Add bms_next_member(), and use it where appropriate.

This patch adds a way of iterating through the members of a bitmapset
nondestructively, unlike the old way with bms_first_member().  While
bms_next_member() is very slightly slower than bms_first_member()
(at least for typical-size bitmapsets), eliminating the need to palloc
and pfree a temporary copy of the target bitmapset is a significant win.
So this method should be preferred in all cases where a temporary copy
would be necessary.

Tom Lane, with suggestions from Dean Rasheed and David Rowley

1 files changed, 2 insertions, 4 deletions

diff --git a/src/backend/optimizer/util/var.c b/src/backend/optimizer/util/var.c
index d4f46b8d461..a64a8d7d5ff 100644
--- a/src/backend/optimizer/util/var.c
+++ b/src/backend/optimizer/util/var.c
@@ -773,11 +773,10 @@ static Relids
 alias_relid_set(PlannerInfo *root, Relids relids)
 {
 	Relids		result = NULL;
-	Relids		tmprelids;
 	int			rtindex;
 
-	tmprelids = bms_copy(relids);
-	while ((rtindex = bms_first_member(tmprelids)) >= 0)
+	rtindex = -1;
+	while ((rtindex = bms_next_member(relids, rtindex)) >= 0)
 	{
 		RangeTblEntry *rte = rt_fetch(rtindex, root->parse->rtable);
 
@@ -786,6 +785,5 @@ alias_relid_set(PlannerInfo *root, Relids relids)
 		else
 			result = bms_add_member(result, rtindex);
 	}
-	bms_free(tmprelids);
 	return result;
 }