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, 4 insertions, 8 deletions

diff --git a/src/backend/optimizer/util/joininfo.c b/src/backend/optimizer/util/joininfo.c
index 0418946d714..40af38d7ada 100644
--- a/src/backend/optimizer/util/joininfo.c
+++ b/src/backend/optimizer/util/joininfo.c
@@ -96,17 +96,15 @@ add_join_clause_to_rels(PlannerInfo *root,
 						RestrictInfo *restrictinfo,
 						Relids join_relids)
 {
-	Relids		tmprelids;
 	int			cur_relid;
 
-	tmprelids = bms_copy(join_relids);
-	while ((cur_relid = bms_first_member(tmprelids)) >= 0)
+	cur_relid = -1;
+	while ((cur_relid = bms_next_member(join_relids, cur_relid)) >= 0)
 	{
 		RelOptInfo *rel = find_base_rel(root, cur_relid);
 
 		rel->joininfo = lappend(rel->joininfo, restrictinfo);
 	}
-	bms_free(tmprelids);
 }
 
 /*
@@ -125,11 +123,10 @@ remove_join_clause_from_rels(PlannerInfo *root,
 							 RestrictInfo *restrictinfo,
 							 Relids join_relids)
 {
-	Relids		tmprelids;
 	int			cur_relid;
 
-	tmprelids = bms_copy(join_relids);
-	while ((cur_relid = bms_first_member(tmprelids)) >= 0)
+	cur_relid = -1;
+	while ((cur_relid = bms_next_member(join_relids, cur_relid)) >= 0)
 	{
 		RelOptInfo *rel = find_base_rel(root, cur_relid);
 
@@ -140,5 +137,4 @@ remove_join_clause_from_rels(PlannerInfo *root,
 		Assert(list_member_ptr(rel->joininfo, restrictinfo));
 		rel->joininfo = list_delete_ptr(rel->joininfo, restrictinfo);
 	}
-	bms_free(tmprelids);
 }