Fix PlanRowMark/ExecRowMark structures to handle inheritance correctly.

In an inherited UPDATE/DELETE, each target table has its own subplan,
because it might have a column set different from other targets.  This
means that the resjunk columns we add to support EvalPlanQual might be
at different physical column numbers in each subplan.  The EvalPlanQual
rewrite I did for 9.0 failed to account for this, resulting in possible
misbehavior or even crashes during concurrent updates to the same row,
as seen in a recent report from Gordon Shannon.  Revise the data structure
so that we track resjunk column numbers separately for each subplan.

I also chose to move responsibility for identifying the physical column
numbers back to executor startup, instead of assuming that numbers derived
during preprocess_targetlist would stay valid throughout subsequent
massaging of the plan.  That's a bit slower, so we might want to consider
undoing it someday; but it would complicate the patch considerably and
didn't seem justifiable in a bug fix that has to be back-patched to 9.0.

src/backend/executor/execJunk.c

@@ -207,10 +207,22 @@ ExecInitJunkFilterConversion(List *targetList,
  */
 AttrNumber
 ExecFindJunkAttribute(JunkFilter *junkfilter, const char *attrName)
+{
+	return ExecFindJunkAttributeInTlist(junkfilter->jf_targetList, attrName);
+}
+
+/*
+ * ExecFindJunkAttributeInTlist
+ *
+ * Find a junk attribute given a subplan's targetlist (not necessarily
+ * part of a JunkFilter).
+ */
+AttrNumber
+ExecFindJunkAttributeInTlist(List *targetlist, const char *attrName)
 {
 	ListCell   *t;
 
-	foreach(t, junkfilter->jf_targetList)
+	foreach(t, targetlist)
 	{
 		TargetEntry *tle = lfirst(t);
 

src/backend/executor/execMain.c

@@ -744,9 +744,6 @@ InitPlan(QueryDesc *queryDesc, int eflags)
 		erm->prti = rc->prti;
 		erm->markType = rc->markType;
 		erm->noWait = rc->noWait;
-		erm->ctidAttNo = rc->ctidAttNo;
-		erm->toidAttNo = rc->toidAttNo;
-		erm->wholeAttNo = rc->wholeAttNo;
 		ItemPointerSetInvalid(&(erm->curCtid));
 		estate->es_rowMarks = lappend(estate->es_rowMarks, erm);
 	}
@@ -1386,6 +1383,71 @@ ExecConstraints(ResultRelInfo *resultRelInfo,
 }
 
 
+/*
+ * ExecFindRowMark -- find the ExecRowMark struct for given rangetable index
+ */
+ExecRowMark *
+ExecFindRowMark(EState *estate, Index rti)
+{
+	ListCell   *lc;
+
+	foreach(lc, estate->es_rowMarks)
+	{
+		ExecRowMark *erm = (ExecRowMark *) lfirst(lc);
+
+		if (erm->rti == rti)
+			return erm;
+	}
+	elog(ERROR, "failed to find ExecRowMark for rangetable index %u", rti);
+	return NULL;				/* keep compiler quiet */
+}
+
+/*
+ * ExecBuildAuxRowMark -- create an ExecAuxRowMark struct
+ *
+ * Inputs are the underlying ExecRowMark struct and the targetlist of the
+ * input plan node (not planstate node!).  We need the latter to find out
+ * the column numbers of the resjunk columns.
+ */
+ExecAuxRowMark *
+ExecBuildAuxRowMark(ExecRowMark *erm, List *targetlist)
+{
+	ExecAuxRowMark *aerm = (ExecAuxRowMark *) palloc0(sizeof(ExecAuxRowMark));
+	char		resname[32];
+
+	aerm->rowmark = erm;
+
+	/* Look up the resjunk columns associated with this rowmark */
+	if (erm->relation)
+	{
+		Assert(erm->markType != ROW_MARK_COPY);
+
+		/* if child rel, need tableoid */
+		if (erm->rti != erm->prti)
+		{
+			snprintf(resname, sizeof(resname), "tableoid%u", erm->prti);
+			aerm->toidAttNo = ExecFindJunkAttributeInTlist(targetlist,
+														   resname);
+		}
+
+		/* always need ctid for real relations */
+		snprintf(resname, sizeof(resname), "ctid%u", erm->prti);
+		aerm->ctidAttNo = ExecFindJunkAttributeInTlist(targetlist,
+													   resname);
+	}
+	else
+	{
+		Assert(erm->markType == ROW_MARK_COPY);
+
+		snprintf(resname, sizeof(resname), "wholerow%u", erm->prti);
+		aerm->wholeAttNo = ExecFindJunkAttributeInTlist(targetlist,
+														resname);
+	}
+
+	return aerm;
+}
+
+
 /*
  * EvalPlanQual logic --- recheck modified tuple(s) to see if we want to
  * process the updated version under READ COMMITTED rules.
@@ -1676,11 +1738,13 @@ EvalPlanQualFetch(EState *estate, Relation relation, int lockmode,
 /*
  * EvalPlanQualInit -- initialize during creation of a plan state node
  * that might need to invoke EPQ processing.
- * Note: subplan can be NULL if it will be set later with EvalPlanQualSetPlan.
+ *
+ * Note: subplan/auxrowmarks can be NULL/NIL if they will be set later
+ * with EvalPlanQualSetPlan.
  */
 void
 EvalPlanQualInit(EPQState *epqstate, EState *estate,
-				 Plan *subplan, int epqParam)
+				 Plan *subplan, List *auxrowmarks, int epqParam)
 {
 	/* Mark the EPQ state inactive */
 	epqstate->estate = NULL;
@@ -1688,7 +1752,7 @@ EvalPlanQualInit(EPQState *epqstate, EState *estate,
 	epqstate->origslot = NULL;
 	/* ... and remember data that EvalPlanQualBegin will need */
 	epqstate->plan = subplan;
-	epqstate->rowMarks = NIL;
+	epqstate->arowMarks = auxrowmarks;
 	epqstate->epqParam = epqParam;
 }
 
@@ -1698,25 +1762,14 @@ EvalPlanQualInit(EPQState *epqstate, EState *estate,
  * We need this so that ModifyTuple can deal with multiple subplans.
  */
 void
-EvalPlanQualSetPlan(EPQState *epqstate, Plan *subplan)
+EvalPlanQualSetPlan(EPQState *epqstate, Plan *subplan, List *auxrowmarks)
 {
 	/* If we have a live EPQ query, shut it down */
 	EvalPlanQualEnd(epqstate);
 	/* And set/change the plan pointer */
 	epqstate->plan = subplan;
-}
-
-/*
- * EvalPlanQualAddRowMark -- add an ExecRowMark that EPQ needs to handle.
- *
- * Currently, only non-locking RowMarks are supported.
- */
-void
-EvalPlanQualAddRowMark(EPQState *epqstate, ExecRowMark *erm)
-{
-	if (RowMarkRequiresRowShareLock(erm->markType))
-		elog(ERROR, "EvalPlanQual doesn't support locking rowmarks");
-	epqstate->rowMarks = lappend(epqstate->rowMarks, erm);
+	/* The rowmarks depend on the plan, too */
+	epqstate->arowMarks = auxrowmarks;
 }
 
 /*
@@ -1766,13 +1819,17 @@ EvalPlanQualFetchRowMarks(EPQState *epqstate)
 
 	Assert(epqstate->origslot != NULL);
 
-	foreach(l, epqstate->rowMarks)
+	foreach(l, epqstate->arowMarks)
 	{
-		ExecRowMark *erm = (ExecRowMark *) lfirst(l);
+		ExecAuxRowMark *aerm = (ExecAuxRowMark *) lfirst(l);
+		ExecRowMark *erm = aerm->rowmark;
 		Datum		datum;
 		bool		isNull;
 		HeapTupleData tuple;
 
+		if (RowMarkRequiresRowShareLock(erm->markType))
+			elog(ERROR, "EvalPlanQual doesn't support locking rowmarks");
+
 		/* clear any leftover test tuple for this rel */
 		EvalPlanQualSetTuple(epqstate, erm->rti, NULL);
 
@@ -1788,7 +1845,7 @@ EvalPlanQualFetchRowMarks(EPQState *epqstate)
 				Oid			tableoid;
 
 				datum = ExecGetJunkAttribute(epqstate->origslot,
-											 erm->toidAttNo,
+											 aerm->toidAttNo,
 											 &isNull);
 				/* non-locked rels could be on the inside of outer joins */
 				if (isNull)
@@ -1804,7 +1861,7 @@ EvalPlanQualFetchRowMarks(EPQState *epqstate)
 
 			/* fetch the tuple's ctid */
 			datum = ExecGetJunkAttribute(epqstate->origslot,
-										 erm->ctidAttNo,
+										 aerm->ctidAttNo,
 										 &isNull);
 			/* non-locked rels could be on the inside of outer joins */
 			if (isNull)
@@ -1829,7 +1886,7 @@ EvalPlanQualFetchRowMarks(EPQState *epqstate)
 
 			/* fetch the whole-row Var for the relation */
 			datum = ExecGetJunkAttribute(epqstate->origslot,
-										 erm->wholeAttNo,
+										 aerm->wholeAttNo,
 										 &isNull);
 			/* non-locked rels could be on the inside of outer joins */
 			if (isNull)

src/backend/executor/nodeLockRows.c

@@ -58,12 +58,13 @@ lnext:
 
 	/*
 	 * Attempt to lock the source tuple(s).  (Note we only have locking
-	 * rowmarks in lr_rowMarks.)
+	 * rowmarks in lr_arowMarks.)
 	 */
 	epq_started = false;
-	foreach(lc, node->lr_rowMarks)
+	foreach(lc, node->lr_arowMarks)
 	{
-		ExecRowMark *erm = (ExecRowMark *) lfirst(lc);
+		ExecAuxRowMark *aerm = (ExecAuxRowMark *) lfirst(lc);
+		ExecRowMark *erm = aerm->rowmark;
 		Datum		datum;
 		bool		isNull;
 		HeapTupleData tuple;
@@ -84,7 +85,7 @@ lnext:
 			Oid			tableoid;
 
 			datum = ExecGetJunkAttribute(slot,
-										 erm->toidAttNo,
+										 aerm->toidAttNo,
 										 &isNull);
 			/* shouldn't ever get a null result... */
 			if (isNull)
@@ -101,7 +102,7 @@ lnext:
 
 		/* fetch the tuple's ctid */
 		datum = ExecGetJunkAttribute(slot,
-									 erm->ctidAttNo,
+									 aerm->ctidAttNo,
 									 &isNull);
 		/* shouldn't ever get a null result... */
 		if (isNull)
@@ -189,9 +190,10 @@ lnext:
 		 * so as to avoid overhead in the common case where there are no
 		 * concurrent updates.)
 		 */
-		foreach(lc, node->lr_rowMarks)
+		foreach(lc, node->lr_arowMarks)
 		{
-			ExecRowMark *erm = (ExecRowMark *) lfirst(lc);
+			ExecAuxRowMark *aerm = (ExecAuxRowMark *) lfirst(lc);
+			ExecRowMark *erm = aerm->rowmark;
 			HeapTupleData tuple;
 			Buffer		buffer;
 
@@ -251,6 +253,7 @@ ExecInitLockRows(LockRows *node, EState *estate, int eflags)
 {
 	LockRowsState *lrstate;
 	Plan	   *outerPlan = outerPlan(node);
+	List	   *epq_arowmarks;
 	ListCell   *lc;
 
 	/* check for unsupported flags */
@@ -262,7 +265,6 @@ ExecInitLockRows(LockRows *node, EState *estate, int eflags)
 	lrstate = makeNode(LockRowsState);
 	lrstate->ps.plan = (Plan *) node;
 	lrstate->ps.state = estate;
-	EvalPlanQualInit(&lrstate->lr_epqstate, estate, outerPlan, node->epqParam);
 
 	/*
 	 * Miscellaneous initialization
@@ -288,15 +290,17 @@ ExecInitLockRows(LockRows *node, EState *estate, int eflags)
 	lrstate->ps.ps_ProjInfo = NULL;
 
 	/*
-	 * Locate the ExecRowMark(s) that this node is responsible for. (InitPlan
-	 * should already have built the global list of ExecRowMarks.)
+	 * Locate the ExecRowMark(s) that this node is responsible for, and
+	 * construct ExecAuxRowMarks for them.  (InitPlan should already have
+	 * built the global list of ExecRowMarks.)
 	 */
-	lrstate->lr_rowMarks = NIL;
+	lrstate->lr_arowMarks = NIL;
+	epq_arowmarks = NIL;
 	foreach(lc, node->rowMarks)
 	{
 		PlanRowMark *rc = (PlanRowMark *) lfirst(lc);
-		ExecRowMark *erm = NULL;
-		ListCell   *lce;
+		ExecRowMark *erm;
+		ExecAuxRowMark *aerm;
 
 		Assert(IsA(rc, PlanRowMark));
 
@@ -304,16 +308,9 @@ ExecInitLockRows(LockRows *node, EState *estate, int eflags)
 		if (rc->isParent)
 			continue;
 
-		foreach(lce, estate->es_rowMarks)
-		{
-			erm = (ExecRowMark *) lfirst(lce);
-			if (erm->rti == rc->rti)
-				break;
-			erm = NULL;
-		}
-		if (erm == NULL)
-			elog(ERROR, "failed to find ExecRowMark for PlanRowMark %u",
-				 rc->rti);
+		/* find ExecRowMark and build ExecAuxRowMark */
+		erm = ExecFindRowMark(estate, rc->rti);
+		aerm = ExecBuildAuxRowMark(erm, outerPlan->targetlist);
 
 		/*
 		 * Only locking rowmarks go into our own list.	Non-locking marks are
@@ -322,11 +319,15 @@ ExecInitLockRows(LockRows *node, EState *estate, int eflags)
 		 * do an EPQ recheck.
 		 */
 		if (RowMarkRequiresRowShareLock(erm->markType))
-			lrstate->lr_rowMarks = lappend(lrstate->lr_rowMarks, erm);
+			lrstate->lr_arowMarks = lappend(lrstate->lr_arowMarks, aerm);
 		else
-			EvalPlanQualAddRowMark(&lrstate->lr_epqstate, erm);
+			epq_arowmarks = lappend(epq_arowmarks, aerm);
 	}
 
+	/* Now we have the info needed to set up EPQ state */
+	EvalPlanQualInit(&lrstate->lr_epqstate, estate,
+					 outerPlan, epq_arowmarks, node->epqParam);
+
 	return lrstate;
 }
 

src/backend/executor/nodeModifyTable.c

@@ -824,7 +824,8 @@ ExecModifyTable(ModifyTableState *node)
 				estate->es_result_relation_info++;
 				subplanstate = node->mt_plans[node->mt_whichplan];
 				junkfilter = estate->es_result_relation_info->ri_junkFilter;
-				EvalPlanQualSetPlan(&node->mt_epqstate, subplanstate->plan);
+				EvalPlanQualSetPlan(&node->mt_epqstate, subplanstate->plan,
+									node->mt_arowmarks[node->mt_whichplan]);
 				continue;
 			}
 			else
@@ -953,10 +954,11 @@ ExecInitModifyTable(ModifyTable *node, EState *estate, int eflags)
 	mtstate->ps.targetlist = NIL;		/* not actually used */
 
 	mtstate->mt_plans = (PlanState **) palloc0(sizeof(PlanState *) * nplans);
+	mtstate->mt_arowmarks = (List **) palloc0(sizeof(List *) * nplans);
 	mtstate->mt_nplans = nplans;
 	mtstate->operation = operation;
-	/* set up epqstate with dummy subplan pointer for the moment */
-	EvalPlanQualInit(&mtstate->mt_epqstate, estate, NULL, node->epqParam);
+	/* set up epqstate with dummy subplan data for the moment */
+	EvalPlanQualInit(&mtstate->mt_epqstate, estate, NULL, NIL, node->epqParam);
 	mtstate->fireBSTriggers = true;
 
 	/* For the moment, assume our targets are exactly the global result rels */
@@ -978,11 +980,6 @@ ExecInitModifyTable(ModifyTable *node, EState *estate, int eflags)
 	}
 	estate->es_result_relation_info = NULL;
 
-	/* select first subplan */
-	mtstate->mt_whichplan = 0;
-	subplan = (Plan *) linitial(node->plans);
-	EvalPlanQualSetPlan(&mtstate->mt_epqstate, subplan);
-
 	/*
 	 * Initialize RETURNING projections if needed.
 	 */
@@ -1046,8 +1043,7 @@ ExecInitModifyTable(ModifyTable *node, EState *estate, int eflags)
 	foreach(l, node->rowMarks)
 	{
 		PlanRowMark *rc = (PlanRowMark *) lfirst(l);
-		ExecRowMark *erm = NULL;
-		ListCell   *lce;
+		ExecRowMark *erm;
 
 		Assert(IsA(rc, PlanRowMark));
 
@@ -1055,20 +1051,26 @@ ExecInitModifyTable(ModifyTable *node, EState *estate, int eflags)
 		if (rc->isParent)
 			continue;
 
-		foreach(lce, estate->es_rowMarks)
+		/* find ExecRowMark (same for all subplans) */
+		erm = ExecFindRowMark(estate, rc->rti);
+
+		/* build ExecAuxRowMark for each subplan */
+		for (i = 0; i < nplans; i++)
 		{
-			erm = (ExecRowMark *) lfirst(lce);
-			if (erm->rti == rc->rti)
-				break;
-			erm = NULL;
-		}
-		if (erm == NULL)
-			elog(ERROR, "failed to find ExecRowMark for PlanRowMark %u",
-				 rc->rti);
+			ExecAuxRowMark *aerm;
 
-		EvalPlanQualAddRowMark(&mtstate->mt_epqstate, erm);
+			subplan = mtstate->mt_plans[i]->plan;
+			aerm = ExecBuildAuxRowMark(erm, subplan->targetlist);
+			mtstate->mt_arowmarks[i] = lappend(mtstate->mt_arowmarks[i], aerm);
+		}
 	}
 
+	/* select first subplan */
+	mtstate->mt_whichplan = 0;
+	subplan = (Plan *) linitial(node->plans);
+	EvalPlanQualSetPlan(&mtstate->mt_epqstate, subplan,
+						mtstate->mt_arowmarks[0]);
+
 	/*
 	 * Initialize the junk filter(s) if needed.  INSERT queries need a filter
 	 * if there are any junk attrs in the tlist.  UPDATE and DELETE always

src/backend/nodes/copyfuncs.c

@@ -905,9 +905,6 @@ _copyPlanRowMark(PlanRowMark *from)
 	COPY_SCALAR_FIELD(markType);
 	COPY_SCALAR_FIELD(noWait);
 	COPY_SCALAR_FIELD(isParent);
-	COPY_SCALAR_FIELD(ctidAttNo);
-	COPY_SCALAR_FIELD(toidAttNo);
-	COPY_SCALAR_FIELD(wholeAttNo);
 
 	return newnode;
 }

src/backend/nodes/outfuncs.c

@@ -798,9 +798,6 @@ _outPlanRowMark(StringInfo str, PlanRowMark *node)
 	WRITE_ENUM_FIELD(markType, RowMarkType);
 	WRITE_BOOL_FIELD(noWait);
 	WRITE_BOOL_FIELD(isParent);
-	WRITE_INT_FIELD(ctidAttNo);
-	WRITE_INT_FIELD(toidAttNo);
-	WRITE_INT_FIELD(wholeAttNo);
 }
 
 static void

src/backend/optimizer/plan/planner.c

@@ -1929,10 +1929,6 @@ preprocess_rowmarks(PlannerInfo *root)
 			newrc->markType = ROW_MARK_SHARE;
 		newrc->noWait = rc->noWait;
 		newrc->isParent = false;
-		/* attnos will be assigned in preprocess_targetlist */
-		newrc->ctidAttNo = InvalidAttrNumber;
-		newrc->toidAttNo = InvalidAttrNumber;
-		newrc->wholeAttNo = InvalidAttrNumber;
 
 		prowmarks = lappend(prowmarks, newrc);
 	}
@@ -1959,10 +1955,6 @@ preprocess_rowmarks(PlannerInfo *root)
 			newrc->markType = ROW_MARK_COPY;
 		newrc->noWait = false;	/* doesn't matter */
 		newrc->isParent = false;
-		/* attnos will be assigned in preprocess_targetlist */
-		newrc->ctidAttNo = InvalidAttrNumber;
-		newrc->toidAttNo = InvalidAttrNumber;
-		newrc->wholeAttNo = InvalidAttrNumber;
 
 		prowmarks = lappend(prowmarks, newrc);
 	}

src/backend/optimizer/prep/preptlist.c

@@ -80,8 +80,7 @@ preprocess_targetlist(PlannerInfo *root, List *tlist)
 	/*
 	 * Add necessary junk columns for rowmarked rels.  These values are needed
 	 * for locking of rels selected FOR UPDATE/SHARE, and to do EvalPlanQual
-	 * rechecking.	While we are at it, store these junk attnos in the
-	 * PlanRowMark list so that we don't have to redetermine them at runtime.
+	 * rechecking.  See comments for PlanRowMark in plannodes.h.
 	 */
 	foreach(lc, root->rowMarks)
 	{
@@ -90,18 +89,9 @@ preprocess_targetlist(PlannerInfo *root, List *tlist)
 		char		resname[32];
 		TargetEntry *tle;
 
-		/* child rels should just use the same junk attrs as their parents */
+		/* child rels use the same junk attrs as their parents */
 		if (rc->rti != rc->prti)
-		{
-			PlanRowMark *prc = get_plan_rowmark(root->rowMarks, rc->prti);
-
-			/* parent should have appeared earlier in list */
-			if (prc == NULL || prc->toidAttNo == InvalidAttrNumber)
-				elog(ERROR, "parent PlanRowMark not processed yet");
-			rc->ctidAttNo = prc->ctidAttNo;
-			rc->toidAttNo = prc->toidAttNo;
 			continue;
-		}
 
 		if (rc->markType != ROW_MARK_COPY)
 		{
@@ -117,7 +107,6 @@ preprocess_targetlist(PlannerInfo *root, List *tlist)
 								  pstrdup(resname),
 								  true);
 			tlist = lappend(tlist, tle);
-			rc->ctidAttNo = tle->resno;
 
 			/* if parent of inheritance tree, need the tableoid too */
 			if (rc->isParent)
@@ -133,7 +122,6 @@ preprocess_targetlist(PlannerInfo *root, List *tlist)
 									  pstrdup(resname),
 									  true);
 				tlist = lappend(tlist, tle);
-				rc->toidAttNo = tle->resno;
 			}
 		}
 		else
@@ -148,7 +136,6 @@ preprocess_targetlist(PlannerInfo *root, List *tlist)
 								  pstrdup(resname),
 								  true);
 			tlist = lappend(tlist, tle);
-			rc->wholeAttNo = tle->resno;
 		}
 	}
 

src/backend/optimizer/prep/prepunion.c

@@ -1292,10 +1292,6 @@ expand_inherited_rtentry(PlannerInfo *root, RangeTblEntry *rte, Index rti)
 			newrc->markType = oldrc->markType;
 			newrc->noWait = oldrc->noWait;
 			newrc->isParent = false;
-			/* junk attrs for children are not identified yet */
-			newrc->ctidAttNo = InvalidAttrNumber;
-			newrc->toidAttNo = InvalidAttrNumber;
-			newrc->wholeAttNo = InvalidAttrNumber;
 
 			root->rowMarks = lappend(root->rowMarks, newrc);
 		}

src/include/executor/executor.h

@@ -142,6 +142,8 @@ extern JunkFilter *ExecInitJunkFilterConversion(List *targetList,
 							 TupleTableSlot *slot);
 extern AttrNumber ExecFindJunkAttribute(JunkFilter *junkfilter,
 					  const char *attrName);
+extern AttrNumber ExecFindJunkAttributeInTlist(List *targetlist,
+					  const char *attrName);
 extern Datum ExecGetJunkAttribute(TupleTableSlot *slot, AttrNumber attno,
 					 bool *isNull);
 extern TupleTableSlot *ExecFilterJunk(JunkFilter *junkfilter,
@@ -171,15 +173,17 @@ extern ResultRelInfo *ExecGetTriggerResultRel(EState *estate, Oid relid);
 extern bool ExecContextForcesOids(PlanState *planstate, bool *hasoids);
 extern void ExecConstraints(ResultRelInfo *resultRelInfo,
 				TupleTableSlot *slot, EState *estate);
+extern ExecRowMark *ExecFindRowMark(EState *estate, Index rti);
+extern ExecAuxRowMark *ExecBuildAuxRowMark(ExecRowMark *erm, List *targetlist);
 extern TupleTableSlot *EvalPlanQual(EState *estate, EPQState *epqstate,
 			 Relation relation, Index rti,
 			 ItemPointer tid, TransactionId priorXmax);
 extern HeapTuple EvalPlanQualFetch(EState *estate, Relation relation,
 				  int lockmode, ItemPointer tid, TransactionId priorXmax);
 extern void EvalPlanQualInit(EPQState *epqstate, EState *estate,
-				 Plan *subplan, int epqParam);
-extern void EvalPlanQualSetPlan(EPQState *epqstate, Plan *subplan);
-extern void EvalPlanQualAddRowMark(EPQState *epqstate, ExecRowMark *erm);
+				 Plan *subplan, List *auxrowmarks, int epqParam);
+extern void EvalPlanQualSetPlan(EPQState *epqstate,
+								Plan *subplan, List *auxrowmarks);
 extern void EvalPlanQualSetTuple(EPQState *epqstate, Index rti,
 					 HeapTuple tuple);
 extern HeapTuple EvalPlanQualGetTuple(EPQState *epqstate, Index rti);

src/include/nodes/execnodes.h

@@ -407,12 +407,10 @@ typedef struct EState
  * When doing UPDATE, DELETE, or SELECT FOR UPDATE/SHARE, we should have an
  * ExecRowMark for each non-target relation in the query (except inheritance
  * parent RTEs, which can be ignored at runtime).  See PlanRowMark for details
- * about most of the fields.
+ * about most of the fields.  In addition to fields directly derived from
+ * PlanRowMark, we store curCtid, which is used by the WHERE CURRENT OF code.
  *
- * es_rowMarks is a list of these structs.	Each LockRows node has its own
- * list, which is the subset of locks that it is supposed to enforce; note
- * that the per-node lists point to the same structs that are in the global
- * list.
+ * EState->es_rowMarks is a list of these structs.
  */
 typedef struct ExecRowMark
 {
@@ -421,11 +419,28 @@ typedef struct ExecRowMark
 	Index		prti;			/* parent range table index, if child */
 	RowMarkType markType;		/* see enum in nodes/plannodes.h */
 	bool		noWait;			/* NOWAIT option */
+	ItemPointerData curCtid;	/* ctid of currently locked tuple, if any */
+} ExecRowMark;
+
+/*
+ * ExecAuxRowMark -
+ *	   additional runtime representation of FOR UPDATE/SHARE clauses
+ *
+ * Each LockRows and ModifyTable node keeps a list of the rowmarks it needs to
+ * deal with.  In addition to a pointer to the related entry in es_rowMarks,
+ * this struct carries the column number(s) of the resjunk columns associated
+ * with the rowmark (see comments for PlanRowMark for more detail).  In the
+ * case of ModifyTable, there has to be a separate ExecAuxRowMark list for
+ * each child plan, because the resjunk columns could be at different physical
+ * column positions in different subplans.
+ */
+typedef struct ExecAuxRowMark
+{
+	ExecRowMark *rowmark;		/* related entry in es_rowMarks */
 	AttrNumber	ctidAttNo;		/* resno of ctid junk attribute, if any */
 	AttrNumber	toidAttNo;		/* resno of tableoid junk attribute, if any */
 	AttrNumber	wholeAttNo;		/* resno of whole-row junk attribute, if any */
-	ItemPointerData curCtid;	/* ctid of currently locked tuple, if any */
-} ExecRowMark;
+} ExecAuxRowMark;
 
 
 /* ----------------------------------------------------------------
@@ -1001,7 +1016,7 @@ typedef struct EPQState
 	PlanState  *planstate;		/* plan state tree ready to be executed */
 	TupleTableSlot *origslot;	/* original output tuple to be rechecked */
 	Plan	   *plan;			/* plan tree to be executed */
-	List	   *rowMarks;		/* ExecRowMarks (non-locking only) */
+	List	   *arowMarks;		/* ExecAuxRowMarks (non-locking only) */
 	int			epqParam;		/* ID of Param to force scan node re-eval */
 } EPQState;
 
@@ -1029,6 +1044,7 @@ typedef struct ModifyTableState
 	PlanState **mt_plans;		/* subplans (one per target rel) */
 	int			mt_nplans;		/* number of plans in the array */
 	int			mt_whichplan;	/* which one is being executed (0..n-1) */
+	List	  **mt_arowmarks;	/* per-subplan ExecAuxRowMark lists */
 	EPQState	mt_epqstate;	/* for evaluating EvalPlanQual rechecks */
 	bool		fireBSTriggers; /* do we need to fire stmt triggers? */
 } ModifyTableState;
@@ -1739,7 +1755,7 @@ typedef struct SetOpState
 typedef struct LockRowsState
 {
 	PlanState	ps;				/* its first field is NodeTag */
-	List	   *lr_rowMarks;	/* List of ExecRowMarks */
+	List	   *lr_arowMarks;	/* List of ExecAuxRowMarks */
 	EPQState	lr_epqstate;	/* for evaluating EvalPlanQual rechecks */
 } LockRowsState;
 

src/include/nodes/plannodes.h

@@ -158,6 +158,9 @@ typedef struct Result
  *	 ModifyTable node -
  *		Apply rows produced by subplan(s) to result table(s),
  *		by inserting, updating, or deleting.
+ *
+ * Note that rowMarks and epqParam are presumed to be valid for all the
+ * subplan(s); they can't contain any info that varies across subplans.
  * ----------------
  */
 typedef struct ModifyTable
@@ -734,9 +737,18 @@ typedef enum RowMarkType
  * prti == parent's RT index, and can therefore be recognized as children by
  * the fact that prti != rti.
  *
- * The AttrNumbers are filled in during preprocess_targetlist.	We use
- * different subsets of them for plain relations, inheritance children,
- * and non-table relations.
+ * The planner also adds resjunk output columns to the plan that carry
+ * information sufficient to identify the locked or fetched rows.  For
+ * tables (markType != ROW_MARK_COPY), these columns are named
+ *		tableoid%u			OID of table
+ *		ctid%u				TID of row
+ * The tableoid column is only present for an inheritance hierarchy.
+ * When markType == ROW_MARK_COPY, there is instead a single column named
+ *		wholerow%u			whole-row value of relation
+ * In all three cases, %u represents the parent rangetable index (prti).
+ * Note this means that all tables in an inheritance hierarchy share the
+ * same resjunk column names.  However, in an inherited UPDATE/DELETE the
+ * columns could have different physical column numbers in each subplan.
  */
 typedef struct PlanRowMark
 {
@@ -746,9 +758,6 @@ typedef struct PlanRowMark
 	RowMarkType markType;		/* see enum above */
 	bool		noWait;			/* NOWAIT option */
 	bool		isParent;		/* true if this is a "dummy" parent entry */
-	AttrNumber	ctidAttNo;		/* resno of ctid junk attribute, if any */
-	AttrNumber	toidAttNo;		/* resno of tableoid junk attribute, if any */
-	AttrNumber	wholeAttNo;		/* resno of whole-row junk attribute, if any */
 } PlanRowMark;