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Rule rewriter was doing the wrong thing with conditional INSTEAD rules

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whose conditions might yield NULL.  The negated qual to attach to the
original query is properly 'x IS NOT TRUE', not 'NOT x'.  This fix
produces correct behavior, but we may be taking a performance hit because
the planner is much stupider about IS NOT TRUE than it is about NOT
clauses.  Future TODO: teach prepqual, other parts of planner how to
cope with BooleanTest clauses more effectively.
This commit is contained in:
Tom Lane
2002-10-20 00:58:55 +00:00
parent 6d6b582850
commit a044e2abdd
3 changed files with 30 additions and 36 deletions
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34
src/backend/rewrite/rewriteManip.c
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@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteManip.c,v 1.66 2002/09/11 14:48:54 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteManip.c,v 1.67 2002/10/20 00:58:55 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -690,34 +690,26 @@ AddHavingQual(Query *parsetree, Node *havingQual)
parsetree->hasSubLinks |= checkExprHasSubLink(copy);
}
#ifdef NOT_USED
/*
* Invert the given clause and add it to the WHERE qualifications of the
* given querytree. Inversion means "x IS NOT TRUE", not just "NOT x",
* else we will do the wrong thing when x evaluates to NULL.
*/
void
AddNotHavingQual(Query *parsetree, Node *havingQual)
AddInvertedQual(Query *parsetree, Node *qual)
{
Node *notqual;
if (havingQual == NULL)
return;
/* Need not copy input qual, because AddHavingQual will... */
notqual = (Node *) make_notclause((Expr *) havingQual);
AddHavingQual(parsetree, notqual);
}
#endif
void
AddNotQual(Query *parsetree, Node *qual)
{
Node *notqual;
BooleanTest *invqual;
if (qual == NULL)
return;
/* Need not copy input qual, because AddQual will... */
notqual = (Node *) make_notclause((Expr *) qual);
invqual = makeNode(BooleanTest);
invqual->arg = qual;
invqual->booltesttype = IS_NOT_TRUE;
AddQual(parsetree, notqual);
AddQual(parsetree, (Node *) invqual);
}