/* ** Call exprAnalyze on all terms in a WHERE clause. ** ** Note that exprAnalyze() might add new virtual terms onto the ** end of the WHERE clause. We do not want to analyze these new ** virtual terms, so start analyzing at the end and work forward ** so that the added virtual terms are never processed. */ void sqlite3WhereExprAnalyze( 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); } }
/* ** Subterms pOne and pTwo are contained within WHERE clause pWC. The ** two subterms are in disjunction - they are OR-ed together. ** ** If these two terms are both of the form: "A op B" with the same ** A and B values but different operators and if the operators are ** compatible (if one is = and the other is <, for example) then ** add a new virtual AND term to pWC that is the combination of the ** two. ** ** Some examples: ** ** x<y OR x=y --> x<=y ** x=y OR x=y --> x=y ** x<=y OR x<y --> x<=y ** ** The following is NOT generated: ** ** x<y OR x>y --> x!=y */ static void whereCombineDisjuncts( SrcList *pSrc, /* the FROM clause */ WhereClause *pWC, /* The complete WHERE clause */ WhereTerm *pOne, /* First disjunct */ WhereTerm *pTwo /* Second disjunct */ ){ u16 eOp = pOne->eOperator | pTwo->eOperator; sqlite3 *db; /* Database connection (for malloc) */ Expr *pNew; /* New virtual expression */ int op; /* Operator for the combined expression */ int idxNew; /* Index in pWC of the next virtual term */ if( (pOne->eOperator & (WO_EQ|WO_LT|WO_LE|WO_GT|WO_GE))==0 ) return; if( (pTwo->eOperator & (WO_EQ|WO_LT|WO_LE|WO_GT|WO_GE))==0 ) return; if( (eOp & (WO_EQ|WO_LT|WO_LE))!=eOp && (eOp & (WO_EQ|WO_GT|WO_GE))!=eOp ) return; assert( pOne->pExpr->pLeft!=0 && pOne->pExpr->pRight!=0 ); assert( pTwo->pExpr->pLeft!=0 && pTwo->pExpr->pRight!=0 ); if( sqlite3ExprCompare(pOne->pExpr->pLeft, pTwo->pExpr->pLeft, -1) ) return; if( sqlite3ExprCompare(pOne->pExpr->pRight, pTwo->pExpr->pRight, -1) )return; /* If we reach this point, it means the two subterms can be combined */ if( (eOp & (eOp-1))!=0 ){ if( eOp & (WO_LT|WO_LE) ){ eOp = WO_LE; }else{ assert( eOp & (WO_GT|WO_GE) ); eOp = WO_GE; } } db = pWC->pWInfo->pParse->db; pNew = sqlite3ExprDup(db, pOne->pExpr, 0); if( pNew==0 ) return; for(op=TK_EQ; eOp!=(WO_EQ<<(op-TK_EQ)); op++){ assert( op<TK_GE ); } pNew->op = op; idxNew = whereClauseInsert(pWC, pNew, TERM_VIRTUAL|TERM_DYNAMIC); exprAnalyze(pSrc, pWC, idxNew); }
/* ** 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; /* uppercase equivalent to lowercase */ 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 = sqlite3WhereExprUsage(pMaskSet, pExpr->pLeft); op = pExpr->op; if( op==TK_IN ){ assert( pExpr->pRight==0 ); if( ExprHasProperty(pExpr, EP_xIsSelect) ){ pTerm->prereqRight = exprSelectUsage(pMaskSet, pExpr->x.pSelect); }else{ pTerm->prereqRight = sqlite3WhereExprListUsage(pMaskSet, pExpr->x.pList); } }else if( op==TK_ISNULL ){ pTerm->prereqRight = 0; }else{ pTerm->prereqRight = sqlite3WhereExprUsage(pMaskSet, pExpr->pRight); } prereqAll = sqlite3WhereExprUsage(pMaskSet, pExpr); if( ExprHasProperty(pExpr, EP_FromJoin) ){ Bitmask x = sqlite3WhereGetMask(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( op==TK_IS ) pTerm->wtFlags |= TERM_IS; 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]; markTermAsChild(pWC, idxNew, idxTerm); if( op==TK_IS ) pNew->wtFlags |= TERM_IS; pTerm = &pWC->a[idxTerm]; pTerm->wtFlags |= TERM_COPIED; if( termIsEquivalence(pParse, pDup) ){ 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]; markTermAsChild(pWC, idxNew, idxTerm); } } #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 case is not significant (the default ** for LIKE) then the lower-bound is made all uppercase and the upper- ** bound is made all lowercase so that the bounds also work when comparing ** BLOBs. */ 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 */ const u16 wtFlags = TERM_LIKEOPT | TERM_VIRTUAL | TERM_DYNAMIC; pLeft = pExpr->x.pList->a[1].pExpr; pStr2 = sqlite3ExprDup(db, pStr1, 0); /* Convert the lower bound to upper-case and the upper bound to ** lower-case (upper-case is less than lower-case in ASCII) so that ** the range constraints also work for BLOBs */ if( noCase && !pParse->db->mallocFailed ){ int i; char c; pTerm->wtFlags |= TERM_LIKE; for(i=0; (c = pStr1->u.zToken[i])!=0; i++){ pStr1->u.zToken[i] = sqlite3Toupper(c); pStr2->u.zToken[i] = sqlite3Tolower(c); } } 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, wtFlags); 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, wtFlags); testcase( idxNew2==0 ); exprAnalyze(pSrc, pWC, idxNew2); pTerm = &pWC->a[idxTerm]; if( isComplete ){ markTermAsChild(pWC, idxNew1, idxTerm); markTermAsChild(pWC, idxNew2, idxTerm); } } #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 = sqlite3WhereExprUsage(pMaskSet, pRight); prereqColumn = sqlite3WhereExprUsage(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; markTermAsChild(pWC, idxNew, idxTerm); pTerm = &pWC->a[idxTerm]; 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. */ if( pExpr->op==TK_NOTNULL && pExpr->pLeft->op==TK_COLUMN && pExpr->pLeft->iColumn>=0 && OptimizationEnabled(db, SQLITE_Stat34) ){ 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; markTermAsChild(pWC, idxNew, idxTerm); pTerm = &pWC->a[idxTerm]; 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; }
/* ** 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) ** (F) x>A OR (x=A AND y>=B) ** ** 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 there are exactly two disjuncts and one side has x>A and the other side ** has x=A (for the same x and A) then add a new virtual conjunct term to the ** WHERE clause of the form "x>=A". Example: ** ** x>A OR (x=A AND y>B) adds: x>=A ** ** The added conjunct can sometimes be helpful in query planning. ** ** CASE 3: ** ** 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 3. 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 3 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 3 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 none of cases 1, 2, or 3 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; sqlite3WhereClauseInit(pOrWc, pWInfo); sqlite3WhereSplit(pOrWc, pExpr, TK_OR); sqlite3WhereExprAnalyze(pSrc, pOrWc); if( db->mallocFailed ) return; assert( pOrWc->nTerm>=2 ); /* ** Compute the set of tables that might satisfy cases 1 or 3. */ 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; sqlite3WhereClauseInit(pAndWC, pWC->pWInfo); sqlite3WhereSplit(pAndWC, pOrTerm->pExpr, TK_AND); sqlite3WhereExprAnalyze(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 |= sqlite3WhereGetMask(&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 = sqlite3WhereGetMask(&pWInfo->sMaskSet, pOrTerm->leftCursor); if( pOrTerm->wtFlags & TERM_VIRTUAL ){ WhereTerm *pOther = &pOrWc->a[pOrTerm->iParent]; b |= sqlite3WhereGetMask(&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 3. The set might be ** empty. */ pOrInfo->indexable = indexable; pTerm->eOperator = indexable==0 ? 0 : WO_OR; /* For a two-way OR, attempt to implementation case 2. */ if( indexable && pOrWc->nTerm==2 ){ int iOne = 0; WhereTerm *pOne; while( (pOne = whereNthSubterm(&pOrWc->a[0],iOne++))!=0 ){ int iTwo = 0; WhereTerm *pTwo; while( (pTwo = whereNthSubterm(&pOrWc->a[1],iTwo++))!=0 ){ whereCombineDisjuncts(pSrc, pWC, pOne, pTwo); } } } /* ** 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 & sqlite3WhereGetMask(&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==sqlite3WhereGetMask(&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]; markTermAsChild(pWC, idxNew, idxTerm); }else{ sqlite3ExprListDelete(db, pList); } pTerm->eOperator = WO_NOOP; /* case 1 trumps case 3 */ } } }
/* ** 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 sqliteWhereEnd() 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 sqliteWhereBegin() ** foreach row3 in t3 do / ** ... ** end \ Code generated ** end |-- by sqliteWhereEnd() ** end / ** ** 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 sqliteWhereEnd() generates the code to close them. ** ** 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 ** ** *ppOrderBy is a pointer to the ORDER BY clause 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 ppOrderBy is NULL. ** ** If an index can be used so that the natural output order of the table ** scan is correct for the ORDER BY clause, then that index is used and ** *ppOrderBy is set to NULL. This is an optimization that prevents an ** unnecessary sort of the result set if an index appropriate for the ** ORDER BY clause already exists. ** ** If the where clause loops cannot be arranged to provide the correct ** output order, then the *ppOrderBy is unchanged. */ WhereInfo *sqliteWhereBegin( Parse *pParse, /* The parser context */ SrcList *pTabList, /* A list of all tables to be scanned */ Expr *pWhere, /* The WHERE clause */ int pushKey, /* If TRUE, leave the table key on the stack */ ExprList **ppOrderBy /* An ORDER BY clause, or NULL */ ){ int i; /* Loop counter */ WhereInfo *pWInfo; /* Will become the return value of this function */ Vdbe *v = pParse->pVdbe; /* The virtual database engine */ int brk, cont = 0; /* Addresses used during code generation */ int nExpr; /* Number of subexpressions in the WHERE clause */ int loopMask; /* One bit set for each outer loop */ int haveKey; /* True if KEY is on the stack */ ExprMaskSet maskSet; /* The expression mask set */ int iDirectEq[32]; /* Term of the form ROWID==X for the N-th table */ int iDirectLt[32]; /* Term of the form ROWID<X or ROWID<=X */ int iDirectGt[32]; /* Term of the form ROWID>X or ROWID>=X */ ExprInfo aExpr[101]; /* The WHERE clause is divided into these expressions */ /* pushKey is only allowed if there is a single table (as in an INSERT or ** UPDATE statement) */ assert( pushKey==0 || pTabList->nSrc==1 ); /* Split the WHERE clause into separate subexpressions where each ** subexpression is separated by an AND operator. If the aExpr[] ** array fills up, the last entry might point to an expression which ** contains additional unfactored AND operators. */ initMaskSet(&maskSet); memset(aExpr, 0, sizeof(aExpr)); nExpr = exprSplit(ARRAYSIZE(aExpr), aExpr, pWhere); if( nExpr==ARRAYSIZE(aExpr) ){ sqliteErrorMsg(pParse, "WHERE clause too complex - no more " "than %d terms allowed", (int)ARRAYSIZE(aExpr)-1); return 0; } /* Allocate and initialize the WhereInfo structure that will become the ** return value. */ pWInfo = sqliteMalloc( sizeof(WhereInfo) + pTabList->nSrc*sizeof(WhereLevel)); if( sqlite_malloc_failed ){ sqliteFree(pWInfo); return 0; } pWInfo->pParse = pParse; pWInfo->pTabList = pTabList; pWInfo->peakNTab = pWInfo->savedNTab = pParse->nTab; pWInfo->iBreak = sqliteVdbeMakeLabel(v); /* Special case: a WHERE clause that is constant. Evaluate the ** expression and either jump over all of the code or fall thru. */ if( pWhere && (pTabList->nSrc==0 || sqliteExprIsConstant(pWhere)) ){ sqliteExprIfFalse(pParse, pWhere, pWInfo->iBreak, 1); pWhere = 0; } /* Analyze all of the subexpressions. */ for(i=0; i<nExpr; i++){ exprAnalyze(&maskSet, &aExpr[i]); /* If we are executing a trigger body, remove all references to ** new.* and old.* tables from the prerequisite masks. */ if( pParse->trigStack ){ int x; if( (x = pParse->trigStack->newIdx) >= 0 ){ int mask = ~getMask(&maskSet, x); aExpr[i].prereqRight &= mask; aExpr[i].prereqLeft &= mask; aExpr[i].prereqAll &= mask; } if( (x = pParse->trigStack->oldIdx) >= 0 ){ int mask = ~getMask(&maskSet, x); aExpr[i].prereqRight &= mask; aExpr[i].prereqLeft &= mask; aExpr[i].prereqAll &= mask; } } } /* Figure out what index to use (if any) for each nested loop. ** Make pWInfo->a[i].pIdx point to the index to use for the i-th nested ** loop where i==0 is the outer loop and i==pTabList->nSrc-1 is the inner ** loop. ** ** If terms exist that use the ROWID of any table, then set the ** iDirectEq[], iDirectLt[], or iDirectGt[] elements for that table ** to the index of the term containing the ROWID. We always prefer ** to use a ROWID which can directly access a table rather than an ** index which requires reading an index first to get the rowid then ** doing a second read of the actual database table. ** ** Actually, if there are more than 32 tables in the join, only the ** first 32 tables are candidates for indices. This is (again) due ** to the limit of 32 bits in an integer bitmask. */ loopMask = 0; for(i=0; i<pTabList->nSrc && i<ARRAYSIZE(iDirectEq); i++){ int j; int iCur = pTabList->a[i].iCursor; /* The cursor for this table */ int mask = getMask(&maskSet, iCur); /* Cursor mask for this table */ Table *pTab = pTabList->a[i].pTab; Index *pIdx; Index *pBestIdx = 0; int bestScore = 0; /* Check to see if there is an expression that uses only the ** ROWID field of this table. For terms of the form ROWID==expr ** set iDirectEq[i] to the index of the term. For terms of the ** form ROWID<expr or ROWID<=expr set iDirectLt[i] to the term index. ** For terms like ROWID>expr or ROWID>=expr set iDirectGt[i]. ** ** (Added:) Treat ROWID IN expr like ROWID=expr. */ pWInfo->a[i].iCur = -1; iDirectEq[i] = -1; iDirectLt[i] = -1; iDirectGt[i] = -1; for(j=0; j<nExpr; j++){ if( aExpr[j].idxLeft==iCur && aExpr[j].p->pLeft->iColumn<0 && (aExpr[j].prereqRight & loopMask)==aExpr[j].prereqRight ){ switch( aExpr[j].p->op ){ case TK_IN: case TK_EQ: iDirectEq[i] = j; break; case TK_LE: case TK_LT: iDirectLt[i] = j; break; case TK_GE: case TK_GT: iDirectGt[i] = j; break; } } if( aExpr[j].idxRight==iCur && aExpr[j].p->pRight->iColumn<0 && (aExpr[j].prereqLeft & loopMask)==aExpr[j].prereqLeft ){ switch( aExpr[j].p->op ){ case TK_EQ: iDirectEq[i] = j; break; case TK_LE: case TK_LT: iDirectGt[i] = j; break; case TK_GE: case TK_GT: iDirectLt[i] = j; break; } } } if( iDirectEq[i]>=0 ){ loopMask |= mask; pWInfo->a[i].pIdx = 0; continue; } /* Do a search for usable indices. Leave pBestIdx pointing to ** the "best" index. pBestIdx is left set to NULL if no indices ** are usable. ** ** The best index is determined as follows. For each of the ** left-most terms that is fixed by an equality operator, add ** 8 to the score. The right-most term of the index may be ** constrained by an inequality. Add 1 if for an "x<..." constraint ** and add 2 for an "x>..." constraint. Chose the index that ** gives the best score. ** ** This scoring system is designed so that the score can later be ** used to determine how the index is used. If the score&7 is 0 ** then all constraints are equalities. If score&1 is not 0 then ** there is an inequality used as a termination key. (ex: "x<...") ** If score&2 is not 0 then there is an inequality used as the ** start key. (ex: "x>..."). A score or 4 is the special case ** of an IN operator constraint. (ex: "x IN ..."). ** ** The IN operator (as in "<expr> IN (...)") is treated the same as ** an equality comparison except that it can only be used on the ** left-most column of an index and other terms of the WHERE clause ** cannot be used in conjunction with the IN operator to help satisfy ** other columns of the index. */ for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){ int eqMask = 0; /* Index columns covered by an x=... term */ int ltMask = 0; /* Index columns covered by an x<... term */ int gtMask = 0; /* Index columns covered by an x>... term */ int inMask = 0; /* Index columns covered by an x IN .. term */ int nEq, m, score; if( pIdx->nColumn>32 ) continue; /* Ignore indices too many columns */ for(j=0; j<nExpr; j++){ if( aExpr[j].idxLeft==iCur && (aExpr[j].prereqRight & loopMask)==aExpr[j].prereqRight ){ int iColumn = aExpr[j].p->pLeft->iColumn; int k; for(k=0; k<pIdx->nColumn; k++){ if( pIdx->aiColumn[k]==iColumn ){ switch( aExpr[j].p->op ){ case TK_IN: { if( k==0 ) inMask |= 1; break; } case TK_EQ: { eqMask |= 1<<k; break; } case TK_LE: case TK_LT: { ltMask |= 1<<k; break; } case TK_GE: case TK_GT: { gtMask |= 1<<k; break; } default: { /* CANT_HAPPEN */ assert( 0 ); break; } } break; } } } if( aExpr[j].idxRight==iCur && (aExpr[j].prereqLeft & loopMask)==aExpr[j].prereqLeft ){ int iColumn = aExpr[j].p->pRight->iColumn; int k; for(k=0; k<pIdx->nColumn; k++){ if( pIdx->aiColumn[k]==iColumn ){ switch( aExpr[j].p->op ){ case TK_EQ: { eqMask |= 1<<k; break; } case TK_LE: case TK_LT: { gtMask |= 1<<k; break; } case TK_GE: case TK_GT: { ltMask |= 1<<k; break; } default: { /* CANT_HAPPEN */ assert( 0 ); break; } } break; } } } } /* The following loop ends with nEq set to the number of columns ** on the left of the index with == constraints. */ for(nEq=0; nEq<pIdx->nColumn; nEq++){ m = (1<<(nEq+1))-1; if( (m & eqMask)!=m ) break; } score = nEq*8; /* Base score is 8 times number of == constraints */ m = 1<<nEq; if( m & ltMask ) score++; /* Increase score for a < constraint */ if( m & gtMask ) score+=2; /* Increase score for a > constraint */ if( score==0 && inMask ) score = 4; /* Default score for IN constraint */ if( score>bestScore ){ pBestIdx = pIdx; bestScore = score; } } pWInfo->a[i].pIdx = pBestIdx; pWInfo->a[i].score = bestScore; pWInfo->a[i].bRev = 0; loopMask |= mask; if( pBestIdx ){ pWInfo->a[i].iCur = pParse->nTab++; pWInfo->peakNTab = pParse->nTab; } } /* Check to see if the ORDER BY clause is or can be satisfied by the ** use of an index on the first table. */ if( ppOrderBy && *ppOrderBy && pTabList->nSrc>0 ){ Index *pSortIdx; Index *pIdx; Table *pTab; int bRev = 0; pTab = pTabList->a[0].pTab; pIdx = pWInfo->a[0].pIdx; if( pIdx && pWInfo->a[0].score==4 ){ /* If there is already an IN index on the left-most table, ** it will not give the correct sort order. ** So, pretend that no suitable index is found. */ pSortIdx = 0; }else if( iDirectEq[0]>=0 || iDirectLt[0]>=0 || iDirectGt[0]>=0 ){ /* If the left-most column is accessed using its ROWID, then do ** not try to sort by index. */ pSortIdx = 0; }else{ int nEqCol = (pWInfo->a[0].score+4)/8; pSortIdx = findSortingIndex(pTab, pTabList->a[0].iCursor, *ppOrderBy, pIdx, nEqCol, &bRev); } if( pSortIdx && (pIdx==0 || pIdx==pSortIdx) ){ if( pIdx==0 ){ pWInfo->a[0].pIdx = pSortIdx; pWInfo->a[0].iCur = pParse->nTab++; pWInfo->peakNTab = pParse->nTab; } pWInfo->a[0].bRev = bRev; *ppOrderBy = 0; } } /* Open all tables in the pTabList and all indices used by those tables. */ for(i=0; i<pTabList->nSrc; i++){ Table *pTab; Index *pIx; pTab = pTabList->a[i].pTab; if( pTab->isTransient || pTab->pSelect ) continue; sqliteVdbeAddOp(v, OP_Integer, pTab->iDb, 0); sqliteVdbeOp3(v, OP_OpenRead, pTabList->a[i].iCursor, pTab->tnum, pTab->zName, P3_STATIC); sqliteCodeVerifySchema(pParse, pTab->iDb); if( (pIx = pWInfo->a[i].pIdx)!=0 ){ sqliteVdbeAddOp(v, OP_Integer, pIx->iDb, 0); sqliteVdbeOp3(v, OP_OpenRead, pWInfo->a[i].iCur, pIx->tnum, pIx->zName,0); } } /* Generate the code to do the search */ loopMask = 0; for(i=0; i<pTabList->nSrc; i++){ int j, k; int iCur = pTabList->a[i].iCursor; Index *pIdx; WhereLevel *pLevel = &pWInfo->a[i]; /* 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( i>0 && (pTabList->a[i-1].jointype & JT_LEFT)!=0 ){ if( !pParse->nMem ) pParse->nMem++; pLevel->iLeftJoin = pParse->nMem++; sqliteVdbeAddOp(v, OP_String, 0, 0); sqliteVdbeAddOp(v, OP_MemStore, pLevel->iLeftJoin, 1); } pIdx = pLevel->pIdx; pLevel->inOp = OP_Noop; if( i<ARRAYSIZE(iDirectEq) && iDirectEq[i]>=0 ){ /* Case 1: 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. */ k = iDirectEq[i]; assert( k<nExpr ); assert( aExpr[k].p!=0 ); assert( aExpr[k].idxLeft==iCur || aExpr[k].idxRight==iCur ); brk = pLevel->brk = sqliteVdbeMakeLabel(v); if( aExpr[k].idxLeft==iCur ){ Expr *pX = aExpr[k].p; if( pX->op!=TK_IN ){ sqliteExprCode(pParse, aExpr[k].p->pRight); }else if( pX->pList ){ sqliteVdbeAddOp(v, OP_SetFirst, pX->iTable, brk); pLevel->inOp = OP_SetNext; pLevel->inP1 = pX->iTable; pLevel->inP2 = sqliteVdbeCurrentAddr(v); }else{ assert( pX->pSelect ); sqliteVdbeAddOp(v, OP_Rewind, pX->iTable, brk); sqliteVdbeAddOp(v, OP_KeyAsData, pX->iTable, 1); pLevel->inP2 = sqliteVdbeAddOp(v, OP_FullKey, pX->iTable, 0); pLevel->inOp = OP_Next; pLevel->inP1 = pX->iTable; } }else{ sqliteExprCode(pParse, aExpr[k].p->pLeft); } disableTerm(pLevel, &aExpr[k].p); cont = pLevel->cont = sqliteVdbeMakeLabel(v); sqliteVdbeAddOp(v, OP_MustBeInt, 1, brk); haveKey = 0; sqliteVdbeAddOp(v, OP_NotExists, iCur, brk); pLevel->op = OP_Noop; }else if( pIdx!=0 && pLevel->score>0 && pLevel->score%4==0 ){ /* Case 2: There is an index and all terms of the WHERE clause that ** refer to the index use the "==" or "IN" operators. */ int start; int testOp; int nColumn = (pLevel->score+4)/8; brk = pLevel->brk = sqliteVdbeMakeLabel(v); for(j=0; j<nColumn; j++){ for(k=0; k<nExpr; k++){ Expr *pX = aExpr[k].p; if( pX==0 ) continue; if( aExpr[k].idxLeft==iCur && (aExpr[k].prereqRight & loopMask)==aExpr[k].prereqRight && pX->pLeft->iColumn==pIdx->aiColumn[j] ){ if( pX->op==TK_EQ ){ sqliteExprCode(pParse, pX->pRight); disableTerm(pLevel, &aExpr[k].p); break; } if( pX->op==TK_IN && nColumn==1 ){ if( pX->pList ){ sqliteVdbeAddOp(v, OP_SetFirst, pX->iTable, brk); pLevel->inOp = OP_SetNext; pLevel->inP1 = pX->iTable; pLevel->inP2 = sqliteVdbeCurrentAddr(v); }else{ assert( pX->pSelect ); sqliteVdbeAddOp(v, OP_Rewind, pX->iTable, brk); sqliteVdbeAddOp(v, OP_KeyAsData, pX->iTable, 1); pLevel->inP2 = sqliteVdbeAddOp(v, OP_FullKey, pX->iTable, 0); pLevel->inOp = OP_Next; pLevel->inP1 = pX->iTable; } disableTerm(pLevel, &aExpr[k].p); break; } } if( aExpr[k].idxRight==iCur && aExpr[k].p->op==TK_EQ && (aExpr[k].prereqLeft & loopMask)==aExpr[k].prereqLeft && aExpr[k].p->pRight->iColumn==pIdx->aiColumn[j] ){ sqliteExprCode(pParse, aExpr[k].p->pLeft); disableTerm(pLevel, &aExpr[k].p); break; } } } pLevel->iMem = pParse->nMem++; cont = pLevel->cont = sqliteVdbeMakeLabel(v); sqliteVdbeAddOp(v, OP_NotNull, -nColumn, sqliteVdbeCurrentAddr(v)+3); sqliteVdbeAddOp(v, OP_Pop, nColumn, 0); sqliteVdbeAddOp(v, OP_Goto, 0, brk); sqliteVdbeAddOp(v, OP_MakeKey, nColumn, 0); sqliteAddIdxKeyType(v, pIdx); if( nColumn==pIdx->nColumn || pLevel->bRev ){ sqliteVdbeAddOp(v, OP_MemStore, pLevel->iMem, 0); testOp = OP_IdxGT; }else{ sqliteVdbeAddOp(v, OP_Dup, 0, 0); sqliteVdbeAddOp(v, OP_IncrKey, 0, 0); sqliteVdbeAddOp(v, OP_MemStore, pLevel->iMem, 1); testOp = OP_IdxGE; } if( pLevel->bRev ){ /* Scan in reverse order */ sqliteVdbeAddOp(v, OP_IncrKey, 0, 0); sqliteVdbeAddOp(v, OP_MoveLt, pLevel->iCur, brk); start = sqliteVdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0); sqliteVdbeAddOp(v, OP_IdxLT, pLevel->iCur, brk); pLevel->op = OP_Prev; }else{ /* Scan in the forward order */ sqliteVdbeAddOp(v, OP_MoveTo, pLevel->iCur, brk); start = sqliteVdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0); sqliteVdbeAddOp(v, testOp, pLevel->iCur, brk); pLevel->op = OP_Next; } sqliteVdbeAddOp(v, OP_RowKey, pLevel->iCur, 0); sqliteVdbeAddOp(v, OP_IdxIsNull, nColumn, cont); sqliteVdbeAddOp(v, OP_IdxRecno, pLevel->iCur, 0); if( i==pTabList->nSrc-1 && pushKey ){ haveKey = 1; }else{ sqliteVdbeAddOp(v, OP_MoveTo, iCur, 0); haveKey = 0; } pLevel->p1 = pLevel->iCur; pLevel->p2 = start; }else if( i<ARRAYSIZE(iDirectLt) && (iDirectLt[i]>=0 || iDirectGt[i]>=0) ){ /* Case 3: We have an inequality comparison against the ROWID field. */ int testOp = OP_Noop; int start; brk = pLevel->brk = sqliteVdbeMakeLabel(v); cont = pLevel->cont = sqliteVdbeMakeLabel(v); if( iDirectGt[i]>=0 ){ k = iDirectGt[i]; assert( k<nExpr ); assert( aExpr[k].p!=0 ); assert( aExpr[k].idxLeft==iCur || aExpr[k].idxRight==iCur ); if( aExpr[k].idxLeft==iCur ){ sqliteExprCode(pParse, aExpr[k].p->pRight); }else{ sqliteExprCode(pParse, aExpr[k].p->pLeft); } sqliteVdbeAddOp(v, OP_ForceInt, aExpr[k].p->op==TK_LT || aExpr[k].p->op==TK_GT, brk); sqliteVdbeAddOp(v, OP_MoveTo, iCur, brk); disableTerm(pLevel, &aExpr[k].p); }else{ sqliteVdbeAddOp(v, OP_Rewind, iCur, brk); } if( iDirectLt[i]>=0 ){ k = iDirectLt[i]; assert( k<nExpr ); assert( aExpr[k].p!=0 ); assert( aExpr[k].idxLeft==iCur || aExpr[k].idxRight==iCur ); if( aExpr[k].idxLeft==iCur ){ sqliteExprCode(pParse, aExpr[k].p->pRight); }else{ sqliteExprCode(pParse, aExpr[k].p->pLeft); } /* sqliteVdbeAddOp(v, OP_MustBeInt, 0, sqliteVdbeCurrentAddr(v)+1); */ pLevel->iMem = pParse->nMem++; sqliteVdbeAddOp(v, OP_MemStore, pLevel->iMem, 1); if( aExpr[k].p->op==TK_LT || aExpr[k].p->op==TK_GT ){ testOp = OP_Ge; }else{ testOp = OP_Gt; } disableTerm(pLevel, &aExpr[k].p); } start = sqliteVdbeCurrentAddr(v); pLevel->op = OP_Next; pLevel->p1 = iCur; pLevel->p2 = start; if( testOp!=OP_Noop ){ sqliteVdbeAddOp(v, OP_Recno, iCur, 0); sqliteVdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0); sqliteVdbeAddOp(v, testOp, 0, brk); } haveKey = 0; }else if( pIdx==0 ){ /* Case 4: There is no usable index. We must do a complete ** scan of the entire database table. */ int start; brk = pLevel->brk = sqliteVdbeMakeLabel(v); cont = pLevel->cont = sqliteVdbeMakeLabel(v); sqliteVdbeAddOp(v, OP_Rewind, iCur, brk); start = sqliteVdbeCurrentAddr(v); pLevel->op = OP_Next; pLevel->p1 = iCur; pLevel->p2 = start; haveKey = 0; }else{ /* Case 5: The WHERE clause term that refers to the right-most ** column of the index is an inequality. For example, if ** the index is on (x,y,z) and the WHERE clause is of the ** form "x=5 AND y<10" then this case is used. Only the ** right-most column can be an inequality - the rest must ** use the "==" operator. ** ** 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. */ int score = pLevel->score; int nEqColumn = score/8; int start; int leFlag, geFlag; int testOp; /* Evaluate the equality constraints */ for(j=0; j<nEqColumn; j++){ for(k=0; k<nExpr; k++){ if( aExpr[k].p==0 ) continue; if( aExpr[k].idxLeft==iCur && aExpr[k].p->op==TK_EQ && (aExpr[k].prereqRight & loopMask)==aExpr[k].prereqRight && aExpr[k].p->pLeft->iColumn==pIdx->aiColumn[j] ){ sqliteExprCode(pParse, aExpr[k].p->pRight); disableTerm(pLevel, &aExpr[k].p); break; } if( aExpr[k].idxRight==iCur && aExpr[k].p->op==TK_EQ && (aExpr[k].prereqLeft & loopMask)==aExpr[k].prereqLeft && aExpr[k].p->pRight->iColumn==pIdx->aiColumn[j] ){ sqliteExprCode(pParse, aExpr[k].p->pLeft); disableTerm(pLevel, &aExpr[k].p); break; } } } /* Duplicate the equality term values because they will all be ** used twice: once to make the termination key and once to make the ** start key. */ for(j=0; j<nEqColumn; j++){ sqliteVdbeAddOp(v, OP_Dup, nEqColumn-1, 0); } /* Labels for the beginning and end of the loop */ cont = pLevel->cont = sqliteVdbeMakeLabel(v); brk = pLevel->brk = sqliteVdbeMakeLabel(v); /* Generate the termination key. This is the key value that ** will end the search. There is no termination key if there ** are no equality terms and no "X<..." term. ** ** 2002-Dec-04: On a reverse-order scan, the so-called "termination" ** key computed here really ends up being the start key. */ if( (score & 1)!=0 ){ for(k=0; k<nExpr; k++){ Expr *pExpr = aExpr[k].p; if( pExpr==0 ) continue; if( aExpr[k].idxLeft==iCur && (pExpr->op==TK_LT || pExpr->op==TK_LE) && (aExpr[k].prereqRight & loopMask)==aExpr[k].prereqRight && pExpr->pLeft->iColumn==pIdx->aiColumn[j] ){ sqliteExprCode(pParse, pExpr->pRight); leFlag = pExpr->op==TK_LE; disableTerm(pLevel, &aExpr[k].p); break; } if( aExpr[k].idxRight==iCur && (pExpr->op==TK_GT || pExpr->op==TK_GE) && (aExpr[k].prereqLeft & loopMask)==aExpr[k].prereqLeft && pExpr->pRight->iColumn==pIdx->aiColumn[j] ){ sqliteExprCode(pParse, pExpr->pLeft); leFlag = pExpr->op==TK_GE; disableTerm(pLevel, &aExpr[k].p); break; } } testOp = OP_IdxGE; }else{ testOp = nEqColumn>0 ? OP_IdxGE : OP_Noop; leFlag = 1; } if( testOp!=OP_Noop ){ int nCol = nEqColumn + (score & 1); pLevel->iMem = pParse->nMem++; sqliteVdbeAddOp(v, OP_NotNull, -nCol, sqliteVdbeCurrentAddr(v)+3); sqliteVdbeAddOp(v, OP_Pop, nCol, 0); sqliteVdbeAddOp(v, OP_Goto, 0, brk); sqliteVdbeAddOp(v, OP_MakeKey, nCol, 0); sqliteAddIdxKeyType(v, pIdx); if( leFlag ){ sqliteVdbeAddOp(v, OP_IncrKey, 0, 0); } if( pLevel->bRev ){ sqliteVdbeAddOp(v, OP_MoveLt, pLevel->iCur, brk); }else{ sqliteVdbeAddOp(v, OP_MemStore, pLevel->iMem, 1); } }else if( pLevel->bRev ){ sqliteVdbeAddOp(v, OP_Last, pLevel->iCur, brk); } /* Generate the start key. This is the key that defines the lower ** bound on the search. There is no start key if there are no ** equality terms and if there is no "X>..." term. In ** that case, generate a "Rewind" instruction in place of the ** start key search. ** ** 2002-Dec-04: In the case of a reverse-order search, the so-called ** "start" key really ends up being used as the termination key. */ if( (score & 2)!=0 ){ for(k=0; k<nExpr; k++){ Expr *pExpr = aExpr[k].p; if( pExpr==0 ) continue; if( aExpr[k].idxLeft==iCur && (pExpr->op==TK_GT || pExpr->op==TK_GE) && (aExpr[k].prereqRight & loopMask)==aExpr[k].prereqRight && pExpr->pLeft->iColumn==pIdx->aiColumn[j] ){ sqliteExprCode(pParse, pExpr->pRight); geFlag = pExpr->op==TK_GE; disableTerm(pLevel, &aExpr[k].p); break; } if( aExpr[k].idxRight==iCur && (pExpr->op==TK_LT || pExpr->op==TK_LE) && (aExpr[k].prereqLeft & loopMask)==aExpr[k].prereqLeft && pExpr->pRight->iColumn==pIdx->aiColumn[j] ){ sqliteExprCode(pParse, pExpr->pLeft); geFlag = pExpr->op==TK_LE; disableTerm(pLevel, &aExpr[k].p); break; } } }else{ geFlag = 1; } if( nEqColumn>0 || (score&2)!=0 ){ int nCol = nEqColumn + ((score&2)!=0); sqliteVdbeAddOp(v, OP_NotNull, -nCol, sqliteVdbeCurrentAddr(v)+3); sqliteVdbeAddOp(v, OP_Pop, nCol, 0); sqliteVdbeAddOp(v, OP_Goto, 0, brk); sqliteVdbeAddOp(v, OP_MakeKey, nCol, 0); sqliteAddIdxKeyType(v, pIdx); if( !geFlag ){ sqliteVdbeAddOp(v, OP_IncrKey, 0, 0); } if( pLevel->bRev ){ pLevel->iMem = pParse->nMem++; sqliteVdbeAddOp(v, OP_MemStore, pLevel->iMem, 1); testOp = OP_IdxLT; }else{ sqliteVdbeAddOp(v, OP_MoveTo, pLevel->iCur, brk); } }else if( pLevel->bRev ){ testOp = OP_Noop; }else{ sqliteVdbeAddOp(v, OP_Rewind, pLevel->iCur, brk); } /* Generate the the top of the loop. If there is a termination ** key we have to test for that key and abort at the top of the ** loop. */ start = sqliteVdbeCurrentAddr(v); if( testOp!=OP_Noop ){ sqliteVdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0); sqliteVdbeAddOp(v, testOp, pLevel->iCur, brk); } sqliteVdbeAddOp(v, OP_RowKey, pLevel->iCur, 0); sqliteVdbeAddOp(v, OP_IdxIsNull, nEqColumn + (score & 1), cont); sqliteVdbeAddOp(v, OP_IdxRecno, pLevel->iCur, 0); if( i==pTabList->nSrc-1 && pushKey ){ haveKey = 1; }else{ sqliteVdbeAddOp(v, OP_MoveTo, iCur, 0); haveKey = 0; } /* Record the instruction used to terminate the loop. */ pLevel->op = pLevel->bRev ? OP_Prev : OP_Next; pLevel->p1 = pLevel->iCur; pLevel->p2 = start; } loopMask |= getMask(&maskSet, iCur); /* Insert code to test every subexpression that can be completely ** computed using the current set of tables. */ for(j=0; j<nExpr; j++){ if( aExpr[j].p==0 ) continue; if( (aExpr[j].prereqAll & loopMask)!=aExpr[j].prereqAll ) continue; if( pLevel->iLeftJoin && !ExprHasProperty(aExpr[j].p,EP_FromJoin) ){ continue; } if( haveKey ){ haveKey = 0; sqliteVdbeAddOp(v, OP_MoveTo, iCur, 0); } sqliteExprIfFalse(pParse, aExpr[j].p, cont, 1); aExpr[j].p = 0; } brk = cont; /* 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->top = sqliteVdbeCurrentAddr(v); sqliteVdbeAddOp(v, OP_Integer, 1, 0); sqliteVdbeAddOp(v, OP_MemStore, pLevel->iLeftJoin, 1); for(j=0; j<nExpr; j++){ if( aExpr[j].p==0 ) continue; if( (aExpr[j].prereqAll & loopMask)!=aExpr[j].prereqAll ) continue; if( haveKey ){ /* Cannot happen. "haveKey" can only be true if pushKey is true ** an pushKey can only be true for DELETE and UPDATE and there are ** no outer joins with DELETE and UPDATE. */ haveKey = 0; sqliteVdbeAddOp(v, OP_MoveTo, iCur, 0); } sqliteExprIfFalse(pParse, aExpr[j].p, cont, 1); aExpr[j].p = 0; } } } pWInfo->iContinue = cont; if( pushKey && !haveKey ){ sqliteVdbeAddOp(v, OP_Recno, pTabList->a[0].iCursor, 0); } freeMaskSet(&maskSet); return pWInfo; }