}
}
-#ifdef SQLITE_DEBUG
-/* Return true if the pSub ExprList is a subset of pMain. The terms
-** of pSub can be in a different order from pMain. The only requirement
-** is that every term in pSub must exist somewhere in pMain.
+
+/*
+** pX is an expression of the form: (vector) IN (SELECT ...)
+** In other words, it is a vector IN operator with a SELECT clause on the
+** LHS. But not all terms in the vector are indexable and the terms might
+** not be in the correct order for indexing.
+**
+** This routine makes a copy of the input pX expression and then adjusts
+** the vector on the LHS with corresponding changes to the SELECT so that
+** the vector contains only index terms and those terms are in the correct
+** order. The modified IN expression is returned. The caller is responsible
+** for deleting the returned expression.
+**
+** Example:
+**
+** CREATE TABLE t1(a,b,c,d,e,f);
+** CREATE INDEX t1x1 ON t1(e,c);
+** SELECT * FROM t1 WHERE (a,b,c,d,e) IN (SELECT v,w,x,y,z FROM t2)
+** \_______________________________________/
+** The pX expression
+**
+** Since only columns e and c can be used with the index, in that order,
+** the modified IN expression that is returned will be:
+**
+** (e,c) IN (SELECT z,x FROM t2)
**
-** Return false if pSub contains any term that is not found in pMain.
+** The reduced pX is different from the original (obviously) and thus is
+** only used for indexing, to improve performance. The original unaltered
+** IN expression must also be run on each output row for correctness.
*/
-static int exprListSubset(ExprList *pSub, ExprList *pMain){
- int i, j;
- for(i=0; i<pSub->nExpr; i++){
- Expr *p = pSub->a[i].pExpr;
- for(j=0; j<pMain->nExpr; j++){
- if( sqlite3ExprCompare(0, p, pMain->a[j].pExpr, 0)==0 ) break;
+static Expr *removeUnindexableInClauseTerms(
+ Parse *pParse, /* The parsing context */
+ int iEq, /* Look at loop terms starting here */
+ WhereLoop *pLoop, /* The current loop */
+ Expr *pX /* The IN expression to be reduced */
+){
+ sqlite3 *db = pParse->db;
+ Expr *pNew = sqlite3ExprDup(db, pX, 0);
+ if( db->mallocFailed==0 ){
+ ExprList *pOrigRhs = pNew->x.pSelect->pEList; /* Original unmodified RHS */
+ ExprList *pOrigLhs = pNew->pLeft->x.pList; /* Original unmodified LHS */
+ ExprList *pRhs = 0; /* New RHS after modifications */
+ ExprList *pLhs = 0; /* New LHS after mods */
+ int i; /* Loop counter */
+ Select *pSelect; /* Pointer to the SELECT on the RHS */
+
+ for(i=iEq; i<pLoop->nLTerm; i++){
+ if( pLoop->aLTerm[i]->pExpr==pX ){
+ int iField = pLoop->aLTerm[i]->iField - 1;
+ assert( pOrigRhs->a[iField].pExpr!=0 );
+ pRhs = sqlite3ExprListAppend(pParse, pRhs, pOrigRhs->a[iField].pExpr);
+ pOrigRhs->a[iField].pExpr = 0;
+ assert( pOrigLhs->a[iField].pExpr!=0 );
+ pLhs = sqlite3ExprListAppend(pParse, pLhs, pOrigLhs->a[iField].pExpr);
+ pOrigLhs->a[iField].pExpr = 0;
+ }
+ }
+ sqlite3ExprListDelete(db, pOrigRhs);
+ sqlite3ExprListDelete(db, pOrigLhs);
+ pNew->pLeft->x.pList = pLhs;
+ pNew->x.pSelect->pEList = pRhs;
+ if( pLhs && pLhs->nExpr==1 ){
+ /* Take care here not to generate a TK_VECTOR containing only a
+ ** single value. Since the parser never creates such a vector, some
+ ** of the subroutines do not handle this case. */
+ Expr *p = pLhs->a[0].pExpr;
+ pLhs->a[0].pExpr = 0;
+ sqlite3ExprDelete(db, pNew->pLeft);
+ pNew->pLeft = p;
+ }
+ pSelect = pNew->x.pSelect;
+ if( pSelect->pOrderBy ){
+ /* If the SELECT statement has an ORDER BY clause, zero the
+ ** iOrderByCol variables. These are set to non-zero when an
+ ** ORDER BY term exactly matches one of the terms of the
+ ** result-set. Since the result-set of the SELECT statement may
+ ** have been modified or reordered, these variables are no longer
+ ** set correctly. Since setting them is just an optimization,
+ ** it's easiest just to zero them here. */
+ ExprList *pOrderBy = pSelect->pOrderBy;
+ for(i=0; i<pOrderBy->nExpr; i++){
+ pOrderBy->a[i].u.x.iOrderByCol = 0;
+ }
}
- if( j>=pMain->nExpr ) return 0;
+
+#if 0
+ printf("For indexing, change the IN expr:\n");
+ sqlite3TreeViewExpr(0, pX, 0);
+ printf("Into:\n");
+ sqlite3TreeViewExpr(0, pNew, 0);
+#endif
}
- return 1;
+ return pNew;
}
-#endif /* SQLITE_DEBUG */
/*
}
}
for(i=iEq;i<pLoop->nLTerm; i++){
- if( ALWAYS(pLoop->aLTerm[i]) && pLoop->aLTerm[i]->pExpr==pX ) nEq++;
+ assert( pLoop->aLTerm[i]!=0 );
+ if( pLoop->aLTerm[i]->pExpr==pX ) nEq++;
}
if( (pX->flags & EP_xIsSelect)==0 || pX->x.pSelect->pEList->nExpr==1 ){
eType = sqlite3FindInIndex(pParse, pX, IN_INDEX_LOOP, 0, 0);
}else{
- Select *pSelect = pX->x.pSelect;
sqlite3 *db = pParse->db;
- u16 savedDbOptFlags = db->dbOptFlags;
- ExprList *pOrigRhs = pSelect->pEList;
- ExprList *pOrigLhs = pX->pLeft->x.pList;
- ExprList *pRhs = 0; /* New Select.pEList for RHS */
- ExprList *pLhs = 0; /* New pX->pLeft vector */
-
- for(i=iEq;i<pLoop->nLTerm; i++){
- if( pLoop->aLTerm[i]->pExpr==pX ){
- int iField = pLoop->aLTerm[i]->iField - 1;
- Expr *pNewRhs = sqlite3ExprDup(db, pOrigRhs->a[iField].pExpr, 0);
- Expr *pNewLhs = sqlite3ExprDup(db, pOrigLhs->a[iField].pExpr, 0);
-
- pRhs = sqlite3ExprListAppend(pParse, pRhs, pNewRhs);
- pLhs = sqlite3ExprListAppend(pParse, pLhs, pNewLhs);
- }
- }
-
- /* pRhs should be a subset of pOrigRhs (though possibly in a different
- ** order). And pLhs should be a subset of pOrigLhs. To put it
- ** another way: Every term of pRhs should exist in pOrigRhs and
- ** every term of pLhs should exist in pOrigLhs. */
- assert( db->mallocFailed || exprListSubset(pRhs, pOrigRhs) );
- assert( db->mallocFailed || exprListSubset(pLhs, pOrigLhs) );
+ pX = removeUnindexableInClauseTerms(pParse, iEq, pLoop, pX);
if( !db->mallocFailed ){
- Expr *pLeft = pX->pLeft;
-
- if( pSelect->pOrderBy ){
- /* If the SELECT statement has an ORDER BY clause, zero the
- ** iOrderByCol variables. These are set to non-zero when an
- ** ORDER BY term exactly matches one of the terms of the
- ** result-set. Since the result-set of the SELECT statement may
- ** have been modified or reordered, these variables are no longer
- ** set correctly. Since setting them is just an optimization,
- ** it's easiest just to zero them here. */
- ExprList *pOrderBy = pSelect->pOrderBy;
- for(i=0; i<pOrderBy->nExpr; i++){
- pOrderBy->a[i].u.x.iOrderByCol = 0;
- }
- }
-
- /* Take care here not to generate a TK_VECTOR containing only a
- ** single value. Since the parser never creates such a vector, some
- ** of the subroutines do not handle this case. */
- if( pLhs->nExpr==1 ){
- pX->pLeft = pLhs->a[0].pExpr;
- }else{
- pLeft->x.pList = pLhs;
- aiMap = (int*)sqlite3DbMallocZero(pParse->db, sizeof(int) * nEq);
- testcase( aiMap==0 );
- }
- pSelect->pEList = pRhs;
- db->dbOptFlags |= SQLITE_QueryFlattener;
+ aiMap = (int*)sqlite3DbMallocZero(pParse->db, sizeof(int)*nEq);
eType = sqlite3FindInIndex(pParse, pX, IN_INDEX_LOOP, 0, aiMap);
- db->dbOptFlags = savedDbOptFlags;
- testcase( aiMap!=0 && aiMap[0]!=0 );
- pSelect->pEList = pOrigRhs;
- pLeft->x.pList = pOrigLhs;
- pX->pLeft = pLeft;
+ pTerm->pExpr->iTable = pX->iTable;
}
- sqlite3ExprListDelete(pParse->db, pLhs);
- sqlite3ExprListDelete(pParse->db, pRhs);
+ sqlite3ExprDelete(db, pX);
+ pX = pTerm->pExpr;
}
if( eType==IN_INDEX_INDEX_DESC ){
projects / thirdparty / sqlite.git / commitdiff
