| /* |
| ** 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" |
| |
| /* |
| ** Return the estimated number of output rows from a WHERE clause |
| */ |
| u64 sqlite3WhereOutputRowCount(WhereInfo *pWInfo){ |
| return sqlite3LogEstToInt(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 TRUE if the WHERE clause returns rows in ORDER BY order. |
| ** Return FALSE if the output needs to be sorted. |
| */ |
| int sqlite3WhereIsOrdered(WhereInfo *pWInfo){ |
| return pWInfo->nOBSat; |
| } |
| |
| /* |
| ** 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 TRUE if an UPDATE or DELETE statement can operate directly on |
| ** the rowids returned by a WHERE clause. Return FALSE if doing an |
| ** UPDATE or DELETE might change subsequent WHERE clause results. |
| ** |
| ** 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); |
| return pWInfo->okOnePass; |
| } |
| |
| /* |
| ** 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; |
| } |
| |
| /* |
| ** Initialize a preallocated WhereClause structure. |
| */ |
| static void whereClauseInit( |
| WhereClause *pWC, /* The WhereClause to be initialized */ |
| WhereInfo *pWInfo /* The WHERE processing context */ |
| ){ |
| pWC->pWInfo = pWInfo; |
| pWC->pOuter = 0; |
| pWC->nTerm = 0; |
| pWC->nSlot = ArraySize(pWC->aStatic); |
| pWC->a = pWC->aStatic; |
| } |
| |
| /* Forward reference */ |
| static void whereClauseClear(WhereClause*); |
| |
| /* |
| ** Deallocate all memory associated with a WhereOrInfo object. |
| */ |
| static void whereOrInfoDelete(sqlite3 *db, WhereOrInfo *p){ |
| whereClauseClear(&p->wc); |
| sqlite3DbFree(db, p); |
| } |
| |
| /* |
| ** Deallocate all memory associated with a WhereAndInfo object. |
| */ |
| static void whereAndInfoDelete(sqlite3 *db, WhereAndInfo *p){ |
| whereClauseClear(&p->wc); |
| sqlite3DbFree(db, p); |
| } |
| |
| /* |
| ** Deallocate a WhereClause structure. The WhereClause structure |
| ** itself is not freed. This routine is the inverse of whereClauseInit(). |
| */ |
| static void whereClauseClear(WhereClause *pWC){ |
| int i; |
| WhereTerm *a; |
| sqlite3 *db = pWC->pWInfo->pParse->db; |
| for(i=pWC->nTerm-1, a=pWC->a; i>=0; i--, a++){ |
| if( a->wtFlags & TERM_DYNAMIC ){ |
| sqlite3ExprDelete(db, a->pExpr); |
| } |
| if( a->wtFlags & TERM_ORINFO ){ |
| whereOrInfoDelete(db, a->u.pOrInfo); |
| }else if( a->wtFlags & TERM_ANDINFO ){ |
| whereAndInfoDelete(db, a->u.pAndInfo); |
| } |
| } |
| if( pWC->a!=pWC->aStatic ){ |
| sqlite3DbFree(db, pWC->a); |
| } |
| } |
| |
| /* |
| ** Add a single new WhereTerm entry to the WhereClause object pWC. |
| ** The new WhereTerm object is constructed from Expr p and with wtFlags. |
| ** The index in pWC->a[] of the new WhereTerm is returned on success. |
| ** 0 is returned if the new WhereTerm could not be added due to a memory |
| ** allocation error. The memory allocation failure will be recorded in |
| ** the db->mallocFailed flag so that higher-level functions can detect it. |
| ** |
| ** This routine will increase the size of the pWC->a[] array as necessary. |
| ** |
| ** If the wtFlags argument includes TERM_DYNAMIC, then responsibility |
| ** for freeing the expression p is assumed by the WhereClause object pWC. |
| ** This is true even if this routine fails to allocate a new WhereTerm. |
| ** |
| ** WARNING: This routine might reallocate the space used to store |
| ** WhereTerms. All pointers to WhereTerms should be invalidated after |
| ** calling this routine. Such pointers may be reinitialized by referencing |
| ** the pWC->a[] array. |
| */ |
| static int whereClauseInsert(WhereClause *pWC, Expr *p, u8 wtFlags){ |
| WhereTerm *pTerm; |
| int idx; |
| testcase( wtFlags & TERM_VIRTUAL ); |
| if( pWC->nTerm>=pWC->nSlot ){ |
| WhereTerm *pOld = pWC->a; |
| sqlite3 *db = pWC->pWInfo->pParse->db; |
| pWC->a = sqlite3DbMallocRaw(db, sizeof(pWC->a[0])*pWC->nSlot*2 ); |
| if( pWC->a==0 ){ |
| if( wtFlags & TERM_DYNAMIC ){ |
| sqlite3ExprDelete(db, p); |
| } |
| pWC->a = pOld; |
| return 0; |
| } |
| memcpy(pWC->a, pOld, sizeof(pWC->a[0])*pWC->nTerm); |
| if( pOld!=pWC->aStatic ){ |
| sqlite3DbFree(db, pOld); |
| } |
| pWC->nSlot = sqlite3DbMallocSize(db, pWC->a)/sizeof(pWC->a[0]); |
| } |
| pTerm = &pWC->a[idx = pWC->nTerm++]; |
| if( p && ExprHasProperty(p, EP_Unlikely) ){ |
| pTerm->truthProb = sqlite3LogEst(p->iTable) - 99; |
| }else{ |
| pTerm->truthProb = 1; |
| } |
| pTerm->pExpr = sqlite3ExprSkipCollate(p); |
| pTerm->wtFlags = wtFlags; |
| pTerm->pWC = pWC; |
| pTerm->iParent = -1; |
| return idx; |
| } |
| |
| /* |
| ** This routine identifies subexpressions in the WHERE clause where |
| ** each subexpression is separated by the AND operator or some other |
| ** operator specified in the op parameter. The WhereClause structure |
| ** is filled with pointers to subexpressions. For example: |
| ** |
| ** WHERE a=='hello' AND coalesce(b,11)<10 AND (c+12!=d OR c==22) |
| ** \________/ \_______________/ \________________/ |
| ** slot[0] slot[1] slot[2] |
| ** |
| ** The original WHERE clause in pExpr is unaltered. All this routine |
| ** does is make slot[] entries point to substructure within pExpr. |
| ** |
| ** In the previous sentence and in the diagram, "slot[]" refers to |
| ** the WhereClause.a[] array. The slot[] array grows as needed to contain |
| ** all terms of the WHERE clause. |
| */ |
| static void whereSplit(WhereClause *pWC, Expr *pExpr, u8 op){ |
| pWC->op = op; |
| if( pExpr==0 ) return; |
| if( pExpr->op!=op ){ |
| whereClauseInsert(pWC, pExpr, 0); |
| }else{ |
| whereSplit(pWC, pExpr->pLeft, op); |
| whereSplit(pWC, pExpr->pRight, op); |
| } |
| } |
| |
| /* |
| ** Initialize a WhereMaskSet object |
| */ |
| #define initMaskSet(P) (P)->n=0 |
| |
| /* |
| ** Return the bitmask for the given cursor number. Return 0 if |
| ** iCursor is not in the set. |
| */ |
| static Bitmask getMask(WhereMaskSet *pMaskSet, int iCursor){ |
| int i; |
| assert( pMaskSet->n<=(int)sizeof(Bitmask)*8 ); |
| for(i=0; i<pMaskSet->n; i++){ |
| if( pMaskSet->ix[i]==iCursor ){ |
| return MASKBIT(i); |
| } |
| } |
| return 0; |
| } |
| |
| /* |
| ** 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; |
| } |
| |
| /* |
| ** These routines walk (recursively) an expression tree and generate |
| ** a bitmask indicating which tables are used in that expression |
| ** tree. |
| */ |
| static Bitmask exprListTableUsage(WhereMaskSet*, ExprList*); |
| static Bitmask exprSelectTableUsage(WhereMaskSet*, Select*); |
| static Bitmask exprTableUsage(WhereMaskSet *pMaskSet, Expr *p){ |
| Bitmask mask = 0; |
| if( p==0 ) return 0; |
| if( p->op==TK_COLUMN ){ |
| mask = getMask(pMaskSet, p->iTable); |
| return mask; |
| } |
| mask = exprTableUsage(pMaskSet, p->pRight); |
| mask |= exprTableUsage(pMaskSet, p->pLeft); |
| if( ExprHasProperty(p, EP_xIsSelect) ){ |
| mask |= exprSelectTableUsage(pMaskSet, p->x.pSelect); |
| }else{ |
| mask |= exprListTableUsage(pMaskSet, p->x.pList); |
| } |
| return mask; |
| } |
| static Bitmask exprListTableUsage(WhereMaskSet *pMaskSet, ExprList *pList){ |
| int i; |
| Bitmask mask = 0; |
| if( pList ){ |
| for(i=0; i<pList->nExpr; i++){ |
| mask |= exprTableUsage(pMaskSet, pList->a[i].pExpr); |
| } |
| } |
| return mask; |
| } |
| static Bitmask exprSelectTableUsage(WhereMaskSet *pMaskSet, Select *pS){ |
| Bitmask mask = 0; |
| while( pS ){ |
| SrcList *pSrc = pS->pSrc; |
| mask |= exprListTableUsage(pMaskSet, pS->pEList); |
| mask |= exprListTableUsage(pMaskSet, pS->pGroupBy); |
| mask |= exprListTableUsage(pMaskSet, pS->pOrderBy); |
| mask |= exprTableUsage(pMaskSet, pS->pWhere); |
| mask |= exprTableUsage(pMaskSet, pS->pHaving); |
| if( ALWAYS(pSrc!=0) ){ |
| int i; |
| for(i=0; i<pSrc->nSrc; i++){ |
| mask |= exprSelectTableUsage(pMaskSet, pSrc->a[i].pSelect); |
| mask |= exprTableUsage(pMaskSet, pSrc->a[i].pOn); |
| } |
| } |
| pS = pS->pPrior; |
| } |
| return mask; |
| } |
| |
| /* |
| ** Return TRUE if the given operator is one of the operators that is |
| ** allowed for an indexable WHERE clause term. The allowed operators are |
| ** "=", "<", ">", "<=", ">=", "IN", and "IS NULL" |
| */ |
| static int allowedOp(int op){ |
| assert( TK_GT>TK_EQ && TK_GT<TK_GE ); |
| assert( TK_LT>TK_EQ && TK_LT<TK_GE ); |
| assert( TK_LE>TK_EQ && TK_LE<TK_GE ); |
| assert( TK_GE==TK_EQ+4 ); |
| return op==TK_IN || (op>=TK_EQ && op<=TK_GE) || op==TK_ISNULL; |
| } |
| |
| /* |
| ** Commute a comparison operator. Expressions of the form "X op Y" |
| ** are converted into "Y op X". |
| ** |
| ** If left/right precedence rules come into play when determining the |
| ** collating sequence, then COLLATE operators are adjusted to ensure |
| ** that the collating sequence does not change. For example: |
| ** "Y collate NOCASE op X" becomes "X op Y" because any collation sequence on |
| ** the left hand side of a comparison overrides any collation sequence |
| ** attached to the right. For the same reason the EP_Collate flag |
| ** is not commuted. |
| */ |
| static void exprCommute(Parse *pParse, Expr *pExpr){ |
| u16 expRight = (pExpr->pRight->flags & EP_Collate); |
| u16 expLeft = (pExpr->pLeft->flags & EP_Collate); |
| assert( allowedOp(pExpr->op) && pExpr->op!=TK_IN ); |
| if( expRight==expLeft ){ |
| /* Either X and Y both have COLLATE operator or neither do */ |
| if( expRight ){ |
| /* Both X and Y have COLLATE operators. Make sure X is always |
| ** used by clearing the EP_Collate flag from Y. */ |
| pExpr->pRight->flags &= ~EP_Collate; |
| }else if( sqlite3ExprCollSeq(pParse, pExpr->pLeft)!=0 ){ |
| /* Neither X nor Y have COLLATE operators, but X has a non-default |
| ** collating sequence. So add the EP_Collate marker on X to cause |
| ** it to be searched first. */ |
| pExpr->pLeft->flags |= EP_Collate; |
| } |
| } |
| SWAP(Expr*,pExpr->pRight,pExpr->pLeft); |
| if( pExpr->op>=TK_GT ){ |
| assert( TK_LT==TK_GT+2 ); |
| assert( TK_GE==TK_LE+2 ); |
| assert( TK_GT>TK_EQ ); |
| assert( TK_GT<TK_LE ); |
| assert( pExpr->op>=TK_GT && pExpr->op<=TK_GE ); |
| pExpr->op = ((pExpr->op-TK_GT)^2)+TK_GT; |
| } |
| } |
| |
| /* |
| ** Translate from TK_xx operator to WO_xx bitmask. |
| */ |
| static u16 operatorMask(int op){ |
| u16 c; |
| assert( allowedOp(op) ); |
| if( op==TK_IN ){ |
| c = WO_IN; |
| }else if( op==TK_ISNULL ){ |
| c = WO_ISNULL; |
| }else{ |
| assert( (WO_EQ<<(op-TK_EQ)) < 0x7fff ); |
| c = (u16)(WO_EQ<<(op-TK_EQ)); |
| } |
| assert( op!=TK_ISNULL || c==WO_ISNULL ); |
| assert( op!=TK_IN || c==WO_IN ); |
| assert( op!=TK_EQ || c==WO_EQ ); |
| assert( op!=TK_LT || c==WO_LT ); |
| assert( op!=TK_LE || c==WO_LE ); |
| assert( op!=TK_GT || c==WO_GT ); |
| assert( op!=TK_GE || c==WO_GE ); |
| return c; |
| } |
| |
| /* |
| ** 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 */ |
| int 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 */ |
| |
| while( pScan->iEquiv<=pScan->nEquiv ){ |
| iCur = pScan->aEquiv[pScan->iEquiv-2]; |
| iColumn = pScan->aEquiv[pScan->iEquiv-1]; |
| while( (pWC = pScan->pWC)!=0 ){ |
| for(pTerm=pWC->a+k; k<pWC->nTerm; k++, pTerm++){ |
| if( pTerm->leftCursor==iCur |
| && pTerm->u.leftColumn==iColumn |
| && (pScan->iEquiv<=2 || !ExprHasProperty(pTerm->pExpr, EP_FromJoin)) |
| ){ |
| if( (pTerm->eOperator & WO_EQUIV)!=0 |
| && pScan->nEquiv<ArraySize(pScan->aEquiv) |
| ){ |
| int j; |
| pX = sqlite3ExprSkipCollate(pTerm->pExpr->pRight); |
| assert( pX->op==TK_COLUMN ); |
| for(j=0; j<pScan->nEquiv; j+=2){ |
| if( pScan->aEquiv[j]==pX->iTable |
| && pScan->aEquiv[j+1]==pX->iColumn ){ |
| break; |
| } |
| } |
| if( j==pScan->nEquiv ){ |
| pScan->aEquiv[j] = pX->iTable; |
| pScan->aEquiv[j+1] = pX->iColumn; |
| pScan->nEquiv += 2; |
| } |
| } |
| 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 = sqlite3BinaryCompareCollSeq(pParse, |
| pX->pLeft, pX->pRight); |
| if( pColl==0 ) pColl = pParse->db->pDfltColl; |
| if( sqlite3StrICmp(pColl->zName, pScan->zCollName) ){ |
| continue; |
| } |
| } |
| if( (pTerm->eOperator & WO_EQ)!=0 |
| && (pX = pTerm->pExpr->pRight)->op==TK_COLUMN |
| && pX->iTable==pScan->aEquiv[0] |
| && pX->iColumn==pScan->aEquiv[1] |
| ){ |
| continue; |
| } |
| pScan->k = k+1; |
| return pTerm; |
| } |
| } |
| } |
| pScan->pWC = pScan->pWC->pOuter; |
| k = 0; |
| } |
| pScan->pWC = pScan->pOrigWC; |
| k = 0; |
| pScan->iEquiv += 2; |
| } |
| return 0; |
| } |
| |
| /* |
| ** 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. 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 */ |
| ){ |
| int j; |
| |
| /* memset(pScan, 0, sizeof(*pScan)); */ |
| pScan->pOrigWC = pWC; |
| pScan->pWC = pWC; |
| if( pIdx && iColumn>=0 ){ |
| pScan->idxaff = pIdx->pTable->aCol[iColumn].affinity; |
| for(j=0; pIdx->aiColumn[j]!=iColumn; j++){ |
| if( NEVER(j>pIdx->nColumn) ) return 0; |
| } |
| pScan->zCollName = pIdx->azColl[j]; |
| }else{ |
| pScan->idxaff = 0; |
| pScan->zCollName = 0; |
| } |
| pScan->opMask = opMask; |
| pScan->k = 0; |
| pScan->aEquiv[0] = iCur; |
| pScan->aEquiv[1] = iColumn; |
| pScan->nEquiv = 2; |
| pScan->iEquiv = 2; |
| 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 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. |
| ** |
| ** 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 |
| ** aEquiv[] array holds X and all its equivalents, with each SQL variable |
| ** taking up two slots in aEquiv[]. The first slot is for the cursor number |
| ** and the second is for the column number. There are 22 slots in aEquiv[] |
| ** 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. |
| */ |
| static WhereTerm *findTerm( |
| 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); |
| while( p ){ |
| if( (p->prereqRight & notReady)==0 ){ |
| if( p->prereqRight==0 && (p->eOperator&WO_EQ)!=0 ){ |
| return p; |
| } |
| if( pResult==0 ) pResult = p; |
| } |
| p = whereScanNext(&scan); |
| } |
| return pResult; |
| } |
| |
| /* Forward reference */ |
| static void exprAnalyze(SrcList*, WhereClause*, int); |
| |
| /* |
| ** Call exprAnalyze on all terms in a WHERE clause. |
| */ |
| static void exprAnalyzeAll( |
| SrcList *pTabList, /* the FROM clause */ |
| WhereClause *pWC /* the WHERE clause to be analyzed */ |
| ){ |
| int i; |
| for(i=pWC->nTerm-1; i>=0; i--){ |
| exprAnalyze(pTabList, pWC, i); |
| } |
| } |
| |
| #ifndef SQLITE_OMIT_LIKE_OPTIMIZATION |
| /* |
| ** Check to see if the given expression is a LIKE or GLOB operator that |
| ** can be optimized using inequality constraints. Return TRUE if it is |
| ** so and false if not. |
| ** |
| ** In order for the operator to be optimizible, the RHS must be a string |
| ** literal that does not begin with a wildcard. |
| */ |
| static int isLikeOrGlob( |
| Parse *pParse, /* Parsing and code generating context */ |
| Expr *pExpr, /* Test this expression */ |
| Expr **ppPrefix, /* Pointer to TK_STRING expression with pattern prefix */ |
| int *pisComplete, /* True if the only wildcard is % in the last character */ |
| int *pnoCase /* True if uppercase is equivalent to lowercase */ |
| ){ |
| const char *z = 0; /* String on RHS of LIKE operator */ |
| Expr *pRight, *pLeft; /* Right and left size of LIKE operator */ |
| ExprList *pList; /* List of operands to the LIKE operator */ |
| int c; /* One character in z[] */ |
| int cnt; /* Number of non-wildcard prefix characters */ |
| char wc[3]; /* Wildcard characters */ |
| sqlite3 *db = pParse->db; /* Database connection */ |
| sqlite3_value *pVal = 0; |
| int op; /* Opcode of pRight */ |
| |
| if( !sqlite3IsLikeFunction(db, pExpr, pnoCase, wc) ){ |
| return 0; |
| } |
| #ifdef SQLITE_EBCDIC |
| if( *pnoCase ) return 0; |
| #endif |
| pList = pExpr->x.pList; |
| pLeft = pList->a[1].pExpr; |
| if( pLeft->op!=TK_COLUMN |
| || sqlite3ExprAffinity(pLeft)!=SQLITE_AFF_TEXT |
| || IsVirtual(pLeft->pTab) |
| ){ |
| /* IMP: R-02065-49465 The left-hand side of the LIKE or GLOB operator must |
| ** be the name of an indexed column with TEXT affinity. */ |
| return 0; |
| } |
| assert( pLeft->iColumn!=(-1) ); /* Because IPK never has AFF_TEXT */ |
| |
| pRight = sqlite3ExprSkipCollate(pList->a[0].pExpr); |
| op = pRight->op; |
| if( op==TK_VARIABLE ){ |
| Vdbe *pReprepare = pParse->pReprepare; |
| int iCol = pRight->iColumn; |
| pVal = sqlite3VdbeGetBoundValue(pReprepare, iCol, SQLITE_AFF_NONE); |
| if( pVal && sqlite3_value_type(pVal)==SQLITE_TEXT ){ |
| z = (char *)sqlite3_value_text(pVal); |
| } |
| sqlite3VdbeSetVarmask(pParse->pVdbe, iCol); |
| assert( pRight->op==TK_VARIABLE || pRight->op==TK_REGISTER ); |
| }else if( op==TK_STRING ){ |
| z = pRight->u.zToken; |
| } |
| if( z ){ |
| cnt = 0; |
| while( (c=z[cnt])!=0 && c!=wc[0] && c!=wc[1] && c!=wc[2] ){ |
| cnt++; |
| } |
| if( cnt!=0 && 255!=(u8)z[cnt-1] ){ |
| Expr *pPrefix; |
| *pisComplete = c==wc[0] && z[cnt+1]==0; |
| pPrefix = sqlite3Expr(db, TK_STRING, z); |
| if( pPrefix ) pPrefix->u.zToken[cnt] = 0; |
| *ppPrefix = pPrefix; |
| if( op==TK_VARIABLE ){ |
| Vdbe *v = pParse->pVdbe; |
| sqlite3VdbeSetVarmask(v, pRight->iColumn); |
| if( *pisComplete && pRight->u.zToken[1] ){ |
| /* If the rhs of the LIKE expression is a variable, and the current |
| ** value of the variable means there is no need to invoke the LIKE |
| ** function, then no OP_Variable will be added to the program. |
| ** This causes problems for the sqlite3_bind_parameter_name() |
| ** API. To work around them, add a dummy OP_Variable here. |
| */ |
| int r1 = sqlite3GetTempReg(pParse); |
| sqlite3ExprCodeTarget(pParse, pRight, r1); |
| sqlite3VdbeChangeP3(v, sqlite3VdbeCurrentAddr(v)-1, 0); |
| sqlite3ReleaseTempReg(pParse, r1); |
| } |
| } |
| }else{ |
| z = 0; |
| } |
| } |
| |
| sqlite3ValueFree(pVal); |
| return (z!=0); |
| } |
| #endif /* SQLITE_OMIT_LIKE_OPTIMIZATION */ |
| |
| |
| #ifndef SQLITE_OMIT_VIRTUALTABLE |
| /* |
| ** Check to see if the given expression is of the form |
| ** |
| ** column MATCH expr |
| ** |
| ** If it is then return TRUE. If not, return FALSE. |
| */ |
| static int isMatchOfColumn( |
| Expr *pExpr /* Test this expression */ |
| ){ |
| ExprList *pList; |
| |
| if( pExpr->op!=TK_FUNCTION ){ |
| return 0; |
| } |
| if( sqlite3StrICmp(pExpr->u.zToken,"match")!=0 ){ |
| return 0; |
| } |
| pList = pExpr->x.pList; |
| if( pList->nExpr!=2 ){ |
| return 0; |
| } |
| if( pList->a[1].pExpr->op != TK_COLUMN ){ |
| return 0; |
| } |
| return 1; |
| } |
| #endif /* SQLITE_OMIT_VIRTUALTABLE */ |
| |
| /* |
| ** If the pBase expression originated in the ON or USING clause of |
| ** a join, then transfer the appropriate markings over to derived. |
| */ |
| static void transferJoinMarkings(Expr *pDerived, Expr *pBase){ |
| if( pDerived ){ |
| pDerived->flags |= pBase->flags & EP_FromJoin; |
| pDerived->iRightJoinTable = pBase->iRightJoinTable; |
| } |
| } |
| |
| #if !defined(SQLITE_OMIT_OR_OPTIMIZATION) && !defined(SQLITE_OMIT_SUBQUERY) |
| /* |
| ** Analyze a term that consists of two or more OR-connected |
| ** subterms. So in: |
| ** |
| ** ... WHERE (a=5) AND (b=7 OR c=9 OR d=13) AND (d=13) |
| ** ^^^^^^^^^^^^^^^^^^^^ |
| ** |
| ** This routine analyzes terms such as the middle term in the above example. |
| ** A WhereOrTerm object is computed and attached to the term under |
| ** analysis, regardless of the outcome of the analysis. Hence: |
| ** |
| ** WhereTerm.wtFlags |= TERM_ORINFO |
| ** WhereTerm.u.pOrInfo = a dynamically allocated WhereOrTerm object |
| ** |
| ** The term being analyzed must have two or more of OR-connected subterms. |
| ** A single subterm might be a set of AND-connected sub-subterms. |
| ** Examples of terms under analysis: |
| ** |
| ** (A) t1.x=t2.y OR t1.x=t2.z OR t1.y=15 OR t1.z=t3.a+5 |
| ** (B) x=expr1 OR expr2=x OR x=expr3 |
| ** (C) t1.x=t2.y OR (t1.x=t2.z AND t1.y=15) |
| ** (D) x=expr1 OR (y>11 AND y<22 AND z LIKE '*hello*') |
| ** (E) (p.a=1 AND q.b=2 AND r.c=3) OR (p.x=4 AND q.y=5 AND r.z=6) |
| ** |
| ** CASE 1: |
| ** |
| ** If all subterms are of the form T.C=expr for some single column of C and |
| ** a single table T (as shown in example B above) then create a new virtual |
| ** term that is an equivalent IN expression. In other words, if the term |
| ** being analyzed is: |
| ** |
| ** x = expr1 OR expr2 = x OR x = expr3 |
| ** |
| ** then create a new virtual term like this: |
| ** |
| ** x IN (expr1,expr2,expr3) |
| ** |
| ** CASE 2: |
| ** |
| ** If all subterms are indexable by a single table T, then set |
| ** |
| ** WhereTerm.eOperator = WO_OR |
| ** WhereTerm.u.pOrInfo->indexable |= the cursor number for table T |
| ** |
| ** A subterm is "indexable" if it is of the form |
| ** "T.C <op> <expr>" where C is any column of table T and |
| ** <op> is one of "=", "<", "<=", ">", ">=", "IS NULL", or "IN". |
| ** A subterm is also indexable if it is an AND of two or more |
| ** subsubterms at least one of which is indexable. Indexable AND |
| ** subterms have their eOperator set to WO_AND and they have |
| ** u.pAndInfo set to a dynamically allocated WhereAndTerm object. |
| ** |
| ** From another point of view, "indexable" means that the subterm could |
| ** potentially be used with an index if an appropriate index exists. |
| ** This analysis does not consider whether or not the index exists; that |
| ** is decided elsewhere. This analysis only looks at whether subterms |
| ** appropriate for indexing exist. |
| ** |
| ** All examples A through E above satisfy case 2. But if a term |
| ** also satisfies case 1 (such as B) we know that the optimizer will |
| ** always prefer case 1, so in that case we pretend that case 2 is not |
| ** satisfied. |
| ** |
| ** It might be the case that multiple tables are indexable. For example, |
| ** (E) above is indexable on tables P, Q, and R. |
| ** |
| ** Terms that satisfy case 2 are candidates for lookup by using |
| ** separate indices to find rowids for each subterm and composing |
| ** the union of all rowids using a RowSet object. This is similar |
| ** to "bitmap indices" in other database engines. |
| ** |
| ** OTHERWISE: |
| ** |
| ** If neither case 1 nor case 2 apply, then leave the eOperator set to |
| ** zero. This term is not useful for search. |
| */ |
| static void exprAnalyzeOrTerm( |
| SrcList *pSrc, /* the FROM clause */ |
| WhereClause *pWC, /* the complete WHERE clause */ |
| int idxTerm /* Index of the OR-term to be analyzed */ |
| ){ |
| WhereInfo *pWInfo = pWC->pWInfo; /* WHERE clause processing context */ |
| Parse *pParse = pWInfo->pParse; /* Parser context */ |
| sqlite3 *db = pParse->db; /* Database connection */ |
| WhereTerm *pTerm = &pWC->a[idxTerm]; /* The term to be analyzed */ |
| Expr *pExpr = pTerm->pExpr; /* The expression of the term */ |
| int i; /* Loop counters */ |
| WhereClause *pOrWc; /* Breakup of pTerm into subterms */ |
| WhereTerm *pOrTerm; /* A Sub-term within the pOrWc */ |
| WhereOrInfo *pOrInfo; /* Additional information associated with pTerm */ |
| Bitmask chngToIN; /* Tables that might satisfy case 1 */ |
| Bitmask indexable; /* Tables that are indexable, satisfying case 2 */ |
| |
| /* |
| ** Break the OR clause into its separate subterms. The subterms are |
| ** stored in a WhereClause structure containing within the WhereOrInfo |
| ** object that is attached to the original OR clause term. |
| */ |
| assert( (pTerm->wtFlags & (TERM_DYNAMIC|TERM_ORINFO|TERM_ANDINFO))==0 ); |
| assert( pExpr->op==TK_OR ); |
| pTerm->u.pOrInfo = pOrInfo = sqlite3DbMallocZero(db, sizeof(*pOrInfo)); |
| if( pOrInfo==0 ) return; |
| pTerm->wtFlags |= TERM_ORINFO; |
| pOrWc = &pOrInfo->wc; |
| whereClauseInit(pOrWc, pWInfo); |
| whereSplit(pOrWc, pExpr, TK_OR); |
| exprAnalyzeAll(pSrc, pOrWc); |
| if( db->mallocFailed ) return; |
| assert( pOrWc->nTerm>=2 ); |
| |
| /* |
| ** Compute the set of tables that might satisfy cases 1 or 2. |
| */ |
| indexable = ~(Bitmask)0; |
| chngToIN = ~(Bitmask)0; |
| for(i=pOrWc->nTerm-1, pOrTerm=pOrWc->a; i>=0 && indexable; i--, pOrTerm++){ |
| if( (pOrTerm->eOperator & WO_SINGLE)==0 ){ |
| WhereAndInfo *pAndInfo; |
| assert( (pOrTerm->wtFlags & (TERM_ANDINFO|TERM_ORINFO))==0 ); |
| chngToIN = 0; |
| pAndInfo = sqlite3DbMallocRaw(db, sizeof(*pAndInfo)); |
| if( pAndInfo ){ |
| WhereClause *pAndWC; |
| WhereTerm *pAndTerm; |
| int j; |
| Bitmask b = 0; |
| pOrTerm->u.pAndInfo = pAndInfo; |
| pOrTerm->wtFlags |= TERM_ANDINFO; |
| pOrTerm->eOperator = WO_AND; |
| pAndWC = &pAndInfo->wc; |
| whereClauseInit(pAndWC, pWC->pWInfo); |
| whereSplit(pAndWC, pOrTerm->pExpr, TK_AND); |
| exprAnalyzeAll(pSrc, pAndWC); |
| pAndWC->pOuter = pWC; |
| testcase( db->mallocFailed ); |
| if( !db->mallocFailed ){ |
| for(j=0, pAndTerm=pAndWC->a; j<pAndWC->nTerm; j++, pAndTerm++){ |
| assert( pAndTerm->pExpr ); |
| if( allowedOp(pAndTerm->pExpr->op) ){ |
| b |= getMask(&pWInfo->sMaskSet, pAndTerm->leftCursor); |
| } |
| } |
| } |
| indexable &= b; |
| } |
| }else if( pOrTerm->wtFlags & TERM_COPIED ){ |
| /* Skip this term for now. We revisit it when we process the |
| ** corresponding TERM_VIRTUAL term */ |
| }else{ |
| Bitmask b; |
| b = getMask(&pWInfo->sMaskSet, pOrTerm->leftCursor); |
| if( pOrTerm->wtFlags & TERM_VIRTUAL ){ |
| WhereTerm *pOther = &pOrWc->a[pOrTerm->iParent]; |
| b |= getMask(&pWInfo->sMaskSet, pOther->leftCursor); |
| } |
| indexable &= b; |
| if( (pOrTerm->eOperator & WO_EQ)==0 ){ |
| chngToIN = 0; |
| }else{ |
| chngToIN &= b; |
| } |
| } |
| } |
| |
| /* |
| ** Record the set of tables that satisfy case 2. The set might be |
| ** empty. |
| */ |
| pOrInfo->indexable = indexable; |
| pTerm->eOperator = indexable==0 ? 0 : WO_OR; |
| |
| /* |
| ** chngToIN holds a set of tables that *might* satisfy case 1. But |
| ** we have to do some additional checking to see if case 1 really |
| ** is satisfied. |
| ** |
| ** chngToIN will hold either 0, 1, or 2 bits. The 0-bit case means |
| ** that there is no possibility of transforming the OR clause into an |
| ** IN operator because one or more terms in the OR clause contain |
| ** something other than == on a column in the single table. The 1-bit |
| ** case means that every term of the OR clause is of the form |
| ** "table.column=expr" for some single table. The one bit that is set |
| ** will correspond to the common table. We still need to check to make |
| ** sure the same column is used on all terms. The 2-bit case is when |
| ** the all terms are of the form "table1.column=table2.column". It |
| ** might be possible to form an IN operator with either table1.column |
| ** or table2.column as the LHS if either is common to every term of |
| ** the OR clause. |
| ** |
| ** Note that terms of the form "table.column1=table.column2" (the |
| ** same table on both sizes of the ==) cannot be optimized. |
| */ |
| if( chngToIN ){ |
| int okToChngToIN = 0; /* True if the conversion to IN is valid */ |
| int iColumn = -1; /* Column index on lhs of IN operator */ |
| int iCursor = -1; /* Table cursor common to all terms */ |
| int j = 0; /* Loop counter */ |
| |
| /* Search for a table and column that appears on one side or the |
| ** other of the == operator in every subterm. That table and column |
| ** will be recorded in iCursor and iColumn. There might not be any |
| ** such table and column. Set okToChngToIN if an appropriate table |
| ** and column is found but leave okToChngToIN false if not found. |
| */ |
| for(j=0; j<2 && !okToChngToIN; j++){ |
| pOrTerm = pOrWc->a; |
| for(i=pOrWc->nTerm-1; i>=0; i--, pOrTerm++){ |
| assert( pOrTerm->eOperator & WO_EQ ); |
| pOrTerm->wtFlags &= ~TERM_OR_OK; |
| if( pOrTerm->leftCursor==iCursor ){ |
| /* This is the 2-bit case and we are on the second iteration and |
| ** current term is from the first iteration. So skip this term. */ |
| assert( j==1 ); |
| continue; |
| } |
| if( (chngToIN & getMask(&pWInfo->sMaskSet, pOrTerm->leftCursor))==0 ){ |
| /* This term must be of the form t1.a==t2.b where t2 is in the |
| ** chngToIN set but t1 is not. This term will be either preceded |
| ** or follwed by an inverted copy (t2.b==t1.a). Skip this term |
| ** and use its inversion. */ |
| testcase( pOrTerm->wtFlags & TERM_COPIED ); |
| testcase( pOrTerm->wtFlags & TERM_VIRTUAL ); |
| assert( pOrTerm->wtFlags & (TERM_COPIED|TERM_VIRTUAL) ); |
| continue; |
| } |
| iColumn = pOrTerm->u.leftColumn; |
| iCursor = pOrTerm->leftCursor; |
| break; |
| } |
| if( i<0 ){ |
| /* No candidate table+column was found. This can only occur |
| ** on the second iteration */ |
| assert( j==1 ); |
| assert( IsPowerOfTwo(chngToIN) ); |
| assert( chngToIN==getMask(&pWInfo->sMaskSet, iCursor) ); |
| break; |
| } |
| testcase( j==1 ); |
| |
| /* We have found a candidate table and column. Check to see if that |
| ** table and column is common to every term in the OR clause */ |
| okToChngToIN = 1; |
| for(; i>=0 && okToChngToIN; i--, pOrTerm++){ |
| assert( pOrTerm->eOperator & WO_EQ ); |
| if( pOrTerm->leftCursor!=iCursor ){ |
| pOrTerm->wtFlags &= ~TERM_OR_OK; |
| }else if( pOrTerm->u.leftColumn!=iColumn ){ |
| okToChngToIN = 0; |
| }else{ |
| int affLeft, affRight; |
| /* If the right-hand side is also a column, then the affinities |
| ** of both right and left sides must be such that no type |
| ** conversions are required on the right. (Ticket #2249) |
| */ |
| affRight = sqlite3ExprAffinity(pOrTerm->pExpr->pRight); |
| affLeft = sqlite3ExprAffinity(pOrTerm->pExpr->pLeft); |
| if( affRight!=0 && affRight!=affLeft ){ |
| okToChngToIN = 0; |
| }else{ |
| pOrTerm->wtFlags |= TERM_OR_OK; |
| } |
| } |
| } |
| } |
| |
| /* At this point, okToChngToIN is true if original pTerm satisfies |
| ** case 1. In that case, construct a new virtual term that is |
| ** pTerm converted into an IN operator. |
| */ |
| if( okToChngToIN ){ |
| Expr *pDup; /* A transient duplicate expression */ |
| ExprList *pList = 0; /* The RHS of the IN operator */ |
| Expr *pLeft = 0; /* The LHS of the IN operator */ |
| Expr *pNew; /* The complete IN operator */ |
| |
| for(i=pOrWc->nTerm-1, pOrTerm=pOrWc->a; i>=0; i--, pOrTerm++){ |
| if( (pOrTerm->wtFlags & TERM_OR_OK)==0 ) continue; |
| assert( pOrTerm->eOperator & WO_EQ ); |
| assert( pOrTerm->leftCursor==iCursor ); |
| assert( pOrTerm->u.leftColumn==iColumn ); |
| pDup = sqlite3ExprDup(db, pOrTerm->pExpr->pRight, 0); |
| pList = sqlite3ExprListAppend(pWInfo->pParse, pList, pDup); |
| pLeft = pOrTerm->pExpr->pLeft; |
| } |
| assert( pLeft!=0 ); |
| pDup = sqlite3ExprDup(db, pLeft, 0); |
| pNew = sqlite3PExpr(pParse, TK_IN, pDup, 0, 0); |
| if( pNew ){ |
| int idxNew; |
| transferJoinMarkings(pNew, pExpr); |
| assert( !ExprHasProperty(pNew, EP_xIsSelect) ); |
| pNew->x.pList = pList; |
| idxNew = whereClauseInsert(pWC, pNew, TERM_VIRTUAL|TERM_DYNAMIC); |
| testcase( idxNew==0 ); |
| exprAnalyze(pSrc, pWC, idxNew); |
| pTerm = &pWC->a[idxTerm]; |
| pWC->a[idxNew].iParent = idxTerm; |
| pTerm->nChild = 1; |
| }else{ |
| sqlite3ExprListDelete(db, pList); |
| } |
| pTerm->eOperator = WO_NOOP; /* case 1 trumps case 2 */ |
| } |
| } |
| } |
| #endif /* !SQLITE_OMIT_OR_OPTIMIZATION && !SQLITE_OMIT_SUBQUERY */ |
| |
| /* |
| ** The input to this routine is an WhereTerm structure with only the |
| ** "pExpr" field filled in. The job of this routine is to analyze the |
| ** subexpression and populate all the other fields of the WhereTerm |
| ** structure. |
| ** |
| ** If the expression is of the form "<expr> <op> X" it gets commuted |
| ** to the standard form of "X <op> <expr>". |
| ** |
| ** If the expression is of the form "X <op> Y" where both X and Y are |
| ** columns, then the original expression is unchanged and a new virtual |
| ** term of the form "Y <op> X" is added to the WHERE clause and |
| ** analyzed separately. The original term is marked with TERM_COPIED |
| ** and the new term is marked with TERM_DYNAMIC (because it's pExpr |
| ** needs to be freed with the WhereClause) and TERM_VIRTUAL (because it |
| ** is a commuted copy of a prior term.) The original term has nChild=1 |
| ** and the copy has idxParent set to the index of the original term. |
| */ |
| static void exprAnalyze( |
| SrcList *pSrc, /* the FROM clause */ |
| WhereClause *pWC, /* the WHERE clause */ |
| int idxTerm /* Index of the term to be analyzed */ |
| ){ |
| WhereInfo *pWInfo = pWC->pWInfo; /* WHERE clause processing context */ |
| WhereTerm *pTerm; /* The term to be analyzed */ |
| WhereMaskSet *pMaskSet; /* Set of table index masks */ |
| Expr *pExpr; /* The expression to be analyzed */ |
| Bitmask prereqLeft; /* Prerequesites of the pExpr->pLeft */ |
| Bitmask prereqAll; /* Prerequesites of pExpr */ |
| Bitmask extraRight = 0; /* Extra dependencies on LEFT JOIN */ |
| Expr *pStr1 = 0; /* RHS of LIKE/GLOB operator */ |
| int isComplete = 0; /* RHS of LIKE/GLOB ends with wildcard */ |
| int noCase = 0; /* LIKE/GLOB distinguishes case */ |
| int op; /* Top-level operator. pExpr->op */ |
| Parse *pParse = pWInfo->pParse; /* Parsing context */ |
| sqlite3 *db = pParse->db; /* Database connection */ |
| |
| if( db->mallocFailed ){ |
| return; |
| } |
| pTerm = &pWC->a[idxTerm]; |
| pMaskSet = &pWInfo->sMaskSet; |
| pExpr = pTerm->pExpr; |
| assert( pExpr->op!=TK_AS && pExpr->op!=TK_COLLATE ); |
| prereqLeft = exprTableUsage(pMaskSet, pExpr->pLeft); |
| op = pExpr->op; |
| if( op==TK_IN ){ |
| assert( pExpr->pRight==0 ); |
| if( ExprHasProperty(pExpr, EP_xIsSelect) ){ |
| pTerm->prereqRight = exprSelectTableUsage(pMaskSet, pExpr->x.pSelect); |
| }else{ |
| pTerm->prereqRight = exprListTableUsage(pMaskSet, pExpr->x.pList); |
| } |
| }else if( op==TK_ISNULL ){ |
| pTerm->prereqRight = 0; |
| }else{ |
| pTerm->prereqRight = exprTableUsage(pMaskSet, pExpr->pRight); |
| } |
| prereqAll = exprTableUsage(pMaskSet, pExpr); |
| if( ExprHasProperty(pExpr, EP_FromJoin) ){ |
| Bitmask x = getMask(pMaskSet, pExpr->iRightJoinTable); |
| prereqAll |= x; |
| extraRight = x-1; /* ON clause terms may not be used with an index |
| ** on left table of a LEFT JOIN. Ticket #3015 */ |
| } |
| pTerm->prereqAll = prereqAll; |
| pTerm->leftCursor = -1; |
| pTerm->iParent = -1; |
| pTerm->eOperator = 0; |
| if( allowedOp(op) ){ |
| Expr *pLeft = sqlite3ExprSkipCollate(pExpr->pLeft); |
| Expr *pRight = sqlite3ExprSkipCollate(pExpr->pRight); |
| u16 opMask = (pTerm->prereqRight & prereqLeft)==0 ? WO_ALL : WO_EQUIV; |
| if( pLeft->op==TK_COLUMN ){ |
| pTerm->leftCursor = pLeft->iTable; |
| pTerm->u.leftColumn = pLeft->iColumn; |
| pTerm->eOperator = operatorMask(op) & opMask; |
| } |
| if( pRight && pRight->op==TK_COLUMN ){ |
| WhereTerm *pNew; |
| Expr *pDup; |
| u16 eExtraOp = 0; /* Extra bits for pNew->eOperator */ |
| if( pTerm->leftCursor>=0 ){ |
| int idxNew; |
| pDup = sqlite3ExprDup(db, pExpr, 0); |
| if( db->mallocFailed ){ |
| sqlite3ExprDelete(db, pDup); |
| return; |
| } |
| idxNew = whereClauseInsert(pWC, pDup, TERM_VIRTUAL|TERM_DYNAMIC); |
| if( idxNew==0 ) return; |
| pNew = &pWC->a[idxNew]; |
| pNew->iParent = idxTerm; |
| pTerm = &pWC->a[idxTerm]; |
| pTerm->nChild = 1; |
| pTerm->wtFlags |= TERM_COPIED; |
| if( pExpr->op==TK_EQ |
| && !ExprHasProperty(pExpr, EP_FromJoin) |
| && OptimizationEnabled(db, SQLITE_Transitive) |
| ){ |
| pTerm->eOperator |= WO_EQUIV; |
| eExtraOp = WO_EQUIV; |
| } |
| }else{ |
| pDup = pExpr; |
| pNew = pTerm; |
| } |
| exprCommute(pParse, pDup); |
| pLeft = sqlite3ExprSkipCollate(pDup->pLeft); |
| pNew->leftCursor = pLeft->iTable; |
| pNew->u.leftColumn = pLeft->iColumn; |
| testcase( (prereqLeft | extraRight) != prereqLeft ); |
| pNew->prereqRight = prereqLeft | extraRight; |
| pNew->prereqAll = prereqAll; |
| pNew->eOperator = (operatorMask(pDup->op) + eExtraOp) & opMask; |
| } |
| } |
| |
| #ifndef SQLITE_OMIT_BETWEEN_OPTIMIZATION |
| /* If a term is the BETWEEN operator, create two new virtual terms |
| ** that define the range that the BETWEEN implements. For example: |
| ** |
| ** a BETWEEN b AND c |
| ** |
| ** is converted into: |
| ** |
| ** (a BETWEEN b AND c) AND (a>=b) AND (a<=c) |
| ** |
| ** The two new terms are added onto the end of the WhereClause object. |
| ** The new terms are "dynamic" and are children of the original BETWEEN |
| ** term. That means that if the BETWEEN term is coded, the children are |
| ** skipped. Or, if the children are satisfied by an index, the original |
| ** BETWEEN term is skipped. |
| */ |
| else if( pExpr->op==TK_BETWEEN && pWC->op==TK_AND ){ |
| ExprList *pList = pExpr->x.pList; |
| int i; |
| static const u8 ops[] = {TK_GE, TK_LE}; |
| assert( pList!=0 ); |
| assert( pList->nExpr==2 ); |
| for(i=0; i<2; i++){ |
| Expr *pNewExpr; |
| int idxNew; |
| pNewExpr = sqlite3PExpr(pParse, ops[i], |
| sqlite3ExprDup(db, pExpr->pLeft, 0), |
| sqlite3ExprDup(db, pList->a[i].pExpr, 0), 0); |
| transferJoinMarkings(pNewExpr, pExpr); |
| idxNew = whereClauseInsert(pWC, pNewExpr, TERM_VIRTUAL|TERM_DYNAMIC); |
| testcase( idxNew==0 ); |
| exprAnalyze(pSrc, pWC, idxNew); |
| pTerm = &pWC->a[idxTerm]; |
| pWC->a[idxNew].iParent = idxTerm; |
| } |
| pTerm->nChild = 2; |
| } |
| #endif /* SQLITE_OMIT_BETWEEN_OPTIMIZATION */ |
| |
| #if !defined(SQLITE_OMIT_OR_OPTIMIZATION) && !defined(SQLITE_OMIT_SUBQUERY) |
| /* Analyze a term that is composed of two or more subterms connected by |
| ** an OR operator. |
| */ |
| else if( pExpr->op==TK_OR ){ |
| assert( pWC->op==TK_AND ); |
| exprAnalyzeOrTerm(pSrc, pWC, idxTerm); |
| pTerm = &pWC->a[idxTerm]; |
| } |
| #endif /* SQLITE_OMIT_OR_OPTIMIZATION */ |
| |
| #ifndef SQLITE_OMIT_LIKE_OPTIMIZATION |
| /* Add constraints to reduce the search space on a LIKE or GLOB |
| ** operator. |
| ** |
| ** A like pattern of the form "x LIKE 'abc%'" is changed into constraints |
| ** |
| ** x>='abc' AND x<'abd' AND x LIKE 'abc%' |
| ** |
| ** The last character of the prefix "abc" is incremented to form the |
| ** termination condition "abd". |
| */ |
| if( pWC->op==TK_AND |
| && isLikeOrGlob(pParse, pExpr, &pStr1, &isComplete, &noCase) |
| ){ |
| Expr *pLeft; /* LHS of LIKE/GLOB operator */ |
| Expr *pStr2; /* Copy of pStr1 - RHS of LIKE/GLOB operator */ |
| Expr *pNewExpr1; |
| Expr *pNewExpr2; |
| int idxNew1; |
| int idxNew2; |
| const char *zCollSeqName; /* Name of collating sequence */ |
| |
| pLeft = pExpr->x.pList->a[1].pExpr; |
| pStr2 = sqlite3ExprDup(db, pStr1, 0); |
| if( !db->mallocFailed ){ |
| u8 c, *pC; /* Last character before the first wildcard */ |
| pC = (u8*)&pStr2->u.zToken[sqlite3Strlen30(pStr2->u.zToken)-1]; |
| c = *pC; |
| if( noCase ){ |
| /* The point is to increment the last character before the first |
| ** wildcard. But if we increment '@', that will push it into the |
| ** alphabetic range where case conversions will mess up the |
| ** inequality. To avoid this, make sure to also run the full |
| ** LIKE on all candidate expressions by clearing the isComplete flag |
| */ |
| if( c=='A'-1 ) isComplete = 0; |
| c = sqlite3UpperToLower[c]; |
| } |
| *pC = c + 1; |
| } |
| zCollSeqName = noCase ? "NOCASE" : "BINARY"; |
| pNewExpr1 = sqlite3ExprDup(db, pLeft, 0); |
| pNewExpr1 = sqlite3PExpr(pParse, TK_GE, |
| sqlite3ExprAddCollateString(pParse,pNewExpr1,zCollSeqName), |
| pStr1, 0); |
| transferJoinMarkings(pNewExpr1, pExpr); |
| idxNew1 = whereClauseInsert(pWC, pNewExpr1, TERM_VIRTUAL|TERM_DYNAMIC); |
| testcase( idxNew1==0 ); |
| exprAnalyze(pSrc, pWC, idxNew1); |
| pNewExpr2 = sqlite3ExprDup(db, pLeft, 0); |
| pNewExpr2 = sqlite3PExpr(pParse, TK_LT, |
| sqlite3ExprAddCollateString(pParse,pNewExpr2,zCollSeqName), |
| pStr2, 0); |
| transferJoinMarkings(pNewExpr2, pExpr); |
| idxNew2 = whereClauseInsert(pWC, pNewExpr2, TERM_VIRTUAL|TERM_DYNAMIC); |
| testcase( idxNew2==0 ); |
| exprAnalyze(pSrc, pWC, idxNew2); |
| pTerm = &pWC->a[idxTerm]; |
| if( isComplete ){ |
| pWC->a[idxNew1].iParent = idxTerm; |
| pWC->a[idxNew2].iParent = idxTerm; |
| pTerm->nChild = 2; |
| } |
| } |
| #endif /* SQLITE_OMIT_LIKE_OPTIMIZATION */ |
| |
| #ifndef SQLITE_OMIT_VIRTUALTABLE |
| /* Add a WO_MATCH auxiliary term to the constraint set if the |
| ** current expression is of the form: column MATCH expr. |
| ** This information is used by the xBestIndex methods of |
| ** virtual tables. The native query optimizer does not attempt |
| ** to do anything with MATCH functions. |
| */ |
| if( isMatchOfColumn(pExpr) ){ |
| int idxNew; |
| Expr *pRight, *pLeft; |
| WhereTerm *pNewTerm; |
| Bitmask prereqColumn, prereqExpr; |
| |
| pRight = pExpr->x.pList->a[0].pExpr; |
| pLeft = pExpr->x.pList->a[1].pExpr; |
| prereqExpr = exprTableUsage(pMaskSet, pRight); |
| prereqColumn = exprTableUsage(pMaskSet, pLeft); |
| if( (prereqExpr & prereqColumn)==0 ){ |
| Expr *pNewExpr; |
| pNewExpr = sqlite3PExpr(pParse, TK_MATCH, |
| 0, sqlite3ExprDup(db, pRight, 0), 0); |
| idxNew = whereClauseInsert(pWC, pNewExpr, TERM_VIRTUAL|TERM_DYNAMIC); |
| testcase( idxNew==0 ); |
| pNewTerm = &pWC->a[idxNew]; |
| pNewTerm->prereqRight = prereqExpr; |
| pNewTerm->leftCursor = pLeft->iTable; |
| pNewTerm->u.leftColumn = pLeft->iColumn; |
| pNewTerm->eOperator = WO_MATCH; |
| pNewTerm->iParent = idxTerm; |
| pTerm = &pWC->a[idxTerm]; |
| pTerm->nChild = 1; |
| pTerm->wtFlags |= TERM_COPIED; |
| pNewTerm->prereqAll = pTerm->prereqAll; |
| } |
| } |
| #endif /* SQLITE_OMIT_VIRTUALTABLE */ |
| |
| #ifdef SQLITE_ENABLE_STAT3_OR_STAT4 |
| /* When sqlite_stat3 histogram data is available an operator of the |
| ** form "x IS NOT NULL" can sometimes be evaluated more efficiently |
| ** as "x>NULL" if x is not an INTEGER PRIMARY KEY. So construct a |
| ** virtual term of that form. |
| ** |
| ** Note that the virtual term must be tagged with TERM_VNULL. This |
| ** TERM_VNULL tag will suppress the not-null check at the beginning |
| ** of the loop. Without the TERM_VNULL flag, the not-null check at |
| ** the start of the loop will prevent any results from being returned. |
| */ |
| if( pExpr->op==TK_NOTNULL |
| && pExpr->pLeft->op==TK_COLUMN |
| && pExpr->pLeft->iColumn>=0 |
| && OptimizationEnabled(db, SQLITE_Stat3) |
| ){ |
| Expr *pNewExpr; |
| Expr *pLeft = pExpr->pLeft; |
| int idxNew; |
| WhereTerm *pNewTerm; |
| |
| pNewExpr = sqlite3PExpr(pParse, TK_GT, |
| sqlite3ExprDup(db, pLeft, 0), |
| sqlite3PExpr(pParse, TK_NULL, 0, 0, 0), 0); |
| |
| idxNew = whereClauseInsert(pWC, pNewExpr, |
| TERM_VIRTUAL|TERM_DYNAMIC|TERM_VNULL); |
| if( idxNew ){ |
| pNewTerm = &pWC->a[idxNew]; |
| pNewTerm->prereqRight = 0; |
| pNewTerm->leftCursor = pLeft->iTable; |
| pNewTerm->u.leftColumn = pLeft->iColumn; |
| pNewTerm->eOperator = WO_GT; |
| pNewTerm->iParent = idxTerm; |
| pTerm = &pWC->a[idxTerm]; |
| pTerm->nChild = 1; |
| pTerm->wtFlags |= TERM_COPIED; |
| pNewTerm->prereqAll = pTerm->prereqAll; |
| } |
| } |
| #endif /* SQLITE_ENABLE_STAT3_OR_STAT4 */ |
| |
| /* Prevent ON clause terms of a LEFT JOIN from being used to drive |
| ** an index for tables to the left of the join. |
| */ |
| pTerm->prereqRight |= extraRight; |
| } |
| |
| /* |
| ** 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 = sqlite3ExprSkipCollate(pList->a[i].pExpr); |
| if( p->op==TK_COLUMN |
| && p->iColumn==pIdx->aiColumn[iCol] |
| && p->iTable==iBase |
| ){ |
| CollSeq *pColl = sqlite3ExprCollSeq(pParse, pList->a[i].pExpr); |
| if( ALWAYS(pColl) && 0==sqlite3StrICmp(pColl->zName, zColl) ){ |
| return i; |
| } |
| } |
| } |
| |
| return -1; |
| } |
| |
| /* |
| ** Return true if the DISTINCT expression-list passed as the third argument |
| ** is redundant. |
| ** |
| ** A DISTINCT list is redundant if the database contains some subset of |
| ** columns that are unique and 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 = sqlite3ExprSkipCollate(pDistinct->a[i].pExpr); |
| if( p->op==TK_COLUMN && 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; |
| for(i=0; i<pIdx->nKeyCol; i++){ |
| i16 iCol = pIdx->aiColumn[i]; |
| if( 0==findTerm(pWC, iBase, iCol, ~(Bitmask)0, WO_EQ, pIdx) ){ |
| int iIdxCol = findIndexCol(pParse, pDistinct, iBase, pIdx, i); |
| if( iIdxCol<0 || pTab->aCol[iCol].notNull==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; |
| } |
| |
| /* |
| ** 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 TRACE_IDX_INPUTS(sqlite3_index_info *p){ |
| int i; |
| if( !sqlite3WhereTrace ) return; |
| for(i=0; i<p->nConstraint; i++){ |
| sqlite3DebugPrintf(" constraint[%d]: col=%d termid=%d op=%d usabled=%d\n", |
| i, |
| p->aConstraint[i].iColumn, |
| p->aConstraint[i].iTermOffset, |
| p->aConstraint[i].op, |
| p->aConstraint[i].usable); |
| } |
| 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 TRACE_IDX_OUTPUTS(sqlite3_index_info *p){ |
| int i; |
| if( !sqlite3WhereTrace ) 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 TRACE_IDX_INPUTS(A) |
| #define TRACE_IDX_OUTPUTS(A) |
| #endif |
| |
| #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( |
| WhereTerm *pTerm, /* WHERE clause term to check */ |
| struct SrcList_item *pSrc, /* Table we are trying to access */ |
| Bitmask notReady /* Tables in outer loops of the join */ |
| ){ |
| char aff; |
| if( pTerm->leftCursor!=pSrc->iCursor ) return 0; |
| if( (pTerm->eOperator & WO_EQ)==0 ) return 0; |
| if( (pTerm->prereqRight & notReady)!=0 ) return 0; |
| if( pTerm->u.leftColumn<0 ) return 0; |
| aff = pSrc->pTab->aCol[pTerm->u.leftColumn].affinity; |
| if( !sqlite3IndexAffinityOk(pTerm->pExpr, aff) ) return 0; |
| return 1; |
| } |
| #endif |
| |
| |
| #ifndef SQLITE_OMIT_AUTOMATIC_INDEX |
| /* |
| ** 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 void constructAutomaticIndex( |
| Parse *pParse, /* The parsing context */ |
| WhereClause *pWC, /* The WHERE clause */ |
| struct SrcList_item *pSrc, /* The FROM clause term to get the next index */ |
| 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 warnning has been issued */ |
| |
| /* 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 = sqlite3CodeOnce(pParse); VdbeCoverage(v); |
| |
| /* Count the number of columns that will be added to the index |
| ** and used to match WHERE clause constraints */ |
| nKeyCol = 0; |
| pTable = pSrc->pTab; |
| pWCEnd = &pWC->a[pWC->nTerm]; |
| pLoop = pLevel->pWLoop; |
| idxCols = 0; |
| for(pTerm=pWC->a; pTerm<pWCEnd; pTerm++){ |
| if( termCanDriveIndex(pTerm, pSrc, notReady) ){ |
| int iCol = pTerm->u.leftColumn; |
| Bitmask 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].zName); |
| sentWarning = 1; |
| } |
| if( (idxCols & cMask)==0 ){ |
| if( whereLoopResize(pParse->db, pLoop, nKeyCol+1) ) return; |
| pLoop->aLTerm[nKeyCol++] = pTerm; |
| idxCols |= cMask; |
| } |
| } |
| } |
| assert( nKeyCol>0 ); |
| 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. |
| */ |
| extraCols = pSrc->colUsed & (~idxCols | MASKBIT(BMS-1)); |
| mxBitCol = (pTable->nCol >= BMS-1) ? 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; |
| } |
| pLoop->wsFlags |= WHERE_COLUMN_EQ | WHERE_IDX_ONLY; |
| |
| /* Construct the Index object to describe this index */ |
| pIdx = sqlite3AllocateIndexObject(pParse->db, nKeyCol+1, 0, &zNotUsed); |
| if( pIdx==0 ) return; |
| 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 = pTerm->u.leftColumn; |
| Bitmask 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.leftColumn; |
| pColl = sqlite3BinaryCompareCollSeq(pParse, pX->pLeft, pX->pRight); |
| pIdx->azColl[n] = ALWAYS(pColl) ? pColl->zName : "BINARY"; |
| n++; |
| } |
| } |
| } |
| 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] = "BINARY"; |
| n++; |
| } |
| } |
| if( pSrc->colUsed & MASKBIT(BMS-1) ){ |
| for(i=BMS-1; i<pTable->nCol; i++){ |
| pIdx->aiColumn[n] = i; |
| pIdx->azColl[n] = "BINARY"; |
| n++; |
| } |
| } |
| assert( n==nKeyCol ); |
| pIdx->aiColumn[n] = -1; |
| pIdx->azColl[n] = "BINARY"; |
| |
| /* Create the automatic index */ |
| 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)); |
| |
| /* Fill the automatic index with content */ |
| addrTop = sqlite3VdbeAddOp1(v, OP_Rewind, pLevel->iTabCur); VdbeCoverage(v); |
| regRecord = sqlite3GetTempReg(pParse); |
| sqlite3GenerateIndexKey(pParse, pIdx, pLevel->iTabCur, regRecord, 0, 0, 0, 0); |
| sqlite3VdbeAddOp2(v, OP_IdxInsert, pLevel->iIdxCur, regRecord); |
| sqlite3VdbeChangeP5(v, OPFLAG_USESEEKRESULT); |
| 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); |
| } |
| #endif /* SQLITE_OMIT_AUTOMATIC_INDEX */ |
| |
| #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 sqlite3_free(). |
| */ |
| static sqlite3_index_info *allocateIndexInfo( |
| Parse *pParse, |
| WhereClause *pWC, |
| struct SrcList_item *pSrc, |
| ExprList *pOrderBy |
| ){ |
| int i, j; |
| int nTerm; |
| struct sqlite3_index_constraint *pIdxCons; |
| struct sqlite3_index_orderby *pIdxOrderBy; |
| struct sqlite3_index_constraint_usage *pUsage; |
| WhereTerm *pTerm; |
| int nOrderBy; |
| sqlite3_index_info *pIdxInfo; |
| |
| /* Count the number of possible WHERE clause constraints referring |
| ** to this virtual table */ |
| for(i=nTerm=0, pTerm=pWC->a; i<pWC->nTerm; i++, pTerm++){ |
| if( pTerm->leftCursor != pSrc->iCursor ) continue; |
| assert( IsPowerOfTwo(pTerm->eOperator & ~WO_EQUIV) ); |
| testcase( pTerm->eOperator & WO_IN ); |
| testcase( pTerm->eOperator & WO_ISNULL ); |
| testcase( pTerm->eOperator & WO_ALL ); |
| if( (pTerm->eOperator & ~(WO_ISNULL|WO_EQUIV))==0 ) continue; |
| if( pTerm->wtFlags & TERM_VNULL ) continue; |
| nTerm++; |
| } |
| |
| /* 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; |
| if( pExpr->op!=TK_COLUMN || pExpr->iTable!=pSrc->iCursor ) break; |
| } |
| if( i==n){ |
| nOrderBy = n; |
| } |
| } |
| |
| /* Allocate the sqlite3_index_info structure |
| */ |
| pIdxInfo = sqlite3DbMallocZero(pParse->db, sizeof(*pIdxInfo) |
| + (sizeof(*pIdxCons) + sizeof(*pUsage))*nTerm |
| + sizeof(*pIdxOrderBy)*nOrderBy ); |
| if( pIdxInfo==0 ){ |
| sqlite3ErrorMsg(pParse, "out of memory"); |
| return 0; |
| } |
| |
| /* Initialize the structure. The sqlite3_index_info structure contains |
| ** many fields that are declared "const" to prevent xBestIndex from |
| ** changing them. We have to do some funky casting in order to |
| ** initialize those fields. |
| */ |
| pIdxCons = (struct sqlite3_index_constraint*)&pIdxInfo[1]; |
| pIdxOrderBy = (struct sqlite3_index_orderby*)&pIdxCons[nTerm]; |
| pUsage = (struct sqlite3_index_constraint_usage*)&pIdxOrderBy[nOrderBy]; |
| *(int*)&pIdxInfo->nConstraint = nTerm; |
| *(int*)&pIdxInfo->nOrderBy = nOrderBy; |
| *(struct sqlite3_index_constraint**)&pIdxInfo->aConstraint = pIdxCons; |
| *(struct sqlite3_index_orderby**)&pIdxInfo->aOrderBy = pIdxOrderBy; |
| *(struct sqlite3_index_constraint_usage**)&pIdxInfo->aConstraintUsage = |
| pUsage; |
| |
| for(i=j=0, pTerm=pWC->a; i<pWC->nTerm; i++, pTerm++){ |
| u8 op; |
| if( pTerm->leftCursor != pSrc->iCursor ) continue; |
| assert( IsPowerOfTwo(pTerm->eOperator & ~WO_EQUIV) ); |
| testcase( pTerm->eOperator & WO_IN ); |
| testcase( pTerm->eOperator & WO_ISNULL ); |
| testcase( pTerm->eOperator & WO_ALL ); |
| if( (pTerm->eOperator & ~(WO_ISNULL|WO_EQUIV))==0 ) continue; |
| if( pTerm->wtFlags & TERM_VNULL ) continue; |
| pIdxCons[j].iColumn = pTerm->u.leftColumn; |
| pIdxCons[j].iTermOffset = i; |
| op = (u8)pTerm->eOperator & WO_ALL; |
| if( op==WO_IN ) op = WO_EQ; |
| pIdxCons[j].op = 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( WO_MATCH==SQLITE_INDEX_CONSTRAINT_MATCH ); |
| assert( pTerm->eOperator & (WO_IN|WO_EQ|WO_LT|WO_LE|WO_GT|WO_GE|WO_MATCH) ); |
| j++; |
| } |
| for(i=0; i<nOrderBy; i++){ |
| Expr *pExpr = pOrderBy->a[i].pExpr; |
| pIdxOrderBy[i].iColumn = pExpr->iColumn; |
| pIdxOrderBy[i].desc = pOrderBy->a[i].sortOrder; |
| } |
| |
| return 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 a |
| ** non-zero value is returned. Otherwise, 0 is returned and the output |
| ** part of the sqlite3_index_info structure is left populated. |
| ** |
| ** 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 i; |
| int rc; |
| |
| TRACE_IDX_INPUTS(p); |
| rc = pVtab->pModule->xBestIndex(pVtab, p); |
| TRACE_IDX_OUTPUTS(p); |
| |
| if( rc!=SQLITE_OK ){ |
| if( rc==SQLITE_NOMEM ){ |
| pParse->db->mallocFailed = 1; |
| }else if( !pVtab->zErrMsg ){ |
| sqlite3ErrorMsg(pParse, "%s", sqlite3ErrStr(rc)); |
| }else{ |
| sqlite3ErrorMsg(pParse, "%s", pVtab->zErrMsg); |
| } |
| } |
| sqlite3_free(pVtab->zErrMsg); |
| pVtab->zErrMsg = 0; |
| |
| for(i=0; i<p->nConstraint; i++){ |
| if( !p->aConstraint[i].usable && p->aConstraintUsage[i].argvIndex>0 ){ |
| sqlite3ErrorMsg(pParse, |
| "table %s: xBestIndex returned an invalid plan", pTab->zName); |
| } |
| } |
| |
| return pParse->nErr; |
| } |
| #endif /* !defined(SQLITE_OMIT_VIRTUALTABLE) */ |
| |
| |
| #ifdef SQLITE_ENABLE_STAT3_OR_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 pVal |
| ** aStat[1] Est. number of rows equal to pVal |
| ** |
| ** Return SQLITE_OK on success. |
| */ |
| static void 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 iMin = 0; /* Smallest sample not yet tested */ |
| int i = pIdx->nSample; /* Smallest sample larger than or equal to pRec */ |
| int iTest; /* Next sample to test */ |
| int res; /* Result of comparison operation */ |
| |
| #ifndef SQLITE_DEBUG |
| UNUSED_PARAMETER( pParse ); |
| #endif |
| assert( pRec!=0 ); |
| iCol = pRec->nField - 1; |
| assert( pIdx->nSample>0 ); |
| assert( pRec->nField>0 && iCol<pIdx->nSampleCol ); |
| do{ |
| iTest = (iMin+i)/2; |
| res = sqlite3VdbeRecordCompare(aSample[iTest].n, aSample[iTest].p, pRec); |
| if( res<0 ){ |
| iMin = iTest+1; |
| }else{ |
| i = iTest; |
| } |
| }while( res && iMin<i ); |
| |
| #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( res==0 ){ |
| /* If (res==0) is true, then sample $i must be equal to pRec */ |
| assert( i<pIdx->nSample ); |
| assert( 0==sqlite3VdbeRecordCompare(aSample[i].n, aSample[i].p, pRec) |
| || pParse->db->mallocFailed ); |
| }else{ |
| /* Otherwise, pRec must be smaller than sample $i and larger than |
| ** sample ($i-1). */ |
| assert( i==pIdx->nSample |
| || sqlite3VdbeRecordCompare(aSample[i].n, aSample[i].p, pRec)>0 |
| || pParse->db->mallocFailed ); |
| assert( i==0 |
| || sqlite3VdbeRecordCompare(aSample[i-1].n, aSample[i-1].p, pRec)<0 |
| || pParse->db->mallocFailed ); |
| } |
| #endif /* ifdef SQLITE_DEBUG */ |
| |
| /* At this point, aSample[i] is the first sample that is greater than |
| ** or equal to pVal. Or if i==pIdx->nSample, then all samples are less |
| ** than pVal. If aSample[i]==pVal, then res==0. |
| */ |
| if( res==0 ){ |
| aStat[0] = aSample[i].anLt[iCol]; |
| aStat[1] = aSample[i].anEq[iCol]; |
| }else{ |
| tRowcnt iLower, iUpper, iGap; |
| if( i==0 ){ |
| iLower = 0; |
| iUpper = aSample[0].anLt[iCol]; |
| }else{ |
| i64 nRow0 = sqlite3LogEstToInt(pIdx->aiRowLogEst[0]); |
| iUpper = i>=pIdx->nSample ? nRow0 : aSample[i].anLt[iCol]; |
| iLower = aSample[i-1].anEq[iCol] + aSample[i-1].anLt[iCol]; |
| } |
| aStat[1] = pIdx->aAvgEq[iCol]; |
| if( iLower>=iUpper ){ |
| iGap = 0; |
| }else{ |
| iGap = iUpper - iLower; |
| } |
| if( roundUp ){ |
| iGap = (iGap*2)/3; |
| }else{ |
| iGap = iGap/3; |
| } |
| aStat[0] = iLower + iGap; |
| } |
| } |
| #endif /* SQLITE_ENABLE_STAT3_OR_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_STAT3_OR_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 peformed 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; |
| int iCol = p->aiColumn[nEq]; |
| u8 aff = iCol>=0 ? p->pTable->aCol[iCol].affinity : SQLITE_AFF_INTEGER; |
| 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(0x10, ("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_STAT3_OR_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 index 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, this 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_STAT3_OR_STAT4 |
| Index *p = pLoop->u.btree.pIndex; |
| int nEq = pLoop->u.btree.nEq; |
| |
| if( p->nSample>0 |
| && nEq<p->nSampleCol |
| && OptimizationEnabled(pParse->db, SQLITE_Stat3) |
| ){ |
| if( nEq==pBuilder->nRecValid ){ |
| UnpackedRecord *pRec = pBuilder->pRec; |
| tRowcnt a[2]; |
| u8 aff; |
| |
| /* 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 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 $U is available, both values |
| ** of iUpper are requested of whereKeyStats() and the smaller used. |
| */ |
| tRowcnt iLower; |
| tRowcnt iUpper; |
| |
| if( pRec ){ |
| testcase( pRec->nField!=pBuilder->nRecValid ); |
| pRec->nField = pBuilder->nRecValid; |
| } |
| if( nEq==p->nKeyCol ){ |
| aff = SQLITE_AFF_INTEGER; |
| }else{ |
| aff = p->pTable->aCol[p->aiColumn[nEq]].affinity; |
| } |
| /* Determine iLower and iUpper using ($P) only. */ |
| if( nEq==0 ){ |
| iLower = 0; |
| iUpper = sqlite3LogEstToInt(p->aiRowLogEst[0]); |
| }else{ |
| /* Note: this call could be optimized away - since the same values must |
| ** have been requested when testing key $P in whereEqualScanEst(). */ |
| whereKeyStats(pParse, p, pRec, 0, a); |
| iLower = a[0]; |
| iUpper = a[0] + a[1]; |
| } |
| |
| assert( pLower==0 || (pLower->eOperator & (WO_GT|WO_GE))!=0 ); |
| assert( pUpper==0 || (pUpper->eOperator & (WO_LT|WO_LE))!=0 ); |
| assert( p->aSortOrder!=0 ); |
| if( p->aSortOrder[nEq] ){ |
| /* The roles of pLower and pUpper are swapped for a DESC index */ |
| SWAP(WhereTerm*, pLower, pUpper); |
| } |
| |
| /* If possible, improve on the iLower estimate using ($P:$L). */ |
| if( pLower ){ |
| int bOk; /* True if value is extracted from pExpr */ |
| Expr *pExpr = pLower->pExpr->pRight; |
| rc = sqlite3Stat4ProbeSetValue(pParse, p, &pRec, pExpr, aff, nEq, &bOk); |
| if( rc==SQLITE_OK && bOk ){ |
| tRowcnt iNew; |
| whereKeyStats(pParse, p, pRec, 0, a); |
| iNew = a[0] + ((pLower->eOperator & (WO_GT|WO_LE)) ? a[1] : 0); |
| if( iNew>iLower ) iLower = iNew; |
| nOut--; |
| pLower = 0; |
| } |
| } |
| |
| /* If possible, improve on the iUpper estimate using ($P:$U). */ |
| if( pUpper ){ |
| int bOk; /* True if value is extracted from pExpr */ |
| Expr *pExpr = pUpper->pExpr->pRight; |
| rc = sqlite3Stat4ProbeSetValue(pParse, p, &pRec, pExpr, aff, nEq, &bOk); |
| if( rc==SQLITE_OK && bOk ){ |
| tRowcnt iNew; |
| whereKeyStats(pParse, p, pRec, 1, a); |
| iNew = a[0] + ((pUpper->eOperator & (WO_GT|WO_LE)) ? 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); |
| }else{ |
| nNew = 10; assert( 10==sqlite3LogEst(2) ); |
| } |
| if( nNew<nOut ){ |
| nOut = nNew; |
| } |
| WHERETRACE(0x10, ("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 ); |
| nNew = whereRangeAdjust(pLower, nOut); |
| nNew = whereRangeAdjust(pUpper, nNew); |
| |
| /* TUNING: If there is both an upper and lower limit, 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 && pUpper ) 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(0x10,("Range scan lowers nOut from %d to %d\n", |
| pLoop->nOut, nOut)); |
| } |
| #endif |
| pLoop->nOut = (LogEst)nOut; |
| return rc; |
| } |
| |
| #ifdef SQLITE_ENABLE_STAT3_OR_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_stat3 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; |
| u8 aff; /* Column affinity */ |
| 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; |
| } |
| |
| aff = p->pTable->aCol[p->aiColumn[nEq-1]].affinity; |
| rc = sqlite3Stat4ProbeSetValue(pParse, p, &pRec, pExpr, aff, 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(0x10,("equality scan regions: %d\n", (int)a[1])); |
| *pnRow = a[1]; |
| |
| return rc; |
| } |
| #endif /* SQLITE_ENABLE_STAT3_OR_STAT4 */ |
| |
| #ifdef SQLITE_ENABLE_STAT3_OR_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 > nRow0 ) nRowEst = nRow0; |
| *pnRow = nRowEst; |
| WHERETRACE(0x10,("IN row estimate: est=%d\n", nRowEst)); |
| } |
| assert( pBuilder->nRecValid==nRecValid ); |
| return rc; |
| } |
| #endif /* SQLITE_ENABLE_STAT3_OR_STAT4 */ |
| |
| /* |
| ** Disable a term in the WHERE clause. Except, do not disable the term |
| ** if it controls a LEFT OUTER JOIN and it did not originate in the ON |
| ** or USING clause of that join. |
| ** |
| ** Consider the term t2.z='ok' in the following queries: |
| ** |
| ** (1) SELECT * FROM t1 LEFT JOIN t2 ON t1.a=t2.x WHERE t2.z='ok' |
| ** (2) SELECT * FROM t1 LEFT JOIN t2 ON t1.a=t2.x AND t2.z='ok' |
| ** (3) SELECT * FROM t1, t2 WHERE t1.a=t2.x AND t2.z='ok' |
| ** |
| ** The t2.z='ok' is disabled in the in (2) because it originates |
| ** in the ON clause. The term is disabled in (3) because it is not part |
| ** of a LEFT OUTER JOIN. In (1), the term is not disabled. |
| ** |
| ** Disabling a term causes that term to not be tested in the inner loop |
| ** of the join. Disabling is an optimization. When terms are satisfied |
| ** by indices, we disable them to prevent redundant tests in the inner |
| ** loop. We would get the correct results if nothing were ever disabled, |
| ** but joins might run a little slower. The trick is to disable as much |
| ** as we can without disabling too much. If we disabled in (1), we'd get |
| ** the wrong answer. See ticket #813. |
| */ |
| static void disableTerm(WhereLevel *pLevel, WhereTerm *pTerm){ |
| if( pTerm |
| && (pTerm->wtFlags & TERM_CODED)==0 |
| && (pLevel->iLeftJoin==0 || ExprHasProperty(pTerm->pExpr, EP_FromJoin)) |
| && (pLevel->notReady & pTerm->prereqAll)==0 |
| ){ |
| pTerm->wtFlags |= TERM_CODED; |
| if( pTerm->iParent>=0 ){ |
| WhereTerm *pOther = &pTerm->pWC->a[pTerm->iParent]; |
| if( (--pOther->nChild)==0 ){ |
| disableTerm(pLevel, pOther); |
| } |
| } |
| } |
| } |
| |
| /* |
| ** Code an OP_Affinity opcode to apply the column affinity string zAff |
| ** to the n registers starting at base. |
| ** |
| ** As an optimization, SQLITE_AFF_NONE entries (which are no-ops) at the |
| ** beginning and end of zAff are ignored. If all entries in zAff are |
| ** SQLITE_AFF_NONE, then no code gets generated. |
| ** |
| ** This routine makes its own copy of zAff so that the caller is free |
| ** to modify zAff after this routine returns. |
| */ |
| static void codeApplyAffinity(Parse *pParse, int base, int n, char *zAff){ |
| Vdbe *v = pParse->pVdbe; |
| if( zAff==0 ){ |
| assert( pParse->db->mallocFailed ); |
| return; |
| } |
| assert( v!=0 ); |
| |
| /* Adjust base and n to skip over SQLITE_AFF_NONE entries at the beginning |
| ** and end of the affinity string. |
| */ |
| while( n>0 && zAff[0]==SQLITE_AFF_NONE ){ |
| n--; |
| base++; |
| zAff++; |
| } |
| while( n>1 && zAff[n-1]==SQLITE_AFF_NONE ){ |
| n--; |
| } |
| |
| /* Code the OP_Affinity opcode if there is anything left to do. */ |
| if( n>0 ){ |
| sqlite3VdbeAddOp2(v, OP_Affinity, base, n); |
| sqlite3VdbeChangeP4(v, -1, zAff, n); |
| sqlite3ExprCacheAffinityChange(pParse, base, n); |
| } |
| } |
| |
| |
| /* |
| ** Generate code for a single equality term of the WHERE clause. An equality |
| ** term can be either X=expr or X IN (...). pTerm is the term to be |
| ** coded. |
| ** |
| ** The current value for the constraint is left in register iReg. |
| ** |
| ** For a constraint of the form X=expr, the expression is evaluated and its |
| ** result is left on the stack. For constraints of the form X IN (...) |
| ** this routine sets up a loop that will iterate over all values of X. |
| */ |
| static int codeEqualityTerm( |
| Parse *pParse, /* The parsing context */ |
| WhereTerm *pTerm, /* The term of the WHERE clause to be coded */ |
| WhereLevel *pLevel, /* The level of the FROM clause we are working on */ |
| int iEq, /* Index of the equality term within this level */ |
| int bRev, /* True for reverse-order IN operations */ |
| int iTarget /* Attempt to leave results in this register */ |
| ){ |
| Expr *pX = pTerm->pExpr; |
| Vdbe *v = pParse->pVdbe; |
| int iReg; /* Register holding results */ |
| |
| assert( iTarget>0 ); |
| if( pX->op==TK_EQ ){ |
| iReg = sqlite3ExprCodeTarget(pParse, pX->pRight, iTarget); |
| }else if( pX->op==TK_ISNULL ){ |
| iReg = iTarget; |
| sqlite3VdbeAddOp2(v, OP_Null, 0, iReg); |
| #ifndef SQLITE_OMIT_SUBQUERY |
| }else{ |
| int eType; |
| int iTab; |
| struct InLoop *pIn; |
| WhereLoop *pLoop = pLevel->pWLoop; |
| |
| if( (pLoop->wsFlags & WHERE_VIRTUALTABLE)==0 |
| && pLoop->u.btree.pIndex!=0 |
| && pLoop->u.btree.pIndex->aSortOrder[iEq] |
| ){ |
| testcase( iEq==0 ); |
| testcase( bRev ); |
| bRev = !bRev; |
| } |
| assert( pX->op==TK_IN ); |
| iReg = iTarget; |
| eType = sqlite3FindInIndex(pParse, pX, IN_INDEX_LOOP, 0); |
| if( eType==IN_INDEX_INDEX_DESC ){ |
| testcase( bRev ); |
| bRev = !bRev; |
| } |
| iTab = pX->iTable; |
| sqlite3VdbeAddOp2(v, bRev ? OP_Last : OP_Rewind, iTab, 0); |
| VdbeCoverageIf(v, bRev); |
| VdbeCoverageIf(v, !bRev); |
| assert( (pLoop->wsFlags & WHERE_MULTI_OR)==0 ); |
| pLoop->wsFlags |= WHERE_IN_ABLE; |
| if( pLevel->u.in.nIn==0 ){ |
| pLevel->addrNxt = sqlite3VdbeMakeLabel(v); |
| } |
| pLevel->u.in.nIn++; |
| pLevel->u.in.aInLoop = |
| sqlite3DbReallocOrFree(pParse->db, pLevel->u.in.aInLoop, |
| sizeof(pLevel->u.in.aInLoop[0])*pLevel->u.in.nIn); |
| pIn = pLevel->u.in.aInLoop; |
| if( pIn ){ |
| pIn += pLevel->u.in.nIn - 1; |
| pIn->iCur = iTab; |
| if( eType==IN_INDEX_ROWID ){ |
| pIn->addrInTop = sqlite3VdbeAddOp2(v, OP_Rowid, iTab, iReg); |
| }else{ |
| pIn->addrInTop = sqlite3VdbeAddOp3(v, OP_Column, iTab, 0, iReg); |
| } |
| pIn->eEndLoopOp = bRev ? OP_PrevIfOpen : OP_NextIfOpen; |
| sqlite3VdbeAddOp1(v, OP_IsNull, iReg); VdbeCoverage(v); |
| }else{ |
| pLevel->u.in.nIn = 0; |
| } |
| #endif |
| } |
| disableTerm(pLevel, pTerm); |
| return iReg; |
| } |
| |
| /* |
| ** Generate code that will evaluate all == and IN constraints for an |
| ** index scan. |
| ** |
| ** For example, consider table t1(a,b,c,d,e,f) with index i1(a,b,c). |
| ** Suppose the WHERE clause is this: a==5 AND b IN (1,2,3) AND c>5 AND c<10 |
| ** The index has as many as three equality constraints, but in this |
| ** example, the third "c" value is an inequality. So only two |
| ** constraints are coded. This routine will generate code to evaluate |
| ** a==5 and b IN (1,2,3). The current values for a and b will be stored |
| ** in consecutive registers and the index of the first register is returned. |
| ** |
| ** In the example above nEq==2. But this subroutine works for any value |
| ** of nEq including 0. If nEq==0, this routine is nearly a no-op. |
| ** The only thing it does is allocate the pLevel->iMem memory cell and |
| ** compute the affinity string. |
| ** |
| ** The nExtraReg parameter is 0 or 1. It is 0 if all WHERE clause constraints |
| ** are == or IN and are covered by the nEq. nExtraReg is 1 if there is |
| ** an inequality constraint (such as the "c>=5 AND c<10" in the example) that |
| ** occurs after the nEq quality constraints. |
| ** |
| ** This routine allocates a range of nEq+nExtraReg memory cells and returns |
| ** the index of the first memory cell in that range. The code that |
| ** calls this routine will use that memory range to store keys for |
| ** start and termination conditions of the loop. |
| ** key value of the loop. If one or more IN operators appear, then |
| ** this routine allocates an additional nEq memory cells for internal |
| ** use. |
| ** |
| ** Before returning, *pzAff is set to point to a buffer containing a |
| ** copy of the column affinity string of the index allocated using |
| ** sqlite3DbMalloc(). Except, entries in the copy of the string associated |
| ** with equality constraints that use NONE affinity are set to |
| ** SQLITE_AFF_NONE. This is to deal with SQL such as the following: |
| ** |
| ** CREATE TABLE t1(a TEXT PRIMARY KEY, b); |
| ** SELECT ... FROM t1 AS t2, t1 WHERE t1.a = t2.b; |
| ** |
| ** In the example above, the index on t1(a) has TEXT affinity. But since |
| ** the right hand side of the equality constraint (t2.b) has NONE affinity, |
| ** no conversion should be attempted before using a t2.b value as part of |
| ** a key to search the index. Hence the first byte in the returned affinity |
| ** string in this example would be set to SQLITE_AFF_NONE. |
| */ |
| static int codeAllEqualityTerms( |
| Parse *pParse, /* Parsing context */ |
| WhereLevel *pLevel, /* Which nested loop of the FROM we are coding */ |
| int bRev, /* Reverse the order of IN operators */ |
| int nExtraReg, /* Number of extra registers to allocate */ |
| char **pzAff /* OUT: Set to point to affinity string */ |
| ){ |
| u16 nEq; /* The number of == or IN constraints to code */ |
| u16 nSkip; /* Number of left-most columns to skip */ |
| Vdbe *v = pParse->pVdbe; /* The vm under construction */ |
| Index *pIdx; /* The index being used for this loop */ |
| WhereTerm *pTerm; /* A single constraint term */ |
| WhereLoop *pLoop; /* The WhereLoop object */ |
| int j; /* Loop counter */ |
| int regBase; /* Base register */ |
| int nReg; /* Number of registers to allocate */ |
| char *zAff; /* Affinity string to return */ |
| |
| /* This module is only called on query plans that use an index. */ |
| pLoop = pLevel->pWLoop; |
| assert( (pLoop->wsFlags & WHERE_VIRTUALTABLE)==0 ); |
| nEq = pLoop->u.btree.nEq; |
| nSkip = pLoop->u.btree.nSkip; |
| pIdx = pLoop->u.btree.pIndex; |
| assert( pIdx!=0 ); |
| |
| /* Figure out how many memory cells we will need then allocate them. |
| */ |
| regBase = pParse->nMem + 1; |
| nReg = pLoop->u.btree.nEq + nExtraReg; |
| pParse->nMem += nReg; |
| |
| zAff = sqlite3DbStrDup(pParse->db, sqlite3IndexAffinityStr(v, pIdx)); |
| if( !zAff ){ |
| pParse->db->mallocFailed = 1; |
| } |
| |
| if( nSkip ){ |
| int iIdxCur = pLevel->iIdxCur; |
| sqlite3VdbeAddOp1(v, (bRev?OP_Last:OP_Rewind), iIdxCur); |
| VdbeCoverageIf(v, bRev==0); |
| VdbeCoverageIf(v, bRev!=0); |
| VdbeComment((v, "begin skip-scan on %s", pIdx->zName)); |
| j = sqlite3VdbeAddOp0(v, OP_Goto); |
| pLevel->addrSkip = sqlite3VdbeAddOp4Int(v, (bRev?OP_SeekLT:OP_SeekGT), |
| iIdxCur, 0, regBase, nSkip); |
| VdbeCoverageIf(v, bRev==0); |
| VdbeCoverageIf(v, bRev!=0); |
| sqlite3VdbeJumpHere(v, j); |
| for(j=0; j<nSkip; j++){ |
| sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, j, regBase+j); |
| assert( pIdx->aiColumn[j]>=0 ); |
| VdbeComment((v, "%s", pIdx->pTable->aCol[pIdx->aiColumn[j]].zName)); |
| } |
| } |
| |
| /* Evaluate the equality constraints |
| */ |
| assert( zAff==0 || (int)strlen(zAff)>=nEq ); |
| for(j=nSkip; j<nEq; j++){ |
| int r1; |
| pTerm = pLoop->aLTerm[j]; |
| assert( pTerm!=0 ); |
| /* The following testcase is true for indices with redundant columns. |
| ** Ex: CREATE INDEX i1 ON t1(a,b,a); SELECT * FROM t1 WHERE a=0 AND b=0; */ |
| testcase( (pTerm->wtFlags & TERM_CODED)!=0 ); |
| testcase( pTerm->wtFlags & TERM_VIRTUAL ); |
| r1 = codeEqualityTerm(pParse, pTerm, pLevel, j, bRev, regBase+j); |
| if( r1!=regBase+j ){ |
| if( nReg==1 ){ |
| sqlite3ReleaseTempReg(pParse, regBase); |
| regBase = r1; |
| }else{ |
| sqlite3VdbeAddOp2(v, OP_SCopy, r1, regBase+j); |
| } |
| } |
| testcase( pTerm->eOperator & WO_ISNULL ); |
| testcase( pTerm->eOperator & WO_IN ); |
| if( (pTerm->eOperator & (WO_ISNULL|WO_IN))==0 ){ |
| Expr *pRight = pTerm->pExpr->pRight; |
| if( sqlite3ExprCanBeNull(pRight) ){ |
| sqlite3VdbeAddOp2(v, OP_IsNull, regBase+j, pLevel->addrBrk); |
| VdbeCoverage(v); |
| } |
| if( zAff ){ |
| if( sqlite3CompareAffinity(pRight, zAff[j])==SQLITE_AFF_NONE ){ |
| zAff[j] = SQLITE_AFF_NONE; |
| } |
| if( sqlite3ExprNeedsNoAffinityChange(pRight, zAff[j]) ){ |
| zAff[j] = SQLITE_AFF_NONE; |
| } |
| } |
| } |
| } |
| *pzAff = zAff; |
| return regBase; |
| } |
| |
| #ifndef SQLITE_OMIT_EXPLAIN |
| /* |
| ** This routine is a helper for explainIndexRange() below |
| ** |
| ** pStr holds the text of an expression that we are building up one term |
| ** at a time. This routine adds a new term to the end of the expression. |
| ** Terms are separated by AND so add the "AND" text for second and subsequent |
| ** terms only. |
| */ |
| static void explainAppendTerm( |
| StrAccum *pStr, /* The text expression being built */ |
| int iTerm, /* Index of this term. First is zero */ |
| const char *zColumn, /* Name of the column */ |
| const char *zOp /* Name of the operator */ |
| ){ |
| if( iTerm ) sqlite3StrAccumAppend(pStr, " AND ", 5); |
| sqlite3StrAccumAppendAll(pStr, zColumn); |
| sqlite3StrAccumAppend(pStr, zOp, 1); |
| sqlite3StrAccumAppend(pStr, "?", 1); |
| } |
| |
| /* |
| ** Argument pLevel describes a strategy for scanning table pTab. This |
| ** function appends text to pStr that describes the subset of table |
| ** rows scanned by the strategy in the form of an SQL expression. |
| ** |
| ** For example, if the query: |
| ** |
| ** SELECT * FROM t1 WHERE a=1 AND b>2; |
| ** |
| ** is run and there is an index on (a, b), then this function returns a |
| ** string similar to: |
| ** |
| ** "a=? AND b>?" |
| */ |
| static void explainIndexRange(StrAccum *pStr, WhereLoop *pLoop, Table *pTab){ |
| Index *pIndex = pLoop->u.btree.pIndex; |
| u16 nEq = pLoop->u.btree.nEq; |
| u16 nSkip = pLoop->u.btree.nSkip; |
| int i, j; |
| Column *aCol = pTab->aCol; |
| i16 *aiColumn = pIndex->aiColumn; |
| |
| if( nEq==0 && (pLoop->wsFlags&(WHERE_BTM_LIMIT|WHERE_TOP_LIMIT))==0 ) return; |
| sqlite3StrAccumAppend(pStr, " (", 2); |
| for(i=0; i<nEq; i++){ |
| char *z = aiColumn[i] < 0 ? "rowid" : aCol[aiColumn[i]].zName; |
| if( i>=nSkip ){ |
| explainAppendTerm(pStr, i, z, "="); |
| }else{ |
| if( i ) sqlite3StrAccumAppend(pStr, " AND ", 5); |
| sqlite3XPrintf(pStr, 0, "ANY(%s)", z); |
| } |
| } |
| |
| j = i; |
| if( pLoop->wsFlags&WHERE_BTM_LIMIT ){ |
| char *z = aiColumn[j] < 0 ? "rowid" : aCol[aiColumn[j]].zName; |
| explainAppendTerm(pStr, i++, z, ">"); |
| } |
| if( pLoop->wsFlags&WHERE_TOP_LIMIT ){ |
| char *z = aiColumn[j] < 0 ? "rowid" : aCol[aiColumn[j]].zName; |
| explainAppendTerm(pStr, i, z, "<"); |
| } |
| sqlite3StrAccumAppend(pStr, ")", 1); |
| } |
| |
| /* |
| ** This function is a no-op unless currently processing an EXPLAIN QUERY PLAN |
| ** command. If the query being compiled is an EXPLAIN QUERY PLAN, a single |
| ** record is added to the output to describe the table scan strategy in |
| ** pLevel. |
| */ |
| static void explainOneScan( |
| Parse *pParse, /* Parse context */ |
| SrcList *pTabList, /* Table list this loop refers to */ |
| WhereLevel *pLevel, /* Scan to write OP_Explain opcode for */ |
| int iLevel, /* Value for "level" column of output */ |
| int iFrom, /* Value for "from" column of output */ |
| u16 wctrlFlags /* Flags passed to sqlite3WhereBegin() */ |
| ){ |
| #ifndef SQLITE_DEBUG |
| if( pParse->explain==2 ) |
| #endif |
| { |
| struct SrcList_item *pItem = &pTabList->a[pLevel->iFrom]; |
| Vdbe *v = pParse->pVdbe; /* VM being constructed */ |
| sqlite3 *db = pParse->db; /* Database handle */ |
| int iId = pParse->iSelectId; /* Select id (left-most output column) */ |
| int isSearch; /* True for a SEARCH. False for SCAN. */ |
| WhereLoop *pLoop; /* The controlling WhereLoop object */ |
| u32 flags; /* Flags that describe this loop */ |
| char *zMsg; /* Text to add to EQP output */ |
| StrAccum str; /* EQP output string */ |
| char zBuf[100]; /* Initial space for EQP output string */ |
| |
| pLoop = pLevel->pWLoop; |
| flags = pLoop->wsFlags; |
| if( (flags&WHERE_MULTI_OR) || (wctrlFlags&WHERE_ONETABLE_ONLY) ) return; |
| |
| isSearch = (flags&(WHERE_BTM_LIMIT|WHERE_TOP_LIMIT))!=0 |
| || ((flags&WHERE_VIRTUALTABLE)==0 && (pLoop->u.btree.nEq>0)) |
| || (wctrlFlags&(WHERE_ORDERBY_MIN|WHERE_ORDERBY_MAX)); |
| |
| sqlite3StrAccumInit(&str, zBuf, sizeof(zBuf), SQLITE_MAX_LENGTH); |
| str.db = db; |
| sqlite3StrAccumAppendAll(&str, isSearch ? "SEARCH" : "SCAN"); |
| if( pItem->pSelect ){ |
| sqlite3XPrintf(&str, 0, " SUBQUERY %d", pItem->iSelectId); |
| }else{ |
| sqlite3XPrintf(&str, 0, " TABLE %s", pItem->zName); |
| } |
| |
| if( pItem->zAlias ){ |
| sqlite3XPrintf(&str, 0, " AS %s", pItem->zAlias); |
| } |
| if( (flags & (WHERE_IPK|WHERE_VIRTUALTABLE))==0 ){ |
| const char *zFmt = 0; |
| Index *pIdx; |
| |
| assert( pLoop->u.btree.pIndex!=0 ); |
| pIdx = pLoop->u.btree.pIndex; |
| assert( !(flags&WHERE_AUTO_INDEX) || (flags&WHERE_IDX_ONLY) ); |
| if( !HasRowid(pItem->pTab) && IsPrimaryKeyIndex(pIdx) ){ |
| if( isSearch ){ |
| zFmt = "PRIMARY KEY"; |
| } |
| }else if( flags & WHERE_AUTO_INDEX ){ |
| zFmt = "AUTOMATIC COVERING INDEX"; |
| }else if( flags & WHERE_IDX_ONLY ){ |
| zFmt = "COVERING INDEX %s"; |
| }else{ |
| zFmt = "INDEX %s"; |
| } |
| if( zFmt ){ |
| sqlite3StrAccumAppend(&str, " USING ", 7); |
| sqlite3XPrintf(&str, 0, zFmt, pIdx->zName); |
| explainIndexRange(&str, pLoop, pItem->pTab); |
| } |
| }else if( (flags & WHERE_IPK)!=0 && (flags & WHERE_CONSTRAINT)!=0 ){ |
| const char *zRange; |
| if( flags&(WHERE_COLUMN_EQ|WHERE_COLUMN_IN) ){ |
| zRange = "(rowid=?)"; |
| }else if( (flags&WHERE_BOTH_LIMIT)==WHERE_BOTH_LIMIT ){ |
| zRange = "(rowid>? AND rowid<?)"; |
| }else if( flags&WHERE_BTM_LIMIT ){ |
| zRange = "(rowid>?)"; |
| }else{ |
| assert( flags&WHERE_TOP_LIMIT); |
| zRange = "(rowid<?)"; |
| } |
| sqlite3StrAccumAppendAll(&str, " USING INTEGER PRIMARY KEY "); |
| sqlite3StrAccumAppendAll(&str, zRange); |
| } |
| #ifndef SQLITE_OMIT_VIRTUALTABLE |
| else if( (flags & WHERE_VIRTUALTABLE)!=0 ){ |
| sqlite3XPrintf(&str, 0, " VIRTUAL TABLE INDEX %d:%s", |
| pLoop->u.vtab.idxNum, pLoop->u.vtab.idxStr); |
| } |
| #endif |
| #ifdef SQLITE_EXPLAIN_ESTIMATED_ROWS |
| if( pLoop->nOut>=10 ){ |
| sqlite3XPrintf(&str, 0, " (~%llu rows)", sqlite3LogEstToInt(pLoop->nOut)); |
| }else{ |
| sqlite3StrAccumAppend(&str, " (~1 row)", 9); |
| } |
| #endif |
| zMsg = sqlite3StrAccumFinish(&str); |
| sqlite3VdbeAddOp4(v, OP_Explain, iId, iLevel, iFrom, zMsg, P4_DYNAMIC); |
| } |
| } |
| #else |
| # define explainOneScan(u,v,w,x,y,z) |
| #endif /* SQLITE_OMIT_EXPLAIN */ |
| |
| |
| /* |
| ** Generate code for the start of the iLevel-th loop in the WHERE clause |
| ** implementation described by pWInfo. |
| */ |
| static Bitmask codeOneLoopStart( |
| WhereInfo *pWInfo, /* Complete information about the WHERE clause */ |
| int iLevel, /* Which level of pWInfo->a[] should be coded */ |
| Bitmask notReady /* Which tables are currently available */ |
| ){ |
| int j, k; /* Loop counters */ |
| int iCur; /* The VDBE cursor for the table */ |
| int addrNxt; /* Where to jump to continue with the next IN case */ |
| int omitTable; /* True if we use the index only */ |
| int bRev; /* True if we need to scan in reverse order */ |
| WhereLevel *pLevel; /* The where level to be coded */ |
| WhereLoop *pLoop; /* The WhereLoop object being coded */ |
| WhereClause *pWC; /* Decomposition of the entire WHERE clause */ |
| WhereTerm *pTerm; /* A WHERE clause term */ |
| Parse *pParse; /* Parsing context */ |
| sqlite3 *db; /* Database connection */ |
| Vdbe *v; /* The prepared stmt under constructions */ |
| struct SrcList_item *pTabItem; /* FROM clause term being coded */ |
| int addrBrk; /* Jump here to break out of the loop */ |
| int addrCont; /* Jump here to continue with next cycle */ |
| int iRowidReg = 0; /* Rowid is stored in this register, if not zero */ |
| int iReleaseReg = 0; /* Temp register to free before returning */ |
| |
| pParse = pWInfo->pParse; |
| v = pParse->pVdbe; |
| pWC = &pWInfo->sWC; |
| db = pParse->db; |
| pLevel = &pWInfo->a[iLevel]; |
| pLoop = pLevel->pWLoop; |
| pTabItem = &pWInfo->pTabList->a[pLevel->iFrom]; |
| iCur = pTabItem->iCursor; |
| pLevel->notReady = notReady & ~getMask(&pWInfo->sMaskSet, iCur); |
| bRev = (pWInfo->revMask>>iLevel)&1; |
| omitTable = (pLoop->wsFlags & WHERE_IDX_ONLY)!=0 |
| && (pWInfo->wctrlFlags & WHERE_FORCE_TABLE)==0; |
| VdbeModuleComment((v, "Begin WHERE-loop%d: %s",iLevel,pTabItem->pTab->zName)); |
| |
| /* Create labels for the "break" and "continue" instructions |
| ** for the current loop. Jump to addrBrk to break out of a loop. |
| ** Jump to cont to go immediately to the next iteration of the |
| ** loop. |
| ** |
| ** When there is an IN operator, we also have a "addrNxt" label that |
| ** means to continue with the next IN value combination. When |
| ** there are no IN operators in the constraints, the "addrNxt" label |
| ** is the same as "addrBrk". |
| */ |
| addrBrk = pLevel->addrBrk = pLevel->addrNxt = sqlite3VdbeMakeLabel(v); |
| addrCont = pLevel->addrCont = sqlite3VdbeMakeLabel(v); |
| |
| /* If this is the right table of a LEFT OUTER JOIN, allocate and |
| ** initialize a memory cell that records if this table matches any |
| ** row of the left table of the join. |
| */ |
| if( pLevel->iFrom>0 && (pTabItem[0].jointype & JT_LEFT)!=0 ){ |
| pLevel->iLeftJoin = ++pParse->nMem; |
| sqlite3VdbeAddOp2(v, OP_Integer, 0, pLevel->iLeftJoin); |
| VdbeComment((v, "init LEFT JOIN no-match flag")); |
| } |
| |
| /* Special case of a FROM clause subquery implemented as a co-routine */ |
| if( pTabItem->viaCoroutine ){ |
| int regYield = pTabItem->regReturn; |
| sqlite3VdbeAddOp3(v, OP_InitCoroutine, regYield, 0, pTabItem->addrFillSub); |
| pLevel->p2 = sqlite3VdbeAddOp2(v, OP_Yield, regYield, addrBrk); |
| VdbeCoverage(v); |
| VdbeComment((v, "next row of \"%s\"", pTabItem->pTab->zName)); |
| pLevel->op = OP_Goto; |
| }else |
| |
| #ifndef SQLITE_OMIT_VIRTUALTABLE |
| if( (pLoop->wsFlags & WHERE_VIRTUALTABLE)!=0 ){ |
| /* Case 1: The table is a virtual-table. Use the VFilter and VNext |
| ** to access the data. |
| */ |
| int iReg; /* P3 Value for OP_VFilter */ |
| int addrNotFound; |
| int nConstraint = pLoop->nLTerm; |
| |
| sqlite3ExprCachePush(pParse); |
| iReg = sqlite3GetTempRange(pParse, nConstraint+2); |
| addrNotFound = pLevel->addrBrk; |
| for(j=0; j<nConstraint; j++){ |
| int iTarget = iReg+j+2; |
| pTerm = pLoop->aLTerm[j]; |
| if( pTerm==0 ) continue; |
| if( pTerm->eOperator & WO_IN ){ |
| codeEqualityTerm(pParse, pTerm, pLevel, j, bRev, iTarget); |
| addrNotFound = pLevel->addrNxt; |
| }else{ |
| sqlite3ExprCode(pParse, pTerm->pExpr->pRight, iTarget); |
| } |
| } |
| sqlite3VdbeAddOp2(v, OP_Integer, pLoop->u.vtab.idxNum, iReg); |
| sqlite3VdbeAddOp2(v, OP_Integer, nConstraint, iReg+1); |
| sqlite3VdbeAddOp4(v, OP_VFilter, iCur, addrNotFound, iReg, |
| pLoop->u.vtab.idxStr, |
| pLoop->u.vtab.needFree ? P4_MPRINTF : P4_STATIC); |
| VdbeCoverage(v); |
| pLoop->u.vtab.needFree = 0; |
| for(j=0; j<nConstraint && j<16; j++){ |
| if( (pLoop->u.vtab.omitMask>>j)&1 ){ |
| disableTerm(pLevel, pLoop->aLTerm[j]); |
| } |
| } |
| pLevel->op = OP_VNext; |
| pLevel->p1 = iCur; |
| pLevel->p2 = sqlite3VdbeCurrentAddr(v); |
| sqlite3ReleaseTempRange(pParse, iReg, nConstraint+2); |
| sqlite3ExprCachePop(pParse); |
| }else |
| #endif /* SQLITE_OMIT_VIRTUALTABLE */ |
| |
| if( (pLoop->wsFlags & WHERE_IPK)!=0 |
| && (pLoop->wsFlags & (WHERE_COLUMN_IN|WHERE_COLUMN_EQ))!=0 |
| ){ |
| /* Case 2: We can directly reference a single row using an |
| ** equality comparison against the ROWID field. Or |
| ** we reference multiple rows using a "rowid IN (...)" |
| ** construct. |
| */ |
| assert( pLoop->u.btree.nEq==1 ); |
| pTerm = pLoop->aLTerm[0]; |
| assert( pTerm!=0 ); |
| assert( pTerm->pExpr!=0 ); |
| assert( omitTable==0 ); |
| testcase( pTerm->wtFlags & TERM_VIRTUAL ); |
| iReleaseReg = ++pParse->nMem; |
| iRowidReg = codeEqualityTerm(pParse, pTerm, pLevel, 0, bRev, iReleaseReg); |
| if( iRowidReg!=iReleaseReg ) sqlite3ReleaseTempReg(pParse, iReleaseReg); |
| addrNxt = pLevel->addrNxt; |
| sqlite3VdbeAddOp2(v, OP_MustBeInt, iRowidReg, addrNxt); VdbeCoverage(v); |
| sqlite3VdbeAddOp3(v, OP_NotExists, iCur, addrNxt, iRowidReg); |
| VdbeCoverage(v); |
| sqlite3ExprCacheAffinityChange(pParse, iRowidReg, 1); |
| sqlite3ExprCacheStore(pParse, iCur, -1, iRowidReg); |
| VdbeComment((v, "pk")); |
| pLevel->op = OP_Noop; |
| }else if( (pLoop->wsFlags & WHERE_IPK)!=0 |
| && (pLoop->wsFlags & WHERE_COLUMN_RANGE)!=0 |
| ){ |
| /* Case 3: We have an inequality comparison against the ROWID field. |
| */ |
| int testOp = OP_Noop; |
| int start; |
| int memEndValue = 0; |
| WhereTerm *pStart, *pEnd; |
| |
| assert( omitTable==0 ); |
| j = 0; |
| pStart = pEnd = 0; |
| if( pLoop->wsFlags & WHERE_BTM_LIMIT ) pStart = pLoop->aLTerm[j++]; |
| if( pLoop->wsFlags & WHERE_TOP_LIMIT ) pEnd = pLoop->aLTerm[j++]; |
| assert( pStart!=0 || pEnd!=0 ); |
| if( bRev ){ |
| pTerm = pStart; |
| pStart = pEnd; |
| pEnd = pTerm; |
| } |
| if( pStart ){ |
| Expr *pX; /* The expression that defines the start bound */ |
| int r1, rTemp; /* Registers for holding the start boundary */ |
| |
| /* The following constant maps TK_xx codes into corresponding |
| ** seek opcodes. It depends on a particular ordering of TK_xx |
| */ |
| const u8 aMoveOp[] = { |
| /* TK_GT */ OP_SeekGT, |
| /* TK_LE */ OP_SeekLE, |
| /* TK_LT */ OP_SeekLT, |
| /* TK_GE */ OP_SeekGE |
| }; |
| assert( TK_LE==TK_GT+1 ); /* Make sure the ordering.. */ |
| assert( TK_LT==TK_GT+2 ); /* ... of the TK_xx values... */ |
| assert( TK_GE==TK_GT+3 ); /* ... is correcct. */ |
| |
| assert( (pStart->wtFlags & TERM_VNULL)==0 ); |
| testcase( pStart->wtFlags & TERM_VIRTUAL ); |
| pX = pStart->pExpr; |
| assert( pX!=0 ); |
| testcase( pStart->leftCursor!=iCur ); /* transitive constraints */ |
| r1 = sqlite3ExprCodeTemp(pParse, pX->pRight, &rTemp); |
| sqlite3VdbeAddOp3(v, aMoveOp[pX->op-TK_GT], iCur, addrBrk, r1); |
| VdbeComment((v, "pk")); |
| VdbeCoverageIf(v, pX->op==TK_GT); |
| VdbeCoverageIf(v, pX->op==TK_LE); |
| VdbeCoverageIf(v, pX->op==TK_LT); |
| VdbeCoverageIf(v, pX->op==TK_GE); |
| sqlite3ExprCacheAffinityChange(pParse, r1, 1); |
| sqlite3ReleaseTempReg(pParse, rTemp); |
| disableTerm(pLevel, pStart); |
| }else{ |
| sqlite3VdbeAddOp2(v, bRev ? OP_Last : OP_Rewind, iCur, addrBrk); |
| VdbeCoverageIf(v, bRev==0); |
| VdbeCoverageIf(v, bRev!=0); |
| } |
| if( pEnd ){ |
| Expr *pX; |
| pX = pEnd->pExpr; |
| assert( pX!=0 ); |
| assert( (pEnd->wtFlags & TERM_VNULL)==0 ); |
| testcase( pEnd->leftCursor!=iCur ); /* Transitive constraints */ |
| testcase( pEnd->wtFlags & TERM_VIRTUAL ); |
| memEndValue = ++pParse->nMem; |
| sqlite3ExprCode(pParse, pX->pRight, memEndValue); |
| if( pX->op==TK_LT || pX->op==TK_GT ){ |
| testOp = bRev ? OP_Le : OP_Ge; |
| }else{ |
| testOp = bRev ? OP_Lt : OP_Gt; |
| } |
| disableTerm(pLevel, pEnd); |
| } |
| start = sqlite3VdbeCurrentAddr(v); |
| pLevel->op = bRev ? OP_Prev : OP_Next; |
| pLevel->p1 = iCur; |
| pLevel->p2 = start; |
| assert( pLevel->p5==0 ); |
| if( testOp!=OP_Noop ){ |
| iRowidReg = ++pParse->nMem; |
| sqlite3VdbeAddOp2(v, OP_Rowid, iCur, iRowidReg); |
| sqlite3ExprCacheStore(pParse, iCur, -1, iRowidReg); |
| sqlite3VdbeAddOp3(v, testOp, memEndValue, addrBrk, iRowidReg); |
| VdbeCoverageIf(v, testOp==OP_Le); |
| VdbeCoverageIf(v, testOp==OP_Lt); |
| VdbeCoverageIf(v, testOp==OP_Ge); |
| VdbeCoverageIf(v, testOp==OP_Gt); |
| sqlite3VdbeChangeP5(v, SQLITE_AFF_NUMERIC | SQLITE_JUMPIFNULL); |
| } |
| }else if( pLoop->wsFlags & WHERE_INDEXED ){ |
| /* Case 4: A scan using an index. |
| ** |
| ** The WHERE clause may contain zero or more equality |
| ** terms ("==" or "IN" operators) that refer to the N |
| ** left-most columns of the index. It may also contain |
| ** inequality constraints (>, <, >= or <=) on the indexed |
| ** column that immediately follows the N equalities. Only |
| ** the right-most column can be an inequality - the rest must |
| ** use the "==" and "IN" operators. For example, if the |
| ** index is on (x,y,z), then the following clauses are all |
| ** optimized: |
| ** |
| ** x=5 |
| ** x=5 AND y=10 |
| ** x=5 AND y<10 |
| ** x=5 AND y>5 AND y<10 |
| ** x=5 AND y=5 AND z<=10 |
| ** |
| ** The z<10 term of the following cannot be used, only |
| ** the x=5 term: |
| ** |
| ** x=5 AND z<10 |
| ** |
| ** N may be zero if there are inequality constraints. |
| ** If there are no inequality constraints, then N is at |
| ** least one. |
| ** |
| ** This case is also used when there are no WHERE clause |
| ** constraints but an index is selected anyway, in order |
| ** to force the output order to conform to an ORDER BY. |
| */ |
| static const u8 aStartOp[] = { |
| 0, |
| 0, |
| OP_Rewind, /* 2: (!start_constraints && startEq && !bRev) */ |
| OP_Last, /* 3: (!start_constraints && startEq && bRev) */ |
| OP_SeekGT, /* 4: (start_constraints && !startEq && !bRev) */ |
| OP_SeekLT, /* 5: (start_constraints && !startEq && bRev) */ |
| OP_SeekGE, /* 6: (start_constraints && startEq && !bRev) */ |
| OP_SeekLE /* 7: (start_constraints && startEq && bRev) */ |
| }; |
| static const u8 aEndOp[] = { |
| OP_IdxGE, /* 0: (end_constraints && !bRev && !endEq) */ |
| OP_IdxGT, /* 1: (end_constraints && !bRev && endEq) */ |
| OP_IdxLE, /* 2: (end_constraints && bRev && !endEq) */ |
| OP_IdxLT, /* 3: (end_constraints && bRev && endEq) */ |
| }; |
| u16 nEq = pLoop->u.btree.nEq; /* Number of == or IN terms */ |
| int regBase; /* Base register holding constraint values */ |
| WhereTerm *pRangeStart = 0; /* Inequality constraint at range start */ |
| WhereTerm *pRangeEnd = 0; /* Inequality constraint at range end */ |
| int startEq; /* True if range start uses ==, >= or <= */ |
| int endEq; /* True if range end uses ==, >= or <= */ |
| int start_constraints; /* Start of range is constrained */ |
| int nConstraint; /* Number of constraint terms */ |
| Index *pIdx; /* The index we will be using */ |
| int iIdxCur; /* The VDBE cursor for the index */ |
| int nExtraReg = 0; /* Number of extra registers needed */ |
| int op; /* Instruction opcode */ |
| char *zStartAff; /* Affinity for start of range constraint */ |
| char cEndAff = 0; /* Affinity for end of range constraint */ |
| u8 bSeekPastNull = 0; /* True to seek past initial nulls */ |
| u8 bStopAtNull = 0; /* Add condition to terminate at NULLs */ |
| |
| pIdx = pLoop->u.btree.pIndex; |
| iIdxCur = pLevel->iIdxCur; |
| assert( nEq>=pLoop->u.btree.nSkip ); |
| |
| /* If this loop satisfies a sort order (pOrderBy) request that |
| ** was passed to this function to implement a "SELECT min(x) ..." |
| ** query, then the caller will only allow the loop to run for |
| ** a single iteration. This means that the first row returned |
| ** should not have a NULL value stored in 'x'. If column 'x' is |
| ** the first one after the nEq equality constraints in the index, |
| ** this requires some special handling. |
| */ |
| assert( pWInfo->pOrderBy==0 |
| || pWInfo->pOrderBy->nExpr==1 |
| || (pWInfo->wctrlFlags&WHERE_ORDERBY_MIN)==0 ); |
| if( (pWInfo->wctrlFlags&WHERE_ORDERBY_MIN)!=0 |
| && pWInfo->nOBSat>0 |
| && (pIdx->nKeyCol>nEq) |
| ){ |
| assert( pLoop->u.btree.nSkip==0 ); |
| bSeekPastNull = 1; |
| nExtraReg = 1; |
| } |
| |
| /* Find any inequality constraint terms for the start and end |
| ** of the range. |
| */ |
| j = nEq; |
| if( pLoop->wsFlags & WHERE_BTM_LIMIT ){ |
| pRangeStart = pLoop->aLTerm[j++]; |
| nExtraReg = 1; |
| } |
| if( pLoop->wsFlags & WHERE_TOP_LIMIT ){ |
| pRangeEnd = pLoop->aLTerm[j++]; |
| nExtraReg = 1; |
| if( pRangeStart==0 |
| && (j = pIdx->aiColumn[nEq])>=0 |
| && pIdx->pTable->aCol[j].notNull==0 |
| ){ |
| bSeekPastNull = 1; |
| } |
| } |
| assert( pRangeEnd==0 || (pRangeEnd->wtFlags & TERM_VNULL)==0 ); |
| |
| /* Generate code to evaluate all constraint terms using == or IN |
| ** and store the values of those terms in an array of registers |
| ** starting at regBase. |
| */ |
| regBase = codeAllEqualityTerms(pParse,pLevel,bRev,nExtraReg,&zStartAff); |
| assert( zStartAff==0 || sqlite3Strlen30(zStartAff)>=nEq ); |
| if( zStartAff ) cEndAff = zStartAff[nEq]; |
| addrNxt = pLevel->addrNxt; |
| |
| /* If we are doing a reverse order scan on an ascending index, or |
| ** a forward order scan on a descending index, interchange the |
| ** start and end terms (pRangeStart and pRangeEnd). |
| */ |
| if( (nEq<pIdx->nKeyCol && bRev==(pIdx->aSortOrder[nEq]==SQLITE_SO_ASC)) |
| || (bRev && pIdx->nKeyCol==nEq) |
| ){ |
| SWAP(WhereTerm *, pRangeEnd, pRangeStart); |
| SWAP(u8, bSeekPastNull, bStopAtNull); |
| } |
| |
| testcase( pRangeStart && (pRangeStart->eOperator & WO_LE)!=0 ); |
| testcase( pRangeStart && (pRangeStart->eOperator & WO_GE)!=0 ); |
| testcase( pRangeEnd && (pRangeEnd->eOperator & WO_LE)!=0 ); |
| testcase( pRangeEnd && (pRangeEnd->eOperator & WO_GE)!=0 ); |
| startEq = !pRangeStart || pRangeStart->eOperator & (WO_LE|WO_GE); |
| endEq = !pRangeEnd || pRangeEnd->eOperator & (WO_LE|WO_GE); |
| start_constraints = pRangeStart || nEq>0; |
| |
| /* Seek the index cursor to the start of the range. */ |
| nConstraint = nEq; |
| if( pRangeStart ){ |
| Expr *pRight = pRangeStart->pExpr->pRight; |
| sqlite3ExprCode(pParse, pRight, regBase+nEq); |
| if( (pRangeStart->wtFlags & TERM_VNULL)==0 |
| && sqlite3ExprCanBeNull(pRight) |
| ){ |
| sqlite3VdbeAddOp2(v, OP_IsNull, regBase+nEq, addrNxt); |
| VdbeCoverage(v); |
| } |
| if( zStartAff ){ |
| if( sqlite3CompareAffinity(pRight, zStartAff[nEq])==SQLITE_AFF_NONE){ |
| /* Since the comparison is to be performed with no conversions |
| ** applied to the operands, set the affinity to apply to pRight to |
| ** SQLITE_AFF_NONE. */ |
| zStartAff[nEq] = SQLITE_AFF_NONE; |
| } |
| if( sqlite3ExprNeedsNoAffinityChange(pRight, zStartAff[nEq]) ){ |
| zStartAff[nEq] = SQLITE_AFF_NONE; |
| } |
| } |
| nConstraint++; |
| testcase( pRangeStart->wtFlags & TERM_VIRTUAL ); |
| }else if( bSeekPastNull ){ |
| sqlite3VdbeAddOp2(v, OP_Null, 0, regBase+nEq); |
| nConstraint++; |
| startEq = 0; |
| start_constraints = 1; |
| } |
| codeApplyAffinity(pParse, regBase, nConstraint - bSeekPastNull, zStartAff); |
| op = aStartOp[(start_constraints<<2) + (startEq<<1) + bRev]; |
| assert( op!=0 ); |
| sqlite3VdbeAddOp4Int(v, op, iIdxCur, addrNxt, regBase, nConstraint); |
| VdbeCoverage(v); |
| VdbeCoverageIf(v, op==OP_Rewind); testcase( op==OP_Rewind ); |
| VdbeCoverageIf(v, op==OP_Last); testcase( op==OP_Last ); |
| VdbeCoverageIf(v, op==OP_SeekGT); testcase( op==OP_SeekGT ); |
| VdbeCoverageIf(v, op==OP_SeekGE); testcase( op==OP_SeekGE ); |
| VdbeCoverageIf(v, op==OP_SeekLE); testcase( op==OP_SeekLE ); |
| VdbeCoverageIf(v, op==OP_SeekLT); testcase( op==OP_SeekLT ); |
| |
| /* Load the value for the inequality constraint at the end of the |
| ** range (if any). |
| */ |
| nConstraint = nEq; |
| if( pRangeEnd ){ |
| Expr *pRight = pRangeEnd->pExpr->pRight; |
| sqlite3ExprCacheRemove(pParse, regBase+nEq, 1); |
| sqlite3ExprCode(pParse, pRight, regBase+nEq); |
| if( (pRangeEnd->wtFlags & TERM_VNULL)==0 |
| && sqlite3ExprCanBeNull(pRight) |
| ){ |
| sqlite3VdbeAddOp2(v, OP_IsNull, regBase+nEq, addrNxt); |
| VdbeCoverage(v); |
| } |
| if( sqlite3CompareAffinity(pRight, cEndAff)!=SQLITE_AFF_NONE |
| && !sqlite3ExprNeedsNoAffinityChange(pRight, cEndAff) |
| ){ |
| codeApplyAffinity(pParse, regBase+nEq, 1, &cEndAff); |
| } |
| nConstraint++; |
| testcase( pRangeEnd->wtFlags & TERM_VIRTUAL ); |
| }else if( bStopAtNull ){ |
| sqlite3VdbeAddOp2(v, OP_Null, 0, regBase+nEq); |
| endEq = 0; |
| nConstraint++; |
| } |
| sqlite3DbFree(db, zStartAff); |
| |
| /* Top of the loop body */ |
| pLevel->p2 = sqlite3VdbeCurrentAddr(v); |
| |
| /* Check if the index cursor is past the end of the range. */ |
| if( nConstraint ){ |
| op = aEndOp[bRev*2 + endEq]; |
| sqlite3VdbeAddOp4Int(v, op, iIdxCur, addrNxt, regBase, nConstraint); |
| testcase( op==OP_IdxGT ); VdbeCoverageIf(v, op==OP_IdxGT ); |
| testcase( op==OP_IdxGE ); VdbeCoverageIf(v, op==OP_IdxGE ); |
| testcase( op==OP_IdxLT ); VdbeCoverageIf(v, op==OP_IdxLT ); |
| testcase( op==OP_IdxLE ); VdbeCoverageIf(v, op==OP_IdxLE ); |
| } |
| |
| /* Seek the table cursor, if required */ |
| disableTerm(pLevel, pRangeStart); |
| disableTerm(pLevel, pRangeEnd); |
| if( omitTable ){ |
| /* pIdx is a covering index. No need to access the main table. */ |
| }else if( HasRowid(pIdx->pTable) ){ |
| iRowidReg = ++pParse->nMem; |
| sqlite3VdbeAddOp2(v, OP_IdxRowid, iIdxCur, iRowidReg); |
| sqlite3ExprCacheStore(pParse, iCur, -1, iRowidReg); |
| sqlite3VdbeAddOp2(v, OP_Seek, iCur, iRowidReg); /* Deferred seek */ |
| }else if( iCur!=iIdxCur ){ |
| Index *pPk = sqlite3PrimaryKeyIndex(pIdx->pTable); |
| iRowidReg = sqlite3GetTempRange(pParse, pPk->nKeyCol); |
| for(j=0; j<pPk->nKeyCol; j++){ |
| k = sqlite3ColumnOfIndex(pIdx, pPk->aiColumn[j]); |
| sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, k, iRowidReg+j); |
| } |
| sqlite3VdbeAddOp4Int(v, OP_NotFound, iCur, addrCont, |
| iRowidReg, pPk->nKeyCol); VdbeCoverage(v); |
| } |
| |
| /* Record the instruction used to terminate the loop. Disable |
| ** WHERE clause terms made redundant by the index range scan. |
| */ |
| if( pLoop->wsFlags & WHERE_ONEROW ){ |
| pLevel->op = OP_Noop; |
| }else if( bRev ){ |
| pLevel->op = OP_Prev; |
| }else{ |
| pLevel->op = OP_Next; |
| } |
| pLevel->p1 = iIdxCur; |
| pLevel->p3 = (pLoop->wsFlags&WHERE_UNQ_WANTED)!=0 ? 1:0; |
| if( (pLoop->wsFlags & WHERE_CONSTRAINT)==0 ){ |
| pLevel->p5 = SQLITE_STMTSTATUS_FULLSCAN_STEP; |
| }else{ |
| assert( pLevel->p5==0 ); |
| } |
| }else |
| |
| #ifndef SQLITE_OMIT_OR_OPTIMIZATION |
| if( pLoop->wsFlags & WHERE_MULTI_OR ){ |
| /* Case 5: Two or more separately indexed terms connected by OR |
| ** |
| ** Example: |
| ** |
| ** CREATE TABLE t1(a,b,c,d); |
| ** CREATE INDEX i1 ON t1(a); |
| ** CREATE INDEX i2 ON t1(b); |
| ** CREATE INDEX i3 ON t1(c); |
| ** |
| ** SELECT * FROM t1 WHERE a=5 OR b=7 OR (c=11 AND d=13) |
| ** |
| ** In the example, there are three indexed terms connected by OR. |
| ** The top of the loop looks like this: |
| ** |
| ** Null 1 # Zero the rowset in reg 1 |
| ** |
| ** Then, for each indexed term, the following. The arguments to |
| ** RowSetTest are such that the rowid of the current row is inserted |
| ** into the RowSet. If it is already present, control skips the |
| ** Gosub opcode and jumps straight to the code generated by WhereEnd(). |
| ** |
| ** sqlite3WhereBegin(<term>) |
| ** RowSetTest # Insert rowid into rowset |
| ** Gosub 2 A |
| ** sqlite3WhereEnd() |
| ** |
| ** Following the above, code to terminate the loop. Label A, the target |
| ** of the Gosub above, jumps to the instruction right after the Goto. |
| ** |
| ** Null 1 # Zero the rowset in reg 1 |
| ** Goto B # The loop is finished. |
| ** |
| ** A: <loop body> # Return data, whatever. |
| ** |
| ** Return 2 # Jump back to the Gosub |
| ** |
| ** B: <after the loop> |
| ** |
| ** Added 2014-05-26: If the table is a WITHOUT ROWID table, then |
| ** use an ephemeral index instead of a RowSet to record the primary |
| ** keys of the rows we have already seen. |
| ** |
| */ |
| WhereClause *pOrWc; /* The OR-clause broken out into subterms */ |
| SrcList *pOrTab; /* Shortened table list or OR-clause generation */ |
| Index *pCov = 0; /* Potential covering index (or NULL) */ |
| int iCovCur = pParse->nTab++; /* Cursor used for index scans (if any) */ |
| |
| int regReturn = ++pParse->nMem; /* Register used with OP_Gosub */ |
| int regRowset = 0; /* Register for RowSet object */ |
| int regRowid = 0; /* Register holding rowid */ |
| int iLoopBody = sqlite3VdbeMakeLabel(v); /* Start of loop body */ |
| int iRetInit; /* Address of regReturn init */ |
| int untestedTerms = 0; /* Some terms not completely tested */ |
| int ii; /* Loop counter */ |
| u16 wctrlFlags; /* Flags for sub-WHERE clause */ |
| Expr *pAndExpr = 0; /* An ".. AND (...)" expression */ |
| Table *pTab = pTabItem->pTab; |
| |
| pTerm = pLoop->aLTerm[0]; |
| assert( pTerm!=0 ); |
| assert( pTerm->eOperator & WO_OR ); |
| assert( (pTerm->wtFlags & TERM_ORINFO)!=0 ); |
| pOrWc = &pTerm->u.pOrInfo->wc; |
| pLevel->op = OP_Return; |
| pLevel->p1 = regReturn; |
| |
| /* Set up a new SrcList in pOrTab containing the table being scanned |
| ** by this loop in the a[0] slot and all notReady tables in a[1..] slots. |
| ** This becomes the SrcList in the recursive call to sqlite3WhereBegin(). |
| */ |
| if( pWInfo->nLevel>1 ){ |
| int nNotReady; /* The number of notReady tables */ |
| struct SrcList_item *origSrc; /* Original list of tables */ |
| nNotReady = pWInfo->nLevel - iLevel - 1; |
| pOrTab = sqlite3StackAllocRaw(db, |
| sizeof(*pOrTab)+ nNotReady*sizeof(pOrTab->a[0])); |
| if( pOrTab==0 ) return notReady; |
| pOrTab->nAlloc = (u8)(nNotReady + 1); |
| pOrTab->nSrc = pOrTab->nAlloc; |
| memcpy(pOrTab->a, pTabItem, sizeof(*pTabItem)); |
| origSrc = pWInfo->pTabList->a; |
| for(k=1; k<=nNotReady; k++){ |
| memcpy(&pOrTab->a[k], &origSrc[pLevel[k].iFrom], sizeof(pOrTab->a[k])); |
| } |
| }else{ |
| pOrTab = pWInfo->pTabList; |
| } |
| |
| /* Initialize the rowset register to contain NULL. An SQL NULL is |
| ** equivalent to an empty rowset. Or, create an ephemeral index |
| ** capable of holding primary keys in the case of a WITHOUT ROWID. |
| ** |
| ** Also initialize regReturn to contain the address of the instruction |
| ** immediately following the OP_Return at the bottom of the loop. This |
| ** is required in a few obscure LEFT JOIN cases where control jumps |
| ** over the top of the loop into the body of it. In this case the |
| ** correct response for the end-of-loop code (the OP_Return) is to |
| ** fall through to the next instruction, just as an OP_Next does if |
| ** called on an uninitialized cursor. |
| */ |
| if( (pWInfo->wctrlFlags & WHERE_DUPLICATES_OK)==0 ){ |
| if( HasRowid(pTab) ){ |
| regRowset = ++pParse->nMem; |
| sqlite3VdbeAddOp2(v, OP_Null, 0, regRowset); |
| }else{ |
| Index *pPk = sqlite3PrimaryKeyIndex(pTab); |
| regRowset = pParse->nTab++; |
| sqlite3VdbeAddOp2(v, OP_OpenEphemeral, regRowset, pPk->nKeyCol); |
| sqlite3VdbeSetP4KeyInfo(pParse, pPk); |
| } |
| regRowid = ++pParse->nMem; |
| } |
| iRetInit = sqlite3VdbeAddOp2(v, OP_Integer, 0, regReturn); |
| |
| /* If the original WHERE clause is z of the form: (x1 OR x2 OR ...) AND y |
| ** Then for every term xN, evaluate as the subexpression: xN AND z |
| ** That way, terms in y that are factored into the disjunction will |
| ** be picked up by the recursive calls to sqlite3WhereBegin() below. |
| ** |
| ** Actually, each subexpression is converted to "xN AND w" where w is |
| ** the "interesting" terms of z - terms that did not originate in the |
| ** ON or USING clause of a LEFT JOIN, and terms that are usable as |
| ** indices. |
| ** |
| ** This optimization also only applies if the (x1 OR x2 OR ...) term |
| ** is not contained in the ON clause of a LEFT JOIN. |
| ** See ticket http://www.sqlite.org/src/info/f2369304e4 |
| */ |
| if( pWC->nTerm>1 ){ |
| int iTerm; |
| for(iTerm=0; iTerm<pWC->nTerm; iTerm++){ |
| Expr *pExpr = pWC->a[iTerm].pExpr; |
| if( &pWC->a[iTerm] == pTerm ) continue; |
| if( ExprHasProperty(pExpr, EP_FromJoin) ) continue; |
| testcase( pWC->a[iTerm].wtFlags & TERM_ORINFO ); |
| testcase( pWC->a[iTerm].wtFlags & TERM_VIRTUAL ); |
| if( pWC->a[iTerm].wtFlags & (TERM_ORINFO|TERM_VIRTUAL) ) continue; |
| if( (pWC->a[iTerm].eOperator & WO_ALL)==0 ) continue; |
| pExpr = sqlite3ExprDup(db, pExpr, 0); |
| pAndExpr = sqlite3ExprAnd(db, pAndExpr, pExpr); |
| } |
| if( pAndExpr ){ |
| pAndExpr = sqlite3PExpr(pParse, TK_AND, 0, pAndExpr, 0); |
| } |
| } |
| |
| /* Run a separate WHERE clause for each term of the OR clause. After |
| ** eliminating duplicates from other WHERE clauses, the action for each |
| ** sub-WHERE clause is to to invoke the main loop body as a subroutine. |
| */ |
| wctrlFlags = WHERE_OMIT_OPEN_CLOSE |
| | WHERE_FORCE_TABLE |
| | WHERE_ONETABLE_ONLY; |
| for(ii=0; ii<pOrWc->nTerm; ii++){ |
| WhereTerm *pOrTerm = &pOrWc->a[ii]; |
| if( pOrTerm->leftCursor==iCur || (pOrTerm->eOperator & WO_AND)!=0 ){ |
| WhereInfo *pSubWInfo; /* Info for single OR-term scan */ |
| Expr *pOrExpr = pOrTerm->pExpr; /* Current OR clause term */ |
| int j1 = 0; /* Address of jump operation */ |
| if( pAndExpr && !ExprHasProperty(pOrExpr, EP_FromJoin) ){ |
| pAndExpr->pLeft = pOrExpr; |
| pOrExpr = pAndExpr; |
| } |
| /* Loop through table entries that match term pOrTerm. */ |
| WHERETRACE(0xffff, ("Subplan for OR-clause:\n")); |
| pSubWInfo = sqlite3WhereBegin(pParse, pOrTab, pOrExpr, 0, 0, |
| wctrlFlags, iCovCur); |
| assert( pSubWInfo || pParse->nErr || db->mallocFailed ); |
| if( pSubWInfo ){ |
| WhereLoop *pSubLoop; |
| explainOneScan( |
| pParse, pOrTab, &pSubWInfo->a[0], iLevel, pLevel->iFrom, 0 |
| ); |
| /* This is the sub-WHERE clause body. First skip over |
| ** duplicate rows from prior sub-WHERE clauses, and record the |
| ** rowid (or PRIMARY KEY) for the current row so that the same |
| ** row will be skipped in subsequent sub-WHERE clauses. |
| */ |
| if( (pWInfo->wctrlFlags & WHERE_DUPLICATES_OK)==0 ){ |
| int r; |
| int iSet = ((ii==pOrWc->nTerm-1)?-1:ii); |
| if( HasRowid(pTab) ){ |
| r = sqlite3ExprCodeGetColumn(pParse, pTab, -1, iCur, regRowid, 0); |
| j1 = sqlite3VdbeAddOp4Int(v, OP_RowSetTest, regRowset, 0, r,iSet); |
| VdbeCoverage(v); |
| }else{ |
| Index *pPk = sqlite3PrimaryKeyIndex(pTab); |
| int nPk = pPk->nKeyCol; |
| int iPk; |
| |
| /* Read the PK into an array of temp registers. */ |
| r = sqlite3GetTempRange(pParse, nPk); |
| for(iPk=0; iPk<nPk; iPk++){ |
| int iCol = pPk->aiColumn[iPk]; |
| sqlite3ExprCodeGetColumn(pParse, pTab, iCol, iCur, r+iPk, 0); |
| } |
| |
| /* Check if the temp table already contains this key. If so, |
| ** the row has already been included in the result set and |
| ** can be ignored (by jumping past the Gosub below). Otherwise, |
| ** insert the key into the temp table and proceed with processing |
| ** the row. |
| ** |
| ** Use some of the same optimizations as OP_RowSetTest: If iSet |
| ** is zero, assume that the key cannot already be present in |
| ** the temp table. And if iSet is -1, assume that there is no |
| ** need to insert the key into the temp table, as it will never |
| ** be tested for. */ |
| if( iSet ){ |
| j1 = sqlite3VdbeAddOp4Int(v, OP_Found, regRowset, 0, r, nPk); |
| VdbeCoverage(v); |
| } |
| if( iSet>=0 ){ |
| sqlite3VdbeAddOp3(v, OP_MakeRecord, r, nPk, regRowid); |
| sqlite3VdbeAddOp3(v, OP_IdxInsert, regRowset, regRowid, 0); |
| if( iSet ) sqlite3VdbeChangeP5(v, OPFLAG_USESEEKRESULT); |
| } |
| |
| /* Release the array of temp registers */ |
| sqlite3ReleaseTempRange(pParse, r, nPk); |
| } |
| } |
| |
| /* Invoke the main loop body as a subroutine */ |
| sqlite3VdbeAddOp2(v, OP_Gosub, regReturn, iLoopBody); |
| |
| /* Jump here (skipping the main loop body subroutine) if the |
| ** current sub-WHERE row is a duplicate from prior sub-WHEREs. */ |
| if( j1 ) sqlite3VdbeJumpHere(v, j1); |
| |
| /* The pSubWInfo->untestedTerms flag means that this OR term |
| ** contained one or more AND term from a notReady table. The |
| ** terms from the notReady table could not be tested and will |
| ** need to be tested later. |
| */ |
| if( pSubWInfo->untestedTerms ) untestedTerms = 1; |
| |
| /* If all of the OR-connected terms are optimized using the same |
| ** index, and the index is opened using the same cursor number |
| ** by each call to sqlite3WhereBegin() made by this loop, it may |
| ** be possible to use that index as a covering index. |
| ** |
| ** If the call to sqlite3WhereBegin() above resulted in a scan that |
| ** uses an index, and this is either the first OR-connected term |
| ** processed or the index is the same as that used by all previous |
| ** terms, set pCov to the candidate covering index. Otherwise, set |
| ** pCov to NULL to indicate that no candidate covering index will |
| ** be available. |
| */ |
| pSubLoop = pSubWInfo->a[0].pWLoop; |
| assert( (pSubLoop->wsFlags & WHERE_AUTO_INDEX)==0 ); |
| if( (pSubLoop->wsFlags & WHERE_INDEXED)!=0 |
| && (ii==0 || pSubLoop->u.btree.pIndex==pCov) |
| && (HasRowid(pTab) || !IsPrimaryKeyIndex(pSubLoop->u.btree.pIndex)) |
| ){ |
| assert( pSubWInfo->a[0].iIdxCur==iCovCur ); |
| pCov = pSubLoop->u.btree.pIndex; |
| wctrlFlags |= WHERE_REOPEN_IDX; |
| }else{ |
| pCov = 0; |
| } |
| |
| /* Finish the loop through table entries that match term pOrTerm. */ |
| sqlite3WhereEnd(pSubWInfo); |
| } |
| } |
| } |
| pLevel->u.pCovidx = pCov; |
| if( pCov ) pLevel->iIdxCur = iCovCur; |
| if( pAndExpr ){ |
| pAndExpr->pLeft = 0; |
| sqlite3ExprDelete(db, pAndExpr); |
| } |
| sqlite3VdbeChangeP1(v, iRetInit, sqlite3VdbeCurrentAddr(v)); |
| sqlite3VdbeAddOp2(v, OP_Goto, 0, pLevel->addrBrk); |
| sqlite3VdbeResolveLabel(v, iLoopBody); |
| |
| if( pWInfo->nLevel>1 ) sqlite3StackFree(db, pOrTab); |
| if( !untestedTerms ) disableTerm(pLevel, pTerm); |
| }else |
| #endif /* SQLITE_OMIT_OR_OPTIMIZATION */ |
| |
| { |
| /* Case 6: There is no usable index. We must do a complete |
| ** scan of the entire table. |
| */ |
| static const u8 aStep[] = { OP_Next, OP_Prev }; |
| static const u8 aStart[] = { OP_Rewind, OP_Last }; |
| assert( bRev==0 || bRev==1 ); |
| if( pTabItem->isRecursive ){ |
| /* Tables marked isRecursive have only a single row that is stored in |
| ** a pseudo-cursor. No need to Rewind or Next such cursors. */ |
| pLevel->op = OP_Noop; |
| }else{ |
| pLevel->op = aStep[bRev]; |
| pLevel->p1 = iCur; |
| pLevel->p2 = 1 + sqlite3VdbeAddOp2(v, aStart[bRev], iCur, addrBrk); |
| VdbeCoverageIf(v, bRev==0); |
| VdbeCoverageIf(v, bRev!=0); |
| pLevel->p5 = SQLITE_STMTSTATUS_FULLSCAN_STEP; |
| } |
| } |
| |
| /* Insert code to test every subexpression that can be completely |
| ** computed using the current set of tables. |
| */ |
| for(pTerm=pWC->a, j=pWC->nTerm; j>0; j--, pTerm++){ |
| Expr *pE; |
| testcase( pTerm->wtFlags & TERM_VIRTUAL ); |
| testcase( pTerm->wtFlags & TERM_CODED ); |
| if( pTerm->wtFlags & (TERM_VIRTUAL|TERM_CODED) ) continue; |
| if( (pTerm->prereqAll & pLevel->notReady)!=0 ){ |
| testcase( pWInfo->untestedTerms==0 |
| && (pWInfo->wctrlFlags & WHERE_ONETABLE_ONLY)!=0 ); |
| pWInfo->untestedTerms = 1; |
| continue; |
| } |
| pE = pTerm->pExpr; |
| assert( pE!=0 ); |
| if( pLevel->iLeftJoin && !ExprHasProperty(pE, EP_FromJoin) ){ |
| continue; |
| } |
| sqlite3ExprIfFalse(pParse, pE, addrCont, SQLITE_JUMPIFNULL); |
| pTerm->wtFlags |= TERM_CODED; |
| } |
| |
| /* Insert code to test for implied constraints based on transitivity |
| ** of the "==" operator. |
| ** |
| ** Example: If the WHERE clause contains "t1.a=t2.b" and "t2.b=123" |
| ** and we are coding the t1 loop and the t2 loop has not yet coded, |
| ** then we cannot use the "t1.a=t2.b" constraint, but we can code |
| ** the implied "t1.a=123" constraint. |
| */ |
| for(pTerm=pWC->a, j=pWC->nTerm; j>0; j--, pTerm++){ |
| Expr *pE, *pEAlt; |
| WhereTerm *pAlt; |
| if( pTerm->wtFlags & (TERM_VIRTUAL|TERM_CODED) ) continue; |
| if( pTerm->eOperator!=(WO_EQUIV|WO_EQ) ) continue; |
| if( pTerm->leftCursor!=iCur ) continue; |
| if( pLevel->iLeftJoin ) continue; |
| pE = pTerm->pExpr; |
| assert( !ExprHasProperty(pE, EP_FromJoin) ); |
| assert( (pTerm->prereqRight & pLevel->notReady)!=0 ); |
| pAlt = findTerm(pWC, iCur, pTerm->u.leftColumn, notReady, WO_EQ|WO_IN, 0); |
| if( pAlt==0 ) continue; |
| if( pAlt->wtFlags & (TERM_CODED) ) continue; |
| testcase( pAlt->eOperator & WO_EQ ); |
| testcase( pAlt->eOperator & WO_IN ); |
| VdbeModuleComment((v, "begin transitive constraint")); |
| pEAlt = sqlite3StackAllocRaw(db, sizeof(*pEAlt)); |
| if( pEAlt ){ |
| *pEAlt = *pAlt->pExpr; |
| pEAlt->pLeft = pE->pLeft; |
| sqlite3ExprIfFalse(pParse, pEAlt, addrCont, SQLITE_JUMPIFNULL); |
| sqlite3StackFree(db, pEAlt); |
| } |
| } |
| |
| /* For a LEFT OUTER JOIN, generate code that will record the fact that |
| ** at least one row of the right table has matched the left table. |
| */ |
| if( pLevel->iLeftJoin ){ |
| pLevel->addrFirst = sqlite3VdbeCurrentAddr(v); |
| sqlite3VdbeAddOp2(v, OP_Integer, 1, pLevel->iLeftJoin); |
| VdbeComment((v, "record LEFT JOIN hit")); |
| sqlite3ExprCacheClear(pParse); |
| for(pTerm=pWC->a, j=0; j<pWC->nTerm; j++, pTerm++){ |
| testcase( pTerm->wtFlags & TERM_VIRTUAL ); |
| testcase( pTerm->wtFlags & TERM_CODED ); |
| if( pTerm->wtFlags & (TERM_VIRTUAL|TERM_CODED) ) continue; |
| if( (pTerm->prereqAll & pLevel->notReady)!=0 ){ |
| assert( pWInfo->untestedTerms ); |
| continue; |
| } |
| assert( pTerm->pExpr ); |
| sqlite3ExprIfFalse(pParse, pTerm->pExpr, addrCont, SQLITE_JUMPIFNULL); |
| pTerm->wtFlags |= TERM_CODED; |
| } |
| } |
| |
| return pLevel->notReady; |
| } |
| |
| #ifdef WHERETRACE_ENABLED |
| /* |
| ** Print the content of a WhereTerm object |
| */ |
| static void whereTermPrint(WhereTerm *pTerm, int iTerm){ |
| if( pTerm==0 ){ |
| sqlite3DebugPrintf("TERM-%-3d NULL\n", iTerm); |
| }else{ |
| char zType[4]; |
| memcpy(zType, "...", 4); |
| if( pTerm->wtFlags & TERM_VIRTUAL ) zType[0] = 'V'; |
| if( pTerm->eOperator & WO_EQUIV ) zType[1] = 'E'; |
| if( ExprHasProperty(pTerm->pExpr, EP_FromJoin) ) zType[2] = 'L'; |
| sqlite3DebugPrintf("TERM-%-3d %p %s cursor=%-3d prob=%-3d op=0x%03x\n", |
| iTerm, pTerm, zType, pTerm->leftCursor, pTerm->truthProb, |
| pTerm->eOperator); |
| sqlite3TreeViewExpr(0, pTerm->pExpr, 0); |
| } |
| } |
| #endif |
| |
| #ifdef WHERETRACE_ENABLED |
| /* |
| ** Print a WhereLoop object for debugging purposes |
| */ |
| static void whereLoopPrint(WhereLoop *p, WhereClause *pWC){ |
| WhereInfo *pWInfo = pWC->pWInfo; |
| int nb = 1+(pWInfo->pTabList->nSrc+7)/8; |
| struct SrcList_item *pItem = pWInfo->pTabList->a + p->iTab; |
| Table *pTab = pItem->pTab; |
| sqlite3DebugPrintf("%c%2d.%0*llx.%0*llx", p->cId, |
| p->iTab, nb, p->maskSelf, nb, p->prereq); |
| sqlite3DebugPrintf(" %12s", |
| pItem->zAlias ? pItem->zAlias : pTab->zName); |
| 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 %05x %d-%d", p->wsFlags, p->nLTerm,p->u.btree.nSkip); |
| }else{ |
| sqlite3DebugPrintf(" f %05x N %d", p->wsFlags, p->nLTerm); |
| } |
| sqlite3DebugPrintf(" cost %d,%d,%d\n", p->rSetup, p->rRun, p->nOut); |
| if( p->nLTerm && (sqlite3WhereTrace & 0x100)!=0 ){ |
| int i; |
| for(i=0; i<p->nLTerm; i++){ |
| whereTermPrint(p->aLTerm[i], i); |
| } |
| } |
| } |
| #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); |
| sqlite3KeyInfoUnref(p->u.btree.pIndex->pKeyInfo); |
| sqlite3DbFree(db, p->u.btree.pIndex); |
| p->u.btree.pIndex = 0; |
| } |
| } |
| } |
| |
| /* |
| ** Deallocate internal memory used by a WhereLoop object |
| */ |
| static void whereLoopClear(sqlite3 *db, WhereLoop *p){ |
| if( p->aLTerm!=p->aLTermSpace ) sqlite3DbFree(db, p->aLTerm); |
| whereLoopClearUnion(db, p); |
| whereLoopInit(p); |
| } |
| |
| /* |
| ** 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 = sqlite3DbMallocRaw(db, sizeof(p->aLTerm[0])*n); |
| if( paNew==0 ) return SQLITE_NOMEM; |
| memcpy(paNew, p->aLTerm, sizeof(p->aLTerm[0])*p->nLSlot); |
| if( p->aLTerm!=p->aLTermSpace ) sqlite3DbFree(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( whereLoopResize(db, pTo, pFrom->nLTerm) ){ |
| memset(&pTo->u, 0, sizeof(pTo->u)); |
| return SQLITE_NOMEM; |
| } |
| 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){ |
| whereLoopClear(db, p); |
| sqlite3DbFree(db, p); |
| } |
| |
| /* |
| ** Free a WhereInfo structure |
| */ |
| static void whereInfoFree(sqlite3 *db, WhereInfo *pWInfo){ |
| if( ALWAYS(pWInfo) ){ |
| whereClauseClear(&pWInfo->sWC); |
| while( pWInfo->pLoops ){ |
| WhereLoop *p = pWInfo->pLoops; |
| pWInfo->pLoops = p->pNextLoop; |
| whereLoopDelete(db, p); |
| } |
| sqlite3DbFree(db, pWInfo); |
| } |
| } |
| |
| /* |
| ** Return TRUE if both of the following are true: |
| ** |
| ** (1) X has the same or lower cost that Y |
| ** (2) X is a proper subset of Y |
| ** |
| ** By "proper subset" we mean that X uses fewer WHERE clause terms |
| ** than Y and that every WHERE clause term used by X is also used |
| ** by Y. |
| ** |
| ** If X is a proper subset of Y then Y is a better choice and ought |
| ** to have a lower cost. This routine returns TRUE when that cost |
| ** relationship is inverted and needs to be adjusted. |
| */ |
| static int whereLoopCheaperProperSubset( |
| const WhereLoop *pX, /* First WhereLoop to compare */ |
| const WhereLoop *pY /* Compare against this WhereLoop */ |
| ){ |
| int i, j; |
| if( pX->nLTerm >= pY->nLTerm ) return 0; /* X is not a subset of Y */ |
| if( pX->rRun >= pY->rRun ){ |
| if( pX->rRun > pY->rRun ) return 0; /* X costs more than Y */ |
| if( pX->nOut > pY->nOut ) return 0; /* X costs more than Y */ |
| } |
| for(i=pX->nLTerm-1; i>=0; i--){ |
| for(j=pY->nLTerm-1; j>=0; j--){ |
| if( pY->aLTerm[j]==pX->aLTerm[i] ) break; |
| } |
| if( j<0 ) return 0; /* X not a subset of Y since term X[i] not used by Y */ |
| } |
| return 1; /* All conditions meet */ |
| } |
| |
| /* |
| ** Try to adjust the cost 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. |
| ** |
| ** This adjustment is omitted for SKIPSCAN loops. In a SKIPSCAN loop, the |
| ** WhereLoop.nLTerm field is not an accurate measure of the number of WHERE |
| ** clause terms covered, since some of the first nLTerm entries in aLTerm[] |
| ** will be NULL (because they are skipped). That makes it more difficult |
| ** to compare the loops. We could add extra code to do the comparison, and |
| ** perhaps we will someday. But SKIPSCAN is sufficiently uncommon, and this |
| ** adjustment is sufficient minor, that it is very difficult to construct |
| ** a test case where the extra code would improve the query plan. Better |
| ** to avoid the added complexity and just omit cost adjustments to SKIPSCAN |
| ** loops. |
| */ |
| static void whereLoopAdjustCost(const WhereLoop *p, WhereLoop *pTemplate){ |
| if( (pTemplate->wsFlags & WHERE_INDEXED)==0 ) return; |
| if( (pTemplate->wsFlags & WHERE_SKIPSCAN)!=0 ) return; |
| for(; p; p=p->pNextLoop){ |
| if( p->iTab!=pTemplate->iTab ) continue; |
| if( (p->wsFlags & WHERE_INDEXED)==0 ) continue; |
| if( (p->wsFlags & WHERE_SKIPSCAN)!=0 ) continue; |
| if( whereLoopCheaperProperSubset(p, pTemplate) ){ |
| /* Adjust pTemplate cost downward so that it is cheaper than its |
| ** subset p */ |
| pTemplate->rRun = p->rRun; |
| pTemplate->nOut = p->nOut - 1; |
| }else if( whereLoopCheaperProperSubset(pTemplate, p) ){ |
| /* Adjust pTemplate cost upward so that it is costlier than p since |
| ** pTemplate is a proper subset of p */ |
| pTemplate->rRun = p->rRun; |
| pTemplate->nOut = p->nOut + 1; |
| } |
| } |
| } |
| |
| /* |
| ** Search the list of WhereLoops in *ppPrev looking for one that can be |
| ** supplanted by pTemplate. |
| ** |
| ** Return NULL if the WhereLoop list contains an entry that can supplant |
| ** pTemplate, in other words if pTemplate does not belong on the list. |
| ** |
| ** If pX is a WhereLoop that pTemplate can supplant, then return the |
| ** link that points to pX. |
| ** |
| ** If pTemplate cannot supplant any existing element of the list but needs |
| ** to be added to the list, 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 appliation-defined index (or PRIMARY KEY or |
| ** UNIQUE constraint) with one or more == constraints is better |
| ** than an automatic index. */ |
| if( (p->wsFlags & WHERE_AUTO_INDEX)!=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 dependences 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; |
| |
| /* If pBuilder->pOrSet is defined, then only keep track of the costs |
| ** and prereqs. |
| */ |
| if( pBuilder->pOrSet!=0 ){ |
| #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); |
| whereLoopPrint(pTemplate, pBuilder->pWC); |
| } |
| #endif |
| return SQLITE_OK; |
| } |
| |
| /* Look for an existing WhereLoop to replace with pTemplate |
| */ |
| whereLoopAdjustCost(pWInfo->pLoops, 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: "); |
| whereLoopPrint(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: "); |
| whereLoopPrint(p, pBuilder->pWC); |
| } |
| sqlite3DebugPrintf(" add: "); |
| whereLoopPrint(pTemplate, pBuilder->pWC); |
| } |
| #endif |
| if( p==0 ){ |
| /* Allocate a new WhereLoop to add to the end of the list */ |
| *ppPrev = p = sqlite3DbMallocRaw(db, sizeof(WhereLoop)); |
| if( p==0 ) return SQLITE_NOMEM; |
| 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 supplated 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: "); |
| whereLoopPrint(pToDel, pBuilder->pWC); |
| } |
| #endif |
| whereLoopDelete(db, pToDel); |
| } |
| } |
| whereLoopXfer(db, p, pTemplate); |
| if( (p->wsFlags & WHERE_VIRTUALTABLE)==0 ){ |
| Index *pIndex = p->u.btree.pIndex; |
| if( pIndex && pIndex->tnum==0 ){ |
| p->u.btree.pIndex = 0; |
| } |
| } |
| return SQLITE_OK; |
| } |
| |
| /* |
| ** 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. |
| ** |
| ** In the current implementation, the first extra WHERE clause term reduces |
| ** the number of output rows by a factor of 10 and each additional term |
| ** reduces the number of output rows by sqrt(2). |
| */ |
| 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; |
| int nEq = 0; /* Number of = constraints not within likely()/unlikely() */ |
| |
| for(i=pWC->nTerm, pTerm=pWC->a; i>0; i--, pTerm++){ |
| if( (pTerm->wtFlags & TERM_VIRTUAL)!=0 ) break; |
| if( (pTerm->prereqAll & pLoop->maskSelf)==0 ) continue; |
| if( (pTerm->prereqAll & notAllowed)!=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 ){ |
| if( pTerm->truthProb<=0 ){ |
| pLoop->nOut += pTerm->truthProb; |
| }else{ |
| pLoop->nOut--; |
| if( pTerm->eOperator&WO_EQ ) nEq++; |
| } |
| } |
| } |
| /* TUNING: If there is at least one equality constraint in the WHERE |
| ** clause that does not have a likelihood() explicitly assigned to it |
| ** then do not let the estimated number of output rows exceed half |
| ** the number of rows in the table. */ |
| if( nEq && pLoop->nOut>nRow-10 ){ |
| pLoop->nOut = nRow - 10; |
| } |
| } |
| |
| /* |
| ** Adjust the cost C by the costMult facter 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->tnum==0, that means pIndex is a fake index used for the |
| ** INTEGER PRIMARY KEY. |
| */ |
| static int whereLoopAddBtreeIndex( |
| WhereLoopBuilder *pBuilder, /* The WhereLoop factory */ |
| struct SrcList_item *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 analyse 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_nSkip; /* Original value of pNew->u.btree.nSkip */ |
| u32 saved_wsFlags; /* Original value of pNew->wsFlags */ |
| LogEst saved_nOut; /* Original value of pNew->nOut */ |
| int iCol; /* Index of the column in the table */ |
| 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; |
| if( db->mallocFailed ) return SQLITE_NOMEM; |
| |
| 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 if( pProbe->tnum<=0 || (pSrc->jointype & JT_LEFT)!=0 ){ |
| opMask = WO_EQ|WO_IN|WO_GT|WO_GE|WO_LT|WO_LE; |
| }else{ |
| opMask = WO_EQ|WO_IN|WO_ISNULL|WO_GT|WO_GE|WO_LT|WO_LE; |
| } |
| if( pProbe->bUnordered ) opMask &= ~(WO_GT|WO_GE|WO_LT|WO_LE); |
| |
| assert( pNew->u.btree.nEq<pProbe->nColumn ); |
| iCol = pProbe->aiColumn[pNew->u.btree.nEq]; |
| |
| pTerm = whereScanInit(&scan, pBuilder->pWC, pSrc->iCursor, iCol, |
| opMask, pProbe); |
| saved_nEq = pNew->u.btree.nEq; |
| saved_nSkip = pNew->u.btree.nSkip; |
| saved_nLTerm = pNew->nLTerm; |
| saved_wsFlags = pNew->wsFlags; |
| saved_prereq = pNew->prereq; |
| saved_nOut = pNew->nOut; |
| pNew->rSetup = 0; |
| rSize = pProbe->aiRowLogEst[0]; |
| rLogSize = estLog(rSize); |
| |
| /* 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 |
| && 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->u.btree.nSkip++; |
| pNew->aLTerm[pNew->nLTerm++] = 0; |
| pNew->wsFlags |= WHERE_SKIPSCAN; |
| nIter = pProbe->aiRowLogEst[saved_nEq] - pProbe->aiRowLogEst[saved_nEq+1]; |
| if( pTerm ){ |
| /* TUNING: When estimating skip-scan for a term that is also indexable, |
| ** multiply the cost of the skip-scan by 2.0, to make it a little less |
| ** desirable than the regular index lookup. */ |
| nIter += 10; assert( 10==sqlite3LogEst(2) ); |
| } |
| 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->u.btree.nSkip = saved_nSkip; |
| } |
| 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_STAT3_OR_STAT4 |
| int nRecValid = pBuilder->nRecValid; |
| #endif |
| if( (eOp==WO_ISNULL || (pTerm->wtFlags&TERM_VNULL)!=0) |
| && (iCol<0 || pSrc->pTab->aCol[iCol].notNull) |
| ){ |
| continue; /* ignore IS [NOT] NULL constraints on NOT NULL columns */ |
| } |
| if( pTerm->prereqRight & pNew->maskSelf ) continue; |
| |
| pNew->wsFlags = saved_wsFlags; |
| pNew->u.btree.nEq = saved_nEq; |
| pNew->nLTerm = saved_nLTerm; |
| if( whereLoopResize(db, pNew, pNew->nLTerm+1) ) break; /* OOM */ |
| 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; |
| pNew->wsFlags |= WHERE_COLUMN_IN; |
| if( ExprHasProperty(pExpr, EP_xIsSelect) ){ |
| /* "x IN (SELECT ...)": TUNING: the SELECT returns 25 rows */ |
| nIn = 46; assert( 46==sqlite3LogEst(25) ); |
| }else if( ALWAYS(pExpr->x.pList && pExpr->x.pList->nExpr) ){ |
| /* "x IN (value, value, ...)" */ |
| nIn = sqlite3LogEst(pExpr->x.pList->nExpr); |
| } |
| assert( nIn>0 ); /* RHS always has 2 or more terms... The parser |
| ** changes "x IN (?)" into "x=?". */ |
| |
| }else if( eOp & (WO_EQ) ){ |
| pNew->wsFlags |= WHERE_COLUMN_EQ; |
| if( iCol<0 || (nInMul==0 && pNew->u.btree.nEq==pProbe->nKeyCol-1) ){ |
| if( iCol>=0 && !IsUniqueIndex(pProbe) ){ |
| pNew->wsFlags |= WHERE_UNQ_WANTED; |
| }else{ |
| pNew->wsFlags |= WHERE_ONEROW; |
| } |
| } |
| }else if( eOp & WO_ISNULL ){ |
| pNew->wsFlags |= WHERE_COLUMN_NULL; |
| }else if( eOp & (WO_GT|WO_GE) ){ |
| testcase( eOp & WO_GT ); |
| testcase( eOp & WO_GE ); |
| pNew->wsFlags |= WHERE_COLUMN_RANGE|WHERE_BTM_LIMIT; |
| pBtm = pTerm; |
| pTop = 0; |
| }else{ |
| assert( eOp & (WO_LT|WO_LE) ); |
| testcase( eOp & WO_LT ); |
| testcase( eOp & WO_LE ); |
| pNew->wsFlags |= WHERE_COLUMN_RANGE|WHERE_TOP_LIMIT; |
| 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 stat3/stat4 data. Or, if there is no stat3/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) ); |
| |
| assert( pNew->nOut==saved_nOut ); |
| if( pTerm->truthProb<=0 && iCol>=0 ){ |
| assert( (eOp & WO_IN) || nIn==0 ); |
| testcase( eOp & WO_IN ); |
| pNew->nOut += pTerm->truthProb; |
| pNew->nOut -= nIn; |
| }else{ |
| #ifdef SQLITE_ENABLE_STAT3_OR_STAT4 |
| tRowcnt nOut = 0; |
| if( nInMul==0 |
| && pProbe->nSample |
| && pNew->u.btree.nEq<=pProbe->nSampleCol |
| && OptimizationEnabled(db, SQLITE_Stat3) |
| && ((eOp & WO_IN)==0 || !ExprHasProperty(pTerm->pExpr, EP_xIsSelect)) |
| ){ |
| Expr *pExpr = pTerm->pExpr; |
| if( (eOp & (WO_EQ|WO_ISNULL))!=0 ){ |
| testcase( eOp & WO_EQ ); |
| 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( 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. */ |
| rCostIdx = pNew->nOut + 1 + (15*pProbe->szIdxRow)/pSrc->pTab->szTabRow; |
| pNew->rRun = sqlite3LogEstAdd(rLogSize, rCostIdx); |
| if( (pNew->wsFlags & (WHERE_IDX_ONLY|WHERE_IPK))==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 |
| ){ |
| whereLoopAddBtreeIndex(pBuilder, pSrc, pProbe, nInMul+nIn); |
| } |
| pNew->nOut = saved_nOut; |
| #ifdef SQLITE_ENABLE_STAT3_OR_STAT4 |
| pBuilder->nRecValid = nRecValid; |
| #endif |
| } |
| pNew->prereq = saved_prereq; |
| pNew->u.btree.nEq = saved_nEq; |
| pNew->u.btree.nSkip = saved_nSkip; |
| pNew->wsFlags = saved_wsFlags; |
| pNew->nOut = saved_nOut; |
| pNew->nLTerm = saved_nLTerm; |
| 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; |
| 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 = sqlite3ExprSkipCollate(pOB->a[ii].pExpr); |
| if( pExpr->op!=TK_COLUMN ) return 0; |
| if( pExpr->iTable==iCursor ){ |
| if( pExpr->iColumn<0 ) return 1; |
| for(jj=0; jj<pIndex->nKeyCol; jj++){ |
| if( pExpr->iColumn==pIndex->aiColumn[jj] ) return 1; |
| } |
| } |
| } |
| return 0; |
| } |
| |
| /* |
| ** Return a bitmask where 1s indicate that the corresponding column of |
| ** the table is used by an index. Only the first 63 columns are considered. |
| */ |
| static Bitmask columnsInIndex(Index *pIdx){ |
| Bitmask m = 0; |
| int j; |
| for(j=pIdx->nColumn-1; j>=0; j--){ |
| int x = pIdx->aiColumn[j]; |
| if( x>=0 ){ |
| testcase( x==BMS-1 ); |
| testcase( x==BMS-2 ); |
| if( x<BMS-1 ) m |= MASKBIT(x); |
| } |
| } |
| return m; |
| } |
| |
| /* 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, WhereClause *pWC, Expr *pWhere){ |
| int i; |
| WhereTerm *pTerm; |
| for(i=0, pTerm=pWC->a; i<pWC->nTerm; i++, pTerm++){ |
| if( sqlite3ExprImpliesExpr(pTerm->pExpr, pWhere, iTab) ) return 1; |
| } |
| return 0; |
| } |
| |
| /* |
| ** Add all WhereLoop objects for a single table of the join where the table |
| ** is idenfied 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 mExtra /* Extra prerequesites 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 */ |
| struct SrcList_item *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 */ |
| LogEst rLogSize; /* Logarithm of the 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->pIndex ){ |
| /* An INDEXED BY clause specifies a particular index to use */ |
| pProbe = pSrc->pIndex; |
| }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 = pTab->szTabRow; |
| aiRowEstPk[0] = pTab->nRowLogEst; |
| aiRowEstPk[1] = 0; |
| pFirst = pSrc->pTab->pIndex; |
| if( pSrc->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; |
| rLogSize = estLog(rSize); |
| |
| #ifndef SQLITE_OMIT_AUTOMATIC_INDEX |
| /* Automatic indexes */ |
| if( !pBuilder->pOrSet |
| && (pWInfo->pParse->db->flags & SQLITE_AutoIndex)!=0 |
| && pSrc->pIndex==0 |
| && !pSrc->viaCoroutine |
| && !pSrc->notIndexed |
| && HasRowid(pTab) |
| && !pSrc->isCorrelated |
| && !pSrc->isRecursive |
| ){ |
| /* Generate auto-index WhereLoops */ |
| WhereTerm *pTerm; |
| WhereTerm *pWCEnd = pWC->a + pWC->nTerm; |
| 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->u.btree.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 1.375 (LogEst=4) 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 + 4; |
| if( pTab->pSelect==0 && (pTab->tabFlags & TF_Ephemeral)==0 ){ |
| pNew->rSetup += 24; |
| } |
| ApplyCostMultiplier(pNew->rSetup, pTab->costMult); |
| /* 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 = mExtra | pTerm->prereqRight; |
| rc = whereLoopInsert(pBuilder, pNew); |
| } |
| } |
| } |
| #endif /* SQLITE_OMIT_AUTOMATIC_INDEX */ |
| |
| /* Loop over all indices |
| */ |
| for(; rc==SQLITE_OK && pProbe; pProbe=pProbe->pNext, iSortIdx++){ |
| if( pProbe->pPartIdxWhere!=0 |
| && !whereUsablePartialIndex(pSrc->iCursor, pWC, pProbe->pPartIdxWhere) ){ |
| testcase( pNew->iTab!=pSrc->iCursor ); /* See ticket [98d973b8f5] */ |
| continue; /* Partial index inappropriate for this query */ |
| } |
| rSize = pProbe->aiRowLogEst[0]; |
| pNew->u.btree.nEq = 0; |
| pNew->u.btree.nSkip = 0; |
| pNew->nLTerm = 0; |
| pNew->iSortIdx = 0; |
| pNew->rSetup = 0; |
| pNew->prereq = mExtra; |
| 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->tnum<=0 ){ |
| /* Integer primary key index */ |
| pNew->wsFlags = WHERE_IPK; |
| |
| /* Full table scan */ |
| pNew->iSortIdx = b ? iSortIdx : 0; |
| /* TUNING: Cost of full table scan is (N*3.0). */ |
| pNew->rRun = rSize + 16; |
| 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 ){ |
| pNew->wsFlags = WHERE_IDX_ONLY | WHERE_INDEXED; |
| m = 0; |
| }else{ |
| m = pSrc->colUsed & ~columnsInIndex(pProbe); |
| pNew->wsFlags = (m==0) ? (WHERE_IDX_ONLY|WHERE_INDEXED) : WHERE_INDEXED; |
| } |
| |
| /* Full scan via index */ |
| if( b |
| || !HasRowid(pTab) |
| || ( 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. If this is a non-covering index scan, |
| ** also add the cost of visiting table rows (N*3.0). */ |
| pNew->rRun = rSize + 1 + (15*pProbe->szIdxRow)/pTab->szTabRow; |
| if( m!=0 ){ |
| pNew->rRun = sqlite3LogEstAdd(pNew->rRun, rSize+16); |
| } |
| ApplyCostMultiplier(pNew->rRun, pTab->costMult); |
| whereLoopOutputAdjust(pWC, pNew, rSize); |
| rc = whereLoopInsert(pBuilder, pNew); |
| pNew->nOut = rSize; |
| if( rc ) break; |
| } |
| } |
| |
| rc = whereLoopAddBtreeIndex(pBuilder, pSrc, pProbe, 0); |
| #ifdef SQLITE_ENABLE_STAT3_OR_STAT4 |
| sqlite3Stat4ProbeFree(pBuilder->pRec); |
| pBuilder->nRecValid = 0; |
| pBuilder->pRec = 0; |
| #endif |
| |
| /* If there was an INDEXED BY clause, then only that one index is |
| ** considered. */ |
| if( pSrc->pIndex ) break; |
| } |
| return rc; |
| } |
| |
| #ifndef SQLITE_OMIT_VIRTUALTABLE |
| /* |
| ** Add all WhereLoop objects for a table of the join identified by |
| ** pBuilder->pNew->iTab. That table is guaranteed to be a virtual table. |
| */ |
| static int whereLoopAddVirtual( |
| WhereLoopBuilder *pBuilder, /* WHERE clause information */ |
| Bitmask mExtra |
| ){ |
| WhereInfo *pWInfo; /* WHERE analysis context */ |
| Parse *pParse; /* The parsing context */ |
| WhereClause *pWC; /* The WHERE clause */ |
| struct SrcList_item *pSrc; /* The FROM clause term to search */ |
| Table *pTab; |
| sqlite3 *db; |
| sqlite3_index_info *pIdxInfo; |
| struct sqlite3_index_constraint *pIdxCons; |
| struct sqlite3_index_constraint_usage *pUsage; |
| WhereTerm *pTerm; |
| int i, j; |
| int iTerm, mxTerm; |
| int nConstraint; |
| int seenIn = 0; /* True if an IN operator is seen */ |
| int seenVar = 0; /* True if a non-constant constraint is seen */ |
| int iPhase; /* 0: const w/o IN, 1: const, 2: no IN, 2: IN */ |
| WhereLoop *pNew; |
| int rc = SQLITE_OK; |
| |
| pWInfo = pBuilder->pWInfo; |
| pParse = pWInfo->pParse; |
| db = pParse->db; |
| pWC = pBuilder->pWC; |
| pNew = pBuilder->pNew; |
| pSrc = &pWInfo->pTabList->a[pNew->iTab]; |
| pTab = pSrc->pTab; |
| assert( IsVirtual(pTab) ); |
| pIdxInfo = allocateIndexInfo(pParse, pWC, pSrc, pBuilder->pOrderBy); |
| if( pIdxInfo==0 ) return SQLITE_NOMEM; |
| pNew->prereq = 0; |
| pNew->rSetup = 0; |
| pNew->wsFlags = WHERE_VIRTUALTABLE; |
| pNew->nLTerm = 0; |
| pNew->u.vtab.needFree = 0; |
| pUsage = pIdxInfo->aConstraintUsage; |
| nConstraint = pIdxInfo->nConstraint; |
| if( whereLoopResize(db, pNew, nConstraint) ){ |
| sqlite3DbFree(db, pIdxInfo); |
| return SQLITE_NOMEM; |
| } |
| |
| for(iPhase=0; iPhase<=3; iPhase++){ |
| if( !seenIn && (iPhase&1)!=0 ){ |
| iPhase++; |
| if( iPhase>3 ) break; |
| } |
| if( !seenVar && iPhase>1 ) break; |
| pIdxCons = *(struct sqlite3_index_constraint**)&pIdxInfo->aConstraint; |
| for(i=0; i<pIdxInfo->nConstraint; i++, pIdxCons++){ |
| j = pIdxCons->iTermOffset; |
| pTerm = &pWC->a[j]; |
| switch( iPhase ){ |
| case 0: /* Constants without IN operator */ |
| pIdxCons->usable = 0; |
| if( (pTerm->eOperator & WO_IN)!=0 ){ |
| seenIn = 1; |
| } |
| if( pTerm->prereqRight!=0 ){ |
| seenVar = 1; |
| }else if( (pTerm->eOperator & WO_IN)==0 ){ |
| pIdxCons->usable = 1; |
| } |
| break; |
| case 1: /* Constants with IN operators */ |
| assert( seenIn ); |
| pIdxCons->usable = (pTerm->prereqRight==0); |
| break; |
| case 2: /* Variables without IN */ |
| assert( seenVar ); |
| pIdxCons->usable = (pTerm->eOperator & WO_IN)==0; |
| break; |
| default: /* Variables with IN */ |
| assert( seenVar && seenIn ); |
| pIdxCons->usable = 1; |
| break; |
| } |
| } |
| memset(pUsage, 0, sizeof(pUsage[0])*pIdxInfo->nConstraint); |
| if( pIdxInfo->needToFreeIdxStr ) sqlite3_free(pIdxInfo->idxStr); |
| pIdxInfo->idxStr = 0; |
| pIdxInfo->idxNum = 0; |
| pIdxInfo->needToFreeIdxStr = 0; |
| pIdxInfo->orderByConsumed = 0; |
| pIdxInfo->estimatedCost = SQLITE_BIG_DBL / (double)2; |
| pIdxInfo->estimatedRows = 25; |
| rc = vtabBestIndex(pParse, pTab, pIdxInfo); |
| if( rc ) goto whereLoopAddVtab_exit; |
| pIdxCons = *(struct sqlite3_index_constraint**)&pIdxInfo->aConstraint; |
| pNew->prereq = mExtra; |
| mxTerm = -1; |
| assert( pNew->nLSlot>=nConstraint ); |
| for(i=0; i<nConstraint; i++) pNew->aLTerm[i] = 0; |
| pNew->u.vtab.omitMask = 0; |
| for(i=0; i<nConstraint; i++, pIdxCons++){ |
| if( (iTerm = pUsage[i].argvIndex - 1)>=0 ){ |
| j = pIdxCons->iTermOffset; |
| if( iTerm>=nConstraint |
| || j<0 |
| || j>=pWC->nTerm |
| || pNew->aLTerm[iTerm]!=0 |
| ){ |
| rc = SQLITE_ERROR; |
| sqlite3ErrorMsg(pParse, "%s.xBestIndex() malfunction", pTab->zName); |
| goto whereLoopAddVtab_exit; |
| } |
| 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( iTerm<16 && pUsage[i].omit ) pNew->u.vtab.omitMask |= 1<<iTerm; |
| if( (pTerm->eOperator & WO_IN)!=0 ){ |
| if( pUsage[i].omit==0 ){ |
| /* Do not attempt to use an IN constraint if the virtual table |
| ** says that the equivalent EQ constraint cannot be safely omitted. |
| ** If we do attempt to use such a constraint, some rows might be |
| ** repeated in the output. */ |
| break; |
| } |
| /* 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; |
| } |
| } |
| } |
| if( i>=nConstraint ){ |
| pNew->nLTerm = mxTerm+1; |
| 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); |
| whereLoopInsert(pBuilder, pNew); |
| if( pNew->u.vtab.needFree ){ |
| sqlite3_free(pNew->u.vtab.idxStr); |
| pNew->u.vtab.needFree = 0; |
| } |
| } |
| } |
| |
| whereLoopAddVtab_exit: |
| if( pIdxInfo->needToFreeIdxStr ) sqlite3_free(pIdxInfo->idxStr); |
| sqlite3DbFree(db, pIdxInfo); |
| 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 mExtra){ |
| WhereInfo *pWInfo = pBuilder->pWInfo; |
| WhereClause *pWC; |
| WhereLoop *pNew; |
| WhereTerm *pTerm, *pWCEnd; |
| int rc = SQLITE_OK; |
| int iCur; |
| WhereClause tempWC; |
| WhereLoopBuilder sSubBuild; |
| WhereOrSet sSum, sCur; |
| struct SrcList_item *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; |
| |
| 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.pOrderBy = 0; |
| sSubBuild.pOrSet = &sCur; |
| |
| WHERETRACE(0x200, ("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.a = pOrTerm; |
| sSubBuild.pWC = &tempWC; |
| }else{ |
| continue; |
| } |
| sCur.n = 0; |
| #ifdef WHERETRACE_ENABLED |
| WHERETRACE(0x200, ("OR-term %d of %p has %d subterms:\n", |
| (int)(pOrTerm-pOrWC->a), pTerm, sSubBuild.pWC->nTerm)); |
| if( sqlite3WhereTrace & 0x400 ){ |
| for(i=0; i<sSubBuild.pWC->nTerm; i++){ |
| whereTermPrint(&sSubBuild.pWC->a[i], i); |
| } |
| } |
| #endif |
| #ifndef SQLITE_OMIT_VIRTUALTABLE |
| if( IsVirtual(pItem->pTab) ){ |
| rc = whereLoopAddVirtual(&sSubBuild, mExtra); |
| }else |
| #endif |
| { |
| rc = whereLoopAddBtree(&sSubBuild, mExtra); |
| } |
| if( rc==SQLITE_OK ){ |
| rc = whereLoopAddOr(&sSubBuild, mExtra); |
| } |
| assert( rc==SQLITE_OK || sCur.n==0 ); |
| 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(0x200, ("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 mExtra = 0; |
| Bitmask mPrior = 0; |
| int iTab; |
| SrcList *pTabList = pWInfo->pTabList; |
| struct SrcList_item *pItem; |
| sqlite3 *db = pWInfo->pParse->db; |
| int nTabList = pWInfo->nLevel; |
| int rc = SQLITE_OK; |
| u8 priorJoinType = 0; |
| WhereLoop *pNew; |
| |
| /* Loop over the tables in the join, from left to right */ |
| pNew = pBuilder->pNew; |
| whereLoopInit(pNew); |
| for(iTab=0, pItem=pTabList->a; iTab<nTabList; iTab++, pItem++){ |
| pNew->iTab = iTab; |
| pNew->maskSelf = getMask(&pWInfo->sMaskSet, pItem->iCursor); |
| if( ((pItem->jointype|priorJoinType) & (JT_LEFT|JT_CROSS))!=0 ){ |
| mExtra = mPrior; |
| } |
| priorJoinType = pItem->jointype; |
| if( IsVirtual(pItem->pTab) ){ |
| rc = whereLoopAddVirtual(pBuilder, mExtra); |
| }else{ |
| rc = whereLoopAddBtree(pBuilder, mExtra); |
| } |
| if( rc==SQLITE_OK ){ |
| rc = whereLoopAddOr(pBuilder, mExtra); |
| } |
| mPrior |= pNew->maskSelf; |
| if( rc || db->mallocFailed ) break; |
| } |
| whereLoopClear(db, pNew); |
| return rc; |
| } |
| |
| /* |
| ** Examine a WherePath (with the addition of the extra WhereLoop of the 5th |
| ** 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, /* Might contain WHERE_GROUPBY or WHERE_DISTINCTBY */ |
| 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 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; |
| for(iLoop=0; isOrderDistinct && obSat<obDone && iLoop<=nLoop; iLoop++){ |
| if( iLoop>0 ) ready |= pLoop->maskSelf; |
| pLoop = iLoop<nLoop ? pPath->aLoop[iLoop] : pLast; |
| if( pLoop->wsFlags & WHERE_VIRTUALTABLE ){ |
| if( pLoop->u.vtab.isOrdered ) obSat = obDone; |
| break; |
| } |
| 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 = sqlite3ExprSkipCollate(pOrderBy->a[i].pExpr); |
| if( pOBExpr->op!=TK_COLUMN ) continue; |
| if( pOBExpr->iTable!=iCur ) continue; |
| pTerm = findTerm(&pWInfo->sWC, iCur, pOBExpr->iColumn, |
| ~ready, WO_EQ|WO_ISNULL, 0); |
| if( pTerm==0 ) continue; |
| if( (pTerm->eOperator&WO_EQ)!=0 && pOBExpr->iColumn>=0 ){ |
| const char *z1, *z2; |
| pColl = sqlite3ExprCollSeq(pWInfo->pParse, pOrderBy->a[i].pExpr); |
| if( !pColl ) pColl = db->pDfltColl; |
| z1 = pColl->zName; |
| pColl = sqlite3ExprCollSeq(pWInfo->pParse, pTerm->pExpr); |
| if( !pColl ) pColl = db->pDfltColl; |
| z2 = pColl->zName; |
| if( sqlite3StrICmp(z1, z2)!=0 ) continue; |
| } |
| 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]==(-1) || !HasRowid(pIndex->pTable)); |
| isOrderDistinct = IsUniqueIndex(pIndex); |
| } |
| |
| /* 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; /* True to run the ORDER BY search loop */ |
| |
| /* Skip over == and IS NULL terms */ |
| if( j<pLoop->u.btree.nEq |
| && pLoop->u.btree.nSkip==0 |
| && ((i = pLoop->aLTerm[j]->eOperator) & (WO_EQ|WO_ISNULL))!=0 |
| ){ |
| if( i & WO_ISNULL ){ |
| testcase( isOrderDistinct ); |
| isOrderDistinct = 0; |
| } |
| continue; |
| } |
| |
| /* 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]; |
| if( iColumn==pIndex->pTable->iPKey ) iColumn = -1; |
| }else{ |
| iColumn = -1; |
| revIdx = 0; |
| } |
| |
| /* An unconstrained column that might be NULL means that this |
| ** WhereLoop is not well-ordered |
| */ |
| if( isOrderDistinct |
| && iColumn>=0 |
| && j>=pLoop->u.btree.nEq |
| && pIndex->pTable->aCol[iColumn].notNull==0 |
| ){ |
| isOrderDistinct = 0; |
| } |
| |
| /* Find the ORDER BY term that corresponds to the j-th column |
| ** of the index and mark that ORDER BY term off |
| */ |
| bOnce = 1; |
| isMatch = 0; |
| for(i=0; bOnce && i<nOrderBy; i++){ |
| if( MASKBIT(i) & obSat ) continue; |
| pOBExpr = sqlite3ExprSkipCollate(pOrderBy->a[i].pExpr); |
| testcase( wctrlFlags & WHERE_GROUPBY ); |
| testcase( wctrlFlags & WHERE_DISTINCTBY ); |
| if( (wctrlFlags & (WHERE_GROUPBY|WHERE_DISTINCTBY))==0 ) bOnce = 0; |
| if( pOBExpr->op!=TK_COLUMN ) continue; |
| if( pOBExpr->iTable!=iCur ) continue; |
| if( pOBExpr->iColumn!=iColumn ) continue; |
| if( iColumn>=0 ){ |
| pColl = sqlite3ExprCollSeq(pWInfo->pParse, pOrderBy->a[i].pExpr); |
| if( !pColl ) pColl = db->pDfltColl; |
| if( sqlite3StrICmp(pColl->zName, pIndex->azColl[j])!=0 ) continue; |
| } |
| 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].sortOrder ) isMatch = 0; |
| }else{ |
| rev = revIdx ^ pOrderBy->a[i].sortOrder; |
| if( rev ) *pRevMask |= MASKBIT(iLoop); |
| revSet = 1; |
| } |
| } |
| if( isMatch ){ |
| if( iColumn<0 ){ |
| 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 = exprTableUsage(&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 = MASKBIT(i) - 1; |
| 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 ); |
| 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, |
| LogEst nRow, |
| int nOrderBy, |
| int nSorted |
| ){ |
| /* TUNING: Estimated cost of a full external sort, where N is |
| ** the number of rows to sort is: |
| ** |
| ** cost = (3.0 * 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 = (3.0 * N * log(N)) * (Y/X) |
| ** |
| ** The (Y/X) term is implemented using stack variable rScale |
| ** below. */ |
| LogEst rScale, rSortCost; |
| assert( nOrderBy>0 && 66==sqlite3LogEst(100) ); |
| rScale = sqlite3LogEst((nOrderBy-nSorted)*100/nOrderBy) - 66; |
| rSortCost = nRow + estLog(nRow) + rScale + 16; |
| |
| /* TUNING: The cost of implementing DISTINCT using a B-TREE is |
| ** similar but with a larger constant of proportionality. |
| ** Multiply by an additional factor of 3.0. */ |
| if( pWInfo->wctrlFlags & WHERE_WANT_DISTINCT ){ |
| rSortCost += 16; |
| } |
| |
| 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 */ |
| sqlite3 *db; /* The database connection */ |
| 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; |
| db = pParse->db; |
| 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)\n", nRowEst)); |
| |
| /* 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 = sqlite3DbMallocRaw(db, nSpace); |
| if( pSpace==0 ) return SQLITE_NOMEM; |
| 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 25. If the cost |
| ** of computing an automatic index is not paid back within the first 25 |
| ** rows, then do not use the automatic index. */ |
| aFrom[0].nRow = MIN(pParse->nQueryLoop, 46); assert( 46==sqlite3LogEst(25) ); |
| 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 = pFrom->isOrdered; /* isOrdered for (pFrom+pWLoop) */ |
| Bitmask maskNew; /* Mask of src visited by (..) */ |
| Bitmask revMask = 0; /* Mask of rev-order loops for (..) */ |
| |
| if( (pWLoop->prereq & ~pFrom->maskLoop)!=0 ) continue; |
| if( (pWLoop->maskSelf & pFrom->maskLoop)!=0 ) 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; |
| if( isOrdered<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 |
| ); |
| } |
| rCost = sqlite3LogEstAdd(rUnsorted, aSortCost[isOrdered]); |
| |
| WHERETRACE(0x002, |
| ("---- sort cost=%-3d (%d/%d) increases cost %3d to %-3d\n", |
| aSortCost[isOrdered], (nOrderBy-isOrdered), nOrderBy, |
| rUnsorted, rCost)); |
| }else{ |
| rCost = rUnsorted; |
| } |
| |
| /* 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 order=%c\n", |
| wherePathName(pFrom, iLoop, pWLoop), rCost, nOut, |
| 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 order=%c\n", |
| wherePathName(pFrom, iLoop, pWLoop), rCost, nOut, |
| 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 sam isOrdered setting as the |
| ** candidate path. Check to see if the candidate should replace |
| ** pTo or if the candidate should be skipped */ |
| if( pTo->rCost<rCost || (pTo->rCost==rCost && pTo->nRow<=nOut) ){ |
| #ifdef WHERETRACE_ENABLED /* 0x4 */ |
| if( sqlite3WhereTrace&0x4 ){ |
| sqlite3DebugPrintf( |
| "Skip %s cost=%-3d,%3d order=%c", |
| wherePathName(pFrom, iLoop, pWLoop), rCost, nOut, |
| isOrdered>=0 ? isOrdered+'0' : '?'); |
| sqlite3DebugPrintf(" vs %s cost=%-3d,%d order=%c\n", |
| wherePathName(pTo, iLoop+1, 0), pTo->rCost, pTo->nRow, |
| 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 order=%c", |
| wherePathName(pFrom, iLoop, pWLoop), rCost, nOut, |
| isOrdered>=0 ? isOrdered+'0' : '?'); |
| sqlite3DebugPrintf(" was %s cost=%-3d,%3d order=%c\n", |
| wherePathName(pTo, iLoop+1, 0), pTo->rCost, pTo->nRow, |
| 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>=2 ){ |
| 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"); |
| sqlite3DbFree(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; |
| } |
| } |
| if( pWInfo->pOrderBy ){ |
| if( pWInfo->wctrlFlags & WHERE_DISTINCTBY ){ |
| if( pFrom->isOrdered==pWInfo->pOrderBy->nExpr ){ |
| pWInfo->eDistinct = WHERE_DISTINCT_ORDERED; |
| } |
| }else{ |
| pWInfo->nOBSat = pFrom->isOrdered; |
| if( pWInfo->nOBSat<0 ) pWInfo->nOBSat = 0; |
| pWInfo->revMask = pFrom->revLoop; |
| } |
| if( (pWInfo->wctrlFlags & WHERE_SORTBYGROUP) |
| && pWInfo->nOBSat==pWInfo->pOrderBy->nExpr |
| ){ |
| 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 */ |
| sqlite3DbFree(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; |
| struct SrcList_item *pItem; |
| WhereClause *pWC; |
| WhereTerm *pTerm; |
| WhereLoop *pLoop; |
| int iCur; |
| int j; |
| Table *pTab; |
| Index *pIdx; |
| |
| pWInfo = pBuilder->pWInfo; |
| if( pWInfo->wctrlFlags & WHERE_FORCE_TABLE ) return 0; |
| assert( pWInfo->pTabList->nSrc>=1 ); |
| pItem = pWInfo->pTabList->a; |
| pTab = pItem->pTab; |
| if( IsVirtual(pTab) ) return 0; |
| if( pItem->zIndex ) return 0; |
| iCur = pItem->iCursor; |
| pWC = &pWInfo->sWC; |
| pLoop = pBuilder->pNew; |
| pLoop->wsFlags = 0; |
| pLoop->u.btree.nSkip = 0; |
| pTerm = findTerm(pWC, iCur, -1, 0, WO_EQ, 0); |
| if( pTerm ){ |
| 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){ |
| assert( pLoop->aLTermSpace==pLoop->aLTerm ); |
| assert( ArraySize(pLoop->aLTermSpace)==4 ); |
| if( !IsUniqueIndex(pIdx) |
| || pIdx->pPartIdxWhere!=0 |
| || pIdx->nKeyCol>ArraySize(pLoop->aLTermSpace) |
| ) continue; |
| for(j=0; j<pIdx->nKeyCol; j++){ |
| pTerm = findTerm(pWC, iCur, pIdx->aiColumn[j], 0, WO_EQ, pIdx); |
| if( pTerm==0 ) break; |
| pLoop->aLTerm[j] = pTerm; |
| } |
| if( j!=pIdx->nKeyCol ) continue; |
| pLoop->wsFlags = WHERE_COLUMN_EQ|WHERE_ONEROW|WHERE_INDEXED; |
| if( pIdx->isCovering || (pItem->colUsed & ~columnsInIndex(pIdx))==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; |
| pLoop->maskSelf = getMask(&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; |
| } |
| #ifdef SQLITE_DEBUG |
| pLoop->cId = '0'; |
| #endif |
| return 1; |
| } |
| return 0; |
| } |
| |
| /* |
| ** 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 conceptally 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_ONETABLE_ONLY 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, /* Result set of the query */ |
| u16 wctrlFlags, /* One of the WHERE_* flags defined in sqliteInt.h */ |
| int iIdxCur /* If WHERE_ONETABLE_ONLY is set, index cursor number */ |
| ){ |
| 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 */ |
| |
| |
| /* 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; |
| sWLB.pOrderBy = pOrderBy; |
| |
| /* Disable the DISTINCT optimization if SQLITE_DistinctOpt is set via |
| ** sqlite3_test_ctrl(SQLITE_TESTCTRL_OPTIMIZATIONS,...) */ |
| if( OptimizationDisabled(db, SQLITE_DistinctOpt) ){ |
| 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_ONETABLE_ONLY 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_ONETABLE_ONLY) ? 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 = ROUND8(sizeof(WhereInfo)+(nTabList-1)*sizeof(WhereLevel)); |
| pWInfo = sqlite3DbMallocZero(db, nByteWInfo + sizeof(WhereLoop)); |
| if( db->mallocFailed ){ |
| sqlite3DbFree(db, pWInfo); |
| pWInfo = 0; |
| goto whereBeginError; |
| } |
| pWInfo->aiCurOnePass[0] = pWInfo->aiCurOnePass[1] = -1; |
| pWInfo->nLevel = nTabList; |
| pWInfo->pParse = pParse; |
| pWInfo->pTabList = pTabList; |
| pWInfo->pOrderBy = pOrderBy; |
| pWInfo->pResultSet = pResultSet; |
| pWInfo->iBreak = pWInfo->iContinue = sqlite3VdbeMakeLabel(v); |
| pWInfo->wctrlFlags = wctrlFlags; |
| pWInfo->savedNQueryLoop = pParse->nQueryLoop; |
| pMaskSet = &pWInfo->sMaskSet; |
| 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. |
| */ |
| initMaskSet(pMaskSet); |
| whereClauseInit(&pWInfo->sWC, pWInfo); |
| whereSplit(&pWInfo->sWC, pWhere, TK_AND); |
| |
| /* Special case: a WHERE clause that is constant. Evaluate the |
| ** expression and either jump over all of the code or fall thru. |
| */ |
| for(ii=0; ii<sWLB.pWC->nTerm; ii++){ |
| if( nTabList==0 || sqlite3ExprIsConstantNotJoin(sWLB.pWC->a[ii].pExpr) ){ |
| sqlite3ExprIfFalse(pParse, sWLB.pWC->a[ii].pExpr, pWInfo->iBreak, |
| SQLITE_JUMPIFNULL); |
| sWLB.pWC->a[ii].wtFlags |= TERM_CODED; |
| } |
| } |
| |
| /* Special case: No FROM clause |
| */ |
| if( nTabList==0 ){ |
| if( pOrderBy ) pWInfo->nOBSat = pOrderBy->nExpr; |
| if( wctrlFlags & WHERE_WANT_DISTINCT ){ |
| pWInfo->eDistinct = WHERE_DISTINCT_UNIQUE; |
| } |
| } |
| |
| /* Assign a bit from the bitmask to every term in the FROM clause. |
| ** |
| ** When assigning bitmask values to FROM clause cursors, it must be |
| ** the case that if X is the bitmask for the N-th FROM clause term then |
| ** the bitmask for all FROM clause terms to the left of the N-th term |
| ** is (X-1). An expression from the ON clause of a LEFT JOIN can use |
| ** its Expr.iRightJoinTable value to find the bitmask of the right table |
| ** of the join. Subtracting one from the right table bitmask gives a |
| ** bitmask for all tables to the left of the join. 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_ONETABLE_ONLY flag is set. |
| */ |
| for(ii=0; ii<pTabList->nSrc; ii++){ |
| createMask(pMaskSet, pTabList->a[ii].iCursor); |
| } |
| #ifndef NDEBUG |
| { |
| Bitmask toTheLeft = 0; |
| for(ii=0; ii<pTabList->nSrc; ii++){ |
| Bitmask m = getMask(pMaskSet, pTabList->a[ii].iCursor); |
| assert( (m-1)==toTheLeft ); |
| toTheLeft |= m; |
| } |
| } |
| #endif |
| |
| /* Analyze all of the subexpressions. Note that exprAnalyze() might |
| ** add new virtual terms onto the end of the WHERE clause. We do not |
| ** want to analyze these virtual terms, so start analyzing at the end |
| ** and work forward so that the added virtual terms are never processed. |
| */ |
| exprAnalyzeAll(pTabList, &pWInfo->sWC); |
| if( db->mallocFailed ){ |
| goto whereBeginError; |
| } |
| |
| if( wctrlFlags & WHERE_WANT_DISTINCT ){ |
| 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 */ |
| WHERETRACE(0xffff,("*** Optimizer Start ***\n")); |
| #if defined(WHERETRACE_ENABLED) |
| /* Display all terms of the WHERE clause */ |
| if( sqlite3WhereTrace & 0x100 ){ |
| int i; |
| for(i=0; i<sWLB.pWC->nTerm; i++){ |
| whereTermPrint(&sWLB.pWC->a[i], i); |
| } |
| } |
| #endif |
| |
| if( nTabList!=1 || whereShortCut(&sWLB)==0 ){ |
| rc = whereLoopAddAll(&sWLB); |
| if( rc ) goto whereBeginError; |
| |
| /* Display all of the WhereLoop objects if wheretrace is enabled */ |
| #ifdef WHERETRACE_ENABLED /* !=0 */ |
| if( sqlite3WhereTrace ){ |
| WhereLoop *p; |
| int i; |
| static char zLabel[] = "0123456789abcdefghijklmnopqrstuvwyxz" |
| "ABCDEFGHIJKLMNOPQRSTUVWYXZ"; |
| for(p=pWInfo->pLoops, i=0; p; p=p->pNextLoop, i++){ |
| p->cId = zLabel[i%sizeof(zLabel)]; |
| whereLoopPrint(p, sWLB.pWC); |
| } |
| } |
| #endif |
| |
| wherePathSolver(pWInfo, 0); |
| if( db->mallocFailed ) goto whereBeginError; |
| if( pWInfo->pOrderBy ){ |
| wherePathSolver(pWInfo, pWInfo->nRowOut+1); |
| if( db->mallocFailed ) goto whereBeginError; |
| } |
| } |
| if( pWInfo->pOrderBy==0 && (db->flags & SQLITE_ReverseOrder)!=0 ){ |
| pWInfo->revMask = (Bitmask)(-1); |
| } |
| if( pParse->nErr || NEVER(db->mallocFailed) ){ |
| goto whereBeginError; |
| } |
| #ifdef WHERETRACE_ENABLED /* !=0 */ |
| if( sqlite3WhereTrace ){ |
| int ii; |
| 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++){ |
| whereLoopPrint(pWInfo->a[ii].pWLoop, sWLB.pWC); |
| } |
| } |
| #endif |
| /* Attempt to omit tables from the join that do not effect the result */ |
| if( pWInfo->nLevel>=2 |
| && pResultSet!=0 |
| && OptimizationEnabled(db, SQLITE_OmitNoopJoin) |
| ){ |
| Bitmask tabUsed = exprListTableUsage(pMaskSet, pResultSet); |
| if( sWLB.pOrderBy ) tabUsed |= exprListTableUsage(pMaskSet, sWLB.pOrderBy); |
| while( pWInfo->nLevel>=2 ){ |
| WhereTerm *pTerm, *pEnd; |
| pLoop = pWInfo->a[pWInfo->nLevel-1].pWLoop; |
| if( (pWInfo->pTabList->a[pLoop->iTab].jointype & JT_LEFT)==0 ) break; |
| if( (wctrlFlags & WHERE_WANT_DISTINCT)==0 |
| && (pLoop->wsFlags & WHERE_ONEROW)==0 |
| ){ |
| break; |
| } |
| if( (tabUsed & pLoop->maskSelf)!=0 ) break; |
| pEnd = sWLB.pWC->a + sWLB.pWC->nTerm; |
| for(pTerm=sWLB.pWC->a; pTerm<pEnd; pTerm++){ |
| if( (pTerm->prereqAll & pLoop->maskSelf)!=0 |
| && !ExprHasProperty(pTerm->pExpr, EP_FromJoin) |
| ){ |
| break; |
| } |
| } |
| if( pTerm<pEnd ) break; |
| WHERETRACE(0xffff, ("-> drop loop %c not used\n", pLoop->cId)); |
| pWInfo->nLevel--; |
| nTabList--; |
| } |
| } |
| WHERETRACE(0xffff,("*** Optimizer Finished ***\n")); |
| 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. |
| ** The one-pass algorithm only works if the WHERE clause constrains |
| ** the statement to update a single row. |
| */ |
| assert( (wctrlFlags & WHERE_ONEPASS_DESIRED)==0 || pWInfo->nLevel==1 ); |
| if( (wctrlFlags & WHERE_ONEPASS_DESIRED)!=0 |
| && (pWInfo->a[0].pWLoop->wsFlags & WHERE_ONEROW)!=0 ){ |
| pWInfo->okOnePass = 1; |
| if( HasRowid(pTabList->a[0].pTab) ){ |
| pWInfo->a[0].pWLoop->wsFlags &= ~WHERE_IDX_ONLY; |
| } |
| } |
| |
| /* Open all tables in the pTabList and any indices selected for |
| ** searching those tables. |
| */ |
| notReady = ~(Bitmask)0; |
| for(ii=0, pLevel=pWInfo->a; ii<nTabList; ii++, pLevel++){ |
| Table *pTab; /* Table to open */ |
| int iDb; /* Index of database containing table/index */ |
| struct SrcList_item *pTabItem; |
| |
| pTabItem = &pTabList->a[pLevel->iFrom]; |
| pTab = pTabItem->pTab; |
| iDb = sqlite3SchemaToIndex(db, pTab->pSchema); |
| pLoop = pLevel->pWLoop; |
| if( (pTab->tabFlags & TF_Ephemeral)!=0 || pTab->pSelect ){ |
| /* 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_OMIT_OPEN_CLOSE)==0 ){ |
| int op = OP_OpenRead; |
| if( pWInfo->okOnePass ){ |
| op = OP_OpenWrite; |
| pWInfo->aiCurOnePass[0] = pTabItem->iCursor; |
| }; |
| sqlite3OpenTable(pParse, pTabItem->iCursor, iDb, pTab, op); |
| assert( pTabItem->iCursor==pLevel->iTabCur ); |
| testcase( !pWInfo->okOnePass && pTab->nCol==BMS-1 ); |
| testcase( !pWInfo->okOnePass && pTab->nCol==BMS ); |
| if( !pWInfo->okOnePass && pTab->nCol<BMS && HasRowid(pTab) ){ |
| Bitmask b = pTabItem->colUsed; |
| int n = 0; |
| for(; b; b=b>>1, n++){} |
| sqlite3VdbeChangeP4(v, sqlite3VdbeCurrentAddr(v)-1, |
| SQLITE_INT_TO_PTR(n), P4_INT32); |
| assert( n<=pTab->nCol ); |
| } |
| }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; |
| /* iIdxCur is always set if to a positive value if ONEPASS is possible */ |
| assert( iIdxCur!=0 || (pWInfo->wctrlFlags & WHERE_ONEPASS_DESIRED)==0 ); |
| if( !HasRowid(pTab) && IsPrimaryKeyIndex(pIx) |
| && (wctrlFlags & WHERE_ONETABLE_ONLY)!=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->okOnePass ){ |
| Index *pJ = pTabItem->pTab->pIndex; |
| iIndexCur = iIdxCur; |
| assert( wctrlFlags & WHERE_ONEPASS_DESIRED ); |
| while( ALWAYS(pJ) && pJ!=pIx ){ |
| iIndexCur++; |
| pJ = pJ->pNext; |
| } |
| op = OP_OpenWrite; |
| pWInfo->aiCurOnePass[1] = iIndexCur; |
| }else if( iIdxCur && (wctrlFlags & WHERE_ONETABLE_ONLY)!=0 ){ |
| iIndexCur = iIdxCur; |
| if( wctrlFlags & WHERE_REOPEN_IDX ) op = OP_ReopenIdx; |
| }else{ |
| iIndexCur = pParse->nTab++; |
| } |
| pLevel->iIdxCur = iIndexCur; |
| assert( pIx->pSchema==pTab->pSchema ); |
| assert( iIndexCur>=0 ); |
| if( op ){ |
| sqlite3VdbeAddOp3(v, op, iIndexCur, pIx->tnum, iDb); |
| sqlite3VdbeSetP4KeyInfo(pParse, pIx); |
| VdbeComment((v, "%s", pIx->zName)); |
| } |
| } |
| if( iDb>=0 ) sqlite3CodeVerifySchema(pParse, iDb); |
| notReady &= ~getMask(&pWInfo->sMaskSet, pTabItem->iCursor); |
| } |
| 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. |
| */ |
| notReady = ~(Bitmask)0; |
| for(ii=0; ii<nTabList; ii++){ |
| pLevel = &pWInfo->a[ii]; |
| #ifndef SQLITE_OMIT_AUTOMATIC_INDEX |
| if( (pLevel->pWLoop->wsFlags & WHERE_AUTO_INDEX)!=0 ){ |
| constructAutomaticIndex(pParse, &pWInfo->sWC, |
| &pTabList->a[pLevel->iFrom], notReady, pLevel); |
| if( db->mallocFailed ) goto whereBeginError; |
| } |
| #endif |
| explainOneScan(pParse, pTabList, pLevel, ii, pLevel->iFrom, wctrlFlags); |
| pLevel->addrBody = sqlite3VdbeCurrentAddr(v); |
| notReady = codeOneLoopStart(pWInfo, ii, notReady); |
| pWInfo->iContinue = pLevel->addrCont; |
| } |
| |
| /* Done. */ |
| VdbeModuleComment((v, "Begin WHERE-core")); |
| return pWInfo; |
| |
| /* Jump here if malloc fails */ |
| whereBeginError: |
| if( pWInfo ){ |
| pParse->nQueryLoop = pWInfo->savedNQueryLoop; |
| whereInfoFree(db, pWInfo); |
| } |
| return 0; |
| } |
| |
| /* |
| ** 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; |
| |
| /* Generate loop termination code. |
| */ |
| VdbeModuleComment((v, "End WHERE-core")); |
| sqlite3ExprCacheClear(pParse); |
| for(i=pWInfo->nLevel-1; i>=0; i--){ |
| int addr; |
| pLevel = &pWInfo->a[i]; |
| pLoop = pLevel->pWLoop; |
| sqlite3VdbeResolveLabel(v, pLevel->addrCont); |
| if( pLevel->op!=OP_Noop ){ |
| 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( pLoop->wsFlags & WHERE_IN_ABLE && 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--){ |
| sqlite3VdbeJumpHere(v, pIn->addrInTop+1); |
| sqlite3VdbeAddOp2(v, pIn->eEndLoopOp, pIn->iCur, pIn->addrInTop); |
| VdbeCoverage(v); |
| VdbeCoverageIf(v, pIn->eEndLoopOp==OP_PrevIfOpen); |
| VdbeCoverageIf(v, pIn->eEndLoopOp==OP_NextIfOpen); |
| sqlite3VdbeJumpHere(v, pIn->addrInTop-1); |
| } |
| sqlite3DbFree(db, pLevel->u.in.aInLoop); |
| } |
| sqlite3VdbeResolveLabel(v, pLevel->addrBrk); |
| if( pLevel->addrSkip ){ |
| sqlite3VdbeAddOp2(v, OP_Goto, 0, pLevel->addrSkip); |
| VdbeComment((v, "next skip-scan on %s", pLoop->u.btree.pIndex->zName)); |
| sqlite3VdbeJumpHere(v, pLevel->addrSkip); |
| sqlite3VdbeJumpHere(v, pLevel->addrSkip-2); |
| } |
| if( pLevel->iLeftJoin ){ |
| addr = sqlite3VdbeAddOp1(v, OP_IfPos, pLevel->iLeftJoin); VdbeCoverage(v); |
| assert( (pLoop->wsFlags & WHERE_IDX_ONLY)==0 |
| || (pLoop->wsFlags & WHERE_INDEXED)!=0 ); |
| if( (pLoop->wsFlags & WHERE_IDX_ONLY)==0 ){ |
| sqlite3VdbeAddOp1(v, OP_NullRow, pTabList->a[i].iCursor); |
| } |
| if( pLoop->wsFlags & WHERE_INDEXED ){ |
| sqlite3VdbeAddOp1(v, OP_NullRow, pLevel->iIdxCur); |
| } |
| if( pLevel->op==OP_Return ){ |
| sqlite3VdbeAddOp2(v, OP_Gosub, pLevel->p1, pLevel->addrFirst); |
| }else{ |
| sqlite3VdbeAddOp2(v, OP_Goto, 0, pLevel->addrFirst); |
| } |
| sqlite3VdbeJumpHere(v, addr); |
| } |
| VdbeModuleComment((v, "End WHERE-loop%d: %s", i, |
| pWInfo->pTabList->a[pLevel->iFrom].pTab->zName)); |
| } |
| |
| /* The "break" point is here, just past the end of the outer loop. |
| ** Set it. |
| */ |
| sqlite3VdbeResolveLabel(v, pWInfo->iBreak); |
| |
| assert( pWInfo->nLevel<=pTabList->nSrc ); |
| for(i=0, pLevel=pWInfo->a; i<pWInfo->nLevel; i++, pLevel++){ |
| int k, last; |
| VdbeOp *pOp; |
| Index *pIdx = 0; |
| struct SrcList_item *pTabItem = &pTabList->a[pLevel->iFrom]; |
| Table *pTab = pTabItem->pTab; |
| assert( pTab!=0 ); |
| pLoop = pLevel->pWLoop; |
| |
| /* For a co-routine, change all OP_Column references to the table of |
| ** the co-routine into OP_SCopy of result contained in a register. |
| ** OP_Rowid becomes OP_Null. |
| */ |
| if( pTabItem->viaCoroutine && !db->mallocFailed ){ |
| last = sqlite3VdbeCurrentAddr(v); |
| k = pLevel->addrBody; |
| pOp = sqlite3VdbeGetOp(v, k); |
| for(; k<last; k++, pOp++){ |
| if( pOp->p1!=pLevel->iTabCur ) continue; |
| if( pOp->opcode==OP_Column ){ |
| pOp->opcode = OP_Copy; |
| pOp->p1 = pOp->p2 + pTabItem->regResult; |
| pOp->p2 = pOp->p3; |
| pOp->p3 = 0; |
| }else if( pOp->opcode==OP_Rowid ){ |
| pOp->opcode = OP_Null; |
| pOp->p1 = 0; |
| pOp->p3 = 0; |
| } |
| } |
| continue; |
| } |
| |
| /* Close all of the cursors that were opened by sqlite3WhereBegin. |
| ** Except, do not close cursors that will be reused by the OR optimization |
| ** (WHERE_OMIT_OPEN_CLOSE). And do not close the OP_OpenWrite cursors |
| ** created for the ONEPASS optimization. |
| */ |
| if( (pTab->tabFlags & TF_Ephemeral)==0 |
| && pTab->pSelect==0 |
| && (pWInfo->wctrlFlags & WHERE_OMIT_OPEN_CLOSE)==0 |
| ){ |
| int ws = pLoop->wsFlags; |
| if( !pWInfo->okOnePass && (ws & WHERE_IDX_ONLY)==0 ){ |
| sqlite3VdbeAddOp1(v, OP_Close, pTabItem->iCursor); |
| } |
| if( (ws & WHERE_INDEXED)!=0 |
| && (ws & (WHERE_IPK|WHERE_AUTO_INDEX))==0 |
| && pLevel->iIdxCur!=pWInfo->aiCurOnePass[1] |
| ){ |
| sqlite3VdbeAddOp1(v, OP_Close, pLevel->iIdxCur); |
| } |
| } |
| |
| /* 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.pCovidx; |
| } |
| if( pIdx && !db->mallocFailed ){ |
| last = sqlite3VdbeCurrentAddr(v); |
| k = pLevel->addrBody; |
| pOp = sqlite3VdbeGetOp(v, k); |
| for(; k<last; k++, pOp++){ |
| if( pOp->p1!=pLevel->iTabCur ) continue; |
| if( pOp->opcode==OP_Column ){ |
| int x = pOp->p2; |
| assert( pIdx->pTable==pTab ); |
| if( !HasRowid(pTab) ){ |
| Index *pPk = sqlite3PrimaryKeyIndex(pTab); |
| x = pPk->aiColumn[x]; |
| } |
| x = sqlite3ColumnOfIndex(pIdx, x); |
| if( x>=0 ){ |
| pOp->p2 = x; |
| pOp->p1 = pLevel->iIdxCur; |
| } |
| assert( (pLoop->wsFlags & WHERE_IDX_ONLY)==0 || x>=0 ); |
| }else if( pOp->opcode==OP_Rowid ){ |
| pOp->p1 = pLevel->iIdxCur; |
| pOp->opcode = OP_IdxRowid; |
| } |
| } |
| } |
| } |
| |
| /* Final cleanup |
| */ |
| pParse->nQueryLoop = pWInfo->savedNQueryLoop; |
| whereInfoFree(db, pWInfo); |
| return; |
| } |