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Fix an oversight I introduced on 2003-12-28: find_nots/push_nots should

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continue to recurse after eliminating a NOT-below-a-NOT, since the
contained subexpression will now be part of the top-level AND/OR structure
and so deserves to be simplified.  The real-world impact of this is
probably minimal, since it'd require at least three levels of NOT to make
a difference, but it's still a bug.
Also remove some redundant tests for NULL subexpressions.
This commit is contained in:
Tom Lane 2005-07-29 21:40:02 +00:00
parent 80f6c35833
commit 284e4739ef
1 changed files with 10 additions and 19 deletions
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29
src/backend/optimizer/prep/prepqual.c
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@ -25,7 +25,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/prep/prepqual.c,v 1.49 2005/03/28 00:58:23 tgl Exp $
* $PostgreSQL: pgsql/src/backend/optimizer/prep/prepqual.c,v 1.50 2005/07/29 21:40:02 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -167,9 +167,6 @@ pull_ors(List *orlist)
static Expr *
find_nots(Expr *qual)
{
if (qual == NULL)
return NULL;
if (and_clause((Node *) qual))
{
List *t_list = NIL;
@ -204,17 +201,13 @@ find_nots(Expr *qual)
static Expr *
push_nots(Expr *qual)
{
if (qual == NULL)
return make_notclause(qual); /* XXX is this right? Or
* possible? */
/*
* Negate an operator clause if possible: (NOT (< A B)) => (>= A B)
* Otherwise, retain the clause as it is (the NOT can't be pushed down
* any farther).
*/
if (is_opclause(qual))
{
/*
* Negate an operator clause if possible: (NOT (< A B)) => (>= A B)
* Otherwise, retain the clause as it is (the NOT can't be pushed down
* any farther).
*/
OpExpr *opexpr = (OpExpr *) qual;
Oid negator = get_negator(opexpr->opno);
@ -256,15 +249,16 @@ push_nots(Expr *qual)
{
/*
* Another NOT cancels this NOT, so eliminate the NOT and stop
* negating this branch.
* negating this branch. But search the subexpression for more
* NOTs to simplify.
*/
return get_notclausearg(qual);
return find_nots(get_notclausearg(qual));
}
else
{
/*
* We don't know how to negate anything else, place a NOT at this
* level.
* level. No point in recursing deeper, either.
*/
return make_notclause(qual);
}
@ -303,9 +297,6 @@ push_nots(Expr *qual)
static Expr *
find_duplicate_ors(Expr *qual)
{
if (qual == NULL)
return NULL;
if (or_clause((Node *) qual))
{
List *orlist = NIL;