + mxI = 0; + mxCost = aTo[0].rCost; + mxUnsorted = aTo[0].nRow; + for(jj=1, pTo=&aTo[1]; jj<mxChoice; jj++, pTo++){ + if( pTo->rCost>mxCost + || (pTo->rCost==mxCost && pTo->rUnsorted>mxUnsorted) + ){ + mxCost = pTo->rCost; + mxUnsorted = pTo->rUnsorted; + mxI = jj; + } + } + } + } + } + +#ifdef WHERETRACE_ENABLED /* >=2 */ + if( sqlite3WhereTrace & 0x02 ){ + sqlite3DebugPrintf("---- after round %d ----\n", iLoop); + for(ii=0, pTo=aTo; ii<nTo; ii++, pTo++){ + sqlite3DebugPrintf(" %s cost=%-3d nrow=%-3d order=%c", + wherePathName(pTo, iLoop+1, 0), pTo->rCost, pTo->nRow, + pTo->isOrdered>=0 ? (pTo->isOrdered+'0') : '?'); + if( pTo->isOrdered>0 ){ + sqlite3DebugPrintf(" rev=0x%llx\n", pTo->revLoop); + }else{ + sqlite3DebugPrintf("\n"); + } + } + } +#endif + + /* Swap the roles of aFrom and aTo for the next generation */ + pFrom = aTo; + aTo = aFrom; + aFrom = pFrom; + nFrom = nTo; + } + + if( nFrom==0 ){ + sqlite3ErrorMsg(pParse, "no query solution"); + sqlite3StackFreeNN(pParse->db, pSpace); + return SQLITE_ERROR; + } + + /* Find the lowest cost path. pFrom will be left pointing to that path */ + pFrom = aFrom; + for(ii=1; ii<nFrom; ii++){ + if( pFrom->rCost>aFrom[ii].rCost ) pFrom = &aFrom[ii]; + } + assert( pWInfo->nLevel==nLoop ); + /* Load the lowest cost path into pWInfo */ + for(iLoop=0; iLoop<nLoop; iLoop++){ + WhereLevel *pLevel = pWInfo->a + iLoop; + pLevel->pWLoop = pWLoop = pFrom->aLoop[iLoop]; + pLevel->iFrom = pWLoop->iTab; + pLevel->iTabCur = pWInfo->pTabList->a[pLevel->iFrom].iCursor; + } + if( (pWInfo->wctrlFlags & WHERE_WANT_DISTINCT)!=0 + && (pWInfo->wctrlFlags & WHERE_DISTINCTBY)==0 + && pWInfo->eDistinct==WHERE_DISTINCT_NOOP + && nRowEst + ){ + Bitmask notUsed; + int rc = wherePathSatisfiesOrderBy(pWInfo, pWInfo->pResultSet, pFrom, + WHERE_DISTINCTBY, nLoop-1, pFrom->aLoop[nLoop-1], ¬Used); + if( rc==pWInfo->pResultSet->nExpr ){ + pWInfo->eDistinct = WHERE_DISTINCT_ORDERED; + } + } + pWInfo->bOrderedInnerLoop = 0; + if( pWInfo->pOrderBy ){ + pWInfo->nOBSat = pFrom->isOrdered; + if( pWInfo->wctrlFlags & WHERE_DISTINCTBY ){ + if( pFrom->isOrdered==pWInfo->pOrderBy->nExpr ){ + pWInfo->eDistinct = WHERE_DISTINCT_ORDERED; + } + if( pWInfo->pSelect->pOrderBy + && pWInfo->nOBSat > pWInfo->pSelect->pOrderBy->nExpr ){ + pWInfo->nOBSat = pWInfo->pSelect->pOrderBy->nExpr; + } + }else{ + pWInfo->revMask = pFrom->revLoop; + if( pWInfo->nOBSat<=0 ){ + pWInfo->nOBSat = 0; + if( nLoop>0 ){ + u32 wsFlags = pFrom->aLoop[nLoop-1]->wsFlags; + if( (wsFlags & WHERE_ONEROW)==0 + && (wsFlags&(WHERE_IPK|WHERE_COLUMN_IN))!=(WHERE_IPK|WHERE_COLUMN_IN) + ){ + Bitmask m = 0; + int rc = wherePathSatisfiesOrderBy(pWInfo, pWInfo->pOrderBy, pFrom, + WHERE_ORDERBY_LIMIT, nLoop-1, pFrom->aLoop[nLoop-1], &m); + testcase( wsFlags & WHERE_IPK ); + testcase( wsFlags & WHERE_COLUMN_IN ); + if( rc==pWInfo->pOrderBy->nExpr ){ + pWInfo->bOrderedInnerLoop = 1; + pWInfo->revMask = m; + } + } + } + }else if( nLoop + && pWInfo->nOBSat==1 + && (pWInfo->wctrlFlags & (WHERE_ORDERBY_MIN|WHERE_ORDERBY_MAX))!=0 + ){ + pWInfo->bOrderedInnerLoop = 1; + } + } + if( (pWInfo->wctrlFlags & WHERE_SORTBYGROUP) + && pWInfo->nOBSat==pWInfo->pOrderBy->nExpr && nLoop>0 + ){ + Bitmask revMask = 0; + int nOrder = wherePathSatisfiesOrderBy(pWInfo, pWInfo->pOrderBy, + pFrom, 0, nLoop-1, pFrom->aLoop[nLoop-1], &revMask + ); + assert( pWInfo->sorted==0 ); + if( nOrder==pWInfo->pOrderBy->nExpr ){ + pWInfo->sorted = 1; + pWInfo->revMask = revMask; + } + } + } + + + pWInfo->nRowOut = pFrom->nRow; + + /* Free temporary memory and return success */ + sqlite3StackFreeNN(pParse->db, pSpace); + return SQLITE_OK; +} + +/* +** Most queries use only a single table (they are not joins) and have +** simple == constraints against indexed fields. This routine attempts +** to plan those simple cases using much less ceremony than the +** general-purpose query planner, and thereby yield faster sqlite3_prepare() +** times for the common case. +** +** Return non-zero on success, if this query can be handled by this +** no-frills query planner. Return zero if this query needs the +** general-purpose query planner. +*/ +static int whereShortCut(WhereLoopBuilder *pBuilder){ + WhereInfo *pWInfo; + SrcItem *pItem; + WhereClause *pWC; + WhereTerm *pTerm; + WhereLoop *pLoop; + int iCur; + int j; + Table *pTab; + Index *pIdx; + WhereScan scan; + + pWInfo = pBuilder->pWInfo; + if( pWInfo->wctrlFlags & WHERE_OR_SUBCLAUSE ) return 0; + assert( pWInfo->pTabList->nSrc>=1 ); + pItem = pWInfo->pTabList->a; + pTab = pItem->pTab; + if( IsVirtual(pTab) ) return 0; + if( pItem->fg.isIndexedBy || pItem->fg.notIndexed ){ + testcase( pItem->fg.isIndexedBy ); + testcase( pItem->fg.notIndexed ); + return 0; + } + iCur = pItem->iCursor; + pWC = &pWInfo->sWC; + pLoop = pBuilder->pNew; + pLoop->wsFlags = 0; + pLoop->nSkip = 0; + pTerm = whereScanInit(&scan, pWC, iCur, -1, WO_EQ|WO_IS, 0); + while( pTerm && pTerm->prereqRight ) pTerm = whereScanNext(&scan); + if( pTerm ){ + testcase( pTerm->eOperator & WO_IS ); + pLoop->wsFlags = WHERE_COLUMN_EQ|WHERE_IPK|WHERE_ONEROW; + pLoop->aLTerm[0] = pTerm; + pLoop->nLTerm = 1; + pLoop->u.btree.nEq = 1; + /* TUNING: Cost of a rowid lookup is 10 */ + pLoop->rRun = 33; /* 33==sqlite3LogEst(10) */ + }else{ + for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){ + int opMask; + assert( pLoop->aLTermSpace==pLoop->aLTerm ); + if( !IsUniqueIndex(pIdx) + || pIdx->pPartIdxWhere!=0 + || pIdx->nKeyCol>ArraySize(pLoop->aLTermSpace) + ) continue; + opMask = pIdx->uniqNotNull ? (WO_EQ|WO_IS) : WO_EQ; + for(j=0; j<pIdx->nKeyCol; j++){ + pTerm = whereScanInit(&scan, pWC, iCur, j, opMask, pIdx); + while( pTerm && pTerm->prereqRight ) pTerm = whereScanNext(&scan); + if( pTerm==0 ) break; + testcase( pTerm->eOperator & WO_IS ); + pLoop->aLTerm[j] = pTerm; + } + if( j!=pIdx->nKeyCol ) continue; + pLoop->wsFlags = WHERE_COLUMN_EQ|WHERE_ONEROW|WHERE_INDEXED; + if( pIdx->isCovering || (pItem->colUsed & pIdx->colNotIdxed)==0 ){ + pLoop->wsFlags |= WHERE_IDX_ONLY; + } + pLoop->nLTerm = j; + pLoop->u.btree.nEq = j; + pLoop->u.btree.pIndex = pIdx; + /* TUNING: Cost of a unique index lookup is 15 */ + pLoop->rRun = 39; /* 39==sqlite3LogEst(15) */ + break; + } + } + if( pLoop->wsFlags ){ + pLoop->nOut = (LogEst)1; + pWInfo->a[0].pWLoop = pLoop; + assert( pWInfo->sMaskSet.n==1 && iCur==pWInfo->sMaskSet.ix[0] ); + pLoop->maskSelf = 1; /* sqlite3WhereGetMask(&pWInfo->sMaskSet, iCur); */ + pWInfo->a[0].iTabCur = iCur; + pWInfo->nRowOut = 1; + if( pWInfo->pOrderBy ) pWInfo->nOBSat = pWInfo->pOrderBy->nExpr; + if( pWInfo->wctrlFlags & WHERE_WANT_DISTINCT ){ + pWInfo->eDistinct = WHERE_DISTINCT_UNIQUE; + } + if( scan.iEquiv>1 ) pLoop->wsFlags |= WHERE_TRANSCONS; +#ifdef SQLITE_DEBUG + pLoop->cId = '0'; +#endif +#ifdef WHERETRACE_ENABLED + if( sqlite3WhereTrace & 0x02 ){ + sqlite3DebugPrintf("whereShortCut() used to compute solution\n"); + } +#endif + return 1; + } + return 0; +} + +/* +** Helper function for exprIsDeterministic(). +*/ +static int exprNodeIsDeterministic(Walker *pWalker, Expr *pExpr){ + if( pExpr->op==TK_FUNCTION && ExprHasProperty(pExpr, EP_ConstFunc)==0 ){ + pWalker->eCode = 0; + return WRC_Abort; + } + return WRC_Continue; +} + +/* +** Return true if the expression contains no non-deterministic SQL +** functions. Do not consider non-deterministic SQL functions that are +** part of sub-select statements. +*/ +static int exprIsDeterministic(Expr *p){ + Walker w; + memset(&w, 0, sizeof(w)); + w.eCode = 1; + w.xExprCallback = exprNodeIsDeterministic; + w.xSelectCallback = sqlite3SelectWalkFail; + sqlite3WalkExpr(&w, p); + return w.eCode; +} + + +#ifdef WHERETRACE_ENABLED +/* +** Display all WhereLoops in pWInfo +*/ +static void showAllWhereLoops(WhereInfo *pWInfo, WhereClause *pWC){ + if( sqlite3WhereTrace ){ /* Display all of the WhereLoop objects */ + WhereLoop *p; + int i; + static const char zLabel[] = "0123456789abcdefghijklmnopqrstuvwyxz" + "ABCDEFGHIJKLMNOPQRSTUVWYXZ"; + for(p=pWInfo->pLoops, i=0; p; p=p->pNextLoop, i++){ + p->cId = zLabel[i%(sizeof(zLabel)-1)]; + sqlite3WhereLoopPrint(p, pWC); + } + } +} +# define WHERETRACE_ALL_LOOPS(W,C) showAllWhereLoops(W,C) +#else +# define WHERETRACE_ALL_LOOPS(W,C) +#endif + +/* Attempt to omit tables from a join that do not affect the result. +** For a table to not affect the result, the following must be true: +** +** 1) The query must not be an aggregate. +** 2) The table must be the RHS of a LEFT JOIN. +** 3) Either the query must be DISTINCT, or else the ON or USING clause +** must contain a constraint that limits the scan of the table to +** at most a single row. +** 4) The table must not be referenced by any part of the query apart +** from its own USING or ON clause. +** 5) The table must not have an inner-join ON or USING clause if there is +** a RIGHT JOIN anywhere in the query. Otherwise the ON/USING clause +** might move from the right side to the left side of the RIGHT JOIN. +** Note: Due to (2), this condition can only arise if the table is +** the right-most table of a subquery that was flattened into the +** main query and that subquery was the right-hand operand of an +** inner join that held an ON or USING clause. +** +** For example, given: +** +** CREATE TABLE t1(ipk INTEGER PRIMARY KEY, v1); +** CREATE TABLE t2(ipk INTEGER PRIMARY KEY, v2); +** CREATE TABLE t3(ipk INTEGER PRIMARY KEY, v3); +** +** then table t2 can be omitted from the following: +** +** SELECT v1, v3 FROM t1 +** LEFT JOIN t2 ON (t1.ipk=t2.ipk) +** LEFT JOIN t3 ON (t1.ipk=t3.ipk) +** +** or from: +** +** SELECT DISTINCT v1, v3 FROM t1 +** LEFT JOIN t2 +** LEFT JOIN t3 ON (t1.ipk=t3.ipk) +*/ +static SQLITE_NOINLINE Bitmask whereOmitNoopJoin( + WhereInfo *pWInfo, + Bitmask notReady +){ + int i; + Bitmask tabUsed; + int hasRightJoin; + + /* Preconditions checked by the caller */ + assert( pWInfo->nLevel>=2 ); + assert( OptimizationEnabled(pWInfo->pParse->db, SQLITE_OmitNoopJoin) ); + + /* These two preconditions checked by the caller combine to guarantee + ** condition (1) of the header comment */ + assert( pWInfo->pResultSet!=0 ); + assert( 0==(pWInfo->wctrlFlags & WHERE_AGG_DISTINCT) ); + + tabUsed = sqlite3WhereExprListUsage(&pWInfo->sMaskSet, pWInfo->pResultSet); + if( pWInfo->pOrderBy ){ + tabUsed |= sqlite3WhereExprListUsage(&pWInfo->sMaskSet, pWInfo->pOrderBy); + } + hasRightJoin = (pWInfo->pTabList->a[0].fg.jointype & JT_LTORJ)!=0; + for(i=pWInfo->nLevel-1; i>=1; i--){ + WhereTerm *pTerm, *pEnd; + SrcItem *pItem; + WhereLoop *pLoop; + pLoop = pWInfo->a[i].pWLoop; + pItem = &pWInfo->pTabList->a[pLoop->iTab]; + if( (pItem->fg.jointype & (JT_LEFT|JT_RIGHT))!=JT_LEFT ) continue; + if( (pWInfo->wctrlFlags & WHERE_WANT_DISTINCT)==0 + && (pLoop->wsFlags & WHERE_ONEROW)==0 + ){ + continue; + } + if( (tabUsed & pLoop->maskSelf)!=0 ) continue; + pEnd = pWInfo->sWC.a + pWInfo->sWC.nTerm; + for(pTerm=pWInfo->sWC.a; pTerm<pEnd; pTerm++){ + if( (pTerm->prereqAll & pLoop->maskSelf)!=0 ){ + if( !ExprHasProperty(pTerm->pExpr, EP_OuterON) + || pTerm->pExpr->w.iJoin!=pItem->iCursor + ){ + break; + } + } + if( hasRightJoin + && ExprHasProperty(pTerm->pExpr, EP_InnerON) + && pTerm->pExpr->w.iJoin==pItem->iCursor + ){ + break; /* restriction (5) */ + } + } + if( pTerm<pEnd ) continue; + WHERETRACE(0xffffffff, ("-> drop loop %c not used\n", pLoop->cId)); + notReady &= ~pLoop->maskSelf; + for(pTerm=pWInfo->sWC.a; pTerm<pEnd; pTerm++){ + if( (pTerm->prereqAll & pLoop->maskSelf)!=0 ){ + pTerm->wtFlags |= TERM_CODED; + } + } + if( i!=pWInfo->nLevel-1 ){ + int nByte = (pWInfo->nLevel-1-i) * sizeof(WhereLevel); + memmove(&pWInfo->a[i], &pWInfo->a[i+1], nByte); + } + pWInfo->nLevel--; + assert( pWInfo->nLevel>0 ); + } + return notReady; +} + +/* +** Check to see if there are any SEARCH loops that might benefit from +** using a Bloom filter. Consider a Bloom filter if: +** +** (1) The SEARCH happens more than N times where N is the number +** of rows in the table that is being considered for the Bloom +** filter. +** (2) Some searches are expected to find zero rows. (This is determined +** by the WHERE_SELFCULL flag on the term.) +** (3) Bloom-filter processing is not disabled. (Checked by the +** caller.) +** (4) The size of the table being searched is known by ANALYZE. +** +** This block of code merely checks to see if a Bloom filter would be +** appropriate, and if so sets the WHERE_BLOOMFILTER flag on the +** WhereLoop. The implementation of the Bloom filter comes further +** down where the code for each WhereLoop is generated. +*/ +static SQLITE_NOINLINE void whereCheckIfBloomFilterIsUseful( + const WhereInfo *pWInfo +){ + int i; + LogEst nSearch = 0; + + assert( pWInfo->nLevel>=2 ); + assert( OptimizationEnabled(pWInfo->pParse->db, SQLITE_BloomFilter) ); + for(i=0; i<pWInfo->nLevel; i++){ + WhereLoop *pLoop = pWInfo->a[i].pWLoop; + const unsigned int reqFlags = (WHERE_SELFCULL|WHERE_COLUMN_EQ); + SrcItem *pItem = &pWInfo->pTabList->a[pLoop->iTab]; + Table *pTab = pItem->pTab; + if( (pTab->tabFlags & TF_HasStat1)==0 ) break; + pTab->tabFlags |= TF_StatsUsed; + if( i>=1 + && (pLoop->wsFlags & reqFlags)==reqFlags + /* vvvvvv--- Always the case if WHERE_COLUMN_EQ is defined */ + && ALWAYS((pLoop->wsFlags & (WHERE_IPK|WHERE_INDEXED))!=0) + ){ + if( nSearch > pTab->nRowLogEst ){ + testcase( pItem->fg.jointype & JT_LEFT ); + pLoop->wsFlags |= WHERE_BLOOMFILTER; + pLoop->wsFlags &= ~WHERE_IDX_ONLY; + WHERETRACE(0xffffffff, ( + "-> use Bloom-filter on loop %c because there are ~%.1e " + "lookups into %s which has only ~%.1e rows\n", + pLoop->cId, (double)sqlite3LogEstToInt(nSearch), pTab->zName, + (double)sqlite3LogEstToInt(pTab->nRowLogEst))); + } + } + nSearch += pLoop->nOut; + } +} + +/* +** The index pIdx is used by a query and contains one or more expressions. +** In other words pIdx is an index on an expression. iIdxCur is the cursor +** number for the index and iDataCur is the cursor number for the corresponding +** table. +** +** This routine adds IndexedExpr entries to the Parse->pIdxEpr field for +** each of the expressions in the index so that the expression code generator +** will know to replace occurrences of the indexed expression with +** references to the corresponding column of the index. +*/ +static SQLITE_NOINLINE void whereAddIndexedExpr( + Parse *pParse, /* Add IndexedExpr entries to pParse->pIdxEpr */ + Index *pIdx, /* The index-on-expression that contains the expressions */ + int iIdxCur, /* Cursor number for pIdx */ + SrcItem *pTabItem /* The FROM clause entry for the table */ +){ + int i; + IndexedExpr *p; + Table *pTab; + assert( pIdx->bHasExpr ); + pTab = pIdx->pTable; + for(i=0; i<pIdx->nColumn; i++){ + Expr *pExpr; + int j = pIdx->aiColumn[i]; + int bMaybeNullRow; + if( j==XN_EXPR ){ + pExpr = pIdx->aColExpr->a[i].pExpr; + testcase( pTabItem->fg.jointype & JT_LEFT ); + testcase( pTabItem->fg.jointype & JT_RIGHT ); + testcase( pTabItem->fg.jointype & JT_LTORJ ); + bMaybeNullRow = (pTabItem->fg.jointype & (JT_LEFT|JT_LTORJ|JT_RIGHT))!=0; + }else if( j>=0 && (pTab->aCol[j].colFlags & COLFLAG_VIRTUAL)!=0 ){ + pExpr = sqlite3ColumnExpr(pTab, &pTab->aCol[j]); + bMaybeNullRow = 0; + }else{ + continue; + } + if( sqlite3ExprIsConstant(pExpr) ) continue; + if( pExpr->op==TK_FUNCTION ){ + /* Functions that might set a subtype should not be replaced by the + ** value taken from an expression index since the index omits the + ** subtype. https://sqlite.org/forum/forumpost/68d284c86b082c3e */ + int n; + FuncDef *pDef; + sqlite3 *db = pParse->db; + assert( ExprUseXList(pExpr) ); + n = pExpr->x.pList ? pExpr->x.pList->nExpr : 0; + pDef = sqlite3FindFunction(db, pExpr->u.zToken, n, ENC(db), 0); + if( pDef==0 || (pDef->funcFlags & SQLITE_RESULT_SUBTYPE)!=0 ){ + continue; + } + } + p = sqlite3DbMallocRaw(pParse->db, sizeof(IndexedExpr)); + if( p==0 ) break; + p->pIENext = pParse->pIdxEpr; +#ifdef WHERETRACE_ENABLED + if( sqlite3WhereTrace & 0x200 ){ + sqlite3DebugPrintf("New pParse->pIdxEpr term {%d,%d}\n", iIdxCur, i); + if( sqlite3WhereTrace & 0x5000 ) sqlite3ShowExpr(pExpr); + } +#endif + p->pExpr = sqlite3ExprDup(pParse->db, pExpr, 0); + p->iDataCur = pTabItem->iCursor; + p->iIdxCur = iIdxCur; + p->iIdxCol = i; + p->bMaybeNullRow = bMaybeNullRow; + if( sqlite3IndexAffinityStr(pParse->db, pIdx) ){ + p->aff = pIdx->zColAff[i]; + } +#ifdef SQLITE_ENABLE_EXPLAIN_COMMENTS + p->zIdxName = pIdx->zName; +#endif + pParse->pIdxEpr = p; + if( p->pIENext==0 ){ + void *pArg = (void*)&pParse->pIdxEpr; + sqlite3ParserAddCleanup(pParse, whereIndexedExprCleanup, pArg); + } + } +} + +/* +** Set the reverse-scan order mask to one for all tables in the query +** with the exception of MATERIALIZED common table expressions that have +** their own internal ORDER BY clauses. +** +** This implements the PRAGMA reverse_unordered_selects=ON setting. +** (Also SQLITE_DBCONFIG_REVERSE_SCANORDER). +*/ +static SQLITE_NOINLINE void whereReverseScanOrder(WhereInfo *pWInfo){ + int ii; + for(ii=0; ii<pWInfo->pTabList->nSrc; ii++){ + SrcItem *pItem = &pWInfo->pTabList->a[ii]; + if( !pItem->fg.isCte + || pItem->u2.pCteUse->eM10d!=M10d_Yes + || NEVER(pItem->pSelect==0) + || pItem->pSelect->pOrderBy==0 + ){ + pWInfo->revMask |= MASKBIT(ii); + } + } +} + +/* +** Generate the beginning of the loop used for WHERE clause processing. +** The return value is a pointer to an opaque structure that contains +** information needed to terminate the loop. Later, the calling routine +** should invoke sqlite3WhereEnd() with the return value of this function +** in order to complete the WHERE clause processing. +** +** If an error occurs, this routine returns NULL. +** +** The basic idea is to do a nested loop, one loop for each table in +** the FROM clause of a select. (INSERT and UPDATE statements are the +** same as a SELECT with only a single table in the FROM clause.) For +** example, if the SQL is this: +** +** SELECT * FROM t1, t2, t3 WHERE ...; +** +** Then the code generated is conceptually like the following: +** +** foreach row1 in t1 do \ Code generated +** foreach row2 in t2 do |-- by sqlite3WhereBegin() +** foreach row3 in t3 do / +** ... +** end \ Code generated +** end |-- by sqlite3WhereEnd() +** end / +** +** Note that the loops might not be nested in the order in which they +** appear in the FROM clause if a different order is better able to make +** use of indices. Note also that when the IN operator appears in +** the WHERE clause, it might result in additional nested loops for +** scanning through all values on the right-hand side of the IN. +** +** There are Btree cursors associated with each table. t1 uses cursor +** number pTabList->a[0].iCursor. t2 uses the cursor pTabList->a[1].iCursor. +** And so forth. This routine generates code to open those VDBE cursors +** and sqlite3WhereEnd() generates the code to close them. +** +** The code that sqlite3WhereBegin() generates leaves the cursors named +** in pTabList pointing at their appropriate entries. The [...] code +** can use OP_Column and OP_Rowid opcodes on these cursors to extract +** data from the various tables of the loop. +** +** If the WHERE clause is empty, the foreach loops must each scan their +** entire tables. Thus a three-way join is an O(N^3) operation. But if +** the tables have indices and there are terms in the WHERE clause that +** refer to those indices, a complete table scan can be avoided and the +** code will run much faster. Most of the work of this routine is checking +** to see if there are indices that can be used to speed up the loop. +** +** Terms of the WHERE clause are also used to limit which rows actually +** make it to the "..." in the middle of the loop. After each "foreach", +** terms of the WHERE clause that use only terms in that loop and outer +** loops are evaluated and if false a jump is made around all subsequent +** inner loops (or around the "..." if the test occurs within the inner- +** most loop) +** +** OUTER JOINS +** +** An outer join of tables t1 and t2 is conceptually coded as follows: +** +** foreach row1 in t1 do +** flag = 0 +** foreach row2 in t2 do +** start: +** ... +** flag = 1 +** end +** if flag==0 then +** move the row2 cursor to a null row +** goto start +** fi +** end +** +** ORDER BY CLAUSE PROCESSING +** +** pOrderBy is a pointer to the ORDER BY clause (or the GROUP BY clause +** if the WHERE_GROUPBY flag is set in wctrlFlags) of a SELECT statement +** if there is one. If there is no ORDER BY clause or if this routine +** is called from an UPDATE or DELETE statement, then pOrderBy is NULL. +** +** The iIdxCur parameter is the cursor number of an index. If +** WHERE_OR_SUBCLAUSE is set, iIdxCur is the cursor number of an index +** to use for OR clause processing. The WHERE clause should use this +** specific cursor. If WHERE_ONEPASS_DESIRED is set, then iIdxCur is +** the first cursor in an array of cursors for all indices. iIdxCur should +** be used to compute the appropriate cursor depending on which index is +** used. +*/ +WhereInfo *sqlite3WhereBegin( + Parse *pParse, /* The parser context */ + SrcList *pTabList, /* FROM clause: A list of all tables to be scanned */ + Expr *pWhere, /* The WHERE clause */ + ExprList *pOrderBy, /* An ORDER BY (or GROUP BY) clause, or NULL */ + ExprList *pResultSet, /* Query result set. Req'd for DISTINCT */ + Select *pSelect, /* The entire SELECT statement */ + u16 wctrlFlags, /* The WHERE_* flags defined in sqliteInt.h */ + int iAuxArg /* If WHERE_OR_SUBCLAUSE is set, index cursor number + ** If WHERE_USE_LIMIT, then the limit amount */ +){ + int nByteWInfo; /* Num. bytes allocated for WhereInfo struct */ + int nTabList; /* Number of elements in pTabList */ + WhereInfo *pWInfo; /* Will become the return value of this function */ + Vdbe *v = pParse->pVdbe; /* The virtual database engine */ + Bitmask notReady; /* Cursors that are not yet positioned */ + WhereLoopBuilder sWLB; /* The WhereLoop builder */ + WhereMaskSet *pMaskSet; /* The expression mask set */ + WhereLevel *pLevel; /* A single level in pWInfo->a[] */ + WhereLoop *pLoop; /* Pointer to a single WhereLoop object */ + int ii; /* Loop counter */ + sqlite3 *db; /* Database connection */ + int rc; /* Return code */ + u8 bFordelete = 0; /* OPFLAG_FORDELETE or zero, as appropriate */ + + assert( (wctrlFlags & WHERE_ONEPASS_MULTIROW)==0 || ( + (wctrlFlags & WHERE_ONEPASS_DESIRED)!=0 + && (wctrlFlags & WHERE_OR_SUBCLAUSE)==0 + )); + + /* Only one of WHERE_OR_SUBCLAUSE or WHERE_USE_LIMIT */ + assert( (wctrlFlags & WHERE_OR_SUBCLAUSE)==0 + || (wctrlFlags & WHERE_USE_LIMIT)==0 ); + + /* Variable initialization */ + db = pParse->db; + memset(&sWLB, 0, sizeof(sWLB)); + + /* An ORDER/GROUP BY clause of more than 63 terms cannot be optimized */ + testcase( pOrderBy && pOrderBy->nExpr==BMS-1 ); + if( pOrderBy && pOrderBy->nExpr>=BMS ){ + pOrderBy = 0; + wctrlFlags &= ~WHERE_WANT_DISTINCT; + } + + /* The number of tables in the FROM clause is limited by the number of + ** bits in a Bitmask + */ + testcase( pTabList->nSrc==BMS ); + if( pTabList->nSrc>BMS ){ + sqlite3ErrorMsg(pParse, "at most %d tables in a join", BMS); + return 0; + } + + /* This function normally generates a nested loop for all tables in + ** pTabList. But if the WHERE_OR_SUBCLAUSE flag is set, then we should + ** only generate code for the first table in pTabList and assume that + ** any cursors associated with subsequent tables are uninitialized. + */ + nTabList = (wctrlFlags & WHERE_OR_SUBCLAUSE) ? 1 : pTabList->nSrc; + + /* Allocate and initialize the WhereInfo structure that will become the + ** return value. A single allocation is used to store the WhereInfo + ** struct, the contents of WhereInfo.a[], the WhereClause structure + ** and the WhereMaskSet structure. Since WhereClause contains an 8-byte + ** field (type Bitmask) it must be aligned on an 8-byte boundary on + ** some architectures. Hence the ROUND8() below. + */ + nByteWInfo = ROUND8P(sizeof(WhereInfo)); + if( nTabList>1 ){ + nByteWInfo = ROUND8P(nByteWInfo + (nTabList-1)*sizeof(WhereLevel)); + } + pWInfo = sqlite3DbMallocRawNN(db, nByteWInfo + sizeof(WhereLoop)); + if( db->mallocFailed ){ + sqlite3DbFree(db, pWInfo); + pWInfo = 0; + goto whereBeginError; + } + pWInfo->pParse = pParse; + pWInfo->pTabList = pTabList; + pWInfo->pOrderBy = pOrderBy; +#if WHERETRACE_ENABLED + pWInfo->pWhere = pWhere; +#endif + pWInfo->pResultSet = pResultSet; + pWInfo->aiCurOnePass[0] = pWInfo->aiCurOnePass[1] = -1; + pWInfo->nLevel = nTabList; + pWInfo->iBreak = pWInfo->iContinue = sqlite3VdbeMakeLabel(pParse); + pWInfo->wctrlFlags = wctrlFlags; + pWInfo->iLimit = iAuxArg; + pWInfo->savedNQueryLoop = pParse->nQueryLoop; + pWInfo->pSelect = pSelect; + memset(&pWInfo->nOBSat, 0, + offsetof(WhereInfo,sWC) - offsetof(WhereInfo,nOBSat)); + memset(&pWInfo->a[0], 0, sizeof(WhereLoop)+nTabList*sizeof(WhereLevel)); + assert( pWInfo->eOnePass==ONEPASS_OFF ); /* ONEPASS defaults to OFF */ + pMaskSet = &pWInfo->sMaskSet; + pMaskSet->n = 0; + pMaskSet->ix[0] = -99; /* Initialize ix[0] to a value that can never be + ** a valid cursor number, to avoid an initial + ** test for pMaskSet->n==0 in sqlite3WhereGetMask() */ + sWLB.pWInfo = pWInfo; + sWLB.pWC = &pWInfo->sWC; + sWLB.pNew = (WhereLoop*)(((char*)pWInfo)+nByteWInfo); + assert( EIGHT_BYTE_ALIGNMENT(sWLB.pNew) ); + whereLoopInit(sWLB.pNew); +#ifdef SQLITE_DEBUG + sWLB.pNew->cId = '*'; +#endif + + /* Split the WHERE clause into separate subexpressions where each + ** subexpression is separated by an AND operator. + */ + sqlite3WhereClauseInit(&pWInfo->sWC, pWInfo); + sqlite3WhereSplit(&pWInfo->sWC, pWhere, TK_AND); + + /* Special case: No FROM clause + */ + if( nTabList==0 ){ + if( pOrderBy ) pWInfo->nOBSat = pOrderBy->nExpr; + if( (wctrlFlags & WHERE_WANT_DISTINCT)!=0 + && OptimizationEnabled(db, SQLITE_DistinctOpt) + ){ + pWInfo->eDistinct = WHERE_DISTINCT_UNIQUE; + } + ExplainQueryPlan((pParse, 0, "SCAN CONSTANT ROW")); + }else{ + /* Assign a bit from the bitmask to every term in the FROM clause. + ** + ** The N-th term of the FROM clause is assigned a bitmask of 1<<N. + ** + ** The rule of the previous sentence ensures that if X is the bitmask for + ** a table T, then X-1 is the bitmask for all other tables to the left of T. + ** Knowing the bitmask for all tables to the left of a left join is + ** important. Ticket #3015. + ** + ** Note that bitmasks are created for all pTabList->nSrc tables in + ** pTabList, not just the first nTabList tables. nTabList is normally + ** equal to pTabList->nSrc but might be shortened to 1 if the + ** WHERE_OR_SUBCLAUSE flag is set. + */ + ii = 0; + do{ + createMask(pMaskSet, pTabList->a[ii].iCursor); + sqlite3WhereTabFuncArgs(pParse, &pTabList->a[ii], &pWInfo->sWC); + }while( (++ii)<pTabList->nSrc ); + #ifdef SQLITE_DEBUG + { + Bitmask mx = 0; + for(ii=0; ii<pTabList->nSrc; ii++){ + Bitmask m = sqlite3WhereGetMask(pMaskSet, pTabList->a[ii].iCursor); + assert( m>=mx ); + mx = m; + } + } + #endif + } + + /* Analyze all of the subexpressions. */ + sqlite3WhereExprAnalyze(pTabList, &pWInfo->sWC); + if( pSelect && pSelect->pLimit ){ + sqlite3WhereAddLimit(&pWInfo->sWC, pSelect); + } + if( pParse->nErr ) goto whereBeginError; + + /* The False-WHERE-Term-Bypass optimization: + ** + ** If there are WHERE terms that are false, then no rows will be output, + ** so skip over all of the code generated here. + ** + ** Conditions: + ** + ** (1) The WHERE term must not refer to any tables in the join. + ** (2) The term must not come from an ON clause on the + ** right-hand side of a LEFT or FULL JOIN. + ** (3) The term must not come from an ON clause, or there must be + ** no RIGHT or FULL OUTER joins in pTabList. + ** (4) If the expression contains non-deterministic functions + ** that are not within a sub-select. This is not required + ** for correctness but rather to preserves SQLite's legacy + ** behaviour in the following two cases: + ** + ** WHERE random()>0; -- eval random() once per row + ** WHERE (SELECT random())>0; -- eval random() just once overall + ** + ** Note that the Where term need not be a constant in order for this + ** optimization to apply, though it does need to be constant relative to + ** the current subquery (condition 1). The term might include variables + ** from outer queries so that the value of the term changes from one + ** invocation of the current subquery to the next. + */ + for(ii=0; ii<sWLB.pWC->nBase; ii++){ + WhereTerm *pT = &sWLB.pWC->a[ii]; /* A term of the WHERE clause */ + Expr *pX; /* The expression of pT */ + if( pT->wtFlags & TERM_VIRTUAL ) continue; + pX = pT->pExpr; + assert( pX!=0 ); + assert( pT->prereqAll!=0 || !ExprHasProperty(pX, EP_OuterON) ); + if( pT->prereqAll==0 /* Conditions (1) and (2) */ + && (nTabList==0 || exprIsDeterministic(pX)) /* Condition (4) */ + && !(ExprHasProperty(pX, EP_InnerON) /* Condition (3) */ + && (pTabList->a[0].fg.jointype & JT_LTORJ)!=0 ) + ){ + sqlite3ExprIfFalse(pParse, pX, pWInfo->iBreak, SQLITE_JUMPIFNULL); + pT->wtFlags |= TERM_CODED; + } + } + + if( wctrlFlags & WHERE_WANT_DISTINCT ){ + if( OptimizationDisabled(db, SQLITE_DistinctOpt) ){ + /* Disable the DISTINCT optimization if SQLITE_DistinctOpt is set via + ** sqlite3_test_ctrl(SQLITE_TESTCTRL_OPTIMIZATIONS,...) */ + wctrlFlags &= ~WHERE_WANT_DISTINCT; + pWInfo->wctrlFlags &= ~WHERE_WANT_DISTINCT; + }else if( isDistinctRedundant(pParse, pTabList, &pWInfo->sWC, pResultSet) ){ + /* The DISTINCT marking is pointless. Ignore it. */ + pWInfo->eDistinct = WHERE_DISTINCT_UNIQUE; + }else if( pOrderBy==0 ){ + /* Try to ORDER BY the result set to make distinct processing easier */ + pWInfo->wctrlFlags |= WHERE_DISTINCTBY; + pWInfo->pOrderBy = pResultSet; + } + } + + /* Construct the WhereLoop objects */ +#if defined(WHERETRACE_ENABLED) + if( sqlite3WhereTrace & 0xffffffff ){ + sqlite3DebugPrintf("*** Optimizer Start *** (wctrlFlags: 0x%x",wctrlFlags); + if( wctrlFlags & WHERE_USE_LIMIT ){ + sqlite3DebugPrintf(", limit: %d", iAuxArg); + } + sqlite3DebugPrintf(")\n"); + if( sqlite3WhereTrace & 0x8000 ){ + Select sSelect; + memset(&sSelect, 0, sizeof(sSelect)); + sSelect.selFlags = SF_WhereBegin; + sSelect.pSrc = pTabList; + sSelect.pWhere = pWhere; + sSelect.pOrderBy = pOrderBy; + sSelect.pEList = pResultSet; + sqlite3TreeViewSelect(0, &sSelect, 0); + } + if( sqlite3WhereTrace & 0x4000 ){ /* Display all WHERE clause terms */ + sqlite3DebugPrintf("---- WHERE clause at start of analysis:\n"); + sqlite3WhereClausePrint(sWLB.pWC); + } + } +#endif + + if( nTabList!=1 || whereShortCut(&sWLB)==0 ){ + rc = whereLoopAddAll(&sWLB); + if( rc ) goto whereBeginError; + +#ifdef SQLITE_ENABLE_STAT4 + /* If one or more WhereTerm.truthProb values were used in estimating + ** loop parameters, but then those truthProb values were subsequently + ** changed based on STAT4 information while computing subsequent loops, + ** then we need to rerun the whole loop building process so that all + ** loops will be built using the revised truthProb values. */ + if( sWLB.bldFlags2 & SQLITE_BLDF2_2NDPASS ){ + WHERETRACE_ALL_LOOPS(pWInfo, sWLB.pWC); + WHERETRACE(0xffffffff, + ("**** Redo all loop computations due to" + " TERM_HIGHTRUTH changes ****\n")); + while( pWInfo->pLoops ){ + WhereLoop *p = pWInfo->pLoops; + pWInfo->pLoops = p->pNextLoop; + whereLoopDelete(db, p); + } + rc = whereLoopAddAll(&sWLB); + if( rc ) goto whereBeginError; + } +#endif + WHERETRACE_ALL_LOOPS(pWInfo, sWLB.pWC); + + wherePathSolver(pWInfo, 0); + if( db->mallocFailed ) goto whereBeginError; + if( pWInfo->pOrderBy ){ + wherePathSolver(pWInfo, pWInfo->nRowOut+1); + if( db->mallocFailed ) goto whereBeginError; + } + + /* TUNING: Assume that a DISTINCT clause on a subquery reduces + ** the output size by a factor of 8 (LogEst -30). + */ + if( (pWInfo->wctrlFlags & WHERE_WANT_DISTINCT)!=0 ){ + WHERETRACE(0x0080,("nRowOut reduced from %d to %d due to DISTINCT\n", + pWInfo->nRowOut, pWInfo->nRowOut-30)); + pWInfo->nRowOut -= 30; + } + + } + assert( pWInfo->pTabList!=0 ); + if( pWInfo->pOrderBy==0 && (db->flags & SQLITE_ReverseOrder)!=0 ){ + whereReverseScanOrder(pWInfo); + } + if( pParse->nErr ){ + goto whereBeginError; + } + assert( db->mallocFailed==0 ); +#ifdef WHERETRACE_ENABLED + if( sqlite3WhereTrace ){ + sqlite3DebugPrintf("---- Solution nRow=%d", pWInfo->nRowOut); + if( pWInfo->nOBSat>0 ){ + sqlite3DebugPrintf(" ORDERBY=%d,0x%llx", pWInfo->nOBSat, pWInfo->revMask); + } + switch( pWInfo->eDistinct ){ + case WHERE_DISTINCT_UNIQUE: { + sqlite3DebugPrintf(" DISTINCT=unique"); + break; + } + case WHERE_DISTINCT_ORDERED: { + sqlite3DebugPrintf(" DISTINCT=ordered"); + break; + } + case WHERE_DISTINCT_UNORDERED: { + sqlite3DebugPrintf(" DISTINCT=unordered"); + break; + } + } + sqlite3DebugPrintf("\n"); + for(ii=0; ii<pWInfo->nLevel; ii++){ + sqlite3WhereLoopPrint(pWInfo->a[ii].pWLoop, sWLB.pWC); + } + } +#endif + + /* Attempt to omit tables from a join that do not affect the result. + ** See the comment on whereOmitNoopJoin() for further information. + ** + ** This query optimization is factored out into a separate "no-inline" + ** procedure to keep the sqlite3WhereBegin() procedure from becoming + ** too large. If sqlite3WhereBegin() becomes too large, that prevents + ** some C-compiler optimizers from in-lining the + ** sqlite3WhereCodeOneLoopStart() procedure, and it is important to + ** in-line sqlite3WhereCodeOneLoopStart() for performance reasons. + */ + notReady = ~(Bitmask)0; + if( pWInfo->nLevel>=2 + && pResultSet!=0 /* these two combine to guarantee */ + && 0==(wctrlFlags & WHERE_AGG_DISTINCT) /* condition (1) above */ + && OptimizationEnabled(db, SQLITE_OmitNoopJoin) + ){ + notReady = whereOmitNoopJoin(pWInfo, notReady); + nTabList = pWInfo->nLevel; + assert( nTabList>0 ); + } + + /* Check to see if there are any SEARCH loops that might benefit from + ** using a Bloom filter. + */ + if( pWInfo->nLevel>=2 + && OptimizationEnabled(db, SQLITE_BloomFilter) + ){ + whereCheckIfBloomFilterIsUseful(pWInfo); + } + +#if defined(WHERETRACE_ENABLED) + if( sqlite3WhereTrace & 0x4000 ){ /* Display all terms of the WHERE clause */ + sqlite3DebugPrintf("---- WHERE clause at end of analysis:\n"); + sqlite3WhereClausePrint(sWLB.pWC); + } + WHERETRACE(0xffffffff,("*** Optimizer Finished ***\n")); +#endif + pWInfo->pParse->nQueryLoop += pWInfo->nRowOut; + + /* If the caller is an UPDATE or DELETE statement that is requesting + ** to use a one-pass algorithm, determine if this is appropriate. + ** + ** A one-pass approach can be used if the caller has requested one + ** and either (a) the scan visits at most one row or (b) each + ** of the following are true: + ** + ** * the caller has indicated that a one-pass approach can be used + ** with multiple rows (by setting WHERE_ONEPASS_MULTIROW), and + ** * the table is not a virtual table, and + ** * either the scan does not use the OR optimization or the caller + ** is a DELETE operation (WHERE_DUPLICATES_OK is only specified + ** for DELETE). + ** + ** The last qualification is because an UPDATE statement uses + ** WhereInfo.aiCurOnePass[1] to determine whether or not it really can + ** use a one-pass approach, and this is not set accurately for scans + ** that use the OR optimization. + */ + assert( (wctrlFlags & WHERE_ONEPASS_DESIRED)==0 || pWInfo->nLevel==1 ); + if( (wctrlFlags & WHERE_ONEPASS_DESIRED)!=0 ){ + int wsFlags = pWInfo->a[0].pWLoop->wsFlags; + int bOnerow = (wsFlags & WHERE_ONEROW)!=0; + assert( !(wsFlags & WHERE_VIRTUALTABLE) || IsVirtual(pTabList->a[0].pTab) ); + if( bOnerow || ( + 0!=(wctrlFlags & WHERE_ONEPASS_MULTIROW) + && !IsVirtual(pTabList->a[0].pTab) + && (0==(wsFlags & WHERE_MULTI_OR) || (wctrlFlags & WHERE_DUPLICATES_OK)) + && OptimizationEnabled(db, SQLITE_OnePass) + )){ + pWInfo->eOnePass = bOnerow ? ONEPASS_SINGLE : ONEPASS_MULTI; + if( HasRowid(pTabList->a[0].pTab) && (wsFlags & WHERE_IDX_ONLY) ){ + if( wctrlFlags & WHERE_ONEPASS_MULTIROW ){ + bFordelete = OPFLAG_FORDELETE; + } + pWInfo->a[0].pWLoop->wsFlags = (wsFlags & ~WHERE_IDX_ONLY); + } + } + } + + /* Open all tables in the pTabList and any indices selected for + ** searching those tables. + */ + for(ii=0, pLevel=pWInfo->a; ii<nTabList; ii++, pLevel++){ + Table *pTab; /* Table to open */ + int iDb; /* Index of database containing table/index */ + SrcItem *pTabItem; + + pTabItem = &pTabList->a[pLevel->iFrom]; + pTab = pTabItem->pTab; + iDb = sqlite3SchemaToIndex(db, pTab->pSchema); + pLoop = pLevel->pWLoop; + if( (pTab->tabFlags & TF_Ephemeral)!=0 || IsView(pTab) ){ + /* Do nothing */ + }else +#ifndef SQLITE_OMIT_VIRTUALTABLE + if( (pLoop->wsFlags & WHERE_VIRTUALTABLE)!=0 ){ + const char *pVTab = (const char *)sqlite3GetVTable(db, pTab); + int iCur = pTabItem->iCursor; + sqlite3VdbeAddOp4(v, OP_VOpen, iCur, 0, 0, pVTab, P4_VTAB); + }else if( IsVirtual(pTab) ){ + /* noop */ + }else +#endif + if( ((pLoop->wsFlags & WHERE_IDX_ONLY)==0 + && (wctrlFlags & WHERE_OR_SUBCLAUSE)==0) + || (pTabItem->fg.jointype & (JT_LTORJ|JT_RIGHT))!=0 + ){ + int op = OP_OpenRead; + if( pWInfo->eOnePass!=ONEPASS_OFF ){ + op = OP_OpenWrite; + pWInfo->aiCurOnePass[0] = pTabItem->iCursor; + }; + sqlite3OpenTable(pParse, pTabItem->iCursor, iDb, pTab, op); + assert( pTabItem->iCursor==pLevel->iTabCur ); + testcase( pWInfo->eOnePass==ONEPASS_OFF && pTab->nCol==BMS-1 ); + testcase( pWInfo->eOnePass==ONEPASS_OFF && pTab->nCol==BMS ); + if( pWInfo->eOnePass==ONEPASS_OFF + && pTab->nCol<BMS + && (pTab->tabFlags & (TF_HasGenerated|TF_WithoutRowid))==0 + && (pLoop->wsFlags & (WHERE_AUTO_INDEX|WHERE_BLOOMFILTER))==0 + ){ + /* If we know that only a prefix of the record will be used, + ** it is advantageous to reduce the "column count" field in + ** the P4 operand of the OP_OpenRead/Write opcode. */ + Bitmask b = pTabItem->colUsed; + int n = 0; + for(; b; b=b>>1, n++){} + sqlite3VdbeChangeP4(v, -1, SQLITE_INT_TO_PTR(n), P4_INT32); + assert( n<=pTab->nCol ); + } +#ifdef SQLITE_ENABLE_CURSOR_HINTS + if( pLoop->u.btree.pIndex!=0 && (pTab->tabFlags & TF_WithoutRowid)==0 ){ + sqlite3VdbeChangeP5(v, OPFLAG_SEEKEQ|bFordelete); + }else +#endif + { + sqlite3VdbeChangeP5(v, bFordelete); + } +#ifdef SQLITE_ENABLE_COLUMN_USED_MASK + sqlite3VdbeAddOp4Dup8(v, OP_ColumnsUsed, pTabItem->iCursor, 0, 0, + (const u8*)&pTabItem->colUsed, P4_INT64); +#endif + }else{ + sqlite3TableLock(pParse, iDb, pTab->tnum, 0, pTab->zName); + } + if( pLoop->wsFlags & WHERE_INDEXED ){ + Index *pIx = pLoop->u.btree.pIndex; + int iIndexCur; + int op = OP_OpenRead; + /* iAuxArg is always set to a positive value if ONEPASS is possible */ + assert( iAuxArg!=0 || (pWInfo->wctrlFlags & WHERE_ONEPASS_DESIRED)==0 ); + if( !HasRowid(pTab) && IsPrimaryKeyIndex(pIx) + && (wctrlFlags & WHERE_OR_SUBCLAUSE)!=0 + ){ + /* This is one term of an OR-optimization using the PRIMARY KEY of a + ** WITHOUT ROWID table. No need for a separate index */ + iIndexCur = pLevel->iTabCur; + op = 0; + }else if( pWInfo->eOnePass!=ONEPASS_OFF ){ + Index *pJ = pTabItem->pTab->pIndex; + iIndexCur = iAuxArg; + assert( wctrlFlags & WHERE_ONEPASS_DESIRED ); + while( ALWAYS(pJ) && pJ!=pIx ){ + iIndexCur++; + pJ = pJ->pNext; + } + op = OP_OpenWrite; + pWInfo->aiCurOnePass[1] = iIndexCur; + }else if( iAuxArg && (wctrlFlags & WHERE_OR_SUBCLAUSE)!=0 ){ + iIndexCur = iAuxArg; + op = OP_ReopenIdx; + }else{ + iIndexCur = pParse->nTab++; + if( pIx->bHasExpr && OptimizationEnabled(db, SQLITE_IndexedExpr) ){ + whereAddIndexedExpr(pParse, pIx, iIndexCur, pTabItem); + } + if( pIx->pPartIdxWhere && (pTabItem->fg.jointype & JT_RIGHT)==0 ){ + wherePartIdxExpr( + pParse, pIx, pIx->pPartIdxWhere, 0, iIndexCur, pTabItem + ); + } + } + pLevel->iIdxCur = iIndexCur; + assert( pIx!=0 ); + assert( pIx->pSchema==pTab->pSchema ); + assert( iIndexCur>=0 ); + if( op ){ + sqlite3VdbeAddOp3(v, op, iIndexCur, pIx->tnum, iDb); + sqlite3VdbeSetP4KeyInfo(pParse, pIx); + if( (pLoop->wsFlags & WHERE_CONSTRAINT)!=0 + && (pLoop->wsFlags & (WHERE_COLUMN_RANGE|WHERE_SKIPSCAN))==0 + && (pLoop->wsFlags & WHERE_BIGNULL_SORT)==0 + && (pLoop->wsFlags & WHERE_IN_SEEKSCAN)==0 + && (pWInfo->wctrlFlags&WHERE_ORDERBY_MIN)==0 + && pWInfo->eDistinct!=WHERE_DISTINCT_ORDERED + ){ + sqlite3VdbeChangeP5(v, OPFLAG_SEEKEQ); + } + VdbeComment((v, "%s", pIx->zName)); +#ifdef SQLITE_ENABLE_COLUMN_USED_MASK + { + u64 colUsed = 0; + int ii, jj; + for(ii=0; ii<pIx->nColumn; ii++){ + jj = pIx->aiColumn[ii]; + if( jj<0 ) continue; + if( jj>63 ) jj = 63; + if( (pTabItem->colUsed & MASKBIT(jj))==0 ) continue; + colUsed |= ((u64)1)<<(ii<63 ? ii : 63); + } + sqlite3VdbeAddOp4Dup8(v, OP_ColumnsUsed, iIndexCur, 0, 0, + (u8*)&colUsed, P4_INT64); + } +#endif /* SQLITE_ENABLE_COLUMN_USED_MASK */ + } + } + if( iDb>=0 ) sqlite3CodeVerifySchema(pParse, iDb); + if( (pTabItem->fg.jointype & JT_RIGHT)!=0 + && (pLevel->pRJ = sqlite3WhereMalloc(pWInfo, sizeof(WhereRightJoin)))!=0 + ){ + WhereRightJoin *pRJ = pLevel->pRJ; + pRJ->iMatch = pParse->nTab++; + pRJ->regBloom = ++pParse->nMem; + sqlite3VdbeAddOp2(v, OP_Blob, 65536, pRJ->regBloom); + pRJ->regReturn = ++pParse->nMem; + sqlite3VdbeAddOp2(v, OP_Null, 0, pRJ->regReturn); + assert( pTab==pTabItem->pTab ); + if( HasRowid(pTab) ){ + KeyInfo *pInfo; + sqlite3VdbeAddOp2(v, OP_OpenEphemeral, pRJ->iMatch, 1); + pInfo = sqlite3KeyInfoAlloc(pParse->db, 1, 0); + if( pInfo ){ + pInfo->aColl[0] = 0; + pInfo->aSortFlags[0] = 0; + sqlite3VdbeAppendP4(v, pInfo, P4_KEYINFO); + } + }else{ + Index *pPk = sqlite3PrimaryKeyIndex(pTab); + sqlite3VdbeAddOp2(v, OP_OpenEphemeral, pRJ->iMatch, pPk->nKeyCol); + sqlite3VdbeSetP4KeyInfo(pParse, pPk); + } + pLoop->wsFlags &= ~WHERE_IDX_ONLY; + /* The nature of RIGHT JOIN processing is such that it messes up + ** the output order. So omit any ORDER BY/GROUP BY elimination + ** optimizations. We need to do an actual sort for RIGHT JOIN. */ + pWInfo->nOBSat = 0; + pWInfo->eDistinct = WHERE_DISTINCT_UNORDERED; + } + } + pWInfo->iTop = sqlite3VdbeCurrentAddr(v); + if( db->mallocFailed ) goto whereBeginError; + + /* Generate the code to do the search. Each iteration of the for + ** loop below generates code for a single nested loop of the VM + ** program. + */ + for(ii=0; ii<nTabList; ii++){ + int addrExplain; + int wsFlags; + SrcItem *pSrc; + if( pParse->nErr ) goto whereBeginError; + pLevel = &pWInfo->a[ii]; + wsFlags = pLevel->pWLoop->wsFlags; + pSrc = &pTabList->a[pLevel->iFrom]; + if( pSrc->fg.isMaterialized ){ + if( pSrc->fg.isCorrelated ){ + sqlite3VdbeAddOp2(v, OP_Gosub, pSrc->regReturn, pSrc->addrFillSub); + }else{ + int iOnce = sqlite3VdbeAddOp0(v, OP_Once); VdbeCoverage(v); + sqlite3VdbeAddOp2(v, OP_Gosub, pSrc->regReturn, pSrc->addrFillSub); + sqlite3VdbeJumpHere(v, iOnce); + } + } + assert( pTabList == pWInfo->pTabList ); + if( (wsFlags & (WHERE_AUTO_INDEX|WHERE_BLOOMFILTER))!=0 ){ + if( (wsFlags & WHERE_AUTO_INDEX)!=0 ){ +#ifndef SQLITE_OMIT_AUTOMATIC_INDEX + constructAutomaticIndex(pParse, &pWInfo->sWC, notReady, pLevel); +#endif + }else{ + sqlite3ConstructBloomFilter(pWInfo, ii, pLevel, notReady); + } + if( db->mallocFailed ) goto whereBeginError; + } + addrExplain = sqlite3WhereExplainOneScan( + pParse, pTabList, pLevel, wctrlFlags + ); + pLevel->addrBody = sqlite3VdbeCurrentAddr(v); + notReady = sqlite3WhereCodeOneLoopStart(pParse,v,pWInfo,ii,pLevel,notReady); + pWInfo->iContinue = pLevel->addrCont; + if( (wsFlags&WHERE_MULTI_OR)==0 && (wctrlFlags&WHERE_OR_SUBCLAUSE)==0 ){ + sqlite3WhereAddScanStatus(v, pTabList, pLevel, addrExplain); + } + } + + /* Done. */ + VdbeModuleComment((v, "Begin WHERE-core")); + pWInfo->iEndWhere = sqlite3VdbeCurrentAddr(v); + return pWInfo; + + /* Jump here if malloc fails */ +whereBeginError: + if( pWInfo ){ + pParse->nQueryLoop = pWInfo->savedNQueryLoop; + whereInfoFree(db, pWInfo); + } +#ifdef WHERETRACE_ENABLED + /* Prevent harmless compiler warnings about debugging routines + ** being declared but never used */ + sqlite3ShowWhereLoopList(0); +#endif /* WHERETRACE_ENABLED */ + return 0; +} + +/* +** Part of sqlite3WhereEnd() will rewrite opcodes to reference the +** index rather than the main table. In SQLITE_DEBUG mode, we want +** to trace those changes if PRAGMA vdbe_addoptrace=on. This routine +** does that. +*/ +#ifndef SQLITE_DEBUG +# define OpcodeRewriteTrace(D,K,P) /* no-op */ +#else +# define OpcodeRewriteTrace(D,K,P) sqlite3WhereOpcodeRewriteTrace(D,K,P) + static void sqlite3WhereOpcodeRewriteTrace( + sqlite3 *db, + int pc, + VdbeOp *pOp + ){ + if( (db->flags & SQLITE_VdbeAddopTrace)==0 ) return; + sqlite3VdbePrintOp(0, pc, pOp); + } +#endif + +#ifdef SQLITE_DEBUG +/* +** Return true if cursor iCur is opened by instruction k of the +** bytecode. Used inside of assert() only. +*/ +static int cursorIsOpen(Vdbe *v, int iCur, int k){ + while( k>=0 ){ + VdbeOp *pOp = sqlite3VdbeGetOp(v,k--); + if( pOp->p1!=iCur ) continue; + if( pOp->opcode==OP_Close ) return 0; + if( pOp->opcode==OP_OpenRead ) return 1; + if( pOp->opcode==OP_OpenWrite ) return 1; + if( pOp->opcode==OP_OpenDup ) return 1; + if( pOp->opcode==OP_OpenAutoindex ) return 1; + if( pOp->opcode==OP_OpenEphemeral ) return 1; + } + return 0; +} +#endif /* SQLITE_DEBUG */ + +/* +** Generate the end of the WHERE loop. See comments on +** sqlite3WhereBegin() for additional information. +*/ +void sqlite3WhereEnd(WhereInfo *pWInfo){ + Parse *pParse = pWInfo->pParse; + Vdbe *v = pParse->pVdbe; + int i; + WhereLevel *pLevel; + WhereLoop *pLoop; + SrcList *pTabList = pWInfo->pTabList; + sqlite3 *db = pParse->db; + int iEnd = sqlite3VdbeCurrentAddr(v); + int nRJ = 0; + + /* Generate loop termination code. + */ + VdbeModuleComment((v, "End WHERE-core")); + for(i=pWInfo->nLevel-1; i>=0; i--){ + int addr; + pLevel = &pWInfo->a[i]; + if( pLevel->pRJ ){ + /* Terminate the subroutine that forms the interior of the loop of + ** the RIGHT JOIN table */ + WhereRightJoin *pRJ = pLevel->pRJ; + sqlite3VdbeResolveLabel(v, pLevel->addrCont); + pLevel->addrCont = 0; + pRJ->endSubrtn = sqlite3VdbeCurrentAddr(v); + sqlite3VdbeAddOp3(v, OP_Return, pRJ->regReturn, pRJ->addrSubrtn, 1); + VdbeCoverage(v); + nRJ++; + } + pLoop = pLevel->pWLoop; + if( pLevel->op!=OP_Noop ){ +#ifndef SQLITE_DISABLE_SKIPAHEAD_DISTINCT + int addrSeek = 0; + Index *pIdx; + int n; + if( pWInfo->eDistinct==WHERE_DISTINCT_ORDERED + && i==pWInfo->nLevel-1 /* Ticket [ef9318757b152e3] 2017-10-21 */ + && (pLoop->wsFlags & WHERE_INDEXED)!=0 + && (pIdx = pLoop->u.btree.pIndex)->hasStat1 + && (n = pLoop->u.btree.nDistinctCol)>0 + && pIdx->aiRowLogEst[n]>=36 + ){ + int r1 = pParse->nMem+1; + int j, op; + for(j=0; j<n; j++){ + sqlite3VdbeAddOp3(v, OP_Column, pLevel->iIdxCur, j, r1+j); + } + pParse->nMem += n+1; + op = pLevel->op==OP_Prev ? OP_SeekLT : OP_SeekGT; + addrSeek = sqlite3VdbeAddOp4Int(v, op, pLevel->iIdxCur, 0, r1, n); + VdbeCoverageIf(v, op==OP_SeekLT); + VdbeCoverageIf(v, op==OP_SeekGT); + sqlite3VdbeAddOp2(v, OP_Goto, 1, pLevel->p2); + } +#endif /* SQLITE_DISABLE_SKIPAHEAD_DISTINCT */ + /* The common case: Advance to the next row */ + if( pLevel->addrCont ) sqlite3VdbeResolveLabel(v, pLevel->addrCont); + sqlite3VdbeAddOp3(v, pLevel->op, pLevel->p1, pLevel->p2, pLevel->p3); + sqlite3VdbeChangeP5(v, pLevel->p5); + VdbeCoverage(v); + VdbeCoverageIf(v, pLevel->op==OP_Next); + VdbeCoverageIf(v, pLevel->op==OP_Prev); + VdbeCoverageIf(v, pLevel->op==OP_VNext); + if( pLevel->regBignull ){ + sqlite3VdbeResolveLabel(v, pLevel->addrBignull); + sqlite3VdbeAddOp2(v, OP_DecrJumpZero, pLevel->regBignull, pLevel->p2-1); + VdbeCoverage(v); + } +#ifndef SQLITE_DISABLE_SKIPAHEAD_DISTINCT + if( addrSeek ) sqlite3VdbeJumpHere(v, addrSeek); +#endif + }else if( pLevel->addrCont ){ + sqlite3VdbeResolveLabel(v, pLevel->addrCont); + } + if( (pLoop->wsFlags & WHERE_IN_ABLE)!=0 && pLevel->u.in.nIn>0 ){ + struct InLoop *pIn; + int j; + sqlite3VdbeResolveLabel(v, pLevel->addrNxt); + for(j=pLevel->u.in.nIn, pIn=&pLevel->u.in.aInLoop[j-1]; j>0; j--, pIn--){ + assert( sqlite3VdbeGetOp(v, pIn->addrInTop+1)->opcode==OP_IsNull + || pParse->db->mallocFailed ); + sqlite3VdbeJumpHere(v, pIn->addrInTop+1); + if( pIn->eEndLoopOp!=OP_Noop ){ + if( pIn->nPrefix ){ + int bEarlyOut = + (pLoop->wsFlags & WHERE_VIRTUALTABLE)==0 + && (pLoop->wsFlags & WHERE_IN_EARLYOUT)!=0; + if( pLevel->iLeftJoin ){ + /* For LEFT JOIN queries, cursor pIn->iCur may not have been + ** opened yet. This occurs for WHERE clauses such as + ** "a = ? AND b IN (...)", where the index is on (a, b). If + ** the RHS of the (a=?) is NULL, then the "b IN (...)" may + ** never have been coded, but the body of the loop run to + ** return the null-row. So, if the cursor is not open yet, + ** jump over the OP_Next or OP_Prev instruction about to + ** be coded. */ + sqlite3VdbeAddOp2(v, OP_IfNotOpen, pIn->iCur, + sqlite3VdbeCurrentAddr(v) + 2 + bEarlyOut); + VdbeCoverage(v); + } + if( bEarlyOut ){ + sqlite3VdbeAddOp4Int(v, OP_IfNoHope, pLevel->iIdxCur, + sqlite3VdbeCurrentAddr(v)+2, + pIn->iBase, pIn->nPrefix); + VdbeCoverage(v); + /* Retarget the OP_IsNull against the left operand of IN so + ** it jumps past the OP_IfNoHope. This is because the + ** OP_IsNull also bypasses the OP_Affinity opcode that is + ** required by OP_IfNoHope. */ + sqlite3VdbeJumpHere(v, pIn->addrInTop+1); + } + } + sqlite3VdbeAddOp2(v, pIn->eEndLoopOp, pIn->iCur, pIn->addrInTop); + VdbeCoverage(v); + VdbeCoverageIf(v, pIn->eEndLoopOp==OP_Prev); + VdbeCoverageIf(v, pIn->eEndLoopOp==OP_Next); + } + sqlite3VdbeJumpHere(v, pIn->addrInTop-1); + } + } + sqlite3VdbeResolveLabel(v, pLevel->addrBrk); + if( pLevel->pRJ ){ + sqlite3VdbeAddOp3(v, OP_Return, pLevel->pRJ->regReturn, 0, 1); + VdbeCoverage(v); + } + if( pLevel->addrSkip ){ + sqlite3VdbeGoto(v, pLevel->addrSkip); + VdbeComment((v, "next skip-scan on %s", pLoop->u.btree.pIndex->zName)); + sqlite3VdbeJumpHere(v, pLevel->addrSkip); + sqlite3VdbeJumpHere(v, pLevel->addrSkip-2); + } +#ifndef SQLITE_LIKE_DOESNT_MATCH_BLOBS + if( pLevel->addrLikeRep ){ + sqlite3VdbeAddOp2(v, OP_DecrJumpZero, (int)(pLevel->iLikeRepCntr>>1), + pLevel->addrLikeRep); + VdbeCoverage(v); + } +#endif + if( pLevel->iLeftJoin ){ + int ws = pLoop->wsFlags; + addr = sqlite3VdbeAddOp1(v, OP_IfPos, pLevel->iLeftJoin); VdbeCoverage(v); + assert( (ws & WHERE_IDX_ONLY)==0 || (ws & WHERE_INDEXED)!=0 ); + if( (ws & WHERE_IDX_ONLY)==0 ){ + assert( pLevel->iTabCur==pTabList->a[pLevel->iFrom].iCursor ); + sqlite3VdbeAddOp1(v, OP_NullRow, pLevel->iTabCur); + } + if( (ws & WHERE_INDEXED) + || ((ws & WHERE_MULTI_OR) && pLevel->u.pCoveringIdx) + ){ + if( ws & WHERE_MULTI_OR ){ + Index *pIx = pLevel->u.pCoveringIdx; + int iDb = sqlite3SchemaToIndex(db, pIx->pSchema); + sqlite3VdbeAddOp3(v, OP_ReopenIdx, pLevel->iIdxCur, pIx->tnum, iDb); + sqlite3VdbeSetP4KeyInfo(pParse, pIx); + } + sqlite3VdbeAddOp1(v, OP_NullRow, pLevel->iIdxCur); + } + if( pLevel->op==OP_Return ){ + sqlite3VdbeAddOp2(v, OP_Gosub, pLevel->p1, pLevel->addrFirst); + }else{ + sqlite3VdbeGoto(v, pLevel->addrFirst); + } + sqlite3VdbeJumpHere(v, addr); + } + VdbeModuleComment((v, "End WHERE-loop%d: %s", i, + pWInfo->pTabList->a[pLevel->iFrom].pTab->zName)); + } + + assert( pWInfo->nLevel<=pTabList->nSrc ); + for(i=0, pLevel=pWInfo->a; i<pWInfo->nLevel; i++, pLevel++){ + int k, last; + VdbeOp *pOp, *pLastOp; + Index *pIdx = 0; + SrcItem *pTabItem = &pTabList->a[pLevel->iFrom]; + Table *pTab = pTabItem->pTab; + assert( pTab!=0 ); + pLoop = pLevel->pWLoop; + + /* Do RIGHT JOIN processing. Generate code that will output the + ** unmatched rows of the right operand of the RIGHT JOIN with + ** all of the columns of the left operand set to NULL. + */ + if( pLevel->pRJ ){ + sqlite3WhereRightJoinLoop(pWInfo, i, pLevel); + continue; + } + + /* For a co-routine, change all OP_Column references to the table of + ** the co-routine into OP_Copy of result contained in a register. + ** OP_Rowid becomes OP_Null. + */ + if( pTabItem->fg.viaCoroutine ){ + testcase( pParse->db->mallocFailed ); + translateColumnToCopy(pParse, pLevel->addrBody, pLevel->iTabCur, + pTabItem->regResult, 0); + continue; + } + + /* If this scan uses an index, make VDBE code substitutions to read data + ** from the index instead of from the table where possible. In some cases + ** this optimization prevents the table from ever being read, which can + ** yield a significant performance boost. + ** + ** Calls to the code generator in between sqlite3WhereBegin and + ** sqlite3WhereEnd will have created code that references the table + ** directly. This loop scans all that code looking for opcodes + ** that reference the table and converts them into opcodes that + ** reference the index. + */ + if( pLoop->wsFlags & (WHERE_INDEXED|WHERE_IDX_ONLY) ){ + pIdx = pLoop->u.btree.pIndex; + }else if( pLoop->wsFlags & WHERE_MULTI_OR ){ + pIdx = pLevel->u.pCoveringIdx; + } + if( pIdx + && !db->mallocFailed + ){ + if( pWInfo->eOnePass==ONEPASS_OFF || !HasRowid(pIdx->pTable) ){ + last = iEnd; + }else{ + last = pWInfo->iEndWhere; + } + if( pIdx->bHasExpr ){ + IndexedExpr *p = pParse->pIdxEpr; + while( p ){ + if( p->iIdxCur==pLevel->iIdxCur ){ +#ifdef WHERETRACE_ENABLED + if( sqlite3WhereTrace & 0x200 ){ + sqlite3DebugPrintf("Disable pParse->pIdxEpr term {%d,%d}\n", + p->iIdxCur, p->iIdxCol); + if( sqlite3WhereTrace & 0x5000 ) sqlite3ShowExpr(p->pExpr); + } +#endif + p->iDataCur = -1; + p->iIdxCur = -1; + } + p = p->pIENext; + } + } + k = pLevel->addrBody + 1; +#ifdef SQLITE_DEBUG + if( db->flags & SQLITE_VdbeAddopTrace ){ + printf("TRANSLATE cursor %d->%d in opcode range %d..%d\n", + pLevel->iTabCur, pLevel->iIdxCur, k, last-1); + } + /* Proof that the "+1" on the k value above is safe */ + pOp = sqlite3VdbeGetOp(v, k - 1); + assert( pOp->opcode!=OP_Column || pOp->p1!=pLevel->iTabCur ); + assert( pOp->opcode!=OP_Rowid || pOp->p1!=pLevel->iTabCur ); + assert( pOp->opcode!=OP_IfNullRow || pOp->p1!=pLevel->iTabCur ); +#endif + pOp = sqlite3VdbeGetOp(v, k); + pLastOp = pOp + (last - k); + assert( pOp<=pLastOp ); + do{ + if( pOp->p1!=pLevel->iTabCur ){ + /* no-op */ + }else if( pOp->opcode==OP_Column +#ifdef SQLITE_ENABLE_OFFSET_SQL_FUNC + || pOp->opcode==OP_Offset +#endif + ){ + int x = pOp->p2; + assert( pIdx->pTable==pTab ); +#ifdef SQLITE_ENABLE_OFFSET_SQL_FUNC + if( pOp->opcode==OP_Offset ){ + /* Do not need to translate the column number */ + }else +#endif + if( !HasRowid(pTab) ){ + Index *pPk = sqlite3PrimaryKeyIndex(pTab); + x = pPk->aiColumn[x]; + assert( x>=0 ); + }else{ + testcase( x!=sqlite3StorageColumnToTable(pTab,x) ); + x = sqlite3StorageColumnToTable(pTab,x); + } + x = sqlite3TableColumnToIndex(pIdx, x); + if( x>=0 ){ + pOp->p2 = x; + pOp->p1 = pLevel->iIdxCur; + OpcodeRewriteTrace(db, k, pOp); + }else{ + /* Unable to translate the table reference into an index + ** reference. Verify that this is harmless - that the + ** table being referenced really is open. + */ +#ifdef SQLITE_ENABLE_OFFSET_SQL_FUNC + assert( (pLoop->wsFlags & WHERE_IDX_ONLY)==0 + || cursorIsOpen(v,pOp->p1,k) + || pOp->opcode==OP_Offset + ); +#else + assert( (pLoop->wsFlags & WHERE_IDX_ONLY)==0 + || cursorIsOpen(v,pOp->p1,k) + ); +#endif + } + }else if( pOp->opcode==OP_Rowid ){ + pOp->p1 = pLevel->iIdxCur; + pOp->opcode = OP_IdxRowid; + OpcodeRewriteTrace(db, k, pOp); + }else if( pOp->opcode==OP_IfNullRow ){ + pOp->p1 = pLevel->iIdxCur; + OpcodeRewriteTrace(db, k, pOp); + } +#ifdef SQLITE_DEBUG + k++; +#endif + }while( (++pOp)<pLastOp ); +#ifdef SQLITE_DEBUG + if( db->flags & SQLITE_VdbeAddopTrace ) printf("TRANSLATE complete\n"); +#endif + } + } + + /* The "break" point is here, just past the end of the outer loop. + ** Set it. + */ + sqlite3VdbeResolveLabel(v, pWInfo->iBreak); + + /* Final cleanup + */ + pParse->nQueryLoop = pWInfo->savedNQueryLoop; + whereInfoFree(db, pWInfo); + pParse->withinRJSubrtn -= nRJ; + return; +} |