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, 22 insertions, 3 deletions

diff --git a/src/backend/executor/nodeTidscan.c b/src/backend/executor/nodeTidscan.c
index 9b6724537e7..986ff1f3f19 100644
--- a/src/backend/executor/nodeTidscan.c
+++ b/src/backend/executor/nodeTidscan.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/executor/nodeTidscan.c,v 1.53 2007/01/05 22:19:28 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/executor/nodeTidscan.c,v 1.54 2007/06/11 01:16:22 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -61,8 +61,8 @@ TidListCreate(TidScanState *tidstate)
 
 	/*
 	 * We initialize the array with enough slots for the case that all quals
-	 * are simple OpExprs.	If there's any ScalarArrayOpExprs, we may have to
-	 * enlarge the array.
+	 * are simple OpExprs or CurrentOfExprs.  If there are any
+	 * ScalarArrayOpExprs, we may have to enlarge the array.
 	 */
 	numAllocTids = list_length(evalList);
 	tidList = (ItemPointerData *)
@@ -148,6 +148,25 @@ TidListCreate(TidScanState *tidstate)
 			pfree(ipdatums);
 			pfree(ipnulls);
 		}
+		else if (expr && IsA(expr, CurrentOfExpr))
+		{
+			CurrentOfExpr *cexpr = (CurrentOfExpr *) expr;
+			ItemPointerData cursor_tid;
+
+			if (execCurrentOf(cexpr->cursor_name,
+						  RelationGetRelid(tidstate->ss.ss_currentRelation),
+							  &cursor_tid))
+			{
+				if (numTids >= numAllocTids)
+				{
+					numAllocTids *= 2;
+					tidList = (ItemPointerData *)
+						repalloc(tidList,
+								 numAllocTids * sizeof(ItemPointerData));
+				}
+				tidList[numTids++] = cursor_tid;
+			}
+		}
 		else
 			elog(ERROR, "could not identify CTID expression");
 	}