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Fix planner to do the right thing when a degenerate outer join (one whose

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joinclause doesn't use any outer-side vars) requires a "bushy" plan to be
created.  The normal heuristic to avoid joins with no joinclause has to be
overridden in that case.  Problem is new in 8.2; before that we forced the
outer join order anyway.  Per example from Teodor.
This commit is contained in:
Tom Lane
2006-12-12 21:31:02 +00:00
parent 0afabecbfd
commit f18c57fdf1
4 changed files with 52 additions and 11 deletions
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15
src/backend/optimizer/path/joinrels.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/path/joinrels.c,v 1.81 2006/10/24 17:50:22 tgl Exp $
* $PostgreSQL: pgsql/src/backend/optimizer/path/joinrels.c,v 1.82 2006/12/12 21:31:02 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -147,8 +147,13 @@ make_rels_by_joins(PlannerInfo *root, int level, List **joinrels)
ListCell *other_rels;
ListCell *r2;
if (old_rel->joininfo == NIL)
continue; /* we ignore clauseless joins here */
/*
* We can ignore clauseless joins here, *except* when there are
* outer joins --- then we might have to force a bushy outer
* join. See have_relevant_joinclause().
*/
if (old_rel->joininfo == NIL && root->oj_info_list == NIL)
continue;
if (k == other_level)
other_rels = lnext(r); /* only consider remaining rels */
@ -166,7 +171,7 @@ make_rels_by_joins(PlannerInfo *root, int level, List **joinrels)
* pair of rels. Do so if there is at least one usable
* join clause.
*/
if (have_relevant_joinclause(old_rel, new_rel))
if (have_relevant_joinclause(root, old_rel, new_rel))
{
RelOptInfo *jrel;
@ -270,7 +275,7 @@ make_rels_by_clause_joins(PlannerInfo *root,
RelOptInfo *other_rel = (RelOptInfo *) lfirst(l);
if (!bms_overlap(old_rel->relids, other_rel->relids) &&
have_relevant_joinclause(old_rel, other_rel))
have_relevant_joinclause(root, old_rel, other_rel))
{
RelOptInfo *jrel;