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Diffstat (limited to 'kexi/3rdparty/kexisql3/src/where.c')
| -rw-r--r-- | kexi/3rdparty/kexisql3/src/where.c | 2052 |
1 files changed, 2052 insertions, 0 deletions
diff --git a/kexi/3rdparty/kexisql3/src/where.c b/kexi/3rdparty/kexisql3/src/where.c new file mode 100644 index 00000000..e63f2763 --- /dev/null +++ b/kexi/3rdparty/kexisql3/src/where.c @@ -0,0 +1,2052 @@ +/* +** 2001 September 15 +** +** The author disclaims copyright to this source code. In place of +** a legal notice, here is a blessing: +** +** May you do good and not evil. +** May you find forgiveness for yourself and forgive others. +** May you share freely, never taking more than you give. +** +************************************************************************* +** This module contains C code that generates VDBE code used to process +** the WHERE clause of SQL statements. This module is reponsible for +** generating the code that loops through a table looking for applicable +** rows. Indices are selected and used to speed the search when doing +** so is applicable. Because this module is responsible for selecting +** indices, you might also think of this module as the "query optimizer". +** +** $Id: where.c 548347 2006-06-05 10:53:00Z staniek $ +*/ +#include "sqliteInt.h" + +/* +** The number of bits in a Bitmask. "BMS" means "BitMask Size". +*/ +#define BMS (sizeof(Bitmask)*8) + +/* +** Determine the number of elements in an array. +*/ +#define ARRAYSIZE(X) (sizeof(X)/sizeof(X[0])) + +/* +** Trace output macros +*/ +#if defined(SQLITE_TEST) || defined(SQLITE_DEBUG) +int sqlite3_where_trace = 0; +# define TRACE(X) if(sqlite3_where_trace) sqlite3DebugPrintf X +#else +# define TRACE(X) +#endif + +/* Forward reference +*/ +typedef struct WhereClause WhereClause; + +/* +** The query generator uses an array of instances of this structure to +** help it analyze the subexpressions of the WHERE clause. Each WHERE +** clause subexpression is separated from the others by an AND operator. +** +** All WhereTerms are collected into a single WhereClause structure. +** The following identity holds: +** +** WhereTerm.pWC->a[WhereTerm.idx] == WhereTerm +** +** When a term is of the form: +** +** X <op> <expr> +** +** where X is a column name and <op> is one of certain operators, +** then WhereTerm.leftCursor and WhereTerm.leftColumn record the +** cursor number and column number for X. WhereTerm.operator records +** the <op> using a bitmask encoding defined by WO_xxx below. The +** use of a bitmask encoding for the operator allows us to search +** quickly for terms that match any of several different operators. +** +** prereqRight and prereqAll record sets of cursor numbers, +** but they do so indirectly. A single ExprMaskSet structure translates +** cursor number into bits and the translated bit is stored in the prereq +** fields. The translation is used in order to maximize the number of +** bits that will fit in a Bitmask. The VDBE cursor numbers might be +** spread out over the non-negative integers. For example, the cursor +** numbers might be 3, 8, 9, 10, 20, 23, 41, and 45. The ExprMaskSet +** translates these sparse cursor numbers into consecutive integers +** beginning with 0 in order to make the best possible use of the available +** bits in the Bitmask. So, in the example above, the cursor numbers +** would be mapped into integers 0 through 7. +*/ +typedef struct WhereTerm WhereTerm; +struct WhereTerm { + Expr *pExpr; /* Pointer to the subexpression */ + i16 iParent; /* Disable pWC->a[iParent] when this term disabled */ + i16 leftCursor; /* Cursor number of X in "X <op> <expr>" */ + i16 leftColumn; /* Column number of X in "X <op> <expr>" */ + u16 operator; /* A WO_xx value describing <op> */ + u8 flags; /* Bit flags. See below */ + u8 nChild; /* Number of children that must disable us */ + WhereClause *pWC; /* The clause this term is part of */ + Bitmask prereqRight; /* Bitmask of tables used by pRight */ + Bitmask prereqAll; /* Bitmask of tables referenced by p */ +}; + +/* +** Allowed values of WhereTerm.flags +*/ +#define TERM_DYNAMIC 0x01 /* Need to call sqlite3ExprDelete(pExpr) */ +#define TERM_VIRTUAL 0x02 /* Added by the optimizer. Do not code */ +#define TERM_CODED 0x04 /* This term is already coded */ +#define TERM_COPIED 0x08 /* Has a child */ +#define TERM_OR_OK 0x10 /* Used during OR-clause processing */ + +/* +** An instance of the following structure holds all information about a +** WHERE clause. Mostly this is a container for one or more WhereTerms. +*/ +struct WhereClause { + Parse *pParse; /* The parser context */ + int nTerm; /* Number of terms */ + int nSlot; /* Number of entries in a[] */ + WhereTerm *a; /* Each a[] describes a term of the WHERE cluase */ + WhereTerm aStatic[10]; /* Initial static space for a[] */ +}; + +/* +** An instance of the following structure keeps track of a mapping +** between VDBE cursor numbers and bits of the bitmasks in WhereTerm. +** +** The VDBE cursor numbers are small integers contained in +** SrcList_item.iCursor and Expr.iTable fields. For any given WHERE +** clause, the cursor numbers might not begin with 0 and they might +** contain gaps in the numbering sequence. But we want to make maximum +** use of the bits in our bitmasks. This structure provides a mapping +** from the sparse cursor numbers into consecutive integers beginning +** with 0. +** +** If ExprMaskSet.ix[A]==B it means that The A-th bit of a Bitmask +** corresponds VDBE cursor number B. The A-th bit of a bitmask is 1<<A. +** +** For example, if the WHERE clause expression used these VDBE +** cursors: 4, 5, 8, 29, 57, 73. Then the ExprMaskSet structure +** would map those cursor numbers into bits 0 through 5. +** +** Note that the mapping is not necessarily ordered. In the example +** above, the mapping might go like this: 4->3, 5->1, 8->2, 29->0, +** 57->5, 73->4. Or one of 719 other combinations might be used. It +** does not really matter. What is important is that sparse cursor +** numbers all get mapped into bit numbers that begin with 0 and contain +** no gaps. +*/ +typedef struct ExprMaskSet ExprMaskSet; +struct ExprMaskSet { + int n; /* Number of assigned cursor values */ + int ix[sizeof(Bitmask)*8]; /* Cursor assigned to each bit */ +}; + + +/* +** Bitmasks for the operators that indices are able to exploit. An +** OR-ed combination of these values can be used when searching for +** terms in the where clause. +*/ +#define WO_IN 1 +#define WO_EQ 2 +#define WO_LT (WO_EQ<<(TK_LT-TK_EQ)) +#define WO_LE (WO_EQ<<(TK_LE-TK_EQ)) +#define WO_GT (WO_EQ<<(TK_GT-TK_EQ)) +#define WO_GE (WO_EQ<<(TK_GE-TK_EQ)) + +/* +** Value for flags returned by bestIndex() +*/ +#define WHERE_ROWID_EQ 0x0001 /* rowid=EXPR or rowid IN (...) */ +#define WHERE_ROWID_RANGE 0x0002 /* rowid<EXPR and/or rowid>EXPR */ +#define WHERE_COLUMN_EQ 0x0010 /* x=EXPR or x IN (...) */ +#define WHERE_COLUMN_RANGE 0x0020 /* x<EXPR and/or x>EXPR */ +#define WHERE_COLUMN_IN 0x0040 /* x IN (...) */ +#define WHERE_TOP_LIMIT 0x0100 /* x<EXPR or x<=EXPR constraint */ +#define WHERE_BTM_LIMIT 0x0200 /* x>EXPR or x>=EXPR constraint */ +#define WHERE_IDX_ONLY 0x0800 /* Use index only - omit table */ +#define WHERE_ORDERBY 0x1000 /* Output will appear in correct order */ +#define WHERE_REVERSE 0x2000 /* Scan in reverse order */ +#define WHERE_UNIQUE 0x4000 /* Selects no more than one row */ + +/* +** Initialize a preallocated WhereClause structure. +*/ +static void whereClauseInit(WhereClause *pWC, Parse *pParse){ + pWC->pParse = pParse; + 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 whereClauseInit(). +*/ +static void whereClauseClear(WhereClause *pWC){ + int i; + WhereTerm *a; + for(i=pWC->nTerm-1, a=pWC->a; i>=0; i--, a++){ + if( a->flags & TERM_DYNAMIC ){ + sqlite3ExprDelete(a->pExpr); + } + } + if( pWC->a!=pWC->aStatic ){ + sqliteFree(pWC->a); + } +} + +/* +** Add a new entries to the WhereClause structure. Increase the allocated +** space as necessary. +** +** WARNING: This routine might reallocate the space used to store +** WhereTerms. All pointers to WhereTerms should be invalided after +** calling this routine. Such pointers may be reinitialized by referencing +** the pWC->a[] array. +*/ +static int whereClauseInsert(WhereClause *pWC, Expr *p, int flags){ + WhereTerm *pTerm; + int idx; + if( pWC->nTerm>=pWC->nSlot ){ + WhereTerm *pOld = pWC->a; + pWC->a = sqliteMalloc( sizeof(pWC->a[0])*pWC->nSlot*2 ); + if( pWC->a==0 ) return 0; + memcpy(pWC->a, pOld, sizeof(pWC->a[0])*pWC->nTerm); + if( pOld!=pWC->aStatic ){ + sqliteFree(pOld); + } + pWC->nSlot *= 2; + } + pTerm = &pWC->a[idx = pWC->nTerm]; + pWC->nTerm++; + pTerm->pExpr = p; + pTerm->flags = flags; + 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. This array grows as needed to contain +** all terms of the WHERE clause. +*/ +static void whereSplit(WhereClause *pWC, Expr *pExpr, int op){ + if( pExpr==0 ) return; + if( pExpr->op!=op ){ + whereClauseInsert(pWC, pExpr, 0); + }else{ + whereSplit(pWC, pExpr->pLeft, op); + whereSplit(pWC, pExpr->pRight, op); + } +} + +/* +** Initialize an expression mask set +*/ +#define initMaskSet(P) memset(P, 0, sizeof(*P)) + +/* +** Return the bitmask for the given cursor number. Return 0 if +** iCursor is not in the set. +*/ +static Bitmask getMask(ExprMaskSet *pMaskSet, int iCursor){ + int i; + for(i=0; i<pMaskSet->n; i++){ + if( pMaskSet->ix[i]==iCursor ){ + return ((Bitmask)1)<<i; + } + } + return 0; +} + +/* +** Create a new mask for cursor iCursor. +** +** There is one cursor per table in the FROM clause. The number of +** tables in the FROM clause is limited by a test early in the +** sqlite3WhereBegin() routine. So we know that the pMaskSet->ix[] +** array will never overflow. +*/ +static void createMask(ExprMaskSet *pMaskSet, int iCursor){ + assert( pMaskSet->n < ARRAYSIZE(pMaskSet->ix) ); + pMaskSet->ix[pMaskSet->n++] = iCursor; +} + +/* +** This routine walks (recursively) an expression tree and generates +** a bitmask indicating which tables are used in that expression +** tree. +** +** In order for this routine to work, the calling function must have +** previously invoked sqlite3ExprResolveNames() on the expression. See +** the header comment on that routine for additional information. +** The sqlite3ExprResolveNames() routines looks for column names and +** sets their opcodes to TK_COLUMN and their Expr.iTable fields to +** the VDBE cursor number of the table. This routine just has to +** translate the cursor numbers into bitmask values and OR all +** the bitmasks together. +*/ +static Bitmask exprListTableUsage(ExprMaskSet*, ExprList*); +static Bitmask exprSelectTableUsage(ExprMaskSet*, Select*); +static Bitmask exprTableUsage(ExprMaskSet *pMaskSet, Expr *p){ + Bitmask mask = 0; + if( p==0 ) return 0; + if( p->op==TK_COLUMN ){ + mask = getMask(pMaskSet, p->iTable); + return mask; + } + mask = exprTableUsage(pMaskSet, p->pRight); + mask |= exprTableUsage(pMaskSet, p->pLeft); + mask |= exprListTableUsage(pMaskSet, p->pList); + mask |= exprSelectTableUsage(pMaskSet, p->pSelect); + return mask; +} +static Bitmask exprListTableUsage(ExprMaskSet *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(ExprMaskSet *pMaskSet, Select *pS){ + Bitmask mask; + if( pS==0 ){ + mask = 0; + }else{ + 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); + } + 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 +** "=", "<", ">", "<=", ">=", and "IN". +*/ +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); +} + +/* +** Swap two objects of type T. +*/ +#define SWAP(TYPE,A,B) {TYPE t=A; A=B; B=t;} + +/* +** Commute a comparision operator. Expressions of the form "X op Y" +** are converted into "Y op X". +*/ +static void exprCommute(Expr *pExpr){ + assert( allowedOp(pExpr->op) && pExpr->op!=TK_IN ); + SWAP(CollSeq*,pExpr->pRight->pColl,pExpr->pLeft->pColl); + 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 int operatorMask(int op){ + int c; + assert( allowedOp(op) ); + if( op==TK_IN ){ + c = WO_IN; + }else{ + c = WO_EQ<<(op-TK_EQ); + } + assert( op!=TK_IN || c==WO_IN ); + assert( op!=TK_EQ || c==WO_EQ ); + assert( op!=TK_LT || c==WO_LT ); + assert( op!=TK_LE || c==WO_LE ); + assert( op!=TK_GT || c==WO_GT ); + assert( op!=TK_GE || c==WO_GE ); + return c; +} + +/* +** Search for a term in the WHERE clause that is of the form "X <op> <expr>" +** where X is a reference to the iColumn of table iCur and <op> is one of +** the WO_xx operator codes specified by the op parameter. +** Return a pointer to the term. Return 0 if not found. +*/ +static WhereTerm *findTerm( + WhereClause *pWC, /* The WHERE clause to be searched */ + int iCur, /* Cursor number of LHS */ + int iColumn, /* Column number of LHS */ + Bitmask notReady, /* RHS must not overlap with this mask */ + u16 op, /* Mask of WO_xx values describing operator */ + Index *pIdx /* Must be compatible with this index, if not NULL */ +){ + WhereTerm *pTerm; + int k; + for(pTerm=pWC->a, k=pWC->nTerm; k; k--, pTerm++){ + if( pTerm->leftCursor==iCur + && (pTerm->prereqRight & notReady)==0 + && pTerm->leftColumn==iColumn + && (pTerm->operator & op)!=0 + ){ + if( iCur>=0 && pIdx ){ + Expr *pX = pTerm->pExpr; + CollSeq *pColl; + char idxaff; + int k; + Parse *pParse = pWC->pParse; + + idxaff = pIdx->pTable->aCol[iColumn].affinity; + if( !sqlite3IndexAffinityOk(pX, idxaff) ) continue; + pColl = sqlite3ExprCollSeq(pParse, pX->pLeft); + if( !pColl ){ + if( pX->pRight ){ + pColl = sqlite3ExprCollSeq(pParse, pX->pRight); + } + if( !pColl ){ + pColl = pParse->db->pDfltColl; + } + } + for(k=0; k<pIdx->nColumn && pIdx->aiColumn[k]!=iColumn; k++){} + assert( k<pIdx->nColumn ); + if( pColl!=pIdx->keyInfo.aColl[k] ) continue; + } + return pTerm; + } + } + return 0; +} + +/* Forward reference */ +static void exprAnalyze(SrcList*, ExprMaskSet*, WhereClause*, int); + +/* +** Call exprAnalyze on all terms in a WHERE clause. +** +** +*/ +static void exprAnalyzeAll( + SrcList *pTabList, /* the FROM clause */ + ExprMaskSet *pMaskSet, /* table masks */ + WhereClause *pWC /* the WHERE clause to be analyzed */ +){ + int i; + for(i=pWC->nTerm-1; i>=0; i--){ + exprAnalyze(pTabList, pMaskSet, pWC, i); + } +} + +#ifndef SQLITE_OMIT_LIKE_OPTIMIZATION +/* +** Check to see if the given expression is a LIKE or GLOB operator that +** can be optimized using inequality constraints. Return TRUE if it is +** so and false if not. +** +** In order for the operator to be optimizible, the RHS must be a string +** literal that does not begin with a wildcard. +*/ +static int isLikeOrGlob( + sqlite3 *db, /* The database */ + Expr *pExpr, /* Test this expression */ + int *pnPattern, /* Number of non-wildcard prefix characters */ + int *pisComplete /* True if the only wildcard is % in the last character */ +){ + const char *z; + Expr *pRight, *pLeft; + ExprList *pList; + int c, cnt; + int noCase; + char wc[3]; + CollSeq *pColl; + + if( !sqlite3IsLikeFunction(db, pExpr, &noCase, wc) ){ + return 0; + } + pList = pExpr->pList; + pRight = pList->a[0].pExpr; + if( pRight->op!=TK_STRING ){ + return 0; + } + pLeft = pList->a[1].pExpr; + if( pLeft->op!=TK_COLUMN ){ + return 0; + } + pColl = pLeft->pColl; + if( pColl==0 ){ + pColl = db->pDfltColl; + } + if( (pColl->type!=SQLITE_COLL_BINARY || noCase) && + (pColl->type!=SQLITE_COLL_NOCASE || !noCase) ){ + return 0; + } + sqlite3DequoteExpr(pRight); + z = pRight->token.z; + for(cnt=0; (c=z[cnt])!=0 && c!=wc[0] && c!=wc[1] && c!=wc[2]; cnt++){} + if( cnt==0 || 255==(u8)z[cnt] ){ + return 0; + } + *pisComplete = z[cnt]==wc[0] && z[cnt+1]==0; + *pnPattern = cnt; + return 1; +} +#endif /* SQLITE_OMIT_LIKE_OPTIMIZATION */ + +/* +** 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 expression of the form +** "Y <op> X" is added to the WHERE clause and analyzed separately. +*/ +static void exprAnalyze( + SrcList *pSrc, /* the FROM clause */ + ExprMaskSet *pMaskSet, /* table masks */ + WhereClause *pWC, /* the WHERE clause */ + int idxTerm /* Index of the term to be analyzed */ +){ + WhereTerm *pTerm = &pWC->a[idxTerm]; + Expr *pExpr = pTerm->pExpr; + Bitmask prereqLeft; + Bitmask prereqAll; + int nPattern; + int isComplete; + + if( sqlite3_malloc_failed ) return; + prereqLeft = exprTableUsage(pMaskSet, pExpr->pLeft); + if( pExpr->op==TK_IN ){ + assert( pExpr->pRight==0 ); + pTerm->prereqRight = exprListTableUsage(pMaskSet, pExpr->pList) + | exprSelectTableUsage(pMaskSet, pExpr->pSelect); + }else{ + pTerm->prereqRight = exprTableUsage(pMaskSet, pExpr->pRight); + } + prereqAll = exprTableUsage(pMaskSet, pExpr); + if( ExprHasProperty(pExpr, EP_FromJoin) ){ + prereqAll |= getMask(pMaskSet, pExpr->iRightJoinTable); + } + pTerm->prereqAll = prereqAll; + pTerm->leftCursor = -1; + pTerm->iParent = -1; + pTerm->operator = 0; + if( allowedOp(pExpr->op) && (pTerm->prereqRight & prereqLeft)==0 ){ + Expr *pLeft = pExpr->pLeft; + Expr *pRight = pExpr->pRight; + if( pLeft->op==TK_COLUMN ){ + pTerm->leftCursor = pLeft->iTable; + pTerm->leftColumn = pLeft->iColumn; + pTerm->operator = operatorMask(pExpr->op); + } + if( pRight && pRight->op==TK_COLUMN ){ + WhereTerm *pNew; + Expr *pDup; + if( pTerm->leftCursor>=0 ){ + int idxNew; + pDup = sqlite3ExprDup(pExpr); + idxNew = whereClauseInsert(pWC, pDup, TERM_VIRTUAL|TERM_DYNAMIC); + if( idxNew==0 ) return; + pNew = &pWC->a[idxNew]; + pNew->iParent = idxTerm; + pTerm = &pWC->a[idxTerm]; + pTerm->nChild = 1; + pTerm->flags |= TERM_COPIED; + }else{ + pDup = pExpr; + pNew = pTerm; + } + exprCommute(pDup); + pLeft = pDup->pLeft; + pNew->leftCursor = pLeft->iTable; + pNew->leftColumn = pLeft->iColumn; + pNew->prereqRight = prereqLeft; + pNew->prereqAll = prereqAll; + pNew->operator = operatorMask(pDup->op); + } + } + +#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. + */ + else if( pExpr->op==TK_BETWEEN ){ + ExprList *pList = pExpr->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 = sqlite3Expr(ops[i], sqlite3ExprDup(pExpr->pLeft), + sqlite3ExprDup(pList->a[i].pExpr), 0); + idxNew = whereClauseInsert(pWC, pNewExpr, TERM_VIRTUAL|TERM_DYNAMIC); + exprAnalyze(pSrc, pMaskSet, pWC, idxNew); + pTerm = &pWC->a[idxTerm]; + pWC->a[idxNew].iParent = idxTerm; + } + pTerm->nChild = 2; + } +#endif /* SQLITE_OMIT_BETWEEN_OPTIMIZATION */ + +#ifndef SQLITE_OMIT_OR_OPTIMIZATION + /* Attempt to convert OR-connected terms into an IN operator so that + ** they can make use of indices. Example: + ** + ** x = expr1 OR expr2 = x OR x = expr3 + ** + ** is converted into + ** + ** x IN (expr1,expr2,expr3) + */ + else if( pExpr->op==TK_OR ){ + int ok; + int i, j; + int iColumn, iCursor; + WhereClause sOr; + WhereTerm *pOrTerm; + + assert( (pTerm->flags & TERM_DYNAMIC)==0 ); + whereClauseInit(&sOr, pWC->pParse); + whereSplit(&sOr, pExpr, TK_OR); + exprAnalyzeAll(pSrc, pMaskSet, &sOr); + assert( sOr.nTerm>0 ); + j = 0; + do{ + iColumn = sOr.a[j].leftColumn; + iCursor = sOr.a[j].leftCursor; + ok = iCursor>=0; + for(i=sOr.nTerm-1, pOrTerm=sOr.a; i>=0 && ok; i--, pOrTerm++){ + if( pOrTerm->operator!=WO_EQ ){ + goto or_not_possible; + } + if( pOrTerm->leftCursor==iCursor && pOrTerm->leftColumn==iColumn ){ + pOrTerm->flags |= TERM_OR_OK; + }else if( (pOrTerm->flags & TERM_COPIED)!=0 || + ((pOrTerm->flags & TERM_VIRTUAL)!=0 && + (sOr.a[pOrTerm->iParent].flags & TERM_OR_OK)!=0) ){ + pOrTerm->flags &= ~TERM_OR_OK; + }else{ + ok = 0; + } + } + }while( !ok && (sOr.a[j++].flags & TERM_COPIED)!=0 && j<sOr.nTerm ); + if( ok ){ + ExprList *pList = 0; + Expr *pNew, *pDup; + for(i=sOr.nTerm-1, pOrTerm=sOr.a; i>=0 && ok; i--, pOrTerm++){ + if( (pOrTerm->flags & TERM_OR_OK)==0 ) continue; + pDup = sqlite3ExprDup(pOrTerm->pExpr->pRight); + pList = sqlite3ExprListAppend(pList, pDup, 0); + } + pDup = sqlite3Expr(TK_COLUMN, 0, 0, 0); + if( pDup ){ + pDup->iTable = iCursor; + pDup->iColumn = iColumn; + } + pNew = sqlite3Expr(TK_IN, pDup, 0, 0); + if( pNew ){ + pNew->pList = pList; + }else{ + sqlite3ExprListDelete(pList); + } + pTerm->pExpr = pNew; + pTerm->flags |= TERM_DYNAMIC; + exprAnalyze(pSrc, pMaskSet, pWC, idxTerm); + pTerm = &pWC->a[idxTerm]; + } +or_not_possible: + whereClauseClear(&sOr); + } +#endif /* SQLITE_OMIT_OR_OPTIMIZATION */ + +#ifndef SQLITE_OMIT_LIKE_OPTIMIZATION + /* Add constraints to reduce the search space on a LIKE or GLOB + ** operator. + */ + if( isLikeOrGlob(pWC->pParse->db, pExpr, &nPattern, &isComplete) ){ + Expr *pLeft, *pRight; + Expr *pStr1, *pStr2; + Expr *pNewExpr1, *pNewExpr2; + int idxNew1, idxNew2; + + pLeft = pExpr->pList->a[1].pExpr; + pRight = pExpr->pList->a[0].pExpr; + pStr1 = sqlite3Expr(TK_STRING, 0, 0, 0); + if( pStr1 ){ + sqlite3TokenCopy(&pStr1->token, &pRight->token); + pStr1->token.n = nPattern; + } + pStr2 = sqlite3ExprDup(pStr1); + if( pStr2 ){ + assert( pStr2->token.dyn ); + ++*(u8*)&pStr2->token.z[nPattern-1]; + } + pNewExpr1 = sqlite3Expr(TK_GE, sqlite3ExprDup(pLeft), pStr1, 0); + idxNew1 = whereClauseInsert(pWC, pNewExpr1, TERM_VIRTUAL|TERM_DYNAMIC); + exprAnalyze(pSrc, pMaskSet, pWC, idxNew1); + pNewExpr2 = sqlite3Expr(TK_LT, sqlite3ExprDup(pLeft), pStr2, 0); + idxNew2 = whereClauseInsert(pWC, pNewExpr2, TERM_VIRTUAL|TERM_DYNAMIC); + exprAnalyze(pSrc, pMaskSet, pWC, idxNew2); + pTerm = &pWC->a[idxTerm]; + if( isComplete ){ + pWC->a[idxNew1].iParent = idxTerm; + pWC->a[idxNew2].iParent = idxTerm; + pTerm->nChild = 2; + } + } +#endif /* SQLITE_OMIT_LIKE_OPTIMIZATION */ +} + + +/* +** This routine decides if pIdx can be used to satisfy the ORDER BY +** clause. If it can, it returns 1. If pIdx cannot satisfy the +** ORDER BY clause, this routine returns 0. +** +** pOrderBy is an ORDER BY clause from a SELECT statement. pTab is the +** left-most table in the FROM clause of that same SELECT statement and +** the table has a cursor number of "base". pIdx is an index on pTab. +** +** nEqCol is the number of columns of pIdx that are used as equality +** constraints. Any of these columns may be missing from the ORDER BY +** clause and the match can still be a success. +** +** All terms of the ORDER BY that match against the index must be either +** ASC or DESC. (Terms of the ORDER BY clause past the end of a UNIQUE +** index do not need to satisfy this constraint.) The *pbRev value is +** set to 1 if the ORDER BY clause is all DESC and it is set to 0 if +** the ORDER BY clause is all ASC. +*/ +static int isSortingIndex( + Parse *pParse, /* Parsing context */ + Index *pIdx, /* The index we are testing */ + Table *pTab, /* The table to be sorted */ + int base, /* Cursor number for pTab */ + ExprList *pOrderBy, /* The ORDER BY clause */ + int nEqCol, /* Number of index columns with == constraints */ + int *pbRev /* Set to 1 if ORDER BY is DESC */ +){ + int i, j; /* Loop counters */ + int sortOrder = SQLITE_SO_ASC; /* Which direction we are sorting */ + int nTerm; /* Number of ORDER BY terms */ + struct ExprList_item *pTerm; /* A term of the ORDER BY clause */ + sqlite3 *db = pParse->db; + + assert( pOrderBy!=0 ); + nTerm = pOrderBy->nExpr; + assert( nTerm>0 ); + + /* Match terms of the ORDER BY clause against columns of + ** the index. + */ + for(i=j=0, pTerm=pOrderBy->a; j<nTerm && i<pIdx->nColumn; i++){ + Expr *pExpr; /* The expression of the ORDER BY pTerm */ + CollSeq *pColl; /* The collating sequence of pExpr */ + + pExpr = pTerm->pExpr; + if( pExpr->op!=TK_COLUMN || pExpr->iTable!=base ){ + /* Can not use an index sort on anything that is not a column in the + ** left-most table of the FROM clause */ + return 0; + } + pColl = sqlite3ExprCollSeq(pParse, pExpr); + if( !pColl ) pColl = db->pDfltColl; + if( pExpr->iColumn!=pIdx->aiColumn[i] || pColl!=pIdx->keyInfo.aColl[i] ){ + /* Term j of the ORDER BY clause does not match column i of the index */ + if( i<nEqCol ){ + /* If an index column that is constrained by == fails to match an + ** ORDER BY term, that is OK. Just ignore that column of the index + */ + continue; + }else{ + /* If an index column fails to match and is not constrained by == + ** then the index cannot satisfy the ORDER BY constraint. + */ + return 0; + } + } + if( i>nEqCol ){ + if( pTerm->sortOrder!=sortOrder ){ + /* Indices can only be used if all ORDER BY terms past the + ** equality constraints are all either DESC or ASC. */ + return 0; + } + }else{ + sortOrder = pTerm->sortOrder; + } + j++; + pTerm++; + } + + /* The index can be used for sorting if all terms of the ORDER BY clause + ** are covered. + */ + if( j>=nTerm ){ + *pbRev = sortOrder==SQLITE_SO_DESC; + return 1; + } + return 0; +} + +/* +** Check table to see if the ORDER BY clause in pOrderBy can be satisfied +** by sorting in order of ROWID. Return true if so and set *pbRev to be +** true for reverse ROWID and false for forward ROWID order. +*/ +static int sortableByRowid( + int base, /* Cursor number for table to be sorted */ + ExprList *pOrderBy, /* The ORDER BY clause */ + int *pbRev /* Set to 1 if ORDER BY is DESC */ +){ + Expr *p; + + assert( pOrderBy!=0 ); + assert( pOrderBy->nExpr>0 ); + p = pOrderBy->a[0].pExpr; + if( pOrderBy->nExpr==1 && p->op==TK_COLUMN && p->iTable==base + && p->iColumn==-1 ){ + *pbRev = pOrderBy->a[0].sortOrder; + return 1; + } + return 0; +} + +/* +** Prepare a crude estimate of the logarithm of the input value. +** The results need not be exact. This is only used for estimating +** the total cost of performing operatings with O(logN) or O(NlogN) +** complexity. Because N is just a guess, it is no great tragedy if +** logN is a little off. +*/ +static double estLog(double N){ + double logN = 1.0; + double x = 10.0; + while( N>x ){ + logN += 1.0; + x *= 10; + } + return logN; +} + +/* +** Find the best index for accessing a particular table. Return a pointer +** to the index, flags that describe how the index should be used, the +** number of equality constraints, and the "cost" for this index. +** +** The lowest cost index wins. The cost is an estimate of the amount of +** CPU and disk I/O need to process the request using the selected index. +** Factors that influence cost include: +** +** * The estimated number of rows that will be retrieved. (The +** fewer the better.) +** +** * Whether or not sorting must occur. +** +** * Whether or not there must be separate lookups in the +** index and in the main table. +** +*/ +static double bestIndex( + Parse *pParse, /* The parsing context */ + WhereClause *pWC, /* The WHERE clause */ + struct SrcList_item *pSrc, /* The FROM clause term to search */ + Bitmask notReady, /* Mask of cursors that are not available */ + ExprList *pOrderBy, /* The order by clause */ + Index **ppIndex, /* Make *ppIndex point to the best index */ + int *pFlags, /* Put flags describing this choice in *pFlags */ + int *pnEq /* Put the number of == or IN constraints here */ +){ + WhereTerm *pTerm; + Index *bestIdx = 0; /* Index that gives the lowest cost */ + double lowestCost = 1.0e99; /* The cost of using bestIdx */ + int bestFlags = 0; /* Flags associated with bestIdx */ + int bestNEq = 0; /* Best value for nEq */ + int iCur = pSrc->iCursor; /* The cursor of the table to be accessed */ + Index *pProbe; /* An index we are evaluating */ + int rev; /* True to scan in reverse order */ + int flags; /* Flags associated with pProbe */ + int nEq; /* Number of == or IN constraints */ + double cost; /* Cost of using pProbe */ + + TRACE(("bestIndex: tbl=%s notReady=%x\n", pSrc->pTab->zName, notReady)); + + /* Check for a rowid=EXPR or rowid IN (...) constraints + */ + pTerm = findTerm(pWC, iCur, -1, notReady, WO_EQ|WO_IN, 0); + if( pTerm ){ + Expr *pExpr; + *ppIndex = 0; + bestFlags = WHERE_ROWID_EQ; + if( pTerm->operator & WO_EQ ){ + /* Rowid== is always the best pick. Look no further. Because only + ** a single row is generated, output is always in sorted order */ + *pFlags = WHERE_ROWID_EQ | WHERE_UNIQUE; + *pnEq = 1; + TRACE(("... best is rowid\n")); + return 0.0; + }else if( (pExpr = pTerm->pExpr)->pList!=0 ){ + /* Rowid IN (LIST): cost is NlogN where N is the number of list + ** elements. */ + lowestCost = pExpr->pList->nExpr; + lowestCost *= estLog(lowestCost); + }else{ + /* Rowid IN (SELECT): cost is NlogN where N is the number of rows + ** in the result of the inner select. We have no way to estimate + ** that value so make a wild guess. */ + lowestCost = 200.0; + } + TRACE(("... rowid IN cost: %.9g\n", lowestCost)); + } + + /* Estimate the cost of a table scan. If we do not know how many + ** entries are in the table, use 1 million as a guess. + */ + pProbe = pSrc->pTab->pIndex; + cost = pProbe ? pProbe->aiRowEst[0] : 1000000.0; + TRACE(("... table scan base cost: %.9g\n", cost)); + flags = WHERE_ROWID_RANGE; + + /* Check for constraints on a range of rowids in a table scan. + */ + pTerm = findTerm(pWC, iCur, -1, notReady, WO_LT|WO_LE|WO_GT|WO_GE, 0); + if( pTerm ){ + if( findTerm(pWC, iCur, -1, notReady, WO_LT|WO_LE, 0) ){ + flags |= WHERE_TOP_LIMIT; + cost *= 0.333; /* Guess that rowid<EXPR eliminates two-thirds or rows */ + } + if( findTerm(pWC, iCur, -1, notReady, WO_GT|WO_GE, 0) ){ + flags |= WHERE_BTM_LIMIT; + cost *= 0.333; /* Guess that rowid>EXPR eliminates two-thirds of rows */ + } + TRACE(("... rowid range reduces cost to %.9g\n", cost)); + }else{ + flags = 0; + } + + /* If the table scan does not satisfy the ORDER BY clause, increase + ** the cost by NlogN to cover the expense of sorting. */ + if( pOrderBy ){ + if( sortableByRowid(iCur, pOrderBy, &rev) ){ + flags |= WHERE_ORDERBY|WHERE_ROWID_RANGE; + if( rev ){ + flags |= WHERE_REVERSE; + } + }else{ + cost += cost*estLog(cost); + TRACE(("... sorting increases cost to %.9g\n", cost)); + } + } + if( cost<lowestCost ){ + lowestCost = cost; + bestFlags = flags; + } + + /* Look at each index. + */ + for(; pProbe; pProbe=pProbe->pNext){ + int i; /* Loop counter */ + double inMultiplier = 1.0; + + TRACE(("... index %s:\n", pProbe->zName)); + + /* Count the number of columns in the index that are satisfied + ** by x=EXPR constraints or x IN (...) constraints. + */ + flags = 0; + for(i=0; i<pProbe->nColumn; i++){ + int j = pProbe->aiColumn[i]; + pTerm = findTerm(pWC, iCur, j, notReady, WO_EQ|WO_IN, pProbe); + if( pTerm==0 ) break; + flags |= WHERE_COLUMN_EQ; + if( pTerm->operator & WO_IN ){ + Expr *pExpr = pTerm->pExpr; + flags |= WHERE_COLUMN_IN; + if( pExpr->pSelect!=0 ){ + inMultiplier *= 100.0; + }else if( pExpr->pList!=0 ){ + inMultiplier *= pExpr->pList->nExpr + 1.0; + } + } + } + cost = pProbe->aiRowEst[i] * inMultiplier * estLog(inMultiplier); + nEq = i; + if( pProbe->onError!=OE_None && (flags & WHERE_COLUMN_IN)==0 + && nEq==pProbe->nColumn ){ + flags |= WHERE_UNIQUE; + } + TRACE(("...... nEq=%d inMult=%.9g cost=%.9g\n", nEq, inMultiplier, cost)); + + /* Look for range constraints + */ + if( nEq<pProbe->nColumn ){ + int j = pProbe->aiColumn[nEq]; + pTerm = findTerm(pWC, iCur, j, notReady, WO_LT|WO_LE|WO_GT|WO_GE, pProbe); + if( pTerm ){ + flags |= WHERE_COLUMN_RANGE; + if( findTerm(pWC, iCur, j, notReady, WO_LT|WO_LE, pProbe) ){ + flags |= WHERE_TOP_LIMIT; + cost *= 0.333; + } + if( findTerm(pWC, iCur, j, notReady, WO_GT|WO_GE, pProbe) ){ + flags |= WHERE_BTM_LIMIT; + cost *= 0.333; + } + TRACE(("...... range reduces cost to %.9g\n", cost)); + } + } + + /* Add the additional cost of sorting if that is a factor. + */ + if( pOrderBy ){ + if( (flags & WHERE_COLUMN_IN)==0 && + isSortingIndex(pParse,pProbe,pSrc->pTab,iCur,pOrderBy,nEq,&rev) ){ + if( flags==0 ){ + flags = WHERE_COLUMN_RANGE; + } + flags |= WHERE_ORDERBY; + if( rev ){ + flags |= WHERE_REVERSE; + } + }else{ + cost += cost*estLog(cost); + TRACE(("...... orderby increases cost to %.9g\n", cost)); + } + } + + /* Check to see if we can get away with using just the index without + ** ever reading the table. If that is the case, then halve the + ** cost of this index. + */ + if( flags && pSrc->colUsed < (((Bitmask)1)<<(BMS-1)) ){ + Bitmask m = pSrc->colUsed; + int j; + for(j=0; j<pProbe->nColumn; j++){ + int x = pProbe->aiColumn[j]; + if( x<BMS-1 ){ + m &= ~(((Bitmask)1)<<x); + } + } + if( m==0 ){ + flags |= WHERE_IDX_ONLY; + cost *= 0.5; + TRACE(("...... idx-only reduces cost to %.9g\n", cost)); + } + } + + /* If this index has achieved the lowest cost so far, then use it. + */ + if( cost < lowestCost ){ + bestIdx = pProbe; + lowestCost = cost; + assert( flags!=0 ); + bestFlags = flags; + bestNEq = nEq; + } + } + + /* Report the best result + */ + *ppIndex = bestIdx; + TRACE(("best index is %s, cost=%.9g, flags=%x, nEq=%d\n", + bestIdx ? bestIdx->zName : "(none)", lowestCost, bestFlags, bestNEq)); + *pFlags = bestFlags; + *pnEq = bestNEq; + return lowestCost; +} + + +/* +** Disable a term in the WHERE clause. Except, do not disable the term +** if it controls a LEFT OUTER JOIN and it did not originate in the ON +** or USING clause of that join. +** +** Consider the term t2.z='ok' in the following queries: +** +** (1) SELECT * FROM t1 LEFT JOIN t2 ON t1.a=t2.x WHERE t2.z='ok' +** (2) SELECT * FROM t1 LEFT JOIN t2 ON t1.a=t2.x AND t2.z='ok' +** (3) SELECT * FROM t1, t2 WHERE t1.a=t2.x AND t2.z='ok' +** +** The t2.z='ok' is disabled in the in (2) because it originates +** in the ON clause. The term is disabled in (3) because it is not part +** of a LEFT OUTER JOIN. In (1), the term is not disabled. +** +** Disabling a term causes that term to not be tested in the inner loop +** of the join. Disabling is an optimization. When terms are satisfied +** by indices, we disable them to prevent redundant tests in the inner +** loop. We would get the correct results if nothing were ever disabled, +** but joins might run a little slower. The trick is to disable as much +** as we can without disabling too much. If we disabled in (1), we'd get +** the wrong answer. See ticket #813. +*/ +static void disableTerm(WhereLevel *pLevel, WhereTerm *pTerm){ + if( pTerm + && (pTerm->flags & TERM_CODED)==0 + && (pLevel->iLeftJoin==0 || ExprHasProperty(pTerm->pExpr, EP_FromJoin)) + ){ + pTerm->flags |= TERM_CODED; + if( pTerm->iParent>=0 ){ + WhereTerm *pOther = &pTerm->pWC->a[pTerm->iParent]; + if( (--pOther->nChild)==0 ){ + disableTerm(pLevel, pOther); + } + } + } +} + +/* +** Generate code that builds a probe for an index. Details: +** +** * Check the top nColumn entries on the stack. If any +** of those entries are NULL, jump immediately to brk, +** which is the loop exit, since no index entry will match +** if any part of the key is NULL. +** +** * Construct a probe entry from the top nColumn entries in +** the stack with affinities appropriate for index pIdx. +*/ +static void buildIndexProbe(Vdbe *v, int nColumn, int brk, Index *pIdx){ + sqlite3VdbeAddOp(v, OP_NotNull, -nColumn, sqlite3VdbeCurrentAddr(v)+3); + sqlite3VdbeAddOp(v, OP_Pop, nColumn, 0); + sqlite3VdbeAddOp(v, OP_Goto, 0, brk); + sqlite3VdbeAddOp(v, OP_MakeRecord, nColumn, 0); + sqlite3IndexAffinityStr(v, pIdx); +} + + +/* +** Generate code for a single equality term of the WHERE clause. An equality +** term can be either X=expr or X IN (...). pTerm is the term to be +** coded. +** +** The current value for the constraint is left on the top of the stack. +** +** For a constraint of the form X=expr, the expression is evaluated and its +** result is left on the stack. For constraints of the form X IN (...) +** this routine sets up a loop that will iterate over all values of X. +*/ +static void codeEqualityTerm( + Parse *pParse, /* The parsing context */ + WhereTerm *pTerm, /* The term of the WHERE clause to be coded */ + int brk, /* Jump here to abandon the loop */ + WhereLevel *pLevel /* When level of the FROM clause we are working on */ +){ + Expr *pX = pTerm->pExpr; + if( pX->op!=TK_IN ){ + assert( pX->op==TK_EQ ); + sqlite3ExprCode(pParse, pX->pRight); +#ifndef SQLITE_OMIT_SUBQUERY + }else{ + int iTab; + int *aIn; + Vdbe *v = pParse->pVdbe; + + sqlite3CodeSubselect(pParse, pX); + iTab = pX->iTable; + sqlite3VdbeAddOp(v, OP_Rewind, iTab, brk); + VdbeComment((v, "# %.*s", pX->span.n, pX->span.z)); + pLevel->nIn++; + sqlite3ReallocOrFree((void**)&pLevel->aInLoop, + sizeof(pLevel->aInLoop[0])*3*pLevel->nIn); + aIn = pLevel->aInLoop; + if( aIn ){ + aIn += pLevel->nIn*3 - 3; + aIn[0] = OP_Next; + aIn[1] = iTab; + aIn[2] = sqlite3VdbeAddOp(v, OP_Column, iTab, 0); + }else{ + pLevel->nIn = 0; + } +#endif + } + disableTerm(pLevel, pTerm); +} + +/* +** Generate code that will evaluate all == and IN constraints for an +** index. The values for all constraints are left on the stack. +** +** For example, consider table t1(a,b,c,d,e,f) with index i1(a,b,c). +** Suppose the WHERE clause is this: a==5 AND b IN (1,2,3) AND c>5 AND c<10 +** The index has as many as three equality constraints, but in this +** example, the third "c" value is an inequality. So only two +** constraints are coded. This routine will generate code to evaluate +** a==5 and b IN (1,2,3). The current values for a and b will be left +** on the stack - a is the deepest and b the shallowest. +** +** In the example above nEq==2. But this subroutine works for any value +** of nEq including 0. If nEq==0, this routine is nearly a no-op. +** The only thing it does is allocate the pLevel->iMem memory cell. +** +** This routine always allocates at least one memory cell and puts +** the address of that memory cell in pLevel->iMem. The code that +** calls this routine will use pLevel->iMem to store the termination +** key value of the loop. If one or more IN operators appear, then +** this routine allocates an additional nEq memory cells for internal +** use. +*/ +static void codeAllEqualityTerms( + Parse *pParse, /* Parsing context */ + WhereLevel *pLevel, /* Which nested loop of the FROM we are coding */ + WhereClause *pWC, /* The WHERE clause */ + Bitmask notReady, /* Which parts of FROM have not yet been coded */ + int brk /* Jump here to end the loop */ +){ + int nEq = pLevel->nEq; /* The number of == or IN constraints to code */ + int termsInMem = 0; /* If true, store value in mem[] cells */ + Vdbe *v = pParse->pVdbe; /* The virtual machine under construction */ + Index *pIdx = pLevel->pIdx; /* The index being used for this loop */ + int iCur = pLevel->iTabCur; /* The cursor of the table */ + WhereTerm *pTerm; /* A single constraint term */ + int j; /* Loop counter */ + + /* Figure out how many memory cells we will need then allocate them. + ** We always need at least one used to store the loop terminator + ** value. If there are IN operators we'll need one for each == or + ** IN constraint. + */ + pLevel->iMem = pParse->nMem++; + if( pLevel->flags & WHERE_COLUMN_IN ){ + pParse->nMem += pLevel->nEq; + termsInMem = 1; + } + + /* Evaluate the equality constraints + */ + for(j=0; j<pIdx->nColumn; j++){ + int k = pIdx->aiColumn[j]; + pTerm = findTerm(pWC, iCur, k, notReady, WO_EQ|WO_IN, pIdx); + if( pTerm==0 ) break; + assert( (pTerm->flags & TERM_CODED)==0 ); + codeEqualityTerm(pParse, pTerm, brk, pLevel); + if( termsInMem ){ + sqlite3VdbeAddOp(v, OP_MemStore, pLevel->iMem+j+1, 1); + } + } + assert( j==nEq ); + + /* Make sure all the constraint values are on the top of the stack + */ + if( termsInMem ){ + for(j=0; j<nEq; j++){ + sqlite3VdbeAddOp(v, OP_MemLoad, pLevel->iMem+j+1, 0); + } + } +} + +#if defined(SQLITE_TEST) +/* +** The following variable holds a text description of query plan generated +** by the most recent call to sqlite3WhereBegin(). Each call to WhereBegin +** overwrites the previous. This information is used for testing and +** analysis only. +*/ +char sqlite3_query_plan[BMS*2*40]; /* Text of the join */ +static int nQPlan = 0; /* Next free slow in _query_plan[] */ + +#endif /* SQLITE_TEST */ + + + +/* +** Generate the beginning of the loop used for WHERE clause processing. +** The return value is a pointer to an opaque structure that contains +** information needed to terminate the loop. Later, the calling routine +** should invoke sqlite3WhereEnd() with the return value of this function +** in order to complete the WHERE clause processing. +** +** If an error occurs, this routine returns NULL. +** +** The basic idea is to do a nested loop, one loop for each table in +** the FROM clause of a select. (INSERT and UPDATE statements are the +** same as a SELECT with only a single table in the FROM clause.) For +** example, if the SQL is this: +** +** SELECT * FROM t1, t2, t3 WHERE ...; +** +** Then the code generated is conceptually like the following: +** +** foreach row1 in t1 do \ Code generated +** foreach row2 in t2 do |-- by sqlite3WhereBegin() +** foreach row3 in t3 do / +** ... +** end \ Code generated +** end |-- by sqlite3WhereEnd() +** end / +** +** Note that the loops might not be nested in the order in which they +** appear in the FROM clause if a different order is better able to make +** use of indices. Note also that when the IN operator appears in +** the WHERE clause, it might result in additional nested loops for +** scanning through all values on the right-hand side of the IN. +** +** There are Btree cursors associated with each table. t1 uses cursor +** number pTabList->a[0].iCursor. t2 uses the cursor pTabList->a[1].iCursor. +** And so forth. This routine generates code to open those VDBE cursors +** and sqlite3WhereEnd() generates the code to close them. +** +** The code that sqlite3WhereBegin() generates leaves the cursors named +** in pTabList pointing at their appropriate entries. The [...] code +** can use OP_Column and OP_Rowid opcodes on these cursors to extract +** data from the various tables of the loop. +** +** If the WHERE clause is empty, the foreach loops must each scan their +** entire tables. Thus a three-way join is an O(N^3) operation. But if +** the tables have indices and there are terms in the WHERE clause that +** refer to those indices, a complete table scan can be avoided and the +** code will run much faster. Most of the work of this routine is checking +** to see if there are indices that can be used to speed up the loop. +** +** Terms of the WHERE clause are also used to limit which rows actually +** make it to the "..." in the middle of the loop. After each "foreach", +** terms of the WHERE clause that use only terms in that loop and outer +** loops are evaluated and if false a jump is made around all subsequent +** inner loops (or around the "..." if the test occurs within the inner- +** most loop) +** +** OUTER JOINS +** +** An outer join of tables t1 and t2 is conceptally coded as follows: +** +** foreach row1 in t1 do +** flag = 0 +** foreach row2 in t2 do +** start: +** ... +** flag = 1 +** end +** if flag==0 then +** move the row2 cursor to a null row +** goto start +** fi +** end +** +** ORDER BY CLAUSE PROCESSING +** +** *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 *sqlite3WhereBegin( + Parse *pParse, /* The parser context */ + SrcList *pTabList, /* A list of all tables to be scanned */ + Expr *pWhere, /* The WHERE clause */ + 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 */ + Bitmask notReady; /* Cursors that are not yet positioned */ + WhereTerm *pTerm; /* A single term in the WHERE clause */ + ExprMaskSet maskSet; /* The expression mask set */ + WhereClause wc; /* The WHERE clause is divided into these terms */ + struct SrcList_item *pTabItem; /* A single entry from pTabList */ + WhereLevel *pLevel; /* A single level in the pWInfo list */ + int iFrom; /* First unused FROM clause element */ + int andFlags; /* AND-ed combination of all wc.a[].flags */ + + /* The number of tables in the FROM clause is limited by the number of + ** bits in a Bitmask + */ + if( pTabList->nSrc>BMS ){ + sqlite3ErrorMsg(pParse, "at most %d tables in a join", BMS); + return 0; + } + + /* Split the WHERE clause into separate subexpressions where each + ** subexpression is separated by an AND operator. + */ + initMaskSet(&maskSet); + whereClauseInit(&wc, pParse); + whereSplit(&wc, pWhere, TK_AND); + + /* Allocate and initialize the WhereInfo structure that will become the + ** return value. + */ + pWInfo = sqliteMalloc( sizeof(WhereInfo) + pTabList->nSrc*sizeof(WhereLevel)); + if( sqlite3_malloc_failed ){ + goto whereBeginNoMem; + } + pWInfo->pParse = pParse; + pWInfo->pTabList = pTabList; + pWInfo->iBreak = sqlite3VdbeMakeLabel(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 || sqlite3ExprIsConstant(pWhere)) ){ + sqlite3ExprIfFalse(pParse, pWhere, pWInfo->iBreak, 1); + pWhere = 0; + } + + /* Analyze all of the subexpressions. Note that exprAnalyze() might + ** add new virtual terms onto the end of the WHERE clause. We do not + ** want to analyze these virtual terms, so start analyzing at the end + ** and work forward so that the added virtual terms are never processed. + */ + for(i=0; i<pTabList->nSrc; i++){ + createMask(&maskSet, pTabList->a[i].iCursor); + } + exprAnalyzeAll(pTabList, &maskSet, &wc); + if( sqlite3_malloc_failed ){ + goto whereBeginNoMem; + } + + /* Chose the best index to use for each table in the FROM clause. + ** + ** This loop fills in the following fields: + ** + ** pWInfo->a[].pIdx The index to use for this level of the loop. + ** pWInfo->a[].flags WHERE_xxx flags associated with pIdx + ** pWInfo->a[].nEq The number of == and IN constraints + ** pWInfo->a[].iFrom When term of the FROM clause is being coded + ** pWInfo->a[].iTabCur The VDBE cursor for the database table + ** pWInfo->a[].iIdxCur The VDBE cursor for the index + ** + ** This loop also figures out the nesting order of tables in the FROM + ** clause. + */ + notReady = ~(Bitmask)0; + pTabItem = pTabList->a; + pLevel = pWInfo->a; + andFlags = ~0; + TRACE(("*** Optimizer Start ***\n")); + for(i=iFrom=0, pLevel=pWInfo->a; i<pTabList->nSrc; i++, pLevel++){ + Index *pIdx; /* Index for FROM table at pTabItem */ + int flags; /* Flags asssociated with pIdx */ + int nEq; /* Number of == or IN constraints */ + double cost; /* The cost for pIdx */ + int j; /* For looping over FROM tables */ + Index *pBest = 0; /* The best index seen so far */ + int bestFlags = 0; /* Flags associated with pBest */ + int bestNEq = 0; /* nEq associated with pBest */ + double lowestCost = 1.0e99; /* Cost of the pBest */ + int bestJ; /* The value of j */ + Bitmask m; /* Bitmask value for j or bestJ */ + + for(j=iFrom, pTabItem=&pTabList->a[j]; j<pTabList->nSrc; j++, pTabItem++){ + m = getMask(&maskSet, pTabItem->iCursor); + if( (m & notReady)==0 ){ + if( j==iFrom ) iFrom++; + continue; + } + cost = bestIndex(pParse, &wc, pTabItem, notReady, + (i==0 && ppOrderBy) ? *ppOrderBy : 0, + &pIdx, &flags, &nEq); + if( cost<lowestCost ){ + lowestCost = cost; + pBest = pIdx; + bestFlags = flags; + bestNEq = nEq; + bestJ = j; + } + if( (pTabItem->jointype & (JT_LEFT|JT_CROSS))!=0 + || (j>0 && (pTabItem[-1].jointype & (JT_LEFT|JT_CROSS))!=0) + ){ + break; + } + } + TRACE(("*** Optimizer choose table %d for loop %d\n", bestJ, + pLevel-pWInfo->a)); + if( (bestFlags & WHERE_ORDERBY)!=0 ){ + *ppOrderBy = 0; + } + andFlags &= bestFlags; + pLevel->flags = bestFlags; + pLevel->pIdx = pBest; + pLevel->nEq = bestNEq; + pLevel->aInLoop = 0; + pLevel->nIn = 0; + if( pBest ){ + pLevel->iIdxCur = pParse->nTab++; + }else{ + pLevel->iIdxCur = -1; + } + notReady &= ~getMask(&maskSet, pTabList->a[bestJ].iCursor); + pLevel->iFrom = bestJ; + } + TRACE(("*** Optimizer Finished ***\n")); + + /* If the total query only selects a single row, then the ORDER BY + ** clause is irrelevant. + */ + if( (andFlags & WHERE_UNIQUE)!=0 && ppOrderBy ){ + *ppOrderBy = 0; + } + + /* Open all tables in the pTabList and any indices selected for + ** searching those tables. + */ + sqlite3CodeVerifySchema(pParse, -1); /* Insert the cookie verifier Goto */ + pLevel = pWInfo->a; + for(i=0, pLevel=pWInfo->a; i<pTabList->nSrc; i++, pLevel++){ + Table *pTab; + Index *pIx; + int iIdxCur = pLevel->iIdxCur; + +#ifndef SQLITE_OMIT_EXPLAIN + if( pParse->explain==2 ){ + char *zMsg; + struct SrcList_item *pItem = &pTabList->a[pLevel->iFrom]; + zMsg = sqlite3MPrintf("TABLE %s", pItem->zName); + if( pItem->zAlias ){ + zMsg = sqlite3MPrintf("%z AS %s", zMsg, pItem->zAlias); + } + if( (pIx = pLevel->pIdx)!=0 ){ + zMsg = sqlite3MPrintf("%z WITH INDEX %s", zMsg, pIx->zName); + } + sqlite3VdbeOp3(v, OP_Explain, i, pLevel->iFrom, zMsg, P3_DYNAMIC); + } +#endif /* SQLITE_OMIT_EXPLAIN */ + pTabItem = &pTabList->a[pLevel->iFrom]; + pTab = pTabItem->pTab; + if( pTab->isTransient || pTab->pSelect ) continue; + if( (pLevel->flags & WHERE_IDX_ONLY)==0 ){ + sqlite3OpenTableForReading(v, pTabItem->iCursor, pTab); + } + pLevel->iTabCur = pTabItem->iCursor; + if( (pIx = pLevel->pIdx)!=0 ){ + sqlite3VdbeAddOp(v, OP_Integer, pIx->iDb, 0); + VdbeComment((v, "# %s", pIx->zName)); + sqlite3VdbeOp3(v, OP_OpenRead, iIdxCur, pIx->tnum, + (char*)&pIx->keyInfo, P3_KEYINFO); + } + if( (pLevel->flags & WHERE_IDX_ONLY)!=0 ){ + sqlite3VdbeAddOp(v, OP_SetNumColumns, iIdxCur, pIx->nColumn+1); + } + sqlite3CodeVerifySchema(pParse, pTab->iDb); + } + pWInfo->iTop = sqlite3VdbeCurrentAddr(v); + + /* Generate the code to do the search. Each iteration of the for + ** loop below generates code for a single nested loop of the VM + ** program. + */ + notReady = ~(Bitmask)0; + for(i=0, pLevel=pWInfo->a; i<pTabList->nSrc; i++, pLevel++){ + int j; + int iCur = pTabItem->iCursor; /* The VDBE cursor for the table */ + Index *pIdx; /* The index we will be using */ + int iIdxCur; /* The VDBE cursor for the index */ + int omitTable; /* True if we use the index only */ + int bRev; /* True if we need to scan in reverse order */ + + pTabItem = &pTabList->a[pLevel->iFrom]; + iCur = pTabItem->iCursor; + pIdx = pLevel->pIdx; + iIdxCur = pLevel->iIdxCur; + bRev = (pLevel->flags & WHERE_REVERSE)!=0; + omitTable = (pLevel->flags & WHERE_IDX_ONLY)!=0; + + /* Create labels for the "break" and "continue" instructions + ** for the current loop. Jump to brk to break out of a loop. + ** Jump to cont to go immediately to the next iteration of the + ** loop. + */ + brk = pLevel->brk = sqlite3VdbeMakeLabel(v); + cont = pLevel->cont = sqlite3VdbeMakeLabel(v); + + /* If this is the right table of a LEFT OUTER JOIN, allocate and + ** initialize a memory cell that records if this table matches any + ** row of the left table of the join. + */ + if( pLevel->iFrom>0 && (pTabItem[-1].jointype & JT_LEFT)!=0 ){ + if( !pParse->nMem ) pParse->nMem++; + pLevel->iLeftJoin = pParse->nMem++; + sqlite3VdbeAddOp(v, OP_MemInt, 0, pLevel->iLeftJoin); + VdbeComment((v, "# init LEFT JOIN no-match flag")); + } + + if( pLevel->flags & WHERE_ROWID_EQ ){ + /* 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. + */ + pTerm = findTerm(&wc, iCur, -1, notReady, WO_EQ|WO_IN, 0); + assert( pTerm!=0 ); + assert( pTerm->pExpr!=0 ); + assert( pTerm->leftCursor==iCur ); + assert( omitTable==0 ); + codeEqualityTerm(pParse, pTerm, brk, pLevel); + sqlite3VdbeAddOp(v, OP_MustBeInt, 1, brk); + sqlite3VdbeAddOp(v, OP_NotExists, iCur, brk); + VdbeComment((v, "pk")); + pLevel->op = OP_Noop; + }else if( pLevel->flags & WHERE_ROWID_RANGE ){ + /* Case 2: We have an inequality comparison against the ROWID field. + */ + int testOp = OP_Noop; + int start; + WhereTerm *pStart, *pEnd; + + assert( omitTable==0 ); + pStart = findTerm(&wc, iCur, -1, notReady, WO_GT|WO_GE, 0); + pEnd = findTerm(&wc, iCur, -1, notReady, WO_LT|WO_LE, 0); + if( bRev ){ + pTerm = pStart; + pStart = pEnd; + pEnd = pTerm; + } + if( pStart ){ + Expr *pX; + pX = pStart->pExpr; + assert( pX!=0 ); + assert( pStart->leftCursor==iCur ); + sqlite3ExprCode(pParse, pX->pRight); + sqlite3VdbeAddOp(v, OP_ForceInt, pX->op==TK_LE || pX->op==TK_GT, brk); + sqlite3VdbeAddOp(v, bRev ? OP_MoveLt : OP_MoveGe, iCur, brk); + VdbeComment((v, "pk")); + disableTerm(pLevel, pStart); + }else{ + sqlite3VdbeAddOp(v, bRev ? OP_Last : OP_Rewind, iCur, brk); + } + if( pEnd ){ + Expr *pX; + pX = pEnd->pExpr; + assert( pX!=0 ); + assert( pEnd->leftCursor==iCur ); + sqlite3ExprCode(pParse, pX->pRight); + pLevel->iMem = pParse->nMem++; + sqlite3VdbeAddOp(v, OP_MemStore, pLevel->iMem, 1); + if( pX->op==TK_LT || pX->op==TK_GT ){ + testOp = bRev ? OP_Le : OP_Ge; + }else{ + testOp = bRev ? OP_Lt : OP_Gt; + } + disableTerm(pLevel, pEnd); + } + start = sqlite3VdbeCurrentAddr(v); + pLevel->op = bRev ? OP_Prev : OP_Next; + pLevel->p1 = iCur; + pLevel->p2 = start; + if( testOp!=OP_Noop ){ + sqlite3VdbeAddOp(v, OP_Rowid, iCur, 0); + sqlite3VdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0); + sqlite3VdbeAddOp(v, testOp, 'n', brk); + } + }else if( pLevel->flags & WHERE_COLUMN_RANGE ){ + /* Case 3: 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 "==" and "IN" operators. + ** + ** 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 start; + int nEq = pLevel->nEq; + int leFlag=0, geFlag=0; + int testOp; + int topLimit = (pLevel->flags & WHERE_TOP_LIMIT)!=0; + int btmLimit = (pLevel->flags & WHERE_BTM_LIMIT)!=0; + + /* Generate code to evaluate all constraint terms using == or IN + ** and level the values of those terms on the stack. + */ + codeAllEqualityTerms(pParse, pLevel, &wc, notReady, brk); + + /* 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<nEq; j++){ + sqlite3VdbeAddOp(v, OP_Dup, nEq-1, 0); + } + + /* 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( topLimit ){ + Expr *pX; + int k = pIdx->aiColumn[j]; + pTerm = findTerm(&wc, iCur, k, notReady, WO_LT|WO_LE, pIdx); + assert( pTerm!=0 ); + pX = pTerm->pExpr; + assert( (pTerm->flags & TERM_CODED)==0 ); + sqlite3ExprCode(pParse, pX->pRight); + leFlag = pX->op==TK_LE; + disableTerm(pLevel, pTerm); + testOp = OP_IdxGE; + }else{ + testOp = nEq>0 ? OP_IdxGE : OP_Noop; + leFlag = 1; + } + if( testOp!=OP_Noop ){ + int nCol = nEq + topLimit; + pLevel->iMem = pParse->nMem++; + buildIndexProbe(v, nCol, brk, pIdx); + if( bRev ){ + int op = leFlag ? OP_MoveLe : OP_MoveLt; + sqlite3VdbeAddOp(v, op, iIdxCur, brk); + }else{ + sqlite3VdbeAddOp(v, OP_MemStore, pLevel->iMem, 1); + } + }else if( bRev ){ + sqlite3VdbeAddOp(v, OP_Last, iIdxCur, 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( btmLimit ){ + Expr *pX; + int k = pIdx->aiColumn[j]; + pTerm = findTerm(&wc, iCur, k, notReady, WO_GT|WO_GE, pIdx); + assert( pTerm!=0 ); + pX = pTerm->pExpr; + assert( (pTerm->flags & TERM_CODED)==0 ); + sqlite3ExprCode(pParse, pX->pRight); + geFlag = pX->op==TK_GE; + disableTerm(pLevel, pTerm); + }else{ + geFlag = 1; + } + if( nEq>0 || btmLimit ){ + int nCol = nEq + btmLimit; + buildIndexProbe(v, nCol, brk, pIdx); + if( bRev ){ + pLevel->iMem = pParse->nMem++; + sqlite3VdbeAddOp(v, OP_MemStore, pLevel->iMem, 1); + testOp = OP_IdxLT; + }else{ + int op = geFlag ? OP_MoveGe : OP_MoveGt; + sqlite3VdbeAddOp(v, op, iIdxCur, brk); + } + }else if( bRev ){ + testOp = OP_Noop; + }else{ + sqlite3VdbeAddOp(v, OP_Rewind, iIdxCur, 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 = sqlite3VdbeCurrentAddr(v); + if( testOp!=OP_Noop ){ + sqlite3VdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0); + sqlite3VdbeAddOp(v, testOp, iIdxCur, brk); + if( (leFlag && !bRev) || (!geFlag && bRev) ){ + sqlite3VdbeChangeP3(v, -1, "+", P3_STATIC); + } + } + sqlite3VdbeAddOp(v, OP_RowKey, iIdxCur, 0); + sqlite3VdbeAddOp(v, OP_IdxIsNull, nEq + topLimit, cont); + if( !omitTable ){ + sqlite3VdbeAddOp(v, OP_IdxRowid, iIdxCur, 0); + sqlite3VdbeAddOp(v, OP_MoveGe, iCur, 0); + } + + /* Record the instruction used to terminate the loop. + */ + pLevel->op = bRev ? OP_Prev : OP_Next; + pLevel->p1 = iIdxCur; + pLevel->p2 = start; + }else if( pLevel->flags & WHERE_COLUMN_EQ ){ + /* Case 4: There is an index and all terms of the WHERE clause that + ** refer to the index using the "==" or "IN" operators. + */ + int start; + int nEq = pLevel->nEq; + + /* Generate code to evaluate all constraint terms using == or IN + ** and leave the values of those terms on the stack. + */ + codeAllEqualityTerms(pParse, pLevel, &wc, notReady, brk); + + /* Generate a single key that will be used to both start and terminate + ** the search + */ + buildIndexProbe(v, nEq, brk, pIdx); + sqlite3VdbeAddOp(v, OP_MemStore, pLevel->iMem, 0); + + /* Generate code (1) to move to the first matching element of the table. + ** Then generate code (2) that jumps to "brk" after the cursor is past + ** the last matching element of the table. The code (1) is executed + ** once to initialize the search, the code (2) is executed before each + ** iteration of the scan to see if the scan has finished. */ + if( bRev ){ + /* Scan in reverse order */ + sqlite3VdbeAddOp(v, OP_MoveLe, iIdxCur, brk); + start = sqlite3VdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0); + sqlite3VdbeAddOp(v, OP_IdxLT, iIdxCur, brk); + pLevel->op = OP_Prev; + }else{ + /* Scan in the forward order */ + sqlite3VdbeAddOp(v, OP_MoveGe, iIdxCur, brk); + start = sqlite3VdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0); + sqlite3VdbeOp3(v, OP_IdxGE, iIdxCur, brk, "+", P3_STATIC); + pLevel->op = OP_Next; + } + sqlite3VdbeAddOp(v, OP_RowKey, iIdxCur, 0); + sqlite3VdbeAddOp(v, OP_IdxIsNull, nEq, cont); + if( !omitTable ){ + sqlite3VdbeAddOp(v, OP_IdxRowid, iIdxCur, 0); + sqlite3VdbeAddOp(v, OP_MoveGe, iCur, 0); + } + pLevel->p1 = iIdxCur; + pLevel->p2 = start; + }else{ + /* Case 5: There is no usable index. We must do a complete + ** scan of the entire table. + */ + assert( omitTable==0 ); + assert( bRev==0 ); + pLevel->op = OP_Next; + pLevel->p1 = iCur; + pLevel->p2 = 1 + sqlite3VdbeAddOp(v, OP_Rewind, iCur, brk); + } + notReady &= ~getMask(&maskSet, iCur); + + /* Insert code to test every subexpression that can be completely + ** computed using the current set of tables. + */ + for(pTerm=wc.a, j=wc.nTerm; j>0; j--, pTerm++){ + Expr *pE; + if( pTerm->flags & (TERM_VIRTUAL|TERM_CODED) ) continue; + if( (pTerm->prereqAll & notReady)!=0 ) continue; + pE = pTerm->pExpr; + assert( pE!=0 ); + if( pLevel->iLeftJoin && !ExprHasProperty(pE, EP_FromJoin) ){ + continue; + } + sqlite3ExprIfFalse(pParse, pE, cont, 1); + pTerm->flags |= TERM_CODED; + } + + /* 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 = sqlite3VdbeCurrentAddr(v); + sqlite3VdbeAddOp(v, OP_MemInt, 1, pLevel->iLeftJoin); + VdbeComment((v, "# record LEFT JOIN hit")); + for(pTerm=wc.a, j=0; j<wc.nTerm; j++, pTerm++){ + if( pTerm->flags & (TERM_VIRTUAL|TERM_CODED) ) continue; + if( (pTerm->prereqAll & notReady)!=0 ) continue; + assert( pTerm->pExpr ); + sqlite3ExprIfFalse(pParse, pTerm->pExpr, cont, 1); + pTerm->flags |= TERM_CODED; + } + } + } + +#ifdef SQLITE_TEST /* For testing and debugging use only */ + /* Record in the query plan information about the current table + ** and the index used to access it (if any). If the table itself + ** is not used, its name is just '{}'. If no index is used + ** the index is listed as "{}". If the primary key is used the + ** index name is '*'. + */ + for(i=0; i<pTabList->nSrc; i++){ + char *z; + int n; + pLevel = &pWInfo->a[i]; + pTabItem = &pTabList->a[pLevel->iFrom]; + z = pTabItem->zAlias; + if( z==0 ) z = pTabItem->pTab->zName; + n = strlen(z); + if( n+nQPlan < sizeof(sqlite3_query_plan)-10 ){ + if( pLevel->flags & WHERE_IDX_ONLY ){ + strcpy(&sqlite3_query_plan[nQPlan], "{}"); + nQPlan += 2; + }else{ + strcpy(&sqlite3_query_plan[nQPlan], z); + nQPlan += n; + } + sqlite3_query_plan[nQPlan++] = ' '; + } + if( pLevel->flags & (WHERE_ROWID_EQ|WHERE_ROWID_RANGE) ){ + strcpy(&sqlite3_query_plan[nQPlan], "* "); + nQPlan += 2; + }else if( pLevel->pIdx==0 ){ + strcpy(&sqlite3_query_plan[nQPlan], "{} "); + nQPlan += 3; + }else{ + n = strlen(pLevel->pIdx->zName); + if( n+nQPlan < sizeof(sqlite3_query_plan)-2 ){ + strcpy(&sqlite3_query_plan[nQPlan], pLevel->pIdx->zName); + nQPlan += n; + sqlite3_query_plan[nQPlan++] = ' '; + } + } + } + while( nQPlan>0 && sqlite3_query_plan[nQPlan-1]==' ' ){ + sqlite3_query_plan[--nQPlan] = 0; + } + sqlite3_query_plan[nQPlan] = 0; + nQPlan = 0; +#endif /* SQLITE_TEST // Testing and debugging use only */ + + /* Record the continuation address in the WhereInfo structure. Then + ** clean up and return. + */ + pWInfo->iContinue = cont; + whereClauseClear(&wc); + return pWInfo; + + /* Jump here if malloc fails */ +whereBeginNoMem: + whereClauseClear(&wc); + sqliteFree(pWInfo); + return 0; +} + +/* +** Generate the end of the WHERE loop. See comments on +** sqlite3WhereBegin() for additional information. +*/ +void sqlite3WhereEnd(WhereInfo *pWInfo){ + Vdbe *v = pWInfo->pParse->pVdbe; + int i; + WhereLevel *pLevel; + SrcList *pTabList = pWInfo->pTabList; + + /* Generate loop termination code. + */ + for(i=pTabList->nSrc-1; i>=0; i--){ + pLevel = &pWInfo->a[i]; + sqlite3VdbeResolveLabel(v, pLevel->cont); + if( pLevel->op!=OP_Noop ){ + sqlite3VdbeAddOp(v, pLevel->op, pLevel->p1, pLevel->p2); + } + sqlite3VdbeResolveLabel(v, pLevel->brk); + if( pLevel->nIn ){ + int *a; + int j; + for(j=pLevel->nIn, a=&pLevel->aInLoop[j*3-3]; j>0; j--, a-=3){ + sqlite3VdbeAddOp(v, a[0], a[1], a[2]); + } + sqliteFree(pLevel->aInLoop); + } + if( pLevel->iLeftJoin ){ + int addr; + addr = sqlite3VdbeAddOp(v, OP_IfMemPos, pLevel->iLeftJoin, 0); + sqlite3VdbeAddOp(v, OP_NullRow, pTabList->a[i].iCursor, 0); + if( pLevel->iIdxCur>=0 ){ + sqlite3VdbeAddOp(v, OP_NullRow, pLevel->iIdxCur, 0); + } + sqlite3VdbeAddOp(v, OP_Goto, 0, pLevel->top); + sqlite3VdbeJumpHere(v, addr); + } + } + + /* The "break" point is here, just past the end of the outer loop. + ** Set it. + */ + sqlite3VdbeResolveLabel(v, pWInfo->iBreak); + + /* Close all of the cursors that were opened by sqlite3WhereBegin. + */ + for(i=0, pLevel=pWInfo->a; i<pTabList->nSrc; i++, pLevel++){ + struct SrcList_item *pTabItem = &pTabList->a[pLevel->iFrom]; + Table *pTab = pTabItem->pTab; + assert( pTab!=0 ); + if( pTab->isTransient || pTab->pSelect ) continue; + if( (pLevel->flags & WHERE_IDX_ONLY)==0 ){ + sqlite3VdbeAddOp(v, OP_Close, pTabItem->iCursor, 0); + } + if( pLevel->pIdx!=0 ){ + sqlite3VdbeAddOp(v, OP_Close, pLevel->iIdxCur, 0); + } + + /* Make cursor substitutions for cases where we want to use + ** just the index and never reference the table. + ** + ** Calls to the code generator in between sqlite3WhereBegin and + ** sqlite3WhereEnd will have created code that references the table + ** directly. This loop scans all that code looking for opcodes + ** that reference the table and converts them into opcodes that + ** reference the index. + */ + if( pLevel->flags & WHERE_IDX_ONLY ){ + int i, j, last; + VdbeOp *pOp; + Index *pIdx = pLevel->pIdx; + + assert( pIdx!=0 ); + pOp = sqlite3VdbeGetOp(v, pWInfo->iTop); + last = sqlite3VdbeCurrentAddr(v); + for(i=pWInfo->iTop; i<last; i++, pOp++){ + if( pOp->p1!=pLevel->iTabCur ) continue; + if( pOp->opcode==OP_Column ){ + pOp->p1 = pLevel->iIdxCur; + for(j=0; j<pIdx->nColumn; j++){ + if( pOp->p2==pIdx->aiColumn[j] ){ + pOp->p2 = j; + break; + } + } + }else if( pOp->opcode==OP_Rowid ){ + pOp->p1 = pLevel->iIdxCur; + pOp->opcode = OP_IdxRowid; + }else if( pOp->opcode==OP_NullRow ){ + pOp->opcode = OP_Noop; + } + } + } + } + + /* Final cleanup + */ + sqliteFree(pWInfo); + return; +} |