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Diffstat (limited to 'ext/pdo_sqlite/sqlite/src/where.c')
| -rw-r--r-- | ext/pdo_sqlite/sqlite/src/where.c | 1439 |
1 files changed, 0 insertions, 1439 deletions
diff --git a/ext/pdo_sqlite/sqlite/src/where.c b/ext/pdo_sqlite/sqlite/src/where.c deleted file mode 100644 index 553de70a25..0000000000 --- a/ext/pdo_sqlite/sqlite/src/where.c +++ /dev/null @@ -1,1439 +0,0 @@ -/* -** 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". -** -** $Id$ -*/ -#include "sqliteInt.h" - -/* -** 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. -** -** The idxLeft and idxRight fields are the VDBE cursor numbers for the -** table that contains the column that appears on the left-hand and -** right-hand side of ExprInfo.p. If either side of ExprInfo.p is -** something other than a simple column reference, then idxLeft or -** idxRight are -1. -** -** It is the VDBE cursor number is the value stored in Expr.iTable -** when Expr.op==TK_COLUMN and the value stored in SrcList.a[].iCursor. -** -** prereqLeft, 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. -** -** prereqLeft tells us every VDBE cursor that is referenced on the -** left-hand side of ExprInfo.p. prereqRight does the same for the -** right-hand side of the expression. The following identity always -** holds: -** -** prereqAll = prereqLeft | prereqRight -** -** The ExprInfo.indexable field is true if the ExprInfo.p expression -** is of a form that might control an index. Indexable expressions -** look like this: -** -** <column> <op> <expr> -** -** Where <column> is a simple column name and <op> is on of the operators -** that allowedOp() recognizes. -*/ -typedef struct ExprInfo ExprInfo; -struct ExprInfo { - Expr *p; /* Pointer to the subexpression */ - u8 indexable; /* True if this subexprssion is usable by an index */ - short int idxLeft; /* p->pLeft is a column in this table number. -1 if - ** p->pLeft is not the column of any table */ - short int idxRight; /* p->pRight is a column in this table number. -1 if - ** p->pRight is not the column of any table */ - Bitmask prereqLeft; /* Bitmask of tables referenced by p->pLeft */ - Bitmask prereqRight; /* Bitmask of tables referenced by p->pRight */ - Bitmask prereqAll; /* Bitmask of tables referenced by p */ -}; - -/* -** An instance of the following structure keeps track of a mapping -** between VDBE cursor numbers and bits of the bitmasks in ExprInfo. -** -** 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 */ -}; - -/* -** Determine the number of elements in an array. -*/ -#define ARRAYSIZE(X) (sizeof(X)/sizeof(X[0])) - -/* -** This routine identifies subexpressions in the WHERE clause where -** each subexpression is separate by the AND operator. aSlot is -** filled with pointers to the 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 aSlot[] entries point to substructure within pExpr. -** -** aSlot[] is an array of subexpressions structures. There are nSlot -** spaces left in this array. This routine finds as many AND-separated -** subexpressions as it can and puts pointers to those subexpressions -** into aSlot[] entries. The return value is the number of slots filled. -*/ -static int exprSplit(int nSlot, ExprInfo *aSlot, Expr *pExpr){ - int cnt = 0; - if( pExpr==0 || nSlot<1 ) return 0; - if( nSlot==1 || pExpr->op!=TK_AND ){ - aSlot[0].p = pExpr; - return 1; - } - if( pExpr->pLeft->op!=TK_AND ){ - aSlot[0].p = pExpr->pLeft; - cnt = 1 + exprSplit(nSlot-1, &aSlot[1], pExpr->pRight); - }else{ - cnt = exprSplit(nSlot, aSlot, pExpr->pLeft); - cnt += exprSplit(nSlot-cnt, &aSlot[cnt], pExpr->pRight); - } - return cnt; -} - -/* -** 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. -*/ -static void createMask(ExprMaskSet *pMaskSet, int iCursor){ - if( pMaskSet->n<ARRAYSIZE(pMaskSet->ix) ){ - pMaskSet->ix[pMaskSet->n++] = iCursor; - } -} - -/* -** Destroy an expression mask set -*/ -#define freeMaskSet(P) /* NO-OP */ - -/* -** 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. -*/ -static Bitmask exprListTableUsage(ExprMaskSet *, ExprList *); -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); - if( p->pSelect ){ - Select *pS = p->pSelect; - 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; -} -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; -} - -/* -** 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_LE-1 && TK_LE==TK_LT-1 && TK_LT==TK_GE-1 && TK_EQ==TK_GT-1); - 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;} - -/* -** Return the index in the SrcList that uses cursor iCur. If iCur is -** used by the first entry in SrcList return 0. If iCur is used by -** the second entry return 1. And so forth. -** -** SrcList is the set of tables in the FROM clause in the order that -** they will be processed. The value returned here gives us an index -** of which tables will be processed first. -*/ -static int tableOrder(SrcList *pList, int iCur){ - int i; - struct SrcList_item *pItem; - for(i=0, pItem=pList->a; i<pList->nSrc; i++, pItem++){ - if( pItem->iCursor==iCur ) return i; - } - return -1; -} - -/* -** The input to this routine is an ExprInfo structure with only the -** "p" field filled in. The job of this routine is to analyze the -** subexpression and populate all the other fields of the ExprInfo -** structure. -*/ -static void exprAnalyze(SrcList *pSrc, ExprMaskSet *pMaskSet, ExprInfo *pInfo){ - Expr *pExpr = pInfo->p; - pInfo->prereqLeft = exprTableUsage(pMaskSet, pExpr->pLeft); - pInfo->prereqRight = exprTableUsage(pMaskSet, pExpr->pRight); - pInfo->prereqAll = exprTableUsage(pMaskSet, pExpr); - pInfo->indexable = 0; - pInfo->idxLeft = -1; - pInfo->idxRight = -1; - if( allowedOp(pExpr->op) && (pInfo->prereqRight & pInfo->prereqLeft)==0 ){ - if( pExpr->pRight && pExpr->pRight->op==TK_COLUMN ){ - pInfo->idxRight = pExpr->pRight->iTable; - pInfo->indexable = 1; - } - if( pExpr->pLeft->op==TK_COLUMN ){ - pInfo->idxLeft = pExpr->pLeft->iTable; - pInfo->indexable = 1; - } - } - if( pInfo->indexable ){ - assert( pInfo->idxLeft!=pInfo->idxRight ); - - /* We want the expression to be of the form "X = expr", not "expr = X". - ** So flip it over if necessary. If the expression is "X = Y", then - ** we want Y to come from an earlier table than X. - ** - ** The collating sequence rule is to always choose the left expression. - ** So if we do a flip, we also have to move the collating sequence. - */ - if( tableOrder(pSrc,pInfo->idxLeft)<tableOrder(pSrc,pInfo->idxRight) ){ - assert( 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; - } - SWAP(unsigned, pInfo->prereqLeft, pInfo->prereqRight); - SWAP(short int, pInfo->idxLeft, pInfo->idxRight); - } - } - -} - -/* -** 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. -** -** If the index is UNIQUE, then the ORDER BY clause is allowed to have -** additional terms past the end of the index and the match will 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; /* 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 - ** or covered or if we ran out of index columns and the it is a UNIQUE - ** index. - */ - if( j>=nTerm || (i>=pIdx->nColumn && pIdx->onError!=OE_None) ){ - *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( p->op==TK_COLUMN && p->iTable==base && p->iColumn==-1 ){ - *pbRev = pOrderBy->a[0].sortOrder; - return 1; - } - return 0; -} - - -/* -** 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. 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, Expr **ppExpr){ - Expr *pExpr = *ppExpr; - if( pLevel->iLeftJoin==0 || ExprHasProperty(pExpr, EP_FromJoin) ){ - *ppExpr = 0; - } -} - -/* -** 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 an equality term of the WHERE clause. An equality -** term can be either X=expr or X IN (...). pTerm is the X. -*/ -static void codeEqualityTerm( - Parse *pParse, /* The parsing context */ - ExprInfo *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->p; - if( pX->op!=TK_IN ){ - assert( pX->op==TK_EQ ); - sqlite3ExprCode(pParse, pX->pRight); -#ifndef SQLITE_OMIT_SUBQUERY - }else{ - int iTab; - 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->inP2 = sqlite3VdbeAddOp(v, OP_Column, iTab, 0); - pLevel->inOp = OP_Next; - pLevel->inP1 = iTab; -#endif - } - disableTerm(pLevel, &pTerm->p); -} - -/* -** The number of bits in a Bitmask -*/ -#define BMS (sizeof(Bitmask)*8-1) - - -/* -** 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 / -** -** 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 */ - int nExpr; /* Number of subexpressions in the WHERE clause */ - Bitmask loopMask; /* One bit set for each outer loop */ - ExprInfo *pTerm; /* A single term in the WHERE clause; ptr to aExpr[] */ - ExprMaskSet maskSet; /* The expression mask set */ - int iDirectEq[BMS]; /* Term of the form ROWID==X for the N-th table */ - int iDirectLt[BMS]; /* Term of the form ROWID<X or ROWID<=X */ - int iDirectGt[BMS]; /* Term of the form ROWID>X or ROWID>=X */ - ExprInfo aExpr[101]; /* 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 */ - - /* The number of terms in the FROM clause is limited by the number of - ** bits in a Bitmask - */ - if( pTabList->nSrc>sizeof(Bitmask)*8 ){ - sqlite3ErrorMsg(pParse, "at most %d tables in a join", - sizeof(Bitmask)*8); - return 0; - } - - /* Split the WHERE clause into separate subexpressions where each - ** subexpression is separated by an AND operator. If the aExpr[] - ** array fills up, the last entry might point to an expression which - ** contains additional unfactored AND operators. - */ - initMaskSet(&maskSet); - memset(aExpr, 0, sizeof(aExpr)); - nExpr = exprSplit(ARRAYSIZE(aExpr), aExpr, pWhere); - if( nExpr==ARRAYSIZE(aExpr) ){ - sqlite3ErrorMsg(pParse, "WHERE clause too complex - no more " - "than %d terms allowed", (int)ARRAYSIZE(aExpr)-1); - return 0; - } - - /* Allocate and initialize the WhereInfo structure that will become the - ** return value. - */ - pWInfo = sqliteMalloc( sizeof(WhereInfo) + pTabList->nSrc*sizeof(WhereLevel)); - if( sqlite3_malloc_failed ){ - sqliteFree(pWInfo); /* Avoid leaking memory when malloc fails */ - return 0; - } - 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. - */ - for(i=0; i<pTabList->nSrc; i++){ - createMask(&maskSet, pTabList->a[i].iCursor); - } - for(pTerm=aExpr, i=0; i<nExpr; i++, pTerm++){ - exprAnalyze(pTabList, &maskSet, pTerm); - } - - /* Figure out what index to use (if any) for each nested loop. - ** Make pWInfo->a[i].pIdx point to the index to use for the i-th nested - ** loop where i==0 is the outer loop and i==pTabList->nSrc-1 is the inner - ** loop. - ** - ** If terms exist that use the ROWID of any table, then set the - ** iDirectEq[], iDirectLt[], or iDirectGt[] elements for that table - ** to the index of the term containing the ROWID. We always prefer - ** to use a ROWID which can directly access a table rather than an - ** index which requires reading an index first to get the rowid then - ** doing a second read of the actual database table. - ** - ** Actually, if there are more than 32 tables in the join, only the - ** first 32 tables are candidates for indices. This is (again) due - ** to the limit of 32 bits in an integer bitmask. - */ - loopMask = 0; - pTabItem = pTabList->a; - pLevel = pWInfo->a; - for(i=0; i<pTabList->nSrc && i<ARRAYSIZE(iDirectEq); i++,pTabItem++,pLevel++){ - int j; - int iCur = pTabItem->iCursor; /* The cursor for this table */ - Bitmask mask = getMask(&maskSet, iCur); /* Cursor mask for this table */ - Table *pTab = pTabItem->pTab; - Index *pIdx; - Index *pBestIdx = 0; - int bestScore = 0; - int bestRev = 0; - - /* Check to see if there is an expression that uses only the - ** ROWID field of this table. For terms of the form ROWID==expr - ** set iDirectEq[i] to the index of the term. For terms of the - ** form ROWID<expr or ROWID<=expr set iDirectLt[i] to the term index. - ** For terms like ROWID>expr or ROWID>=expr set iDirectGt[i]. - ** - ** (Added:) Treat ROWID IN expr like ROWID=expr. - */ - pLevel->iIdxCur = -1; - iDirectEq[i] = -1; - iDirectLt[i] = -1; - iDirectGt[i] = -1; - for(pTerm=aExpr, j=0; j<nExpr; j++, pTerm++){ - Expr *pX = pTerm->p; - if( pTerm->idxLeft==iCur && pX->pLeft->iColumn<0 - && (pTerm->prereqRight & loopMask)==pTerm->prereqRight ){ - switch( pX->op ){ - case TK_IN: - case TK_EQ: iDirectEq[i] = j; break; - case TK_LE: - case TK_LT: iDirectLt[i] = j; break; - case TK_GE: - case TK_GT: iDirectGt[i] = j; break; - } - } - } - - /* If we found a term that tests ROWID with == or IN, that term - ** will be used to locate the rows in the database table. There - ** is not need to continue into the code below that looks for - ** an index. We will always use the ROWID over an index. - */ - if( iDirectEq[i]>=0 ){ - loopMask |= mask; - pLevel->pIdx = 0; - continue; - } - - /* Do a search for usable indices. Leave pBestIdx pointing to - ** the "best" index. pBestIdx is left set to NULL if no indices - ** are usable. - ** - ** The best index is the one with the highest score. The score - ** for the index is determined as follows. For each of the - ** left-most terms that is fixed by an equality operator, add - ** 32 to the score. The right-most term of the index may be - ** constrained by an inequality. Add 4 if for an "x<..." constraint - ** and add 8 for an "x>..." constraint. If both constraints - ** are present, add 12. - ** - ** If the left-most term of the index uses an IN operator - ** (ex: "x IN (...)") then add 16 to the score. - ** - ** If an index can be used for sorting, add 2 to the score. - ** If an index contains all the terms of a table that are ever - ** used by any expression in the SQL statement, then add 1 to - ** the score. - ** - ** This scoring system is designed so that the score can later be - ** used to determine how the index is used. If the score&0x1c is 0 - ** then all constraints are equalities. If score&0x4 is not 0 then - ** there is an inequality used as a termination key. (ex: "x<...") - ** If score&0x8 is not 0 then there is an inequality used as the - ** start key. (ex: "x>..."). A score or 0x10 is the special case - ** of an IN operator constraint. (ex: "x IN ..."). - ** - ** The IN operator (as in "<expr> IN (...)") is treated the same as - ** an equality comparison except that it can only be used on the - ** left-most column of an index and other terms of the WHERE clause - ** cannot be used in conjunction with the IN operator to help satisfy - ** other columns of the index. - */ - for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){ - Bitmask eqMask = 0; /* Index columns covered by an x=... term */ - Bitmask ltMask = 0; /* Index columns covered by an x<... term */ - Bitmask gtMask = 0; /* Index columns covered by an x>... term */ - Bitmask inMask = 0; /* Index columns covered by an x IN .. term */ - Bitmask m; - int nEq, score, bRev = 0; - - if( pIdx->nColumn>sizeof(eqMask)*8 ){ - continue; /* Ignore indices with too many columns to analyze */ - } - for(pTerm=aExpr, j=0; j<nExpr; j++, pTerm++){ - Expr *pX = pTerm->p; - CollSeq *pColl = sqlite3ExprCollSeq(pParse, pX->pLeft); - if( !pColl && pX->pRight ){ - pColl = sqlite3ExprCollSeq(pParse, pX->pRight); - } - if( !pColl ){ - pColl = pParse->db->pDfltColl; - } - if( pTerm->idxLeft==iCur - && (pTerm->prereqRight & loopMask)==pTerm->prereqRight ){ - int iColumn = pX->pLeft->iColumn; - int k; - char idxaff = iColumn>=0 ? pIdx->pTable->aCol[iColumn].affinity : 0; - for(k=0; k<pIdx->nColumn; k++){ - /* If the collating sequences or affinities don't match, - ** ignore this index. */ - if( pColl!=pIdx->keyInfo.aColl[k] ) continue; - if( !sqlite3IndexAffinityOk(pX, idxaff) ) continue; - if( pIdx->aiColumn[k]==iColumn ){ - switch( pX->op ){ - case TK_IN: { - if( k==0 ) inMask |= 1; - break; - } - case TK_EQ: { - eqMask |= ((Bitmask)1)<<k; - break; - } - case TK_LE: - case TK_LT: { - ltMask |= ((Bitmask)1)<<k; - break; - } - case TK_GE: - case TK_GT: { - gtMask |= ((Bitmask)1)<<k; - break; - } - default: { - /* CANT_HAPPEN */ - assert( 0 ); - break; - } - } - break; - } - } - } - } - - /* The following loop ends with nEq set to the number of columns - ** on the left of the index with == constraints. - */ - for(nEq=0; nEq<pIdx->nColumn; nEq++){ - m = (((Bitmask)1)<<(nEq+1))-1; - if( (m & eqMask)!=m ) break; - } - - /* Begin assemblying the score - */ - score = nEq*32; /* Base score is 32 times number of == constraints */ - m = ((Bitmask)1)<<nEq; - if( m & ltMask ) score+=4; /* Increase score for a < constraint */ - if( m & gtMask ) score+=8; /* Increase score for a > constraint */ - if( score==0 && inMask ) score = 16; /* Default score for IN constraint */ - - /* Give bonus points if this index can be used for sorting - */ - if( i==0 && score!=16 && ppOrderBy && *ppOrderBy ){ - int base = pTabList->a[0].iCursor; - if( isSortingIndex(pParse, pIdx, pTab, base, *ppOrderBy, nEq, &bRev) ){ - score += 2; - } - } - - /* Check to see if we can get away with using just the index without - ** ever reading the table. If that is the case, then add one bonus - ** point to the score. - */ - if( score && pTabItem->colUsed < (((Bitmask)1)<<(BMS-1)) ){ - for(m=0, j=0; j<pIdx->nColumn; j++){ - int x = pIdx->aiColumn[j]; - if( x<BMS-1 ){ - m |= ((Bitmask)1)<<x; - } - } - if( (pTabItem->colUsed & m)==pTabItem->colUsed ){ - score++; - } - } - - /* If the score for this index is the best we have seen so far, then - ** save it - */ - if( score>bestScore ){ - pBestIdx = pIdx; - bestScore = score; - bestRev = bRev; - } - } - pLevel->pIdx = pBestIdx; - pLevel->score = bestScore; - pLevel->bRev = bestRev; - loopMask |= mask; - if( pBestIdx ){ - pLevel->iIdxCur = pParse->nTab++; - } - } - - /* Check to see if the ORDER BY clause is or can be satisfied by the - ** use of an index on the first table. - */ - if( ppOrderBy && *ppOrderBy && pTabList->nSrc>0 ){ - Index *pIdx; /* Index derived from the WHERE clause */ - Table *pTab; /* Left-most table in the FROM clause */ - int bRev = 0; /* True to reverse the output order */ - int iCur; /* Btree-cursor that will be used by pTab */ - WhereLevel *pLevel0 = &pWInfo->a[0]; - - pTab = pTabList->a[0].pTab; - pIdx = pLevel0->pIdx; - iCur = pTabList->a[0].iCursor; - if( pIdx==0 && sortableByRowid(iCur, *ppOrderBy, &bRev) ){ - /* The ORDER BY clause specifies ROWID order, which is what we - ** were going to be doing anyway... - */ - *ppOrderBy = 0; - pLevel0->bRev = bRev; - }else if( pLevel0->score==16 ){ - /* If there is already an IN index on the left-most table, - ** it will not give the correct sort order. - ** So, pretend that no suitable index is found. - */ - }else if( iDirectEq[0]>=0 || iDirectLt[0]>=0 || iDirectGt[0]>=0 ){ - /* If the left-most column is accessed using its ROWID, then do - ** not try to sort by index. But do delete the ORDER BY clause - ** if it is redundant. - */ - }else if( (pLevel0->score&2)!=0 ){ - /* The index that was selected for searching will cause rows to - ** appear in sorted order. - */ - *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, pTabItem=pTabList->a; i<pTabList->nSrc; i++, pTabItem++, pLevel++){ - Table *pTab; - Index *pIx; - int iIdxCur = pLevel->iIdxCur; - - pTab = pTabItem->pTab; - if( pTab->isTransient || pTab->pSelect ) continue; - if( (pLevel->score & 1)==0 ){ - sqlite3OpenTableForReading(v, pTabItem->iCursor, pTab); - } - pLevel->iTabCur = pTabItem->iCursor; - if( (pIx = pLevel->pIdx)!=0 ){ - sqlite3VdbeAddOp(v, OP_Integer, pIx->iDb, 0); - sqlite3VdbeOp3(v, OP_OpenRead, iIdxCur, pIx->tnum, - (char*)&pIx->keyInfo, P3_KEYINFO); - } - if( (pLevel->score & 1)!=0 ){ - sqlite3VdbeAddOp(v, OP_SetNumColumns, iIdxCur, pIx->nColumn+1); - } - sqlite3CodeVerifySchema(pParse, pTab->iDb); - } - pWInfo->iTop = sqlite3VdbeCurrentAddr(v); - - /* Generate the code to do the search - */ - loopMask = 0; - pLevel = pWInfo->a; - pTabItem = pTabList->a; - for(i=0; i<pTabList->nSrc; i++, pTabItem++, pLevel++){ - int j, k; - 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 */ - - pIdx = pLevel->pIdx; - iIdxCur = pLevel->iIdxCur; - pLevel->inOp = OP_Noop; - - /* Check to see if it is appropriate to omit the use of the table - ** here and use its index instead. - */ - omitTable = (pLevel->score&1)!=0; - - /* If this is the right table of a LEFT OUTER JOIN, allocate and - ** initialize a memory cell that records if this table matches any - ** row of the left table of the join. - */ - if( i>0 && (pTabList->a[i-1].jointype & JT_LEFT)!=0 ){ - if( !pParse->nMem ) pParse->nMem++; - pLevel->iLeftJoin = pParse->nMem++; - sqlite3VdbeAddOp(v, OP_Null, 0, 0); - sqlite3VdbeAddOp(v, OP_MemStore, pLevel->iLeftJoin, 1); - VdbeComment((v, "# init LEFT JOIN no-match flag")); - } - - if( i<ARRAYSIZE(iDirectEq) && (k = iDirectEq[i])>=0 ){ - /* Case 1: We can directly reference a single row using an - ** equality comparison against the ROWID field. Or - ** we reference multiple rows using a "rowid IN (...)" - ** construct. - */ - assert( k<nExpr ); - pTerm = &aExpr[k]; - assert( pTerm->p!=0 ); - assert( pTerm->idxLeft==iCur ); - assert( omitTable==0 ); - brk = pLevel->brk = sqlite3VdbeMakeLabel(v); - codeEqualityTerm(pParse, pTerm, brk, pLevel); - cont = pLevel->cont = sqlite3VdbeMakeLabel(v); - sqlite3VdbeAddOp(v, OP_MustBeInt, 1, brk); - sqlite3VdbeAddOp(v, OP_NotExists, iCur, brk); - VdbeComment((v, "pk")); - pLevel->op = OP_Noop; - }else if( pIdx!=0 && pLevel->score>3 && (pLevel->score&0x0c)==0 ){ - /* Case 2: There is an index and all terms of the WHERE clause that - ** refer to the index using the "==" or "IN" operators. - */ - int start; - int nColumn = (pLevel->score+16)/32; - brk = pLevel->brk = sqlite3VdbeMakeLabel(v); - - /* For each column of the index, find the term of the WHERE clause that - ** constraints that column. If the WHERE clause term is X=expr, then - ** evaluation expr and leave the result on the stack */ - for(j=0; j<nColumn; j++){ - for(pTerm=aExpr, k=0; k<nExpr; k++, pTerm++){ - Expr *pX = pTerm->p; - if( pX==0 ) continue; - if( pTerm->idxLeft==iCur - && (pTerm->prereqRight & loopMask)==pTerm->prereqRight - && pX->pLeft->iColumn==pIdx->aiColumn[j] - && (pX->op==TK_EQ || pX->op==TK_IN) - ){ - char idxaff = pIdx->pTable->aCol[pX->pLeft->iColumn].affinity; - if( sqlite3IndexAffinityOk(pX, idxaff) ){ - codeEqualityTerm(pParse, pTerm, brk, pLevel); - break; - } - } - } - } - pLevel->iMem = pParse->nMem++; - cont = pLevel->cont = sqlite3VdbeMakeLabel(v); - buildIndexProbe(v, nColumn, 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( pLevel->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, nColumn, cont); - if( !omitTable ){ - sqlite3VdbeAddOp(v, OP_IdxRowid, iIdxCur, 0); - sqlite3VdbeAddOp(v, OP_MoveGe, iCur, 0); - } - pLevel->p1 = iIdxCur; - pLevel->p2 = start; - }else if( i<ARRAYSIZE(iDirectLt) && (iDirectLt[i]>=0 || iDirectGt[i]>=0) ){ - /* Case 3: We have an inequality comparison against the ROWID field. - */ - int testOp = OP_Noop; - int start; - int bRev = pLevel->bRev; - - assert( omitTable==0 ); - brk = pLevel->brk = sqlite3VdbeMakeLabel(v); - cont = pLevel->cont = sqlite3VdbeMakeLabel(v); - if( bRev ){ - int t = iDirectGt[i]; - iDirectGt[i] = iDirectLt[i]; - iDirectLt[i] = t; - } - if( iDirectGt[i]>=0 ){ - Expr *pX; - k = iDirectGt[i]; - assert( k<nExpr ); - pTerm = &aExpr[k]; - pX = pTerm->p; - assert( pX!=0 ); - assert( pTerm->idxLeft==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, &pTerm->p); - }else{ - sqlite3VdbeAddOp(v, bRev ? OP_Last : OP_Rewind, iCur, brk); - } - if( iDirectLt[i]>=0 ){ - Expr *pX; - k = iDirectLt[i]; - assert( k<nExpr ); - pTerm = &aExpr[k]; - pX = pTerm->p; - assert( pX!=0 ); - assert( pTerm->idxLeft==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, &pTerm->p); - } - 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( pIdx==0 ){ - /* Case 4: There is no usable index. We must do a complete - ** scan of the entire database table. - */ - int start; - int opRewind; - - assert( omitTable==0 ); - brk = pLevel->brk = sqlite3VdbeMakeLabel(v); - cont = pLevel->cont = sqlite3VdbeMakeLabel(v); - if( pLevel->bRev ){ - opRewind = OP_Last; - pLevel->op = OP_Prev; - }else{ - opRewind = OP_Rewind; - pLevel->op = OP_Next; - } - sqlite3VdbeAddOp(v, opRewind, iCur, brk); - start = sqlite3VdbeCurrentAddr(v); - pLevel->p1 = iCur; - pLevel->p2 = start; - }else{ - /* Case 5: The WHERE clause term that refers to the right-most - ** column of the index is an inequality. For example, if - ** the index is on (x,y,z) and the WHERE clause is of the - ** form "x=5 AND y<10" then this case is used. Only the - ** right-most column can be an inequality - the rest must - ** use the "==" operator. - ** - ** This case is also used when there are no WHERE clause - ** constraints but an index is selected anyway, in order - ** to force the output order to conform to an ORDER BY. - */ - int score = pLevel->score; - int nEqColumn = score/32; - int start; - int leFlag=0, geFlag=0; - int testOp; - - /* Evaluate the equality constraints - */ - for(j=0; j<nEqColumn; j++){ - int iIdxCol = pIdx->aiColumn[j]; - for(pTerm=aExpr, k=0; k<nExpr; k++, pTerm++){ - Expr *pX = pTerm->p; - if( pX==0 ) continue; - if( pTerm->idxLeft==iCur - && pX->op==TK_EQ - && (pTerm->prereqRight & loopMask)==pTerm->prereqRight - && pX->pLeft->iColumn==iIdxCol - ){ - sqlite3ExprCode(pParse, pX->pRight); - disableTerm(pLevel, &pTerm->p); - break; - } - } - } - - /* Duplicate the equality term values because they will all be - ** used twice: once to make the termination key and once to make the - ** start key. - */ - for(j=0; j<nEqColumn; j++){ - sqlite3VdbeAddOp(v, OP_Dup, nEqColumn-1, 0); - } - - /* Labels for the beginning and end of the loop - */ - cont = pLevel->cont = sqlite3VdbeMakeLabel(v); - brk = pLevel->brk = sqlite3VdbeMakeLabel(v); - - /* Generate the termination key. This is the key value that - ** will end the search. There is no termination key if there - ** are no equality terms and no "X<..." term. - ** - ** 2002-Dec-04: On a reverse-order scan, the so-called "termination" - ** key computed here really ends up being the start key. - */ - if( (score & 4)!=0 ){ - for(pTerm=aExpr, k=0; k<nExpr; k++, pTerm++){ - Expr *pX = pTerm->p; - if( pX==0 ) continue; - if( pTerm->idxLeft==iCur - && (pX->op==TK_LT || pX->op==TK_LE) - && (pTerm->prereqRight & loopMask)==pTerm->prereqRight - && pX->pLeft->iColumn==pIdx->aiColumn[j] - ){ - sqlite3ExprCode(pParse, pX->pRight); - leFlag = pX->op==TK_LE; - disableTerm(pLevel, &pTerm->p); - break; - } - } - testOp = OP_IdxGE; - }else{ - testOp = nEqColumn>0 ? OP_IdxGE : OP_Noop; - leFlag = 1; - } - if( testOp!=OP_Noop ){ - int nCol = nEqColumn + ((score & 4)!=0); - pLevel->iMem = pParse->nMem++; - buildIndexProbe(v, nCol, brk, pIdx); - if( pLevel->bRev ){ - int op = leFlag ? OP_MoveLe : OP_MoveLt; - sqlite3VdbeAddOp(v, op, iIdxCur, brk); - }else{ - sqlite3VdbeAddOp(v, OP_MemStore, pLevel->iMem, 1); - } - }else if( pLevel->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( (score & 8)!=0 ){ - for(pTerm=aExpr, k=0; k<nExpr; k++, pTerm++){ - Expr *pX = pTerm->p; - if( pX==0 ) continue; - if( pTerm->idxLeft==iCur - && (pX->op==TK_GT || pX->op==TK_GE) - && (pTerm->prereqRight & loopMask)==pTerm->prereqRight - && pX->pLeft->iColumn==pIdx->aiColumn[j] - ){ - sqlite3ExprCode(pParse, pX->pRight); - geFlag = pX->op==TK_GE; - disableTerm(pLevel, &pTerm->p); - break; - } - } - }else{ - geFlag = 1; - } - if( nEqColumn>0 || (score&8)!=0 ){ - int nCol = nEqColumn + ((score&8)!=0); - buildIndexProbe(v, nCol, brk, pIdx); - if( pLevel->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( pLevel->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 && !pLevel->bRev) || (!geFlag && pLevel->bRev) ){ - sqlite3VdbeChangeP3(v, -1, "+", P3_STATIC); - } - } - sqlite3VdbeAddOp(v, OP_RowKey, iIdxCur, 0); - sqlite3VdbeAddOp(v, OP_IdxIsNull, nEqColumn + ((score&4)!=0), 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 = pLevel->bRev ? OP_Prev : OP_Next; - pLevel->p1 = iIdxCur; - pLevel->p2 = start; - } - loopMask |= getMask(&maskSet, iCur); - - /* Insert code to test every subexpression that can be completely - ** computed using the current set of tables. - */ - for(pTerm=aExpr, j=0; j<nExpr; j++, pTerm++){ - if( pTerm->p==0 ) continue; - if( (pTerm->prereqAll & loopMask)!=pTerm->prereqAll ) continue; - if( pLevel->iLeftJoin && !ExprHasProperty(pTerm->p,EP_FromJoin) ){ - continue; - } - sqlite3ExprIfFalse(pParse, pTerm->p, cont, 1); - pTerm->p = 0; - } - brk = cont; - - /* For a LEFT OUTER JOIN, generate code that will record the fact that - ** at least one row of the right table has matched the left table. - */ - if( pLevel->iLeftJoin ){ - pLevel->top = sqlite3VdbeCurrentAddr(v); - sqlite3VdbeAddOp(v, OP_Integer, 1, 0); - sqlite3VdbeAddOp(v, OP_MemStore, pLevel->iLeftJoin, 1); - VdbeComment((v, "# record LEFT JOIN hit")); - for(pTerm=aExpr, j=0; j<nExpr; j++, pTerm++){ - if( pTerm->p==0 ) continue; - if( (pTerm->prereqAll & loopMask)!=pTerm->prereqAll ) continue; - sqlite3ExprIfFalse(pParse, pTerm->p, cont, 1); - pTerm->p = 0; - } - } - } - pWInfo->iContinue = cont; - freeMaskSet(&maskSet); - return pWInfo; -} - -/* -** 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; - struct SrcList_item *pTabItem; - - /* 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->inOp!=OP_Noop ){ - sqlite3VdbeAddOp(v, pLevel->inOp, pLevel->inP1, pLevel->inP2); - } - if( pLevel->iLeftJoin ){ - int addr; - addr = sqlite3VdbeAddOp(v, OP_MemLoad, pLevel->iLeftJoin, 0); - sqlite3VdbeAddOp(v, OP_NotNull, 1, addr+4 + (pLevel->iIdxCur>=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); - } - } - - /* 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 opend by sqlite3WhereBegin. - */ - pLevel = pWInfo->a; - pTabItem = pTabList->a; - for(i=0; i<pTabList->nSrc; i++, pTabItem++, pLevel++){ - Table *pTab = pTabItem->pTab; - assert( pTab!=0 ); - if( pTab->isTransient || pTab->pSelect ) continue; - if( (pLevel->score & 1)==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->score & 1 ){ - 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; -} |