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Do not allow changes to sqlite3ExprIsTableConstant() that support pushdown of

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subqueries interfere with the hash-join logic.

FossilOrigin-Name: 8682931f9c6b40e1b09139c10bbe932c38330b5eb0c5c84f2432ad19a6793e37
This commit is contained in:
drh
2024-04-06 18:30:09 +00:00
parent ed27183d83
commit 6951c49779
6 changed files with 33 additions and 20 deletions
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25
src/expr.c
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@@ -2570,14 +2570,22 @@ static int exprSelectWalkTableConstant(Walker *pWalker, Select *pSelect){
** expression must not refer to any non-deterministic function nor any
** table other than iCur.
**
** Enhanced on 2024-04-06: Allow pExpr to contain uncorrelated subqueries.
** Consider uncorrelated subqueries to be constants if the bAllowSubq
** parameter is true.
*/
static int sqlite3ExprIsTableConstant(Expr *p, int iCur){
static int sqlite3ExprIsTableConstant(Expr *p, int iCur, int bAllowSubq){
Walker w;
w.eCode = 3;
w.pParse = 0;
w.xExprCallback = exprNodeIsConstant;
w.xSelectCallback = exprSelectWalkTableConstant;
if( bAllowSubq ){
w.xSelectCallback = exprSelectWalkTableConstant;
}else{
w.xSelectCallback = sqlite3SelectWalkFail;
#ifdef SQLITE_DEBUG
w.xSelectCallback2 = sqlite3SelectWalkAssert2;
#endif
}
w.u.iCur = iCur;
sqlite3WalkExpr(&w, p);
return w.eCode;
@@ -2598,7 +2606,10 @@ static int sqlite3ExprIsTableConstant(Expr *p, int iCur){
**
** (1) pExpr cannot refer to any table other than pSrc->iCursor.
**
** (2) pExpr cannot use subqueries or non-deterministic functions.
** (2a) pExpr cannot use subqueries unless the bAllowSubq parameter is
** true and the subquery is non-correlated
**
** (2b) pExpr cannot use non-deterministic functions.
**
** (3) pSrc cannot be part of the left operand for a RIGHT JOIN.
** (Is there some way to relax this constraint?)
@@ -2627,7 +2638,8 @@ static int sqlite3ExprIsTableConstant(Expr *p, int iCur){
int sqlite3ExprIsSingleTableConstraint(
Expr *pExpr, /* The constraint */
const SrcList *pSrcList, /* Complete FROM clause */
int iSrc /* Which element of pSrcList to use */
int iSrc, /* Which element of pSrcList to use */
int bAllowSubq /* Allow non-correlated subqueries */
){
const SrcItem *pSrc = &pSrcList->a[iSrc];
if( pSrc->fg.jointype & JT_LTORJ ){
@@ -2652,7 +2664,8 @@ int sqlite3ExprIsSingleTableConstraint(
}
}
}
return sqlite3ExprIsTableConstant(pExpr, pSrc->iCursor); /* rules (1), (2) */
/* Rules (1), (2a), and (2b) handled by the following: */
return sqlite3ExprIsTableConstant(pExpr, pSrc->iCursor, bAllowSubq);
}