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Suppress pull-up of subqueries that are in the nullable side of an outer 

join.  This is needed to avoid improper evaluation of expressions that
should be nulled out, as in Victor Wagner's bug report of 4/27/01.
Pretty ugly solution, but no time to do anything better for 7.1.1.
This commit is contained in:
Tom Lane 2001-04-30 19:24:47 +00:00
parent 60ba30d13a
commit e2004dfc69
1 changed files with 36 additions and 3 deletions
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39
src/backend/optimizer/plan/planner.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planner.c,v 1.104 2001/04/18 20:42:55 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planner.c,v 1.105 2001/04/30 19:24:47 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -363,8 +363,41 @@ pull_up_subqueries(Query *parse, Node *jtnode)
{
JoinExpr *j = (JoinExpr *) jtnode;
j->larg = pull_up_subqueries(parse, j->larg);
j->rarg = pull_up_subqueries(parse, j->rarg);
/*
* At the moment, we can't pull up subqueries that are inside the
* nullable side of an outer join, because substituting their target
* list entries for upper Var references wouldn't do the right thing
* (the entries wouldn't go to NULL when they're supposed to).
* Suppressing the pullup is an ugly, performance-losing hack, but
* I see no alternative for now. Find a better way to handle this
* when we redesign query trees --- tgl 4/30/01.
*/
switch (j->jointype)
{
case JOIN_INNER:
j->larg = pull_up_subqueries(parse, j->larg);
j->rarg = pull_up_subqueries(parse, j->rarg);
break;
case JOIN_LEFT:
j->larg = pull_up_subqueries(parse, j->larg);
break;
case JOIN_FULL:
break;
case JOIN_RIGHT:
j->rarg = pull_up_subqueries(parse, j->rarg);
break;
case JOIN_UNION:
/*
* This is where we fail if upper levels of planner
* haven't rewritten UNION JOIN as an Append ...
*/
elog(ERROR, "UNION JOIN is not implemented yet");
break;
default:
elog(ERROR, "pull_up_subqueries: unexpected join type %d",
j->jointype);
break;
}
}
else
elog(ERROR, "pull_up_subqueries: unexpected node type %d",