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Marginal code cleanup in joinpath.c: factor out clause variable-membership 

tests into a small common subroutine, and eliminate an unnecessary difference
in the order in which conditions are tested.  Per a comment from Robert Haas.
This commit is contained in:
Tom Lane 2009-09-18 17:24:51 +00:00
parent f92bbb899a
commit 1bd263537f
1 changed files with 44 additions and 50 deletions
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94
src/backend/optimizer/path/joinpath.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/path/joinpath.c,v 1.124 2009/09/17 20:49:28 tgl Exp $
* $PostgreSQL: pgsql/src/backend/optimizer/path/joinpath.c,v 1.125 2009/09/18 17:24:51 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -102,7 +102,8 @@ add_paths_to_joinrel(PlannerInfo *root,
*
* Note: do this after join_is_removable(), because this sets the
* outer_is_left flags in the mergejoin clauses, while join_is_removable
* uses those flags for its own purposes.
* uses those flags for its own purposes. Currently, they set the flags
* the same way anyway, but let's avoid unnecessary entanglement.
*/
if (enable_mergejoin || jointype == JOIN_FULL)
mergeclause_list = select_mergejoin_clauses(root,
@ -153,6 +154,37 @@ add_paths_to_joinrel(PlannerInfo *root,
restrictlist, jointype, sjinfo);
}
/*
* clause_matches_join
* Determine whether a join clause is of the right form to use in this join.
*
* We already know that the clause is a binary opclause referencing only the
* rels in the current join. The point here is to check whether it has the
* form "outerrel_expr op innerrel_expr" or "innerrel_expr op outerrel_expr",
* rather than mixing outer and inner vars on either side. If it is usable,
* we set the transient flag outer_is_left to identify which side is which.
*/
static inline bool
clause_matches_join(RestrictInfo *rinfo, RelOptInfo *outerrel,
RelOptInfo *innerrel)
{
if (bms_is_subset(rinfo->left_relids, outerrel->relids) &&
bms_is_subset(rinfo->right_relids, innerrel->relids))
{
/* lefthand side is outer */
rinfo->outer_is_left = true;
return true;
}
else if (bms_is_subset(rinfo->left_relids, innerrel->relids) &&
bms_is_subset(rinfo->right_relids, outerrel->relids))
{
/* righthand side is outer */
rinfo->outer_is_left = false;
return true;
}
return false; /* no good for these input relations */
}
/*
* join_is_removable
* Determine whether we need not perform the join at all, because
@ -233,23 +265,9 @@ join_is_removable(PlannerInfo *root,
continue; /* not mergejoinable */
/*
* Check if clause is usable with these input rels. All the vars
* needed on each side of the clause must be available from one or the
* other of the input rels.
* Check if clause has the form "outer op inner" or "inner op outer".
*/
if (bms_is_subset(restrictinfo->left_relids, outerrel->relids) &&
bms_is_subset(restrictinfo->right_relids, innerrel->relids))
{
/* righthand side is inner */
restrictinfo->outer_is_left = true;
}
else if (bms_is_subset(restrictinfo->left_relids, innerrel->relids) &&
bms_is_subset(restrictinfo->right_relids, outerrel->relids))
{
/* lefthand side is inner */
restrictinfo->outer_is_left = false;
}
else
if (!clause_matches_join(restrictinfo, outerrel, innerrel))
continue; /* no good for these input relations */
/* OK, add to list */
@ -977,10 +995,6 @@ hash_inner_and_outer(PlannerInfo *root,
{
RestrictInfo *restrictinfo = (RestrictInfo *) lfirst(l);
if (!restrictinfo->can_join ||
restrictinfo->hashjoinoperator == InvalidOid)
continue; /* not hashjoinable */
/*
* If processing an outer join, only use its own join clauses for
* hashing. For inner joins we need not be so picky.
@ -988,20 +1002,14 @@ hash_inner_and_outer(PlannerInfo *root,
if (isouterjoin && restrictinfo->is_pushed_down)
continue;
if (!restrictinfo->can_join ||
restrictinfo->hashjoinoperator == InvalidOid)
continue; /* not hashjoinable */
/*
* Check if clause is usable with these input rels.
* Check if clause has the form "outer op inner" or "inner op outer".
*/
if (bms_is_subset(restrictinfo->left_relids, outerrel->relids) &&
bms_is_subset(restrictinfo->right_relids, innerrel->relids))
{
/* righthand side is inner */
}
else if (bms_is_subset(restrictinfo->left_relids, innerrel->relids) &&
bms_is_subset(restrictinfo->right_relids, outerrel->relids))
{
/* lefthand side is inner */
}
else
if (!clause_matches_join(restrictinfo, outerrel, innerrel))
continue; /* no good for these input relations */
hashclauses = lappend(hashclauses, restrictinfo);
@ -1176,23 +1184,9 @@ select_mergejoin_clauses(PlannerInfo *root,
}
/*
* Check if clause is usable with these input rels. All the vars
* needed on each side of the clause must be available from one or the
* other of the input rels.
* Check if clause has the form "outer op inner" or "inner op outer".
*/
if (bms_is_subset(restrictinfo->left_relids, outerrel->relids) &&
bms_is_subset(restrictinfo->right_relids, innerrel->relids))
{
/* righthand side is inner */
restrictinfo->outer_is_left = true;
}
else if (bms_is_subset(restrictinfo->left_relids, innerrel->relids) &&
bms_is_subset(restrictinfo->right_relids, outerrel->relids))
{
/* lefthand side is inner */
restrictinfo->outer_is_left = false;
}
else
if (!clause_matches_join(restrictinfo, outerrel, innerrel))
{
have_nonmergeable_joinclause = true;
continue; /* no good for these input relations */