When using a junkfilter, the output tuple should NOT be stored back into

the same tuple slot that the raw tuple came from, because that slot has
the wrong tuple descriptor.  Store it into its own slot with the correct
descriptor, instead.  This repairs problems with SPI functions seeing
inappropriate tuple descriptors --- for example, plpgsql code failing to
cope with SELECT FOR UPDATE.

src/backend/executor/execJunk.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/executor/execJunk.c,v 1.27 2001/03/22 06:16:12 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/executor/execJunk.c,v 1.28 2001/05/27 20:48:51 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -56,10 +56,12 @@
  * Initialize the Junk filter.
  *
  * The initial targetlist and associated tuple descriptor are passed in.
+ * An optional resultSlot can be passed as well.
  *-------------------------------------------------------------------------
  */
 JunkFilter *
-ExecInitJunkFilter(List *targetList, TupleDesc tupType)
+ExecInitJunkFilter(List *targetList, TupleDesc tupType,
+				   TupleTableSlot *slot)
 {
 	MemoryContext oldContext;
 	MemoryContext junkContext;
@@ -245,6 +247,10 @@ ExecInitJunkFilter(List *targetList, TupleDesc tupType)
 	junkfilter->jf_cleanTupType = cleanTupType;
 	junkfilter->jf_cleanMap = cleanMap;
 	junkfilter->jf_junkContext = junkContext;
+	junkfilter->jf_resultSlot = slot;
+
+	if (slot)
+		ExecSetSlotDescriptor(slot, cleanTupType, false);
 
 	MemoryContextSwitchTo(oldContext);
 
@@ -260,7 +266,6 @@ ExecInitJunkFilter(List *targetList, TupleDesc tupType)
 void
 ExecFreeJunkFilter(JunkFilter *junkfilter)
 {
-
 	/*
 	 * Since the junkfilter is inside its own context, we just have to
 	 * delete the context and we're set.
@@ -336,6 +341,10 @@ ExecGetJunkAttribute(JunkFilter *junkfilter,
  * ExecRemoveJunk
  *
  * Construct and return a tuple with all the junk attributes removed.
+ *
+ * Note: for historical reasons, this does not store the constructed
+ * tuple into the junkfilter's resultSlot.  The caller should do that
+ * if it wants to.
  *-------------------------------------------------------------------------
  */
 HeapTuple

src/backend/executor/execMain.c

@@ -27,7 +27,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/executor/execMain.c,v 1.141 2001/05/27 09:59:29 petere Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/executor/execMain.c,v 1.142 2001/05/27 20:48:51 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -598,12 +598,19 @@ InitPlan(CmdType operation, Query *parseTree, Plan *plan, EState *estate)
 	}
 
 	/*
-	 * initialize the executor "tuple" table.
+	 * initialize the executor "tuple" table.  We need slots for all the
+	 * plan nodes, plus possibly output slots for the junkfilter(s).
+	 * At this point we aren't sure if we need junkfilters, so just add
+	 * slots for them unconditionally.
 	 */
 	{
 		int			nSlots = ExecCountSlotsNode(plan);
 
-		estate->es_tupleTable = ExecCreateTupleTable(nSlots + 10); /* why add ten? - jolly */
+		if (parseTree->resultRelations != NIL)
+			nSlots += length(parseTree->resultRelations);
+		else
+			nSlots += 1;
+		estate->es_tupleTable = ExecCreateTupleTable(nSlots);
 	}
 
 	/* mark EvalPlanQual not active */
@@ -686,7 +693,8 @@ InitPlan(CmdType operation, Query *parseTree, Plan *plan, EState *estate)
 					JunkFilter *j;
 
 					j = ExecInitJunkFilter(subplan->targetlist,
-										   ExecGetTupType(subplan));
+										   ExecGetTupType(subplan),
+										   ExecAllocTableSlot(estate->es_tupleTable));
 					resultRelInfo->ri_junkFilter = j;
 					resultRelInfo++;
 					subplans = lnext(subplans);
@@ -702,9 +710,11 @@ InitPlan(CmdType operation, Query *parseTree, Plan *plan, EState *estate)
 			else
 			{
 				/* Normal case with just one JunkFilter */
-				JunkFilter *j = ExecInitJunkFilter(plan->targetlist,
-												   tupType);
+				JunkFilter *j;
 
+				j = ExecInitJunkFilter(plan->targetlist,
+									   tupType,
+									   ExecAllocTableSlot(estate->es_tupleTable));
 				estate->es_junkFilter = j;
 				if (estate->es_result_relation_info)
 					estate->es_result_relation_info->ri_junkFilter = j;
@@ -986,7 +996,9 @@ lnext:	;
 		 * if we have a junk filter, then project a new tuple with the
 		 * junk removed.
 		 *
-		 * Store this new "clean" tuple in the place of the original tuple.
+		 * Store this new "clean" tuple in the junkfilter's resultSlot.
+		 * (Formerly, we stored it back over the "dirty" tuple, which is
+		 * WRONG because that tuple slot has the wrong descriptor.)
 		 *
 		 * Also, extract all the junk information we need.
 		 */
@@ -1088,7 +1100,7 @@ lnext:	;
 			newTuple = ExecRemoveJunk(junkfilter, slot);
 
 			slot = ExecStoreTuple(newTuple,		/* tuple to store */
-								  slot, /* destination slot */
+								  junkfilter->jf_resultSlot, /* dest slot */
 								  InvalidBuffer,		/* this tuple has no
 														 * buffer */
 								  true);		/* tuple should be pfreed */
@@ -1467,7 +1479,9 @@ lreplace:;
 				{
 					*tupleid = ctid;
 					tuple = ExecRemoveJunk(estate->es_junkFilter, epqslot);
-					slot = ExecStoreTuple(tuple, slot, InvalidBuffer, true);
+					slot = ExecStoreTuple(tuple,
+										  estate->es_junkFilter->jf_resultSlot,
+										  InvalidBuffer, true);
 					goto lreplace;
 				}
 			}

src/include/executor/executor.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: executor.h,v 1.57 2001/03/22 04:00:44 momjian Exp $
+ * $Id: executor.h,v 1.58 2001/05/27 20:48:51 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -43,7 +43,8 @@ extern void ExecRestrPos(Plan *node);
 /*
  * prototypes from functions in execJunk.c
  */
-extern JunkFilter *ExecInitJunkFilter(List *targetList, TupleDesc tupType);
+extern JunkFilter *ExecInitJunkFilter(List *targetList, TupleDesc tupType,
+									  TupleTableSlot *slot);
 extern void ExecFreeJunkFilter(JunkFilter *junkfilter);
 extern bool ExecGetJunkAttribute(JunkFilter *junkfilter, TupleTableSlot *slot,
 					 char *attrName, Datum *value, bool *isNull);

src/include/nodes/execnodes.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: execnodes.h,v 1.59 2001/05/15 00:33:36 tgl Exp $
+ * $Id: execnodes.h,v 1.60 2001/05/27 20:48:51 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -166,17 +166,19 @@ typedef struct ProjectionInfo
  *	  cleanLength:		the length of 'cleanTargetList'
  *	  cleanTupType:		the tuple descriptor of the "clean" tuple (with
  *						junk attributes removed).
- *	  cleanMap:			A map with the correspondance between the non-junk
- *						attributes of the "original" tuple and the
- *						attributes of the "clean" tuple.
+ *	  cleanMap:			A map with the correspondence between the non-junk
+ *						attribute numbers of the "original" tuple and the
+ *						attribute numbers of the "clean" tuple.
  *	  junkContext:		memory context holding the JunkFilter node and all
  *						its subsidiary data structures.
- *
- * NOTE: the original targetList and tupType are passed to ExecInitJunkFilter
- * and do not belong to the JunkFilter.  All the other subsidiary structures
- * are created during ExecInitJunkFilter, and all of them can be freed by
- * deleting the memory context junkContext.  This would not be needed if we
- * had a cleaner approach to managing query-lifetime data structures...
+ *	  resultSlot:		tuple slot that can be used to hold cleaned tuple.
+ *
+ * NOTE: the original targetList and tupType are passed to ExecInitJunkFilter,
+ * as is the resultSlot.  These items do not belong to the JunkFilter.  All
+ * the other subsidiary structures are created during ExecInitJunkFilter,
+ * and all of them can be freed by deleting the memory context junkContext.
+ * This would not be needed if we had a cleaner approach to managing
+ * query-lifetime data structures...
  * ----------------
  */
 typedef struct JunkFilter
@@ -190,6 +192,7 @@ typedef struct JunkFilter
 	TupleDesc	jf_cleanTupType;
 	AttrNumber *jf_cleanMap;
 	MemoryContext jf_junkContext;
+	TupleTableSlot *jf_resultSlot;
 } JunkFilter;
 
 /* ----------------