Append and SubqueryScan nodes were not passing changed-parameter signals down

to their children, leading to misbehavior if they had any children that paid
attention to chgParam (most plan node types don't).  Append's bug has been
there a long time, but nobody had noticed because it used to be difficult
to create a query where an Append would be used below the top level of a
plan; so there were never any parameters getting passed down.  SubqueryScan
is new in 7.1 ... and I'd modeled its behavior on Append :-(

Author: tglsfdc

src/backend/executor/nodeAppend.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/executor/nodeAppend.c,v 1.40 2001/03/22 06:16:12 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/executor/nodeAppend.c,v 1.41 2001/05/08 19:47:02 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -362,14 +362,25 @@ ExecReScanAppend(Append *node, ExprContext *exprCtxt, Plan *parent)
 
 	for (i = 0; i < nplans; i++)
 	{
-		Plan	   *rescanNode;
+		Plan	   *subnode;
 
-		appendstate->as_whichplan = i;
-		rescanNode = (Plan *) nth(i, node->appendplans);
-		if (rescanNode->chgParam == NULL)
+		subnode = (Plan *) nth(i, node->appendplans);
+		/*
+		 * ExecReScan doesn't know about my subplans, so I have to do
+		 * changed-parameter signaling myself.
+		 */
+		if (node->plan.chgParam != NULL)
+			SetChangedParamList(subnode, node->plan.chgParam);
+		/*
+		 * if chgParam of subnode is not null then plan will be re-scanned by
+		 * first ExecProcNode.
+		 */
+		if (subnode->chgParam == NULL)
 		{
+			/* make sure estate is correct for this subnode (needed??) */
+			appendstate->as_whichplan = i;
 			exec_append_initialize_next(node);
-			ExecReScan((Plan *) rescanNode, exprCtxt, (Plan *) node);
+			ExecReScan(subnode, exprCtxt, (Plan *) node);
 		}
 	}
 	appendstate->as_whichplan = 0;

src/backend/executor/nodeSubqueryscan.c

@@ -12,7 +12,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/executor/nodeSubqueryscan.c,v 1.6 2001/03/22 06:16:13 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/executor/nodeSubqueryscan.c,v 1.7 2001/05/08 19:47:02 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -267,7 +267,18 @@ ExecSubqueryReScan(SubqueryScan *node, ExprContext *exprCtxt, Plan *parent)
 		return;
 	}
 
-	ExecReScan(node->subplan, NULL, node->subplan);
+	/*
+	 * ExecReScan doesn't know about my subplan, so I have to do
+	 * changed-parameter signaling myself.
+	 */
+	if (node->scan.plan.chgParam != NULL)
+		SetChangedParamList(node->subplan, node->scan.plan.chgParam);
+	/*
+	 * if chgParam of subnode is not null then plan will be re-scanned by
+	 * first ExecProcNode.
+	 */
+	if (node->subplan->chgParam == NULL)
+		ExecReScan(node->subplan, NULL, node->subplan);
 
 	subquerystate->csstate.css_ScanTupleSlot = NULL;
 }