Support UPDATE/DELETE WHERE CURRENT OF cursor_name, per SQL standard.

Along the way, allow FOR UPDATE in non-WITH-HOLD cursors; there may once
have been a reason to disallow that, but it seems to work now, and it's
really rather necessary if you want to select a row via a cursor and then
update it in a concurrent-safe fashion.

Original patch by Arul Shaji, rather heavily editorialized by Tom Lane.

1 files changed, 9 insertions, 1 deletions

diff --git a/src/backend/optimizer/prep/prepunion.c b/src/backend/optimizer/prep/prepunion.c
index 2b273f738a..5e80dc1559 100644
--- a/src/backend/optimizer/prep/prepunion.c
+++ b/src/backend/optimizer/prep/prepunion.c
@@ -22,7 +22,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/prep/prepunion.c,v 1.141 2007/04/21 05:56:41 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/prep/prepunion.c,v 1.142 2007/06/11 01:16:23 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1132,6 +1132,14 @@ adjust_appendrel_attrs_mutator(Node *node, AppendRelInfo *context)
 		}
 		return (Node *) var;
 	}
+	if (IsA(node, CurrentOfExpr))
+	{
+		CurrentOfExpr *cexpr = (CurrentOfExpr *) copyObject(node);
+
+		if (cexpr->cvarno == context->parent_relid)
+			cexpr->cvarno = context->child_relid;
+		return (Node *) cexpr;
+	}
 	if (IsA(node, RangeTblRef))
 	{
 		RangeTblRef *rtr = (RangeTblRef *) copyObject(node);