Attached is a small patch which improves the way get_base_rel_indexes()
works.
The current version creates a new bitmapset on each recursion level then
bms_joins() to the one on the next level up each time. I understand that
this will patch will have about a 0 net performance improvement, but I
thought I'd post anyway as:
1. It removes 5 lines of code.
2. It's a better example to leave in the code.
Is it worth applying?
Regards
David Rowley
--
David Rowley http://www.2ndQuadrant.com/
<http://www.2ndquadrant.com/>
PostgreSQL Development, 24x7 Support, Training & Services
diff --git a/src/backend/optimizer/plan/planner.c
b/src/backend/optimizer/plan/planner.c
index d598c1b..926a41a 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -2638,43 +2638,38 @@ is_dummy_plan(Plan *plan)
* the only good way to distinguish baserels from appendrel children
* is to see what is in the join tree.
*/
-static Bitmapset *
-get_base_rel_indexes(Node *jtnode)
+static void
+get_base_rel_indexes(Node *jtnode, Bitmapset **result)
{
- Bitmapset *result;
if (jtnode == NULL)
- return NULL;
+ return;
if (IsA(jtnode, RangeTblRef))
{
int varno = ((RangeTblRef *)
jtnode)->rtindex;
- result = bms_make_singleton(varno);
+ *result = bms_add_member(*result, varno);
}
else if (IsA(jtnode, FromExpr))
{
FromExpr *f = (FromExpr *) jtnode;
ListCell *l;
- result = NULL;
foreach(l, f->fromlist)
- result = bms_join(result,
-
get_base_rel_indexes(lfirst(l)));
+ get_base_rel_indexes(lfirst(l), result);
}
else if (IsA(jtnode, JoinExpr))
{
JoinExpr *j = (JoinExpr *) jtnode;
- result = bms_join(get_base_rel_indexes(j->larg),
-
get_base_rel_indexes(j->rarg));
+ get_base_rel_indexes(j->larg, result);
+ get_base_rel_indexes(j->rarg, result);
}
else
{
elog(ERROR, "unrecognized node type: %d",
(int) nodeTag(jtnode));
- result = NULL; /* keep compiler quiet */
}
- return result;
}
/*
@@ -2684,7 +2679,7 @@ static void
preprocess_rowmarks(PlannerInfo *root)
{
Query *parse = root->parse;
- Bitmapset *rels;
+ Bitmapset *rels = NULL;
List *prowmarks;
ListCell *l;
int i;
@@ -2716,7 +2711,7 @@ preprocess_rowmarks(PlannerInfo *root)
* make a bitmapset of all base rels and then remove the items we don't
* need or have FOR [KEY] UPDATE/SHARE marks for.
*/
- rels = get_base_rel_indexes((Node *) parse->jointree);
+ get_base_rel_indexes((Node *) parse->jointree, &rels);
if (parse->resultRelation)
rels = bms_del_member(rels, parse->resultRelation);
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