Repair oversight in 8.2 change that improved the handling of "pseudoconstant"

WHERE clauses.  createplan.c is now willing to stick a gating Result node
almost anywhere in the plan tree, and in particular one can wind up directly
underneath a MergeJoin node.  This means it had better be willing to handle
Mark/Restore.  Fortunately, that's trivial in such cases, since we can just
pass off the call to the input node (which the planner has previously ensured
can handle Mark/Restore).  Per report from Phil Frost.

src/backend/executor/execAmi.c

@@ -6,7 +6,7 @@
  * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- *	$PostgreSQL: pgsql/src/backend/executor/execAmi.c,v 1.90 2007/01/05 22:19:27 momjian Exp $
+ *	$PostgreSQL: pgsql/src/backend/executor/execAmi.c,v 1.91 2007/02/15 03:07:13 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -243,6 +243,10 @@ ExecMarkPos(PlanState *node)
 			ExecSortMarkPos((SortState *) node);
 			break;
 
+		case T_ResultState:
+			ExecResultMarkPos((ResultState *) node);
+			break;
+
 		default:
 			/* don't make hard error unless caller asks to restore... */
 			elog(DEBUG2, "unrecognized node type: %d", (int) nodeTag(node));
@@ -296,6 +300,10 @@ ExecRestrPos(PlanState *node)
 			ExecSortRestrPos((SortState *) node);
 			break;
 
+		case T_ResultState:
+			ExecResultRestrPos((ResultState *) node);
+			break;
+
 		default:
 			elog(ERROR, "unrecognized node type: %d", (int) nodeTag(node));
 			break;
@@ -328,6 +336,16 @@ ExecSupportsMarkRestore(NodeTag plantype)
 		case T_Sort:
 			return true;
 
+		case T_Result:
+			/*
+			 * T_Result only supports mark/restore if it has a child plan
+			 * that does, so we do not have enough information to give a
+			 * really correct answer.  However, for current uses it's
+			 * enough to always say "false", because this routine is not
+			 * asked about gating Result plans, only base-case Results.
+			 */
+			return false;
+
 		default:
 			break;
 	}

src/backend/executor/nodeResult.c

@@ -38,7 +38,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/executor/nodeResult.c,v 1.37 2007/02/02 00:07:03 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/executor/nodeResult.c,v 1.38 2007/02/15 03:07:13 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -166,6 +166,36 @@ ExecResult(ResultState *node)
 	return NULL;
 }
 
+/* ----------------------------------------------------------------
+ *		ExecResultMarkPos
+ * ----------------------------------------------------------------
+ */
+void
+ExecResultMarkPos(ResultState *node)
+{
+	PlanState  *outerPlan = outerPlanState(node);
+
+	if (outerPlan != NULL)
+		ExecMarkPos(outerPlan);
+	else
+		elog(DEBUG2, "Result nodes do not support mark/restore");
+}
+
+/* ----------------------------------------------------------------
+ *		ExecResultRestrPos
+ * ----------------------------------------------------------------
+ */
+void
+ExecResultRestrPos(ResultState *node)
+{
+	PlanState  *outerPlan = outerPlanState(node);
+
+	if (outerPlan != NULL)
+		ExecRestrPos(outerPlan);
+	else
+		elog(ERROR, "Result nodes do not support mark/restore");
+}
+
 /* ----------------------------------------------------------------
  *		ExecInitResult
  *
@@ -180,8 +210,8 @@ ExecInitResult(Result *node, EState *estate, int eflags)
 	ResultState *resstate;
 
 	/* check for unsupported flags */
-	Assert(!(eflags & EXEC_FLAG_MARK));
-	Assert(!(eflags & EXEC_FLAG_BACKWARD) || outerPlan(node) != NULL);
+	Assert(!(eflags & (EXEC_FLAG_MARK | EXEC_FLAG_BACKWARD)) ||
+		   outerPlan(node) != NULL);
 
 	/*
 	 * create state structure

src/include/executor/nodeResult.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/executor/nodeResult.h,v 1.23 2007/01/05 22:19:54 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/executor/nodeResult.h,v 1.24 2007/02/15 03:07:13 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -20,6 +20,8 @@ extern int	ExecCountSlotsResult(Result *node);
 extern ResultState *ExecInitResult(Result *node, EState *estate, int eflags);
 extern TupleTableSlot *ExecResult(ResultState *node);
 extern void ExecEndResult(ResultState *node);
+extern void ExecResultMarkPos(ResultState *node);
+extern void ExecResultRestrPos(ResultState *node);
 extern void ExecReScanResult(ResultState *node, ExprContext *exprCtxt);
 
 #endif   /* NODERESULT_H */