Repair bug #2839: the various ExecReScan functions need to reset

ps_TupFromTlist in plan nodes that make use of it.  This was being done
correctly in join nodes and Result nodes but not in any relation-scan nodes.
Bug would lead to bogus results if a set-returning function appeared in the
targetlist of a subquery that could be rescanned after partial execution,
for example a subquery within EXISTS().  Bug has been around forever :-(
... surprising it wasn't reported before.

src/backend/executor/nodeFunctionscan.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/executor/nodeFunctionscan.c,v 1.12 2002/09/04 20:31:18 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/executor/nodeFunctionscan.c,v 1.12.2.1 2006/12/26 19:27:26 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -361,6 +361,7 @@ ExecFunctionReScan(FunctionScan *node, ExprContext *exprCtxt, Plan *parent)
 	scanstate = (FunctionScanState *) node->scan.scanstate;
 
 	ExecClearTuple(scanstate->csstate.cstate.cs_ResultTupleSlot);
+	scanstate->csstate.cstate.cs_TupFromTlist = false;
 
 	/*
 	 * If we haven't materialized yet, just return.

src/backend/executor/nodeIndexscan.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/executor/nodeIndexscan.c,v 1.71 2002/09/04 20:31:18 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/executor/nodeIndexscan.c,v 1.71.2.1 2006/12/26 19:27:26 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -303,6 +303,8 @@ ExecIndexReScan(IndexScan *node, ExprContext *exprCtxt, Plan *parent)
 	runtimeKeyInfo = indexstate->iss_RuntimeKeyInfo;
 	numScanKeys = indexstate->iss_NumScanKeys;
 
+	node->scan.scanstate->cstate.cs_TupFromTlist = false;
+
 	if (econtext)
 	{
 		/*
@@ -639,6 +641,8 @@ ExecInitIndexScan(IndexScan *node, EState *estate, Plan *parent)
 	 */
 	ExecAssignExprContext(estate, &scanstate->cstate);
 
+	scanstate->cstate.cs_TupFromTlist = false;
+
 #define INDEXSCAN_NSLOTS 2
 
 	/*

src/backend/executor/nodeResult.c

@@ -34,7 +34,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/executor/nodeResult.c,v 1.21 2002/06/20 20:29:28 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/executor/nodeResult.c,v 1.21.2.1 2006/12/26 19:27:26 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -202,6 +202,8 @@ ExecInitResult(Result *node, EState *estate, Plan *parent)
 	 */
 	ExecAssignExprContext(estate, &resstate->cstate);
 
+	resstate->cstate.cs_TupFromTlist = false;
+
 #define RESULT_NSLOTS 1
 
 	/*

src/backend/executor/nodeSeqscan.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/executor/nodeSeqscan.c,v 1.37 2002/09/04 20:31:18 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/executor/nodeSeqscan.c,v 1.37.2.1 2006/12/26 19:27:26 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -318,6 +318,8 @@ ExecSeqReScan(SeqScan *node, ExprContext *exprCtxt, Plan *parent)
 	scanstate = node->scanstate;
 	estate = node->plan.state;
 
+	scanstate->cstate.cs_TupFromTlist = false;
+
 	/* If this is re-scanning of PlanQual ... */
 	if (estate->es_evTuple != NULL &&
 		estate->es_evTuple[node->scanrelid - 1] != NULL)

src/backend/executor/nodeSubqueryscan.c

@@ -12,7 +12,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/executor/nodeSubqueryscan.c,v 1.13 2002/06/20 20:29:28 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/executor/nodeSubqueryscan.c,v 1.13.2.1 2006/12/26 19:27:26 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -259,4 +259,5 @@ ExecSubqueryReScan(SubqueryScan *node, ExprContext *exprCtxt, Plan *parent)
 		ExecReScan(node->subplan, NULL, (Plan *) node);
 
 	subquerystate->csstate.css_ScanTupleSlot = NULL;
+	subquerystate->csstate.cstate.cs_TupFromTlist = false;
 }

src/backend/executor/nodeTidscan.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/executor/nodeTidscan.c,v 1.26 2002/09/04 20:31:18 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/executor/nodeTidscan.c,v 1.26.2.1 2006/12/26 19:27:26 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -254,6 +254,8 @@ ExecTidReScan(TidScan *node, ExprContext *exprCtxt, Plan *parent)
 	tidstate = node->tidstate;
 	tidList = tidstate->tss_TidList;
 
+	node->scan.scanstate->cstate.cs_TupFromTlist = false;
+
 	/* If we are being passed an outer tuple, save it for runtime key calc */
 	if (exprCtxt != NULL)
 		node->scan.scanstate->cstate.cs_ExprContext->ecxt_outertuple =
@@ -411,6 +413,8 @@ ExecInitTidScan(TidScan *node, EState *estate, Plan *parent)
 	 */
 	ExecAssignExprContext(estate, &scanstate->cstate);
 
+	scanstate->cstate.cs_TupFromTlist = false;
+
 #define TIDSCAN_NSLOTS 2
 
 	/*