diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/expr.c | 28 | ||||
| -rw-r--r-- | src/whereexpr.c | 20 |
2 files changed, 34 insertions, 14 deletions
diff --git a/src/expr.c b/src/expr.c index c8dfd3af3..ebac654a2 100644 --- a/src/expr.c +++ b/src/expr.c @@ -3896,17 +3896,23 @@ int sqlite3CodeSubselect(Parse *pParse, Expr *pExpr){ VdbeComment((v, "Init EXISTS result")); } if( pSel->pLimit ){ - /* The subquery already has a limit. If the pre-existing limit is X - ** then make the new limit X<>0 so that the new limit is either 1 or 0 */ - sqlite3 *db = pParse->db; - pLimit = sqlite3Expr(db, TK_INTEGER, "0"); - if( pLimit ){ - pLimit->affExpr = SQLITE_AFF_NUMERIC; - pLimit = sqlite3PExpr(pParse, TK_NE, - sqlite3ExprDup(db, pSel->pLimit->pLeft, 0), pLimit); - } - sqlite3ExprDeferredDelete(pParse, pSel->pLimit->pLeft); - pSel->pLimit->pLeft = pLimit; + /* The subquery already has a limit. If the pre-existing limit X is + ** not already integer value 1 or 0, then make the new limit X<>0 so that + ** the new limit is either 1 or 0 */ + Expr *pLeft = pSel->pLimit->pLeft; + if( ExprHasProperty(pLeft, EP_IntValue)==0 + || (pLeft->u.iValue!=1 && pLeft->u.iValue!=0) + ){ + sqlite3 *db = pParse->db; + pLimit = sqlite3Expr(db, TK_INTEGER, "0"); + if( pLimit ){ + pLimit->affExpr = SQLITE_AFF_NUMERIC; + pLimit = sqlite3PExpr(pParse, TK_NE, + sqlite3ExprDup(db, pLeft, 0), pLimit); + } + sqlite3ExprDeferredDelete(pParse, pLeft); + pSel->pLimit->pLeft = pLimit; + } }else{ /* If there is no pre-existing limit add a limit of 1 */ pLimit = sqlite3Expr(pParse->db, TK_INTEGER, "1"); diff --git a/src/whereexpr.c b/src/whereexpr.c index 53c8508e5..fc7a30a42 100644 --- a/src/whereexpr.c +++ b/src/whereexpr.c @@ -1652,7 +1652,7 @@ static void whereAddLimitExpr( ** ** 1. The SELECT statement has a LIMIT clause, and ** 2. The SELECT statement is not an aggregate or DISTINCT query, and -** 3. The SELECT statement has exactly one object in its from clause, and +** 3. The SELECT statement has exactly one object in its FROM clause, and ** that object is a virtual table, and ** 4. There are no terms in the WHERE clause that will not be passed ** to the virtual table xBestIndex method. @@ -1689,8 +1689,22 @@ void SQLITE_NOINLINE sqlite3WhereAddLimit(WhereClause *pWC, Select *p){ ** (leftCursor==iCsr) test below. */ continue; } - if( pWC->a[ii].leftCursor!=iCsr ) return; - if( pWC->a[ii].prereqRight!=0 ) return; + if( pWC->a[ii].leftCursor==iCsr && pWC->a[ii].prereqRight==0 ) continue; + + /* If this term has a parent with exactly one child, and the parent will + ** be passed through to xBestIndex, then this term can be ignored. */ + if( pWC->a[ii].iParent>=0 ){ + WhereTerm *pParent = &pWC->a[ pWC->a[ii].iParent ]; + if( pParent->leftCursor==iCsr + && pParent->prereqRight==0 + && ALWAYS(pParent->nChild==1) + ){ + continue; + } + } + + /* This term will not be passed through. Do not add a LIMIT clause. */ + return; } /* Check condition (5). Return early if it is not met. */ |