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Be a little smarter about qual handling for semi-joins: a qual that mentions

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only the outer side can be pushed down rather than having to be evaluated
at the join.
This commit is contained in:
Tom Lane 2008-10-25 19:51:32 +00:00
parent ddbe8dca08
commit aa0fb53016
1 changed files with 17 additions and 10 deletions
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27
src/backend/optimizer/plan/initsplan.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/plan/initsplan.c,v 1.143 2008/10/21 20:42:53 tgl Exp $
* $PostgreSQL: pgsql/src/backend/optimizer/plan/initsplan.c,v 1.144 2008/10/25 19:51:32 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -48,6 +48,7 @@ static SpecialJoinInfo *make_outerjoininfo(PlannerInfo *root,
static void distribute_qual_to_rels(PlannerInfo *root, Node *clause,
bool is_deduced,
bool below_outer_join,
JoinType jointype,
Relids qualscope,
Relids ojscope,
Relids outerjoin_nonnullable);
@ -342,7 +343,7 @@ deconstruct_recurse(PlannerInfo *root, Node *jtnode, bool below_outer_join,
below_outer_join);
else
distribute_qual_to_rels(root, qual,
false, below_outer_join,
false, below_outer_join, JOIN_INNER,
*qualscope, NULL, NULL);
}
}
@ -452,7 +453,7 @@ deconstruct_recurse(PlannerInfo *root, Node *jtnode, bool below_outer_join,
below_outer_join);
else
distribute_qual_to_rels(root, qual,
false, below_outer_join,
false, below_outer_join, j->jointype,
*qualscope,
ojscope, nonnullable_rels);
}
@ -712,6 +713,7 @@ make_outerjoininfo(PlannerInfo *root,
* 'is_deduced': TRUE if the qual came from implied-equality deduction
* 'below_outer_join': TRUE if the qual is from a JOIN/ON that is below the
* nullable side of a higher-level outer join
* 'jointype': type of join the qual is from (JOIN_INNER for a WHERE clause)
* 'qualscope': set of baserels the qual's syntactic scope covers
* 'ojscope': NULL if not an outer-join qual, else the minimum set of baserels
* needed to form this join
@ -728,6 +730,7 @@ static void
distribute_qual_to_rels(PlannerInfo *root, Node *clause,
bool is_deduced,
bool below_outer_join,
JoinType jointype,
Relids qualscope,
Relids ojscope,
Relids outerjoin_nonnullable)
@ -848,11 +851,16 @@ distribute_qual_to_rels(PlannerInfo *root, Node *clause,
maybe_equivalence = false;
maybe_outer_join = false;
}
else if (bms_overlap(relids, outerjoin_nonnullable))
else if (bms_overlap(relids, outerjoin_nonnullable) &&
(jointype != JOIN_SEMI ||
bms_nonempty_difference(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.
* 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.)
*
* 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
@ -1024,7 +1032,7 @@ distribute_qual_to_rels(PlannerInfo *root, Node *clause,
restrictinfo);
return;
}
if (bms_equal(outerjoin_nonnullable, qualscope))
if (jointype == JOIN_FULL)
{
/* FULL JOIN (above tests cannot match in this case) */
root->full_join_clauses = lappend(root->full_join_clauses,
@ -1077,9 +1085,8 @@ distribute_sublink_quals_to_rels(PlannerInfo *root,
Node *qual = (Node *) lfirst(l);
distribute_qual_to_rels(root, qual,
false, below_outer_join,
qualscope, ojscope,
fslink->lefthand);
false, below_outer_join, fslink->jointype,
qualscope, ojscope, fslink->lefthand);
}
/* Now we can add the SpecialJoinInfo to join_info_list */
@ -1373,7 +1380,7 @@ process_implied_equality(PlannerInfo *root,
* Push the new clause into all the appropriate restrictinfo lists.
*/
distribute_qual_to_rels(root, (Node *) clause,
true, below_outer_join,
true, below_outer_join, JOIN_INNER,
qualscope, NULL, NULL);
}