diff --git a/src/backend/optimizer/path/costsize.c b/src/backend/optimizer/path/costsize.c
index ba33da829a957553da31d1fc3a6e41f79766dfc9..0b9c5819820274de0fc52a30487de106c7f6c05f 100644
--- a/src/backend/optimizer/path/costsize.c
+++ b/src/backend/optimizer/path/costsize.c
@@ -54,7 +54,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/optimizer/path/costsize.c,v 1.200 2008/10/21 20:42:52 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/optimizer/path/costsize.c,v 1.201 2008/11/22 22:47:05 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -2481,7 +2481,7 @@ set_joinrel_size_estimates(PlannerInfo *root, RelOptInfo *rel,
break;
case JOIN_SEMI:
nrows = outer_rel->rows * jselec;
- nrows *= pselec;
+ /* pselec not used */
break;
case JOIN_ANTI:
nrows = outer_rel->rows * (1.0 - jselec);
diff --git a/src/backend/optimizer/path/indxpath.c b/src/backend/optimizer/path/indxpath.c
index 297c50389fb4bc5dcfebbcb582d849bfc7b32655..5d1e31549238af8eacc89ba2fad315b43e99ea8a 100644
--- a/src/backend/optimizer/path/indxpath.c
+++ b/src/backend/optimizer/path/indxpath.c
@@ -9,7 +9,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/optimizer/path/indxpath.c,v 1.233 2008/09/12 14:56:13 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/optimizer/path/indxpath.c,v 1.234 2008/11/22 22:47:05 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -1647,10 +1647,10 @@ best_inner_indexscan(PlannerInfo *root, RelOptInfo *rel,
switch (jointype)
{
case JOIN_INNER:
+ case JOIN_SEMI:
isouterjoin = false;
break;
case JOIN_LEFT:
- case JOIN_SEMI:
case JOIN_ANTI:
isouterjoin = true;
break;
diff --git a/src/backend/optimizer/path/joinpath.c b/src/backend/optimizer/path/joinpath.c
index eaf0ffa4276e87a1a28d3eb126597b56ff14cf31..fe70df49ad4d02eb75f49970ddf88a514f4d9dfe 100644
--- a/src/backend/optimizer/path/joinpath.c
+++ b/src/backend/optimizer/path/joinpath.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/optimizer/path/joinpath.c,v 1.118 2008/10/04 21:56:53 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/optimizer/path/joinpath.c,v 1.119 2008/11/22 22:47:06 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -744,12 +744,12 @@ hash_inner_and_outer(PlannerInfo *root,
switch (jointype)
{
case JOIN_INNER:
+ case JOIN_SEMI:
case JOIN_UNIQUE_OUTER:
case JOIN_UNIQUE_INNER:
isouterjoin = false;
break;
case JOIN_LEFT:
- case JOIN_SEMI:
case JOIN_ANTI:
isouterjoin = true;
break;
diff --git a/src/backend/optimizer/path/joinrels.c b/src/backend/optimizer/path/joinrels.c
index 9ac0cc9743195f8813f0492f353c7a66ac599cb2..5f49ee7e290136b631face5fd5ed16bd538b827b 100644
--- a/src/backend/optimizer/path/joinrels.c
+++ b/src/backend/optimizer/path/joinrels.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/optimizer/path/joinrels.c,v 1.94 2008/08/17 19:40:11 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/optimizer/path/joinrels.c,v 1.95 2008/11/22 22:47:06 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -419,6 +419,27 @@ join_is_legal(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2,
match_sjinfo = sjinfo;
reversed = true;
}
+ else if (sjinfo->jointype == JOIN_SEMI &&
+ bms_equal(sjinfo->syn_righthand, rel2->relids))
+ {
+ /*
+ * For a semijoin, we can join the RHS to anything else by
+ * unique-ifying the RHS.
+ */
+ if (match_sjinfo)
+ return false; /* invalid join path */
+ match_sjinfo = sjinfo;
+ reversed = false;
+ }
+ else if (sjinfo->jointype == JOIN_SEMI &&
+ bms_equal(sjinfo->syn_righthand, rel1->relids))
+ {
+ /* Reversed semijoin case */
+ if (match_sjinfo)
+ return false; /* invalid join path */
+ match_sjinfo = sjinfo;
+ reversed = true;
+ }
else
{
/*----------
@@ -444,14 +465,24 @@ join_is_legal(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2,
* We assume that make_outerjoininfo() set things up correctly
* so that we'll only match to some SJ if the join is valid.
* Set flag here to check at bottom of loop.
+ *
+ * For a semijoin, assume it's okay if either side fully contains
+ * the RHS (per the unique-ification case above).
*----------
*/
- if (bms_overlap(rel1->relids, sjinfo->min_righthand) &&
+ if (sjinfo->jointype != JOIN_SEMI &&
+ bms_overlap(rel1->relids, sjinfo->min_righthand) &&
bms_overlap(rel2->relids, sjinfo->min_righthand))
{
/* seems OK */
Assert(!bms_overlap(joinrelids, sjinfo->min_lefthand));
}
+ else if (sjinfo->jointype == JOIN_SEMI &&
+ (bms_is_subset(sjinfo->syn_righthand, rel1->relids) ||
+ bms_is_subset(sjinfo->syn_righthand, rel2->relids)))
+ {
+ /* seems OK */
+ }
else
is_valid_inner = false;
}
@@ -612,15 +643,23 @@ make_join_rel(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2)
restrictlist);
break;
case JOIN_SEMI:
- if (is_dummy_rel(rel1) || is_dummy_rel(rel2) ||
- restriction_is_constant_false(restrictlist))
+ /*
+ * Do these steps only if we actually have a regular semijoin,
+ * as opposed to a case where we should unique-ify the RHS.
+ */
+ if (bms_is_subset(sjinfo->min_lefthand, rel1->relids) &&
+ bms_is_subset(sjinfo->min_righthand, rel2->relids))
{
- mark_dummy_rel(joinrel);
- break;
+ if (is_dummy_rel(rel1) || is_dummy_rel(rel2) ||
+ restriction_is_constant_false(restrictlist))
+ {
+ mark_dummy_rel(joinrel);
+ break;
+ }
+ add_paths_to_joinrel(root, joinrel, rel1, rel2,
+ JOIN_SEMI, sjinfo,
+ restrictlist);
}
- add_paths_to_joinrel(root, joinrel, rel1, rel2,
- JOIN_SEMI, sjinfo,
- restrictlist);
/*
* If we know how to unique-ify the RHS and one input rel is
diff --git a/src/backend/optimizer/plan/initsplan.c b/src/backend/optimizer/plan/initsplan.c
index d1b590d063120ed6c4645e5afc448ed3cac083c8..1764656da3806a84b5c33d92e9dab20688fd2a27 100644
--- a/src/backend/optimizer/plan/initsplan.c
+++ b/src/backend/optimizer/plan/initsplan.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/optimizer/plan/initsplan.c,v 1.144 2008/10/25 19:51:32 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/optimizer/plan/initsplan.c,v 1.145 2008/11/22 22:47:06 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -851,16 +851,11 @@ distribute_qual_to_rels(PlannerInfo *root, Node *clause,
maybe_equivalence = false;
maybe_outer_join = false;
}
- else if (bms_overlap(relids, outerjoin_nonnullable) &&
- (jointype != JOIN_SEMI ||
- bms_nonempty_difference(relids, outerjoin_nonnullable)))
+ else if (bms_overlap(relids, outerjoin_nonnullable))
{
/*
* The qual is attached to an outer join and mentions (some of the)
- * rels on the nonnullable side, so it's not degenerate. (For a
- * JOIN_SEMI qual, we consider it non-degenerate only if it mentions
- * both sides of the join --- if it mentions only one side, it can
- * be pushed down.)
+ * rels on the nonnullable side, so it's not degenerate.
*
* We can't use such a clause to deduce equivalence (the left and
* right sides might be unequal above the join because one of them has
@@ -1062,6 +1057,7 @@ distribute_sublink_quals_to_rels(PlannerInfo *root,
SpecialJoinInfo *sjinfo;
Relids qualscope;
Relids ojscope;
+ Relids outerjoin_nonnullable;
ListCell *l;
/*
@@ -1076,17 +1072,27 @@ distribute_sublink_quals_to_rels(PlannerInfo *root,
fslink->jointype,
quals);
+ /* Treat as inner join if SEMI, outer join if ANTI */
qualscope = bms_union(sjinfo->syn_lefthand, sjinfo->syn_righthand);
- ojscope = bms_union(sjinfo->min_lefthand, sjinfo->min_righthand);
+ if (fslink->jointype == JOIN_SEMI)
+ {
+ ojscope = outerjoin_nonnullable = NULL;
+ }
+ else
+ {
+ Assert(fslink->jointype == JOIN_ANTI);
+ ojscope = bms_union(sjinfo->min_lefthand, sjinfo->min_righthand);
+ outerjoin_nonnullable = fslink->lefthand;
+ }
- /* Distribute the join quals much as for a regular LEFT JOIN */
+ /* Distribute the join quals much as for a regular JOIN node */
foreach(l, quals)
{
Node *qual = (Node *) lfirst(l);
distribute_qual_to_rels(root, qual,
false, below_outer_join, fslink->jointype,
- qualscope, ojscope, fslink->lefthand);
+ qualscope, ojscope, outerjoin_nonnullable);
}
/* Now we can add the SpecialJoinInfo to join_info_list */
diff --git a/src/include/nodes/nodes.h b/src/include/nodes/nodes.h
index ddd9934cf1ed70b20bb9879ceb264cf03675f202..4161c08ec54da18cb2a680669a06d867d737aa31 100644
--- a/src/include/nodes/nodes.h
+++ b/src/include/nodes/nodes.h
@@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $PostgreSQL: pgsql/src/include/nodes/nodes.h,v 1.214 2008/10/21 20:42:53 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/nodes/nodes.h,v 1.215 2008/11/22 22:47:06 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -542,15 +542,23 @@ typedef enum JoinType
/*
* OUTER joins are those for which pushed-down quals must behave differently
- * from the join's own quals. This is in fact everything except INNER joins.
- * However, this macro must also exclude the JOIN_UNIQUE symbols since those
- * are temporary proxies for what will eventually be an INNER join.
+ * from the join's own quals. This is in fact everything except INNER and
+ * SEMI joins. However, this macro must also exclude the JOIN_UNIQUE symbols
+ * since those are temporary proxies for what will eventually be an INNER
+ * join.
*
- * Note: in some places it is preferable to treat JOIN_SEMI as not being
- * an outer join, since it doesn't produce null-extended rows. Be aware
- * of that distinction when deciding whether to use this macro.
+ * Note: semijoins are a hybrid case, but we choose to treat them as not
+ * being outer joins. This is okay principally because the SQL syntax makes
+ * it impossible to have a pushed-down qual that refers to the inner relation
+ * of a semijoin; so there is no strong need to distinguish join quals from
+ * pushed-down quals. This is convenient because for almost all purposes,
+ * quals attached to a semijoin can be treated the same as innerjoin quals.
*/
#define IS_OUTER_JOIN(jointype) \
- ((jointype) > JOIN_INNER && (jointype) < JOIN_UNIQUE_OUTER)
+ (((1 << (jointype)) & \
+ ((1 << JOIN_LEFT) | \
+ (1 << JOIN_FULL) | \
+ (1 << JOIN_RIGHT) | \
+ (1 << JOIN_ANTI))) != 0)
#endif /* NODES_H */