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/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index ca9bd4f7c7f..edbd09f9425 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -184,15 +184,13 @@ _outList(StringInfo str, const List *node)
 static void
 _outBitmapset(StringInfo str, const Bitmapset *bms)
 {
-	Bitmapset  *tmpset;
 	int			x;
 
 	appendStringInfoChar(str, '(');
 	appendStringInfoChar(str, 'b');
-	tmpset = bms_copy(bms);
-	while ((x = bms_first_member(tmpset)) >= 0)
+	x = -1;
+	while ((x = bms_next_member(bms, x)) >= 0)
 		appendStringInfo(str, " %d", x);
-	bms_free(tmpset);
 	appendStringInfoChar(str, ')');
 }