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Commit1bd2635

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committed
Marginal code cleanup in joinpath.c: factor out clause variable-membership
tests into a small common subroutine, and eliminate an unnecessary differencein the order in which conditions are tested. Per a comment from Robert Haas.
1 parentf92bbb8 commit1bd2635

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1 file changed

+44
-50
lines changed

1 file changed

+44
-50
lines changed

‎src/backend/optimizer/path/joinpath.c

Lines changed: 44 additions & 50 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/optimizer/path/joinpath.c,v 1.124 2009/09/17 20:49:28 tgl Exp $
11+
* $PostgreSQL: pgsql/src/backend/optimizer/path/joinpath.c,v 1.125 2009/09/18 17:24:51 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -102,7 +102,8 @@ add_paths_to_joinrel(PlannerInfo *root,
102102
*
103103
* Note: do this after join_is_removable(), because this sets the
104104
* outer_is_left flags in the mergejoin clauses, while join_is_removable
105-
* uses those flags for its own purposes.
105+
* uses those flags for its own purposes. Currently, they set the flags
106+
* the same way anyway, but let's avoid unnecessary entanglement.
106107
*/
107108
if (enable_mergejoin||jointype==JOIN_FULL)
108109
mergeclause_list=select_mergejoin_clauses(root,
@@ -153,6 +154,37 @@ add_paths_to_joinrel(PlannerInfo *root,
153154
restrictlist,jointype,sjinfo);
154155
}
155156

157+
/*
158+
* clause_matches_join
159+
* Determine whether a join clause is of the right form to use in this join.
160+
*
161+
* We already know that the clause is a binary opclause referencing only the
162+
* rels in the current join. The point here is to check whether it has the
163+
* form "outerrel_expr op innerrel_expr" or "innerrel_expr op outerrel_expr",
164+
* rather than mixing outer and inner vars on either side. If it is usable,
165+
* we set the transient flag outer_is_left to identify which side is which.
166+
*/
167+
staticinlinebool
168+
clause_matches_join(RestrictInfo*rinfo,RelOptInfo*outerrel,
169+
RelOptInfo*innerrel)
170+
{
171+
if (bms_is_subset(rinfo->left_relids,outerrel->relids)&&
172+
bms_is_subset(rinfo->right_relids,innerrel->relids))
173+
{
174+
/* lefthand side is outer */
175+
rinfo->outer_is_left= true;
176+
return true;
177+
}
178+
elseif (bms_is_subset(rinfo->left_relids,innerrel->relids)&&
179+
bms_is_subset(rinfo->right_relids,outerrel->relids))
180+
{
181+
/* righthand side is outer */
182+
rinfo->outer_is_left= false;
183+
return true;
184+
}
185+
return false;/* no good for these input relations */
186+
}
187+
156188
/*
157189
* join_is_removable
158190
* Determine whether we need not perform the join at all, because
@@ -233,23 +265,9 @@ join_is_removable(PlannerInfo *root,
233265
continue;/* not mergejoinable */
234266

235267
/*
236-
* Check if clause is usable with these input rels. All the vars
237-
* needed on each side of the clause must be available from one or the
238-
* other of the input rels.
268+
* Check if clause has the form "outer op inner" or "inner op outer".
239269
*/
240-
if (bms_is_subset(restrictinfo->left_relids,outerrel->relids)&&
241-
bms_is_subset(restrictinfo->right_relids,innerrel->relids))
242-
{
243-
/* righthand side is inner */
244-
restrictinfo->outer_is_left= true;
245-
}
246-
elseif (bms_is_subset(restrictinfo->left_relids,innerrel->relids)&&
247-
bms_is_subset(restrictinfo->right_relids,outerrel->relids))
248-
{
249-
/* lefthand side is inner */
250-
restrictinfo->outer_is_left= false;
251-
}
252-
else
270+
if (!clause_matches_join(restrictinfo,outerrel,innerrel))
253271
continue;/* no good for these input relations */
254272

255273
/* OK, add to list */
@@ -977,31 +995,21 @@ hash_inner_and_outer(PlannerInfo *root,
977995
{
978996
RestrictInfo*restrictinfo= (RestrictInfo*)lfirst(l);
979997

980-
if (!restrictinfo->can_join||
981-
restrictinfo->hashjoinoperator==InvalidOid)
982-
continue;/* not hashjoinable */
983-
984998
/*
985999
* If processing an outer join, only use its own join clauses for
9861000
* hashing. For inner joins we need not be so picky.
9871001
*/
9881002
if (isouterjoin&&restrictinfo->is_pushed_down)
9891003
continue;
9901004

1005+
if (!restrictinfo->can_join||
1006+
restrictinfo->hashjoinoperator==InvalidOid)
1007+
continue;/* not hashjoinable */
1008+
9911009
/*
992-
* Check if clauseis usable with these input rels.
1010+
* Check if clausehas the form "outer op inner" or "inner op outer".
9931011
*/
994-
if (bms_is_subset(restrictinfo->left_relids,outerrel->relids)&&
995-
bms_is_subset(restrictinfo->right_relids,innerrel->relids))
996-
{
997-
/* righthand side is inner */
998-
}
999-
elseif (bms_is_subset(restrictinfo->left_relids,innerrel->relids)&&
1000-
bms_is_subset(restrictinfo->right_relids,outerrel->relids))
1001-
{
1002-
/* lefthand side is inner */
1003-
}
1004-
else
1012+
if (!clause_matches_join(restrictinfo,outerrel,innerrel))
10051013
continue;/* no good for these input relations */
10061014

10071015
hashclauses=lappend(hashclauses,restrictinfo);
@@ -1176,23 +1184,9 @@ select_mergejoin_clauses(PlannerInfo *root,
11761184
}
11771185

11781186
/*
1179-
* Check if clause is usable with these input rels. All the vars
1180-
* needed on each side of the clause must be available from one or the
1181-
* other of the input rels.
1187+
* Check if clause has the form "outer op inner" or "inner op outer".
11821188
*/
1183-
if (bms_is_subset(restrictinfo->left_relids,outerrel->relids)&&
1184-
bms_is_subset(restrictinfo->right_relids,innerrel->relids))
1185-
{
1186-
/* righthand side is inner */
1187-
restrictinfo->outer_is_left= true;
1188-
}
1189-
elseif (bms_is_subset(restrictinfo->left_relids,innerrel->relids)&&
1190-
bms_is_subset(restrictinfo->right_relids,outerrel->relids))
1191-
{
1192-
/* lefthand side is inner */
1193-
restrictinfo->outer_is_left= false;
1194-
}
1195-
else
1189+
if (!clause_matches_join(restrictinfo,outerrel,innerrel))
11961190
{
11971191
have_nonmergeable_joinclause= true;
11981192
continue;/* no good for these input relations */

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