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, 7 insertions, 9 deletions

diff --git a/contrib/sepgsql/dml.c b/contrib/sepgsql/dml.c
index bb82c0d6d2..9e9fa04746 100644
--- a/contrib/sepgsql/dml.c
+++ b/contrib/sepgsql/dml.c
@@ -93,10 +93,7 @@ fixup_whole_row_references(Oid relOid, Bitmapset *columns)
 static Bitmapset *
 fixup_inherited_columns(Oid parentId, Oid childId, Bitmapset *columns)
 {
-	AttrNumber	attno;
-	Bitmapset  *tmpset;
 	Bitmapset  *result = NULL;
-	char	   *attname;
 	int			index;
 
 	/*
@@ -105,10 +102,12 @@ fixup_inherited_columns(Oid parentId, Oid childId, Bitmapset *columns)
 	if (parentId == childId)
 		return columns;
 
-	tmpset = bms_copy(columns);
-	while ((index = bms_first_member(tmpset)) > 0)
+	index = -1;
+	while ((index = bms_next_member(columns, index)) >= 0)
 	{
-		attno = index + FirstLowInvalidHeapAttributeNumber;
+		/* bit numbers are offset by FirstLowInvalidHeapAttributeNumber */
+		AttrNumber	attno = index + FirstLowInvalidHeapAttributeNumber;
+		char	   *attname;
 
 		/*
 		 * whole-row-reference shall be fixed-up later
@@ -128,12 +127,11 @@ fixup_inherited_columns(Oid parentId, Oid childId, Bitmapset *columns)
 			elog(ERROR, "cache lookup failed for attribute %s of relation %u",
 				 attname, childId);
 
-		index = attno - FirstLowInvalidHeapAttributeNumber;
-		result = bms_add_member(result, index);
+		result = bms_add_member(result,
+								attno - FirstLowInvalidHeapAttributeNumber);
 
 		pfree(attname);
 	}
-	bms_free(tmpset);
 
 	return result;
 }