From cf88f005f2662fd1dec2206d0ce1f3ab316c54e0 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Thu, 18 Dec 2003 22:23:55 +0000
Subject: [PATCH] Use a shutdown callback to clear setArgsValid in a
 FuncExprState that is evaluating a set-valued function.  This fixes some
 additional problems with rescanning partially-evaluated SRFs.

---
 src/backend/executor/execQual.c | 27 ++++++++++++++++++++++++++-
 src/include/nodes/execnodes.h   |  9 ++++++++-
 2 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/src/backend/executor/execQual.c b/src/backend/executor/execQual.c
index 1ee41ddb8ce..0484fd4d583 100644
--- a/src/backend/executor/execQual.c
+++ b/src/backend/executor/execQual.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/executor/execQual.c,v 1.150 2003/10/13 22:47:15 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/executor/execQual.c,v 1.150.2.1 2003/12/18 22:23:54 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -636,9 +636,26 @@ init_fcache(Oid foid, FuncExprState *fcache, MemoryContext fcacheCxt)
 
 	/* Initialize additional info */
 	fcache->setArgsValid = false;
+	fcache->shutdown_reg = false;
 	fcache->func.fn_expr = (Node *) fcache->xprstate.expr;
 }
 
+/*
+ * callback function in case a FuncExpr returning a set needs to be shut down
+ * before it has been run to completion
+ */
+static void
+ShutdownFuncExpr(Datum arg)
+{
+	FuncExprState *fcache = (FuncExprState *) DatumGetPointer(arg);
+
+	/* Clear any active set-argument state */
+	fcache->setArgsValid = false;
+
+	/* execUtils will deregister the callback... */
+	fcache->shutdown_reg = false;
+}
+
 /*
  * Evaluate arguments for a function.
  */
@@ -827,6 +844,14 @@ ExecMakeFunctionResult(FuncExprState *fcache,
 					memcpy(&fcache->setArgs, &fcinfo, sizeof(fcinfo));
 					fcache->setHasSetArg = hasSetArg;
 					fcache->setArgsValid = true;
+					/* Register cleanup callback if we didn't already */
+					if (!fcache->shutdown_reg)
+					{
+						RegisterExprContextCallback(econtext,
+													ShutdownFuncExpr,
+													PointerGetDatum(fcache));
+						fcache->shutdown_reg = true;
+					}
 				}
 
 				/*
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index 4112cd49de6..fea27f9df20 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: execnodes.h,v 1.107 2003/10/01 21:30:52 tgl Exp $
+ * $Id: execnodes.h,v 1.107.2.1 2003/12/18 22:23:55 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -481,6 +481,13 @@ typedef struct FuncExprState
 	 */
 	bool		setHasSetArg;	/* some argument returns a set */
 
+	/*
+	 * Flag to remember whether we have registered a shutdown callback for
+	 * this FuncExprState.  We do so only if setArgsValid has been true at
+	 * least once (since all the callback is for is to clear setArgsValid).
+	 */
+	bool		shutdown_reg;	/* a shutdown callback is registered */
+
 	/*
 	 * Current argument data for a set-valued function; contains valid
 	 * data only if setArgsValid is true.