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+/*
+** 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 tqfind forgiveness for yourself and forgive others.
+** May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This module tqcontains C code that generates VDBE code used to process
+** the WHERE clause of SQL statements.
+**
+** $Id: where.c,v 1.89 2004/02/22 20:05:02 drh Exp $
+*/
+#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.
+*/
+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 */
+ unsigned prereqLeft; /* Bittqmask of tables referenced by p->pLeft */
+ unsigned prereqRight; /* Bittqmask of tables referenced by p->pRight */
+ unsigned prereqAll; /* Bittqmask of tables referenced by p */
+};
+
+/*
+** An instance of the following structure keeps track of a mapping
+** between VDBE cursor numbers and bitmasks. The VDBE cursor numbers
+** are small integers contained in SrcList_item.iCursor and Expr.iTable
+** fields. For any given WHERE clause, we want to track which cursors
+** are being used, so we assign a single bit in a 32-bit word to track
+** that cursor. Then a 32-bit integer is able to show the set of all
+** cursors being used.
+*/
+typedef struct ExprMaskSet ExprMaskSet;
+struct ExprMaskSet {
+ int n; /* Number of assigned cursor values */
+ int ix[32]; /* Cursor assigned to each bit */
+};
+
+/*
+** Determine the number of elements in an array.
+*/
+#define ARRAYSIZE(X) (sizeof(X)/sizeof(X[0]))
+
+/*
+** This routine is used to divide the WHERE expression into subexpressions
+** separated by the AND operator.
+**
+** aSlot[] is an array of subexpressions structures.
+** There are nSlot spaces left in this array. This routine attempts to
+** split pExpr into subexpressions and fills aSlot[] with those subexpressions.
+** The return value is the number of Q_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 tqmask set
+*/
+#define initMaskSet(P) memset(P, 0, sizeof(*P))
+
+/*
+** Return the bittqmask for the given cursor. Assign a new bittqmask
+** if this is the first time the cursor has been seen.
+*/
+static int getMask(ExprMaskSet *pMaskSet, int iCursor){
+ int i;
+ for(i=0; i<pMaskSet->n; i++){
+ if( pMaskSet->ix[i]==iCursor ) return 1<<i;
+ }
+ if( i==pMaskSet->n && i<ARRAYSIZE(pMaskSet->ix) ){
+ pMaskSet->n++;
+ pMaskSet->ix[i] = iCursor;
+ return 1<<i;
+ }
+ return 0;
+}
+
+/*
+** Destroy an expression tqmask set
+*/
+#define freeMaskSet(P) /* NO-OP */
+
+/*
+** This routine walks (recursively) an expression tree and generates
+** a bittqmask indicating which tables are used in that expression
+** tree.
+**
+** In order for this routine to work, the calling function must have
+** previously invoked sqliteExprResolveIds() on the expression. See
+** the header comment on that routine for additional information.
+** The sqliteExprResolveIds() 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 int exprTableUsage(ExprMaskSet *pMaskSet, Expr *p){
+ unsigned int tqmask = 0;
+ if( p==0 ) return 0;
+ if( p->op==TK_COLUMN ){
+ return getMask(pMaskSet, p->iTable);
+ }
+ if( p->pRight ){
+ tqmask = exprTableUsage(pMaskSet, p->pRight);
+ }
+ if( p->pLeft ){
+ tqmask |= exprTableUsage(pMaskSet, p->pLeft);
+ }
+ if( p->pList ){
+ int i;
+ for(i=0; i<p->pList->nExpr; i++){
+ tqmask |= exprTableUsage(pMaskSet, p->pList->a[i].pExpr);
+ }
+ }
+ return tqmask;
+}
+
+/*
+** Return TRUE if the given operator is one of the operators that is
+** allowed for an indexable WHERE clause. The allowed operators are
+** "=", "<", ">", "<=", ">=", and "IN".
+*/
+static int allowedOp(int op){
+ switch( op ){
+ case TK_LT:
+ case TK_LE:
+ case TK_GT:
+ case TK_GE:
+ case TK_EQ:
+ case TK_IN:
+ return 1;
+ default:
+ return 0;
+ }
+}
+
+/*
+** 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(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;
+ }
+ }
+}
+
+/*
+** 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".
+**
+** This routine attempts to tqfind an index for pTab that generates the
+** correct record sequence for the given ORDER BY clause. The return value
+** is a pointer to an index that does the job. NULL is returned if the
+** table has no index that will generate the correct sort order.
+**
+** If there are two or more indices that generate the correct sort order
+** and pPreferredIdx is one of those indices, then return pPreferredIdx.
+**
+** nEqCol is the number of columns of pPreferredIdx that are used as
+** equality constraints. Any index returned must have exactly this same
+** set of columns. The ORDER BY clause only matches index columns beyond the
+** the first nEqCol columns.
+**
+** All terms of the ORDER BY clause must be either ASC or DESC. 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 Index *tqfindSortingIndex(
+ Table *pTab, /* The table to be sorted */
+ int base, /* Cursor number for pTab */
+ ExprList *pOrderBy, /* The ORDER BY clause */
+ Index *pPreferredIdx, /* Use this index, if possible and not NULL */
+ int nEqCol, /* Number of index columns used with == constraints */
+ int *pbRev /* Set to 1 if ORDER BY is DESC */
+){
+ int i, j;
+ Index *pMatch;
+ Index *pIdx;
+ int sortOrder;
+
+ assert( pOrderBy!=0 );
+ assert( pOrderBy->nExpr>0 );
+ sortOrder = pOrderBy->a[0].sortOrder & STQLITE_SO_DIRMASK;
+ for(i=0; i<pOrderBy->nExpr; i++){
+ Expr *p;
+ if( (pOrderBy->a[i].sortOrder & STQLITE_SO_DIRMASK)!=sortOrder ){
+ /* Indices can only be used if all ORDER BY terms are either
+ ** DESC or ASC. Indices cannot be used on a mixture. */
+ return 0;
+ }
+ if( (pOrderBy->a[i].sortOrder & STQLITE_SO_TYPEMASK)!=STQLITE_SO_UNK ){
+ /* Do not sort by index if there is a COLLATE clause */
+ return 0;
+ }
+ p = pOrderBy->a[i].pExpr;
+ if( p->op!=TK_COLUMN || p->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;
+ }
+ }
+
+ /* If we get this far, it means the ORDER BY clause consists only of
+ ** ascending columns in the left-most table of the FROM clause. Now
+ ** check for a matching index.
+ */
+ pMatch = 0;
+ for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
+ int nExpr = pOrderBy->nExpr;
+ if( pIdx->nColumn < nEqCol || pIdx->nColumn < nExpr ) continue;
+ for(i=j=0; i<nEqCol; i++){
+ if( pPreferredIdx->aiColumn[i]!=pIdx->aiColumn[i] ) break;
+ if( j<nExpr && pOrderBy->a[j].pExpr->iColumn==pIdx->aiColumn[i] ){ j++; }
+ }
+ if( i<nEqCol ) continue;
+ for(i=0; i+j<nExpr; i++){
+ if( pOrderBy->a[i+j].pExpr->iColumn!=pIdx->aiColumn[i+nEqCol] ) break;
+ }
+ if( i+j>=nExpr ){
+ pMatch = pIdx;
+ if( pIdx==pPreferredIdx ) break;
+ }
+ }
+ if( pMatch && pbRev ){
+ *pbRev = sortOrder==STQLITE_SO_DESC;
+ }
+ return pMatch;
+}
+
+/*
+** Generate the beginning of the loop used for WHERE clause processing.
+** The return value is a pointer to an (opaque) structure that tqcontains
+** information needed to terminate the loop. Later, the calling routine
+** should invoke sqliteWhereEnd() with the return value of this function
+** in order to complete the WHERE clause processing.
+**
+** If an error occurs, this routine returns NULL.
+**
+** The basic idea is to do a nested loop, one loop for each table in
+** the FROM clause of a select. (INSERT and UPDATE statements are the
+** same as a SELECT with only a single table in the FROM clause.) For
+** example, if the SQL is this:
+**
+** SELECT * FROM t1, t2, t3 WHERE ...;
+**
+** Then the code generated is conceptually like the following:
+**
+** foreach row1 in t1 do \ Code generated
+** foreach row2 in t2 do |-- by sqliteWhereBegin()
+** foreach row3 in t3 do /
+** ...
+** end \ Code generated
+** end |-- by sqliteWhereEnd()
+** end /
+**
+** There are Btree cursors associated with each table. t1 uses cursor
+** number pTabList->a[0].iCursor. t2 uses the cursor pTabList->a[1].iCursor.
+** And so forth. This routine generates code to open those VDBE cursors
+** and sqliteWhereEnd() generates the code to close them.
+**
+** If the WHERE clause is empty, the foreach loops must each scan their
+** entire tables. Thus a three-way join is an O(N^3) operation. But if
+** the tables have indices and there are terms in the WHERE clause that
+** refer to those indices, a complete table scan can be avoided and the
+** code will run much faster. Most of the work of this routine is checking
+** to see if there are indices that can be used to speed up the loop.
+**
+** Terms of the WHERE clause are also used to limit which rows actually
+** make it to the "..." in the middle of the loop. After each "foreach",
+** terms of the WHERE clause that use only terms in that loop and outer
+** loops are evaluated and if false a jump is made around all subsequent
+** inner loops (or around the "..." if the test occurs within the inner-
+** most loop)
+**
+** OUTER JOINS
+**
+** An outer join of tables t1 and t2 is conceptally coded as follows:
+**
+** foreach row1 in t1 do
+** flag = 0
+** foreach row2 in t2 do
+** start:
+** ...
+** flag = 1
+** end
+** if flag==0 then
+** move the row2 cursor to a null row
+** goto start
+** fi
+** end
+**
+** ORDER BY CLAUSE PROCESSING
+**
+** *ppOrderBy is a pointer to the ORDER BY clause of a SELECT statement,
+** if there is one. If there is no ORDER BY clause or if this routine
+** is called from an UPDATE or DELETE statement, then ppOrderBy is NULL.
+**
+** If an index can be used so that the natural output order of the table
+** scan is correct for the ORDER BY clause, then that index is used and
+** *ppOrderBy is set to NULL. This is an optimization that prevents an
+** unnecessary sort of the result set if an index appropriate for the
+** ORDER BY clause already exists.
+**
+** If the where clause loops cannot be arranged to provide the correct
+** output order, then the *ppOrderBy is unchanged.
+*/
+WhereInfo *sqliteWhereBegin(
+ Parse *pParse, /* The parser context */
+ SrcList *pTabList, /* A list of all tables to be scanned */
+ Expr *pWhere, /* The WHERE clause */
+ int pushKey, /* If TRUE, leave the table key on the stack */
+ ExprList **ppOrderBy /* An ORDER BY clause, or NULL */
+){
+ int i; /* Loop counter */
+ WhereInfo *pWInfo; /* Will become the return value of this function */
+ Vdbe *v = pParse->pVdbe; /* The virtual database engine */
+ int brk, cont = 0; /* Addresses used during code generation */
+ int nExpr; /* Number of subexpressions in the WHERE clause */
+ int loopMask; /* One bit set for each outer loop */
+ int haveKey; /* True if KEY is on the stack */
+ ExprMaskSet maskSet; /* The expression tqmask set */
+ int iDirectEq[32]; /* Term of the form ROWID==X for the N-th table */
+ int iDirectLt[32]; /* Term of the form ROWID<X or ROWID<=X */
+ int iDirectGt[32]; /* Term of the form ROWID>X or ROWID>=X */
+ ExprInfo aExpr[101]; /* The WHERE clause is divided into these expressions */
+
+ /* pushKey is only allowed if there is a single table (as in an INSERT or
+ ** UPDATE statement)
+ */
+ assert( pushKey==0 || pTabList->nSrc==1 );
+
+ /* Split the WHERE clause into separate subexpressions where each
+ ** subexpression is separated by an AND operator. If the aExpr[]
+ ** array fills up, the last entry might point to an expression which
+ ** tqcontains additional unfactored AND operators.
+ */
+ initMaskSet(&maskSet);
+ memset(aExpr, 0, sizeof(aExpr));
+ nExpr = exprSplit(ARRAYSIZE(aExpr), aExpr, pWhere);
+ if( nExpr==ARRAYSIZE(aExpr) ){
+ sqliteErrorMsg(pParse, "WHERE clause too complex - no more "
+ "than %d terms allowed", (int)ARRAYSIZE(aExpr)-1);
+ return 0;
+ }
+
+ /* Allocate and initialize the WhereInfo structure that will become the
+ ** return value.
+ */
+ pWInfo = sqliteMalloc( sizeof(WhereInfo) + pTabList->nSrc*sizeof(WhereLevel));
+ if( sqlite_malloc_failed ){
+ sqliteFree(pWInfo);
+ return 0;
+ }
+ pWInfo->pParse = pParse;
+ pWInfo->pTabList = pTabList;
+ pWInfo->peakNTab = pWInfo->savedNTab = pParse->nTab;
+ pWInfo->iBreak = sqliteVdbeMakeLabel(v);
+
+ /* Special case: a WHERE clause that is constant. Evaluate the
+ ** expression and either jump over all of the code or fall thru.
+ */
+ if( pWhere && (pTabList->nSrc==0 || sqliteExprIsConstant(pWhere)) ){
+ sqliteExprIfFalse(pParse, pWhere, pWInfo->iBreak, 1);
+ pWhere = 0;
+ }
+
+ /* Analyze all of the subexpressions.
+ */
+ for(i=0; i<nExpr; i++){
+ exprAnalyze(&maskSet, &aExpr[i]);
+
+ /* If we are executing a trigger body, remove all references to
+ ** new.* and old.* tables from the prerequisite masks.
+ */
+ if( pParse->trigStack ){
+ int x;
+ if( (x = pParse->trigStack->newIdx) >= 0 ){
+ int tqmask = ~getMask(&maskSet, x);
+ aExpr[i].prereqRight &= tqmask;
+ aExpr[i].prereqLeft &= tqmask;
+ aExpr[i].prereqAll &= tqmask;
+ }
+ if( (x = pParse->trigStack->oldIdx) >= 0 ){
+ int tqmask = ~getMask(&maskSet, x);
+ aExpr[i].prereqRight &= tqmask;
+ aExpr[i].prereqLeft &= tqmask;
+ aExpr[i].prereqAll &= tqmask;
+ }
+ }
+ }
+
+ /* 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 bittqmask.
+ */
+ loopMask = 0;
+ for(i=0; i<pTabList->nSrc && i<ARRAYSIZE(iDirectEq); i++){
+ int j;
+ int iCur = pTabList->a[i].iCursor; /* The cursor for this table */
+ int tqmask = getMask(&maskSet, iCur); /* Cursor tqmask for this table */
+ Table *pTab = pTabList->a[i].pTab;
+ Index *pIdx;
+ Index *pBestIdx = 0;
+ int bestScore = 0;
+
+ /* Check to see if there is an expression that uses only the
+ ** ROWID field of this table. For terms of the form ROWID==expr
+ ** set iDirectEq[i] to the index of the term. For terms of the
+ ** form ROWID<expr or ROWID<=expr set iDirectLt[i] to the term index.
+ ** For terms like ROWID>expr or ROWID>=expr set iDirectGt[i].
+ **
+ ** (Added:) Treat ROWID IN expr like ROWID=expr.
+ */
+ pWInfo->a[i].iCur = -1;
+ iDirectEq[i] = -1;
+ iDirectLt[i] = -1;
+ iDirectGt[i] = -1;
+ for(j=0; j<nExpr; j++){
+ if( aExpr[j].idxLeft==iCur && aExpr[j].p->pLeft->iColumn<0
+ && (aExpr[j].prereqRight & loopMask)==aExpr[j].prereqRight ){
+ switch( aExpr[j].p->op ){
+ case TK_IN:
+ case TK_EQ: iDirectEq[i] = j; break;
+ case TK_LE:
+ case TK_LT: iDirectLt[i] = j; break;
+ case TK_GE:
+ case TK_GT: iDirectGt[i] = j; break;
+ }
+ }
+ if( aExpr[j].idxRight==iCur && aExpr[j].p->pRight->iColumn<0
+ && (aExpr[j].prereqLeft & loopMask)==aExpr[j].prereqLeft ){
+ switch( aExpr[j].p->op ){
+ case TK_EQ: iDirectEq[i] = j; break;
+ case TK_LE:
+ case TK_LT: iDirectGt[i] = j; break;
+ case TK_GE:
+ case TK_GT: iDirectLt[i] = j; break;
+ }
+ }
+ }
+ if( iDirectEq[i]>=0 ){
+ loopMask |= tqmask;
+ pWInfo->a[i].pIdx = 0;
+ continue;
+ }
+
+ /* Do a search for usable indices. Leave pBestIdx pointing to
+ ** the "best" index. pBestIdx is left set to NULL if no indices
+ ** are usable.
+ **
+ ** The best index is determined as follows. For each of the
+ ** left-most terms that is fixed by an equality operator, add
+ ** 8 to the score. The right-most term of the index may be
+ ** constrained by an inequality. Add 1 if for an "x<..." constraint
+ ** and add 2 for an "x>..." constraint. Chose the index that
+ ** gives the best score.
+ **
+ ** This scoring system is designed so that the score can later be
+ ** used to determine how the index is used. If the score&7 is 0
+ ** then all constraints are equalities. If score&1 is not 0 then
+ ** there is an inequality used as a termination key. (ex: "x<...")
+ ** If score&2 is not 0 then there is an inequality used as the
+ ** start key. (ex: "x>..."). A score or 4 is the special case
+ ** of an IN operator constraint. (ex: "x IN ...").
+ **
+ ** The IN operator (as in "<expr> IN (...)") is treated the same as
+ ** an equality comparison except that it can only be used on the
+ ** left-most column of an index and other terms of the WHERE clause
+ ** cannot be used in conjunction with the IN operator to help satisfy
+ ** other columns of the index.
+ */
+ for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
+ int eqMask = 0; /* Index columns covered by an x=... term */
+ int ltMask = 0; /* Index columns covered by an x<... term */
+ int gtMask = 0; /* Index columns covered by an x>... term */
+ int inMask = 0; /* Index columns covered by an x IN .. term */
+ int nEq, m, score;
+
+ if( pIdx->nColumn>32 ) continue; /* Ignore indices too many columns */
+ for(j=0; j<nExpr; j++){
+ if( aExpr[j].idxLeft==iCur
+ && (aExpr[j].prereqRight & loopMask)==aExpr[j].prereqRight ){
+ int iColumn = aExpr[j].p->pLeft->iColumn;
+ int k;
+ for(k=0; k<pIdx->nColumn; k++){
+ if( pIdx->aiColumn[k]==iColumn ){
+ switch( aExpr[j].p->op ){
+ case TK_IN: {
+ if( k==0 ) inMask |= 1;
+ break;
+ }
+ case TK_EQ: {
+ eqMask |= 1<<k;
+ break;
+ }
+ case TK_LE:
+ case TK_LT: {
+ ltMask |= 1<<k;
+ break;
+ }
+ case TK_GE:
+ case TK_GT: {
+ gtMask |= 1<<k;
+ break;
+ }
+ default: {
+ /* CANT_HAPPEN */
+ assert( 0 );
+ break;
+ }
+ }
+ break;
+ }
+ }
+ }
+ if( aExpr[j].idxRight==iCur
+ && (aExpr[j].prereqLeft & loopMask)==aExpr[j].prereqLeft ){
+ int iColumn = aExpr[j].p->pRight->iColumn;
+ int k;
+ for(k=0; k<pIdx->nColumn; k++){
+ if( pIdx->aiColumn[k]==iColumn ){
+ switch( aExpr[j].p->op ){
+ case TK_EQ: {
+ eqMask |= 1<<k;
+ break;
+ }
+ case TK_LE:
+ case TK_LT: {
+ gtMask |= 1<<k;
+ break;
+ }
+ case TK_GE:
+ case TK_GT: {
+ ltMask |= 1<<k;
+ break;
+ }
+ default: {
+ /* CANT_HAPPEN */
+ assert( 0 );
+ break;
+ }
+ }
+ break;
+ }
+ }
+ }
+ }
+
+ /* The following loop ends with nEq set to the number of columns
+ ** on the left of the index with == constraints.
+ */
+ for(nEq=0; nEq<pIdx->nColumn; nEq++){
+ m = (1<<(nEq+1))-1;
+ if( (m & eqMask)!=m ) break;
+ }
+ score = nEq*8; /* Base score is 8 times number of == constraints */
+ m = 1<<nEq;
+ if( m & ltMask ) score++; /* Increase score for a < constraint */
+ if( m & gtMask ) score+=2; /* Increase score for a > constraint */
+ if( score==0 && inMask ) score = 4; /* Default score for IN constraint */
+ if( score>bestScore ){
+ pBestIdx = pIdx;
+ bestScore = score;
+ }
+ }
+ pWInfo->a[i].pIdx = pBestIdx;
+ pWInfo->a[i].score = bestScore;
+ pWInfo->a[i].bRev = 0;
+ loopMask |= tqmask;
+ if( pBestIdx ){
+ pWInfo->a[i].iCur = pParse->nTab++;
+ pWInfo->peakNTab = pParse->nTab;
+ }
+ }
+
+ /* Check to see if the ORDER BY clause is or can be satisfied by the
+ ** use of an index on the first table.
+ */
+ if( ppOrderBy && *ppOrderBy && pTabList->nSrc>0 ){
+ Index *pSortIdx;
+ Index *pIdx;
+ Table *pTab;
+ int bRev = 0;
+
+ pTab = pTabList->a[0].pTab;
+ pIdx = pWInfo->a[0].pIdx;
+ if( pIdx && pWInfo->a[0].score==4 ){
+ /* If there is already an IN index on the left-most table,
+ ** it will not give the correct sort order.
+ ** So, pretend that no suitable index is found.
+ */
+ pSortIdx = 0;
+ }else if( iDirectEq[0]>=0 || iDirectLt[0]>=0 || iDirectGt[0]>=0 ){
+ /* If the left-most column is accessed using its ROWID, then do
+ ** not try to sort by index.
+ */
+ pSortIdx = 0;
+ }else{
+ int nEqCol = (pWInfo->a[0].score+4)/8;
+ pSortIdx = tqfindSortingIndex(pTab, pTabList->a[0].iCursor,
+ *ppOrderBy, pIdx, nEqCol, &bRev);
+ }
+ if( pSortIdx && (pIdx==0 || pIdx==pSortIdx) ){
+ if( pIdx==0 ){
+ pWInfo->a[0].pIdx = pSortIdx;
+ pWInfo->a[0].iCur = pParse->nTab++;
+ pWInfo->peakNTab = pParse->nTab;
+ }
+ pWInfo->a[0].bRev = bRev;
+ *ppOrderBy = 0;
+ }
+ }
+
+ /* Open all tables in the pTabList and all indices used by those tables.
+ */
+ for(i=0; i<pTabList->nSrc; i++){
+ Table *pTab;
+ Index *pIx;
+
+ pTab = pTabList->a[i].pTab;
+ if( pTab->isTransient || pTab->pSelect ) continue;
+ sqliteVdbeAddOp(v, OP_Integer, pTab->iDb, 0);
+ sqliteVdbeOp3(v, OP_OpenRead, pTabList->a[i].iCursor, pTab->tnum,
+ pTab->zName, P3_STATIC);
+ sqliteCodeVerifySchema(pParse, pTab->iDb);
+ if( (pIx = pWInfo->a[i].pIdx)!=0 ){
+ sqliteVdbeAddOp(v, OP_Integer, pIx->iDb, 0);
+ sqliteVdbeOp3(v, OP_OpenRead, pWInfo->a[i].iCur, pIx->tnum, pIx->zName,0);
+ }
+ }
+
+ /* Generate the code to do the search
+ */
+ loopMask = 0;
+ for(i=0; i<pTabList->nSrc; i++){
+ int j, k;
+ int iCur = pTabList->a[i].iCursor;
+ Index *pIdx;
+ WhereLevel *pLevel = &pWInfo->a[i];
+
+ /* If this is the right table of a LEFT OUTER JOIN, allocate and
+ ** initialize a memory cell that records if this table matches any
+ ** row of the left table of the join.
+ */
+ if( i>0 && (pTabList->a[i-1].jointype & JT_LEFT)!=0 ){
+ if( !pParse->nMem ) pParse->nMem++;
+ pLevel->iLeftJoin = pParse->nMem++;
+ sqliteVdbeAddOp(v, OP_String, 0, 0);
+ sqliteVdbeAddOp(v, OP_MemStore, pLevel->iLeftJoin, 1);
+ }
+
+ pIdx = pLevel->pIdx;
+ pLevel->inOp = OP_Noop;
+ if( i<ARRAYSIZE(iDirectEq) && iDirectEq[i]>=0 ){
+ /* Case 1: We can directly reference a single row using an
+ ** equality comparison against the ROWID field. Or
+ ** we reference multiple rows using a "rowid IN (...)"
+ ** construct.
+ */
+ k = iDirectEq[i];
+ assert( k<nExpr );
+ assert( aExpr[k].p!=0 );
+ assert( aExpr[k].idxLeft==iCur || aExpr[k].idxRight==iCur );
+ brk = pLevel->brk = sqliteVdbeMakeLabel(v);
+ if( aExpr[k].idxLeft==iCur ){
+ Expr *pX = aExpr[k].p;
+ if( pX->op!=TK_IN ){
+ sqliteExprCode(pParse, aExpr[k].p->pRight);
+ }else if( pX->pList ){
+ sqliteVdbeAddOp(v, OP_SetFirst, pX->iTable, brk);
+ pLevel->inOp = OP_SetNext;
+ pLevel->inP1 = pX->iTable;
+ pLevel->inP2 = sqliteVdbeCurrentAddr(v);
+ }else{
+ assert( pX->pSelect );
+ sqliteVdbeAddOp(v, OP_Rewind, pX->iTable, brk);
+ sqliteVdbeAddOp(v, OP_KeyAsData, pX->iTable, 1);
+ pLevel->inP2 = sqliteVdbeAddOp(v, OP_FullKey, pX->iTable, 0);
+ pLevel->inOp = OP_Next;
+ pLevel->inP1 = pX->iTable;
+ }
+ }else{
+ sqliteExprCode(pParse, aExpr[k].p->pLeft);
+ }
+ aExpr[k].p = 0;
+ cont = pLevel->cont = sqliteVdbeMakeLabel(v);
+ sqliteVdbeAddOp(v, OP_MustBeInt, 1, brk);
+ haveKey = 0;
+ sqliteVdbeAddOp(v, OP_NotExists, iCur, brk);
+ pLevel->op = OP_Noop;
+ }else if( pIdx!=0 && pLevel->score>0 && pLevel->score%4==0 ){
+ /* Case 2: There is an index and all terms of the WHERE clause that
+ ** refer to the index use the "==" or "IN" operators.
+ */
+ int start;
+ int testOp;
+ int nColumn = (pLevel->score+4)/8;
+ brk = pLevel->brk = sqliteVdbeMakeLabel(v);
+ for(j=0; j<nColumn; j++){
+ for(k=0; k<nExpr; k++){
+ Expr *pX = aExpr[k].p;
+ if( pX==0 ) continue;
+ if( aExpr[k].idxLeft==iCur
+ && (aExpr[k].prereqRight & loopMask)==aExpr[k].prereqRight
+ && pX->pLeft->iColumn==pIdx->aiColumn[j]
+ ){
+ if( pX->op==TK_EQ ){
+ sqliteExprCode(pParse, pX->pRight);
+ aExpr[k].p = 0;
+ break;
+ }
+ if( pX->op==TK_IN && nColumn==1 ){
+ if( pX->pList ){
+ sqliteVdbeAddOp(v, OP_SetFirst, pX->iTable, brk);
+ pLevel->inOp = OP_SetNext;
+ pLevel->inP1 = pX->iTable;
+ pLevel->inP2 = sqliteVdbeCurrentAddr(v);
+ }else{
+ assert( pX->pSelect );
+ sqliteVdbeAddOp(v, OP_Rewind, pX->iTable, brk);
+ sqliteVdbeAddOp(v, OP_KeyAsData, pX->iTable, 1);
+ pLevel->inP2 = sqliteVdbeAddOp(v, OP_FullKey, pX->iTable, 0);
+ pLevel->inOp = OP_Next;
+ pLevel->inP1 = pX->iTable;
+ }
+ aExpr[k].p = 0;
+ break;
+ }
+ }
+ if( aExpr[k].idxRight==iCur
+ && aExpr[k].p->op==TK_EQ
+ && (aExpr[k].prereqLeft & loopMask)==aExpr[k].prereqLeft
+ && aExpr[k].p->pRight->iColumn==pIdx->aiColumn[j]
+ ){
+ sqliteExprCode(pParse, aExpr[k].p->pLeft);
+ aExpr[k].p = 0;
+ break;
+ }
+ }
+ }
+ pLevel->iMem = pParse->nMem++;
+ cont = pLevel->cont = sqliteVdbeMakeLabel(v);
+ sqliteVdbeAddOp(v, OP_NotNull, -nColumn, sqliteVdbeCurrentAddr(v)+3);
+ sqliteVdbeAddOp(v, OP_Pop, nColumn, 0);
+ sqliteVdbeAddOp(v, OP_Goto, 0, brk);
+ sqliteVdbeAddOp(v, OP_MakeKey, nColumn, 0);
+ sqliteAddIdxKeyType(v, pIdx);
+ if( nColumn==pIdx->nColumn || pLevel->bRev ){
+ sqliteVdbeAddOp(v, OP_MemStore, pLevel->iMem, 0);
+ testOp = OP_IdxGT;
+ }else{
+ sqliteVdbeAddOp(v, OP_Dup, 0, 0);
+ sqliteVdbeAddOp(v, OP_IncrKey, 0, 0);
+ sqliteVdbeAddOp(v, OP_MemStore, pLevel->iMem, 1);
+ testOp = OP_IdxGE;
+ }
+ if( pLevel->bRev ){
+ /* Scan in reverse order */
+ sqliteVdbeAddOp(v, OP_IncrKey, 0, 0);
+ sqliteVdbeAddOp(v, OP_MoveLt, pLevel->iCur, brk);
+ start = sqliteVdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0);
+ sqliteVdbeAddOp(v, OP_IdxLT, pLevel->iCur, brk);
+ pLevel->op = OP_Prev;
+ }else{
+ /* Scan in the forward order */
+ sqliteVdbeAddOp(v, OP_MoveTo, pLevel->iCur, brk);
+ start = sqliteVdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0);
+ sqliteVdbeAddOp(v, testOp, pLevel->iCur, brk);
+ pLevel->op = OP_Next;
+ }
+ sqliteVdbeAddOp(v, OP_RowKey, pLevel->iCur, 0);
+ sqliteVdbeAddOp(v, OP_IdxIsNull, nColumn, cont);
+ sqliteVdbeAddOp(v, OP_IdxRecno, pLevel->iCur, 0);
+ if( i==pTabList->nSrc-1 && pushKey ){
+ haveKey = 1;
+ }else{
+ sqliteVdbeAddOp(v, OP_MoveTo, iCur, 0);
+ haveKey = 0;
+ }
+ pLevel->p1 = pLevel->iCur;
+ pLevel->p2 = start;
+ }else if( i<ARRAYSIZE(iDirectLt) && (iDirectLt[i]>=0 || iDirectGt[i]>=0) ){
+ /* Case 3: We have an inequality comparison against the ROWID field.
+ */
+ int testOp = OP_Noop;
+ int start;
+
+ brk = pLevel->brk = sqliteVdbeMakeLabel(v);
+ cont = pLevel->cont = sqliteVdbeMakeLabel(v);
+ if( iDirectGt[i]>=0 ){
+ k = iDirectGt[i];
+ assert( k<nExpr );
+ assert( aExpr[k].p!=0 );
+ assert( aExpr[k].idxLeft==iCur || aExpr[k].idxRight==iCur );
+ if( aExpr[k].idxLeft==iCur ){
+ sqliteExprCode(pParse, aExpr[k].p->pRight);
+ }else{
+ sqliteExprCode(pParse, aExpr[k].p->pLeft);
+ }
+ sqliteVdbeAddOp(v, OP_ForceInt,
+ aExpr[k].p->op==TK_LT || aExpr[k].p->op==TK_GT, brk);
+ sqliteVdbeAddOp(v, OP_MoveTo, iCur, brk);
+ aExpr[k].p = 0;
+ }else{
+ sqliteVdbeAddOp(v, OP_Rewind, iCur, brk);
+ }
+ if( iDirectLt[i]>=0 ){
+ k = iDirectLt[i];
+ assert( k<nExpr );
+ assert( aExpr[k].p!=0 );
+ assert( aExpr[k].idxLeft==iCur || aExpr[k].idxRight==iCur );
+ if( aExpr[k].idxLeft==iCur ){
+ sqliteExprCode(pParse, aExpr[k].p->pRight);
+ }else{
+ sqliteExprCode(pParse, aExpr[k].p->pLeft);
+ }
+ /* sqliteVdbeAddOp(v, OP_MustBeInt, 0, sqliteVdbeCurrentAddr(v)+1); */
+ pLevel->iMem = pParse->nMem++;
+ sqliteVdbeAddOp(v, OP_MemStore, pLevel->iMem, 1);
+ if( aExpr[k].p->op==TK_LT || aExpr[k].p->op==TK_GT ){
+ testOp = OP_Ge;
+ }else{
+ testOp = OP_Gt;
+ }
+ aExpr[k].p = 0;
+ }
+ start = sqliteVdbeCurrentAddr(v);
+ pLevel->op = OP_Next;
+ pLevel->p1 = iCur;
+ pLevel->p2 = start;
+ if( testOp!=OP_Noop ){
+ sqliteVdbeAddOp(v, OP_Recno, iCur, 0);
+ sqliteVdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0);
+ sqliteVdbeAddOp(v, testOp, 0, brk);
+ }
+ haveKey = 0;
+ }else if( pIdx==0 ){
+ /* Case 4: There is no usable index. We must do a complete
+ ** scan of the entire database table.
+ */
+ int start;
+
+ brk = pLevel->brk = sqliteVdbeMakeLabel(v);
+ cont = pLevel->cont = sqliteVdbeMakeLabel(v);
+ sqliteVdbeAddOp(v, OP_Rewind, iCur, brk);
+ start = sqliteVdbeCurrentAddr(v);
+ pLevel->op = OP_Next;
+ pLevel->p1 = iCur;
+ pLevel->p2 = start;
+ haveKey = 0;
+ }else{
+ /* Case 5: The WHERE clause term that refers to the right-most
+ ** column of the index is an inequality. For example, if
+ ** the index is on (x,y,z) and the WHERE clause is of the
+ ** form "x=5 AND y<10" then this case is used. Only the
+ ** right-most column can be an inequality - the rest must
+ ** use the "==" operator.
+ **
+ ** This case is also used when there are no WHERE clause
+ ** constraints but an index is selected anyway, in order
+ ** to force the output order to conform to an ORDER BY.
+ */
+ int score = pLevel->score;
+ int nEqColumn = score/8;
+ int start;
+ int leFlag, geFlag;
+ int testOp;
+
+ /* Evaluate the equality constraints
+ */
+ for(j=0; j<nEqColumn; j++){
+ for(k=0; k<nExpr; k++){
+ if( aExpr[k].p==0 ) continue;
+ if( aExpr[k].idxLeft==iCur
+ && aExpr[k].p->op==TK_EQ
+ && (aExpr[k].prereqRight & loopMask)==aExpr[k].prereqRight
+ && aExpr[k].p->pLeft->iColumn==pIdx->aiColumn[j]
+ ){
+ sqliteExprCode(pParse, aExpr[k].p->pRight);
+ aExpr[k].p = 0;
+ break;
+ }
+ if( aExpr[k].idxRight==iCur
+ && aExpr[k].p->op==TK_EQ
+ && (aExpr[k].prereqLeft & loopMask)==aExpr[k].prereqLeft
+ && aExpr[k].p->pRight->iColumn==pIdx->aiColumn[j]
+ ){
+ sqliteExprCode(pParse, aExpr[k].p->pLeft);
+ aExpr[k].p = 0;
+ break;
+ }
+ }
+ }
+
+ /* Duplicate the equality term values because they will all be
+ ** used twice: once to make the termination key and once to make the
+ ** start key.
+ */
+ for(j=0; j<nEqColumn; j++){
+ sqliteVdbeAddOp(v, OP_Dup, nEqColumn-1, 0);
+ }
+
+ /* Labels for the beginning and end of the loop
+ */
+ cont = pLevel->cont = sqliteVdbeMakeLabel(v);
+ brk = pLevel->brk = sqliteVdbeMakeLabel(v);
+
+ /* Generate the termination key. This is the key value that
+ ** will end the search. There is no termination key if there
+ ** are no equality terms and no "X<..." term.
+ **
+ ** 2002-Dec-04: On a reverse-order scan, the so-called "termination"
+ ** key computed here really ends up being the start key.
+ */
+ if( (score & 1)!=0 ){
+ for(k=0; k<nExpr; k++){
+ Expr *pExpr = aExpr[k].p;
+ if( pExpr==0 ) continue;
+ if( aExpr[k].idxLeft==iCur
+ && (pExpr->op==TK_LT || pExpr->op==TK_LE)
+ && (aExpr[k].prereqRight & loopMask)==aExpr[k].prereqRight
+ && pExpr->pLeft->iColumn==pIdx->aiColumn[j]
+ ){
+ sqliteExprCode(pParse, pExpr->pRight);
+ leFlag = pExpr->op==TK_LE;
+ aExpr[k].p = 0;
+ break;
+ }
+ if( aExpr[k].idxRight==iCur
+ && (pExpr->op==TK_GT || pExpr->op==TK_GE)
+ && (aExpr[k].prereqLeft & loopMask)==aExpr[k].prereqLeft
+ && pExpr->pRight->iColumn==pIdx->aiColumn[j]
+ ){
+ sqliteExprCode(pParse, pExpr->pLeft);
+ leFlag = pExpr->op==TK_GE;
+ aExpr[k].p = 0;
+ break;
+ }
+ }
+ testOp = OP_IdxGE;
+ }else{
+ testOp = nEqColumn>0 ? OP_IdxGE : OP_Noop;
+ leFlag = 1;
+ }
+ if( testOp!=OP_Noop ){
+ int nCol = nEqColumn + (score & 1);
+ pLevel->iMem = pParse->nMem++;
+ sqliteVdbeAddOp(v, OP_NotNull, -nCol, sqliteVdbeCurrentAddr(v)+3);
+ sqliteVdbeAddOp(v, OP_Pop, nCol, 0);
+ sqliteVdbeAddOp(v, OP_Goto, 0, brk);
+ sqliteVdbeAddOp(v, OP_MakeKey, nCol, 0);
+ sqliteAddIdxKeyType(v, pIdx);
+ if( leFlag ){
+ sqliteVdbeAddOp(v, OP_IncrKey, 0, 0);
+ }
+ if( pLevel->bRev ){
+ sqliteVdbeAddOp(v, OP_MoveLt, pLevel->iCur, brk);
+ }else{
+ sqliteVdbeAddOp(v, OP_MemStore, pLevel->iMem, 1);
+ }
+ }else if( pLevel->bRev ){
+ sqliteVdbeAddOp(v, OP_Last, pLevel->iCur, brk);
+ }
+
+ /* Generate the start key. This is the key that defines the lower
+ ** bound on the search. There is no start key if there are no
+ ** equality terms and if there is no "X>..." term. In
+ ** that case, generate a "Rewind" instruction in place of the
+ ** start key search.
+ **
+ ** 2002-Dec-04: In the case of a reverse-order search, the so-called
+ ** "start" key really ends up being used as the termination key.
+ */
+ if( (score & 2)!=0 ){
+ for(k=0; k<nExpr; k++){
+ Expr *pExpr = aExpr[k].p;
+ if( pExpr==0 ) continue;
+ if( aExpr[k].idxLeft==iCur
+ && (pExpr->op==TK_GT || pExpr->op==TK_GE)
+ && (aExpr[k].prereqRight & loopMask)==aExpr[k].prereqRight
+ && pExpr->pLeft->iColumn==pIdx->aiColumn[j]
+ ){
+ sqliteExprCode(pParse, pExpr->pRight);
+ geFlag = pExpr->op==TK_GE;
+ aExpr[k].p = 0;
+ break;
+ }
+ if( aExpr[k].idxRight==iCur
+ && (pExpr->op==TK_LT || pExpr->op==TK_LE)
+ && (aExpr[k].prereqLeft & loopMask)==aExpr[k].prereqLeft
+ && pExpr->pRight->iColumn==pIdx->aiColumn[j]
+ ){
+ sqliteExprCode(pParse, pExpr->pLeft);
+ geFlag = pExpr->op==TK_LE;
+ aExpr[k].p = 0;
+ break;
+ }
+ }
+ }else{
+ geFlag = 1;
+ }
+ if( nEqColumn>0 || (score&2)!=0 ){
+ int nCol = nEqColumn + ((score&2)!=0);
+ sqliteVdbeAddOp(v, OP_NotNull, -nCol, sqliteVdbeCurrentAddr(v)+3);
+ sqliteVdbeAddOp(v, OP_Pop, nCol, 0);
+ sqliteVdbeAddOp(v, OP_Goto, 0, brk);
+ sqliteVdbeAddOp(v, OP_MakeKey, nCol, 0);
+ sqliteAddIdxKeyType(v, pIdx);
+ if( !geFlag ){
+ sqliteVdbeAddOp(v, OP_IncrKey, 0, 0);
+ }
+ if( pLevel->bRev ){
+ pLevel->iMem = pParse->nMem++;
+ sqliteVdbeAddOp(v, OP_MemStore, pLevel->iMem, 1);
+ testOp = OP_IdxLT;
+ }else{
+ sqliteVdbeAddOp(v, OP_MoveTo, pLevel->iCur, brk);
+ }
+ }else if( pLevel->bRev ){
+ testOp = OP_Noop;
+ }else{
+ sqliteVdbeAddOp(v, OP_Rewind, pLevel->iCur, brk);
+ }
+
+ /* Generate the the top of the loop. If there is a termination
+ ** key we have to test for that key and abort at the top of the
+ ** loop.
+ */
+ start = sqliteVdbeCurrentAddr(v);
+ if( testOp!=OP_Noop ){
+ sqliteVdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0);
+ sqliteVdbeAddOp(v, testOp, pLevel->iCur, brk);
+ }
+ sqliteVdbeAddOp(v, OP_RowKey, pLevel->iCur, 0);
+ sqliteVdbeAddOp(v, OP_IdxIsNull, nEqColumn + (score & 1), cont);
+ sqliteVdbeAddOp(v, OP_IdxRecno, pLevel->iCur, 0);
+ if( i==pTabList->nSrc-1 && pushKey ){
+ haveKey = 1;
+ }else{
+ sqliteVdbeAddOp(v, OP_MoveTo, iCur, 0);
+ haveKey = 0;
+ }
+
+ /* Record the instruction used to terminate the loop.
+ */
+ pLevel->op = pLevel->bRev ? OP_Prev : OP_Next;
+ pLevel->p1 = pLevel->iCur;
+ pLevel->p2 = start;
+ }
+ loopMask |= getMask(&maskSet, iCur);
+
+ /* Insert code to test every subexpression that can be completely
+ ** computed using the current set of tables.
+ */
+ for(j=0; j<nExpr; j++){
+ if( aExpr[j].p==0 ) continue;
+ if( (aExpr[j].prereqAll & loopMask)!=aExpr[j].prereqAll ) continue;
+ if( pLevel->iLeftJoin && !ExprHasProperty(aExpr[j].p,EP_FromJoin) ){
+ continue;
+ }
+ if( haveKey ){
+ haveKey = 0;
+ sqliteVdbeAddOp(v, OP_MoveTo, iCur, 0);
+ }
+ sqliteExprIfFalse(pParse, aExpr[j].p, cont, 1);
+ aExpr[j].p = 0;
+ }
+ brk = cont;
+
+ /* For a LEFT OUTER JOIN, generate code that will record the fact that
+ ** at least one row of the right table has matched the left table.
+ */
+ if( pLevel->iLeftJoin ){
+ pLevel->top = sqliteVdbeCurrentAddr(v);
+ sqliteVdbeAddOp(v, OP_Integer, 1, 0);
+ sqliteVdbeAddOp(v, OP_MemStore, pLevel->iLeftJoin, 1);
+ for(j=0; j<nExpr; j++){
+ if( aExpr[j].p==0 ) continue;
+ if( (aExpr[j].prereqAll & loopMask)!=aExpr[j].prereqAll ) continue;
+ if( haveKey ){
+ /* Cannot happen. "haveKey" can only be true if pushKey is true
+ ** an pushKey can only be true for DELETE and UPDATE and there are
+ ** no outer joins with DELETE and UPDATE.
+ */
+ haveKey = 0;
+ sqliteVdbeAddOp(v, OP_MoveTo, iCur, 0);
+ }
+ sqliteExprIfFalse(pParse, aExpr[j].p, cont, 1);
+ aExpr[j].p = 0;
+ }
+ }
+ }
+ pWInfo->iContinue = cont;
+ if( pushKey && !haveKey ){
+ sqliteVdbeAddOp(v, OP_Recno, pTabList->a[0].iCursor, 0);
+ }
+ freeMaskSet(&maskSet);
+ return pWInfo;
+}
+
+/*
+** Generate the end of the WHERE loop. See comments on
+** sqliteWhereBegin() for additional information.
+*/
+void sqliteWhereEnd(WhereInfo *pWInfo){
+ Vdbe *v = pWInfo->pParse->pVdbe;
+ int i;
+ WhereLevel *pLevel;
+ SrcList *pTabList = pWInfo->pTabList;
+
+ for(i=pTabList->nSrc-1; i>=0; i--){
+ pLevel = &pWInfo->a[i];
+ sqliteVdbeResolveLabel(v, pLevel->cont);
+ if( pLevel->op!=OP_Noop ){
+ sqliteVdbeAddOp(v, pLevel->op, pLevel->p1, pLevel->p2);
+ }
+ sqliteVdbeResolveLabel(v, pLevel->brk);
+ if( pLevel->inOp!=OP_Noop ){
+ sqliteVdbeAddOp(v, pLevel->inOp, pLevel->inP1, pLevel->inP2);
+ }
+ if( pLevel->iLeftJoin ){
+ int addr;
+ addr = sqliteVdbeAddOp(v, OP_MemLoad, pLevel->iLeftJoin, 0);
+ sqliteVdbeAddOp(v, OP_NotNull, 1, addr+4 + (pLevel->iCur>=0));
+ sqliteVdbeAddOp(v, OP_NullRow, pTabList->a[i].iCursor, 0);
+ if( pLevel->iCur>=0 ){
+ sqliteVdbeAddOp(v, OP_NullRow, pLevel->iCur, 0);
+ }
+ sqliteVdbeAddOp(v, OP_Goto, 0, pLevel->top);
+ }
+ }
+ sqliteVdbeResolveLabel(v, pWInfo->iBreak);
+ for(i=0; i<pTabList->nSrc; i++){
+ Table *pTab = pTabList->a[i].pTab;
+ assert( pTab!=0 );
+ if( pTab->isTransient || pTab->pSelect ) continue;
+ pLevel = &pWInfo->a[i];
+ sqliteVdbeAddOp(v, OP_Close, pTabList->a[i].iCursor, 0);
+ if( pLevel->pIdx!=0 ){
+ sqliteVdbeAddOp(v, OP_Close, pLevel->iCur, 0);
+ }
+ }
+#if 0 /* Never reuse a cursor */
+ if( pWInfo->pParse->nTab==pWInfo->peakNTab ){
+ pWInfo->pParse->nTab = pWInfo->savedNTab;
+ }
+#endif
+ sqliteFree(pWInfo);
+ return;
+}