diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/where.c | 1240 | ||||
| -rw-r--r-- | src/whereInt.h | 17 | ||||
| -rw-r--r-- | src/whereexpr.c | 1249 |
3 files changed, 1274 insertions, 1232 deletions
diff --git a/src/where.c b/src/where.c index e446f6db8..5c5022c9f 100644 --- a/src/where.c +++ b/src/where.c @@ -137,150 +137,6 @@ whereOrInsert_done: } /* -** 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, u16 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]); - memset(&pWC->a[pWC->nTerm], 0, sizeof(pWC->a[0])*(pWC->nSlot-pWC->nTerm)); - } - pTerm = &pWC->a[idx = pWC->nTerm++]; - if( p && ExprHasProperty(p, EP_Unlikely) ){ - pTerm->truthProb = sqlite3LogEst(p->iTable) - 270; - }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){ - Expr *pE2 = sqlite3ExprSkipCollate(pExpr); - pWC->op = op; - if( pE2==0 ) return; - if( pE2->op!=op ){ - whereClauseInsert(pWC, pExpr, 0); - }else{ - whereSplit(pWC, pE2->pLeft, op); - whereSplit(pWC, pE2->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. */ @@ -309,140 +165,6 @@ static void createMask(WhereMaskSet *pMaskSet, int 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 = sqlite3WhereGetMask(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 || op==TK_IS; -} - -/* -** 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 if( op==TK_IS ){ - c = WO_IS; - }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 ); - assert( op!=TK_IS || c==WO_IS ); - 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. @@ -620,952 +342,6 @@ WhereTerm *sqlite3WhereFindTerm( return pResult; } -/* Forward reference */ -static void exprAnalyze(SrcList*, WhereClause*, int); - -/* -** 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. -*/ -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. The LHS must be a column -** that may only be NULL, a string, or a BLOB, never a number. (This means -** that virtual tables cannot participate in the LIKE optimization.) The -** collating sequence for the column on the LHS must be appropriate for -** the operator. -*/ -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) /* Value might be numeric */ - ){ - /* 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_BLOB); - 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; - } -} - -/* -** Mark term iChild as being a child of term iParent -*/ -static void markTermAsChild(WhereClause *pWC, int iChild, int iParent){ - pWC->a[iChild].iParent = iParent; - pWC->a[iChild].truthProb = pWC->a[iParent].truthProb; - pWC->a[iParent].nChild++; -} - -/* -** Return the N-th AND-connected subterm of pTerm. Or if pTerm is not -** a conjunction, then return just pTerm when N==0. If N is exceeds -** the number of available subterms, return NULL. -*/ -static WhereTerm *whereNthSubterm(WhereTerm *pTerm, int N){ - if( pTerm->eOperator!=WO_AND ){ - return N==0 ? pTerm : 0; - } - if( N<pTerm->u.pAndInfo->wc.nTerm ){ - return &pTerm->u.pAndInfo->wc.a[N]; - } - return 0; -} - -/* -** 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); -} - -#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) -** (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; - 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 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; - 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 |= 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 */ - } - } -} -#endif /* !SQLITE_OMIT_OR_OPTIMIZATION && !SQLITE_OMIT_SUBQUERY */ - -/* -** We already know that pExpr is a binary operator where both operands are -** column references. This routine checks to see if pExpr is an equivalence -** relation: -** 1. The SQLITE_Transitive optimization must be enabled -** 2. Must be either an == or an IS operator -** 3. Not originating in the ON clause of an OUTER JOIN -** 4. The affinities of A and B must be compatible -** 5a. Both operands use the same collating sequence OR -** 5b. The overall collating sequence is BINARY -** If this routine returns TRUE, that means that the RHS can be substituted -** for the LHS anyplace else in the WHERE clause where the LHS column occurs. -** This is an optimization. No harm comes from returning 0. But if 1 is -** returned when it should not be, then incorrect answers might result. -*/ -static int termIsEquivalence(Parse *pParse, Expr *pExpr){ - char aff1, aff2; - CollSeq *pColl; - const char *zColl1, *zColl2; - if( !OptimizationEnabled(pParse->db, SQLITE_Transitive) ) return 0; - if( pExpr->op!=TK_EQ && pExpr->op!=TK_IS ) return 0; - if( ExprHasProperty(pExpr, EP_FromJoin) ) return 0; - aff1 = sqlite3ExprAffinity(pExpr->pLeft); - aff2 = sqlite3ExprAffinity(pExpr->pRight); - if( aff1!=aff2 - && (!sqlite3IsNumericAffinity(aff1) || !sqlite3IsNumericAffinity(aff2)) - ){ - return 0; - } - pColl = sqlite3BinaryCompareCollSeq(pParse, pExpr->pLeft, pExpr->pRight); - if( pColl==0 || sqlite3StrICmp(pColl->zName, "BINARY")==0 ) return 1; - pColl = sqlite3ExprCollSeq(pParse, pExpr->pLeft); - /* Since pLeft and pRight are both a column references, their collating - ** sequence should always be defined. */ - zColl1 = ALWAYS(pColl) ? pColl->zName : 0; - pColl = sqlite3ExprCollSeq(pParse, pExpr->pRight); - zColl2 = ALWAYS(pColl) ? pColl->zName : 0; - return sqlite3StrICmp(zColl1, zColl2)==0; -} - -/* -** 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 = 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 = 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 = 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; - 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; -} - /* ** This function searches pList for an entry that matches the iCol-th column ** of index pIdx. @@ -2938,7 +1714,7 @@ static void whereInfoFree(sqlite3 *db, WhereInfo *pWInfo){ sqlite3DbFree(db, pLevel->u.in.aInLoop); } } - whereClauseClear(&pWInfo->sWC); + sqlite3WhereClauseClear(&pWInfo->sWC); while( pWInfo->pLoops ){ WhereLoop *p = pWInfo->pLoops; pWInfo->pLoops = p->pNextLoop; @@ -4456,7 +3232,7 @@ static i8 wherePathSatisfiesOrderBy( Bitmask mTerm; if( MASKBIT(i) & obSat ) continue; p = pOrderBy->a[i].pExpr; - mTerm = exprTableUsage(&pWInfo->sMaskSet,p); + mTerm = sqlite3WhereExprUsage(&pWInfo->sMaskSet,p); if( mTerm==0 && !sqlite3ExprIsConstant(p) ) continue; if( (mTerm&~orderDistinctMask)==0 ){ obSat |= MASKBIT(i); @@ -5169,8 +3945,8 @@ WhereInfo *sqlite3WhereBegin( ** subexpression is separated by an AND operator. */ initMaskSet(pMaskSet); - whereClauseInit(&pWInfo->sWC, pWInfo); - whereSplit(&pWInfo->sWC, pWhere, TK_AND); + sqlite3WhereClauseInit(&pWInfo->sWC, pWInfo); + sqlite3WhereSplit(&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. @@ -5223,7 +3999,7 @@ WhereInfo *sqlite3WhereBegin( #endif /* Analyze all of the subexpressions. */ - exprAnalyzeAll(pTabList, &pWInfo->sWC); + sqlite3WhereExprAnalyze(pTabList, &pWInfo->sWC); if( db->mallocFailed ) goto whereBeginError; if( wctrlFlags & WHERE_WANT_DISTINCT ){ @@ -5309,8 +4085,10 @@ WhereInfo *sqlite3WhereBegin( && pResultSet!=0 && OptimizationEnabled(db, SQLITE_OmitNoopJoin) ){ - Bitmask tabUsed = exprListTableUsage(pMaskSet, pResultSet); - if( sWLB.pOrderBy ) tabUsed |= exprListTableUsage(pMaskSet, sWLB.pOrderBy); + Bitmask tabUsed = sqlite3WhereExprListUsage(pMaskSet, pResultSet); + if( sWLB.pOrderBy ){ + tabUsed |= sqlite3WhereExprListUsage(pMaskSet, sWLB.pOrderBy); + } while( pWInfo->nLevel>=2 ){ WhereTerm *pTerm, *pEnd; pLoop = pWInfo->a[pWInfo->nLevel-1].pWLoop; diff --git a/src/whereInt.h b/src/whereInt.h index 075deed4a..8929d8c4b 100644 --- a/src/whereInt.h +++ b/src/whereInt.h @@ -369,6 +369,11 @@ struct WhereMaskSet { }; /* +** Initialize a WhereMaskSet object +*/ +#define initMaskSet(P) (P)->n=0 + +/* ** This object is a convenience wrapper holding all information needed ** to construct WhereLoop objects for a particular query. */ @@ -421,6 +426,8 @@ struct WhereInfo { /* ** Private interfaces - callable only by other where.c routines. +** +** where.c: */ Bitmask sqlite3WhereGetMask(WhereMaskSet*,int); WhereTerm *sqlite3WhereFindTerm( @@ -431,6 +438,8 @@ WhereTerm *sqlite3WhereFindTerm( u32 op, /* Mask of WO_xx values describing operator */ Index *pIdx /* Must be compatible with this index, if not NULL */ ); + +/* wherecode.c: */ #ifndef SQLITE_OMIT_EXPLAIN int sqlite3WhereExplainOneScan( Parse *pParse, /* Parse context */ @@ -459,7 +468,13 @@ Bitmask sqlite3WhereCodeOneLoopStart( Bitmask notReady /* Which tables are currently available */ ); - +/* whereexpr.c: */ +void sqlite3WhereClauseInit(WhereClause*,WhereInfo*); +void sqlite3WhereClauseClear(WhereClause*); +void sqlite3WhereSplit(WhereClause*,Expr*,u8); +Bitmask sqlite3WhereExprUsage(WhereMaskSet*, Expr*); +Bitmask sqlite3WhereExprListUsage(WhereMaskSet*, ExprList*); +void sqlite3WhereExprAnalyze(SrcList*, WhereClause*); diff --git a/src/whereexpr.c b/src/whereexpr.c new file mode 100644 index 000000000..3607ef535 --- /dev/null +++ b/src/whereexpr.c @@ -0,0 +1,1249 @@ +/* +** 2015-06-08 +** +** 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 file was originally part of where.c but was split out to improve +** readability and editabiliity. This file contains utility routines for +** analyzing Expr objects in the WHERE clause. +*/ +#include "sqliteInt.h" +#include "whereInt.h" + +/* Forward declarations */ +static void exprAnalyze(SrcList*, WhereClause*, int); + +/* +** Deallocate all memory associated with a WhereOrInfo object. +*/ +static void whereOrInfoDelete(sqlite3 *db, WhereOrInfo *p){ + sqlite3WhereClauseClear(&p->wc); + sqlite3DbFree(db, p); +} + +/* +** Deallocate all memory associated with a WhereAndInfo object. +*/ +static void whereAndInfoDelete(sqlite3 *db, WhereAndInfo *p){ + sqlite3WhereClauseClear(&p->wc); + sqlite3DbFree(db, p); +} + +/* +** 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, u16 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]); + memset(&pWC->a[pWC->nTerm], 0, sizeof(pWC->a[0])*(pWC->nSlot-pWC->nTerm)); + } + pTerm = &pWC->a[idx = pWC->nTerm++]; + if( p && ExprHasProperty(p, EP_Unlikely) ){ + pTerm->truthProb = sqlite3LogEst(p->iTable) - 270; + }else{ + pTerm->truthProb = 1; + } + pTerm->pExpr = sqlite3ExprSkipCollate(p); + pTerm->wtFlags = wtFlags; + pTerm->pWC = pWC; + pTerm->iParent = -1; + return idx; +} + +/* +** 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 || op==TK_IS; +} + +/* +** 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 if( op==TK_IS ){ + c = WO_IS; + }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 ); + assert( op!=TK_IS || c==WO_IS ); + return c; +} + + +#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. The LHS must be a column +** that may only be NULL, a string, or a BLOB, never a number. (This means +** that virtual tables cannot participate in the LIKE optimization.) The +** collating sequence for the column on the LHS must be appropriate for +** the operator. +*/ +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) /* Value might be numeric */ + ){ + /* 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_BLOB); + 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; + } +} + +/* +** Mark term iChild as being a child of term iParent +*/ +static void markTermAsChild(WhereClause *pWC, int iChild, int iParent){ + pWC->a[iChild].iParent = iParent; + pWC->a[iChild].truthProb = pWC->a[iParent].truthProb; + pWC->a[iParent].nChild++; +} + +/* +** Return the N-th AND-connected subterm of pTerm. Or if pTerm is not +** a conjunction, then return just pTerm when N==0. If N is exceeds +** the number of available subterms, return NULL. +*/ +static WhereTerm *whereNthSubterm(WhereTerm *pTerm, int N){ + if( pTerm->eOperator!=WO_AND ){ + return N==0 ? pTerm : 0; + } + if( N<pTerm->u.pAndInfo->wc.nTerm ){ + return &pTerm->u.pAndInfo->wc.a[N]; + } + return 0; +} + +/* +** 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); +} + +#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) +** (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 */ + } + } +} +#endif /* !SQLITE_OMIT_OR_OPTIMIZATION && !SQLITE_OMIT_SUBQUERY */ + +/* +** We already know that pExpr is a binary operator where both operands are +** column references. This routine checks to see if pExpr is an equivalence +** relation: +** 1. The SQLITE_Transitive optimization must be enabled +** 2. Must be either an == or an IS operator +** 3. Not originating in the ON clause of an OUTER JOIN +** 4. The affinities of A and B must be compatible +** 5a. Both operands use the same collating sequence OR +** 5b. The overall collating sequence is BINARY +** If this routine returns TRUE, that means that the RHS can be substituted +** for the LHS anyplace else in the WHERE clause where the LHS column occurs. +** This is an optimization. No harm comes from returning 0. But if 1 is +** returned when it should not be, then incorrect answers might result. +*/ +static int termIsEquivalence(Parse *pParse, Expr *pExpr){ + char aff1, aff2; + CollSeq *pColl; + const char *zColl1, *zColl2; + if( !OptimizationEnabled(pParse->db, SQLITE_Transitive) ) return 0; + if( pExpr->op!=TK_EQ && pExpr->op!=TK_IS ) return 0; + if( ExprHasProperty(pExpr, EP_FromJoin) ) return 0; + aff1 = sqlite3ExprAffinity(pExpr->pLeft); + aff2 = sqlite3ExprAffinity(pExpr->pRight); + if( aff1!=aff2 + && (!sqlite3IsNumericAffinity(aff1) || !sqlite3IsNumericAffinity(aff2)) + ){ + return 0; + } + pColl = sqlite3BinaryCompareCollSeq(pParse, pExpr->pLeft, pExpr->pRight); + if( pColl==0 || sqlite3StrICmp(pColl->zName, "BINARY")==0 ) return 1; + pColl = sqlite3ExprCollSeq(pParse, pExpr->pLeft); + /* Since pLeft and pRight are both a column references, their collating + ** sequence should always be defined. */ + zColl1 = ALWAYS(pColl) ? pColl->zName : 0; + pColl = sqlite3ExprCollSeq(pParse, pExpr->pRight); + zColl2 = ALWAYS(pColl) ? pColl->zName : 0; + return sqlite3StrICmp(zColl1, zColl2)==0; +} + +/* +** Recursively walk the expressions of a SELECT statement and generate +** a bitmask indicating which tables are used in that expression +** tree. +*/ +static Bitmask exprSelectUsage(WhereMaskSet *pMaskSet, Select *pS){ + Bitmask mask = 0; + while( pS ){ + SrcList *pSrc = pS->pSrc; + mask |= sqlite3WhereExprListUsage(pMaskSet, pS->pEList); + mask |= sqlite3WhereExprListUsage(pMaskSet, pS->pGroupBy); + mask |= sqlite3WhereExprListUsage(pMaskSet, pS->pOrderBy); + mask |= sqlite3WhereExprUsage(pMaskSet, pS->pWhere); + mask |= sqlite3WhereExprUsage(pMaskSet, pS->pHaving); + if( ALWAYS(pSrc!=0) ){ + int i; + for(i=0; i<pSrc->nSrc; i++){ + mask |= exprSelectUsage(pMaskSet, pSrc->a[i].pSelect); + mask |= sqlite3WhereExprUsage(pMaskSet, pSrc->a[i].pOn); + } + } + pS = pS->pPrior; + } + return mask; +} + +/* +** 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; +} + +/*************************************************************************** +** Routines with file scope above. Interface to the rest of the where.c +** subsystem follows. +***************************************************************************/ + +/* +** 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. +*/ +void sqlite3WhereSplit(WhereClause *pWC, Expr *pExpr, u8 op){ + Expr *pE2 = sqlite3ExprSkipCollate(pExpr); + pWC->op = op; + if( pE2==0 ) return; + if( pE2->op!=op ){ + whereClauseInsert(pWC, pExpr, 0); + }else{ + sqlite3WhereSplit(pWC, pE2->pLeft, op); + sqlite3WhereSplit(pWC, pE2->pRight, op); + } +} + +/* +** Initialize a preallocated WhereClause structure. +*/ +void sqlite3WhereClauseInit( + 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; +} + +/* +** Deallocate a WhereClause structure. The WhereClause structure +** itself is not freed. This routine is the inverse of sqlite3WhereClauseInit(). +*/ +void sqlite3WhereClauseClear(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); + } +} + + +/* +** These routines walk (recursively) an expression tree and generate +** a bitmask indicating which tables are used in that expression +** tree. +*/ +Bitmask sqlite3WhereExprUsage(WhereMaskSet *pMaskSet, Expr *p){ + Bitmask mask = 0; + if( p==0 ) return 0; + if( p->op==TK_COLUMN ){ + mask = sqlite3WhereGetMask(pMaskSet, p->iTable); + return mask; + } + mask = sqlite3WhereExprUsage(pMaskSet, p->pRight); + mask |= sqlite3WhereExprUsage(pMaskSet, p->pLeft); + if( ExprHasProperty(p, EP_xIsSelect) ){ + mask |= exprSelectUsage(pMaskSet, p->x.pSelect); + }else{ + mask |= sqlite3WhereExprListUsage(pMaskSet, p->x.pList); + } + return mask; +} +Bitmask sqlite3WhereExprListUsage(WhereMaskSet *pMaskSet, ExprList *pList){ + int i; + Bitmask mask = 0; + if( pList ){ + for(i=0; i<pList->nExpr; i++){ + mask |= sqlite3WhereExprUsage(pMaskSet, pList->a[i].pExpr); + } + } + return mask; +} + + +/* +** 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); + } +} |