Make SELECT FOR UPDATE/SHARE work on inheritance trees, by having the plan

return the tableoid as well as the ctid for any FOR UPDATE targets that
have child tables.  All child tables are listed in the ExecRowMark list,
but the executor just skips the ones that didn't produce the current row.

Curiously, this longstanding restriction doesn't seem to have been documented
anywhere; so no doc changes.

src/backend/executor/execMain.c

@@ -26,7 +26,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/executor/execMain.c,v 1.315 2008/11/06 20:51:14 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/executor/execMain.c,v 1.316 2008/11/15 19:43:45 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -590,18 +590,25 @@ InitPlan(QueryDesc *queryDesc, int eflags)
 	foreach(l, plannedstmt->rowMarks)
 	{
 		RowMarkClause *rc = (RowMarkClause *) lfirst(l);
-		Oid			relid = getrelid(rc->rti, rangeTable);
+		Oid			relid;
 		Relation	relation;
 		ExecRowMark *erm;
 
+		/* ignore "parent" rowmarks; they are irrelevant at runtime */
+		if (rc->isParent)
+			continue;
+
+		relid = getrelid(rc->rti, rangeTable);
 		relation = heap_open(relid, RowShareLock);
 		erm = (ExecRowMark *) palloc(sizeof(ExecRowMark));
 		erm->relation = relation;
 		erm->rti = rc->rti;
+		erm->prti = rc->prti;
 		erm->forUpdate = rc->forUpdate;
 		erm->noWait = rc->noWait;
-		/* We'll set up ctidAttno below */
+		/* We'll locate the junk attrs below */
 		erm->ctidAttNo = InvalidAttrNumber;
+		erm->toidAttNo = InvalidAttrNumber;
 		estate->es_rowMarks = lappend(estate->es_rowMarks, erm);
 	}
 
@@ -822,17 +829,29 @@ InitPlan(QueryDesc *queryDesc, int eflags)
 						elog(ERROR, "could not find junk ctid column");
 				}
 
-				/* For SELECT FOR UPDATE/SHARE, find the ctid attrs now */
+				/* For SELECT FOR UPDATE/SHARE, find the junk attrs now */
 				foreach(l, estate->es_rowMarks)
 				{
 					ExecRowMark *erm = (ExecRowMark *) lfirst(l);
 					char		resname[32];
 
-					snprintf(resname, sizeof(resname), "ctid%u", erm->rti);
+					/* always need the ctid */
+					snprintf(resname, sizeof(resname), "ctid%u",
+							 erm->prti);
 					erm->ctidAttNo = ExecFindJunkAttribute(j, resname);
 					if (!AttributeNumberIsValid(erm->ctidAttNo))
 						elog(ERROR, "could not find junk \"%s\" column",
 							 resname);
+					/* if child relation, need tableoid too */
+					if (erm->rti != erm->prti)
+					{
+						snprintf(resname, sizeof(resname), "tableoid%u",
+								 erm->prti);
+						erm->toidAttNo = ExecFindJunkAttribute(j, resname);
+						if (!AttributeNumberIsValid(erm->toidAttNo))
+							elog(ERROR, "could not find junk \"%s\" column",
+								 resname);
+					}
 				}
 			}
 		}
@@ -1383,13 +1402,33 @@ lnext:	;
 					LockTupleMode lockmode;
 					HTSU_Result test;
 
+					/* if child rel, must check whether it produced this row */
+					if (erm->rti != erm->prti)
+					{
+						Oid		tableoid;
+
+						datum = ExecGetJunkAttribute(slot,
+													 erm->toidAttNo,
+													 &isNull);
+						/* shouldn't ever get a null result... */
+						if (isNull)
+							elog(ERROR, "tableoid is NULL");
+						tableoid = DatumGetObjectId(datum);
+
+						if (tableoid != RelationGetRelid(erm->relation))
+						{
+							/* this child is inactive right now */
+							continue;
+						}
+					}
+
+					/* okay, fetch the tuple by ctid */
 					datum = ExecGetJunkAttribute(slot,
 												 erm->ctidAttNo,
 												 &isNull);
 					/* shouldn't ever get a null result... */
 					if (isNull)
 						elog(ERROR, "ctid is NULL");
-
 					tuple.t_self = *((ItemPointer) DatumGetPointer(datum));
 
 					if (erm->forUpdate)
@@ -2122,9 +2161,11 @@ EvalPlanQual(EState *estate, Index rti,
 		relation = NULL;
 		foreach(l, estate->es_rowMarks)
 		{
-			if (((ExecRowMark *) lfirst(l))->rti == rti)
+			ExecRowMark *erm = lfirst(l);
+
+			if (erm->rti == rti)
 			{
-				relation = ((ExecRowMark *) lfirst(l))->relation;
+				relation = erm->relation;
 				break;
 			}
 		}

src/backend/nodes/copyfuncs.c

@@ -15,7 +15,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.411 2008/11/11 18:13:32 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.412 2008/11/15 19:43:46 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1735,8 +1735,10 @@ _copyRowMarkClause(RowMarkClause *from)
 	RowMarkClause *newnode = makeNode(RowMarkClause);
 
 	COPY_SCALAR_FIELD(rti);
+	COPY_SCALAR_FIELD(prti);
 	COPY_SCALAR_FIELD(forUpdate);
 	COPY_SCALAR_FIELD(noWait);
+	COPY_SCALAR_FIELD(isParent);
 
 	return newnode;
 }

src/backend/nodes/equalfuncs.c

@@ -22,7 +22,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/nodes/equalfuncs.c,v 1.336 2008/11/11 18:13:32 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/nodes/equalfuncs.c,v 1.337 2008/11/15 19:43:46 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -2005,8 +2005,10 @@ static bool
 _equalRowMarkClause(RowMarkClause *a, RowMarkClause *b)
 {
 	COMPARE_SCALAR_FIELD(rti);
+	COMPARE_SCALAR_FIELD(prti);
 	COMPARE_SCALAR_FIELD(forUpdate);
 	COMPARE_SCALAR_FIELD(noWait);
+	COMPARE_SCALAR_FIELD(isParent);
 
 	return true;
 }

src/backend/nodes/outfuncs.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/nodes/outfuncs.c,v 1.344 2008/11/11 18:13:32 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/nodes/outfuncs.c,v 1.345 2008/11/15 19:43:46 tgl Exp $
  *
  * NOTES
  *	  Every node type that can appear in stored rules' parsetrees *must*
@@ -1900,8 +1900,10 @@ _outRowMarkClause(StringInfo str, RowMarkClause *node)
 	WRITE_NODE_TYPE("ROWMARKCLAUSE");
 
 	WRITE_UINT_FIELD(rti);
+	WRITE_UINT_FIELD(prti);
 	WRITE_BOOL_FIELD(forUpdate);
 	WRITE_BOOL_FIELD(noWait);
+	WRITE_BOOL_FIELD(isParent);
 }
 
 static void

src/backend/nodes/readfuncs.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/nodes/readfuncs.c,v 1.216 2008/10/06 17:39:26 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/nodes/readfuncs.c,v 1.217 2008/11/15 19:43:46 tgl Exp $
  *
  * NOTES
  *	  Path and Plan nodes do not have any readfuncs support, because we
@@ -226,8 +226,10 @@ _readRowMarkClause(void)
 	READ_LOCALS(RowMarkClause);
 
 	READ_UINT_FIELD(rti);
+	READ_UINT_FIELD(prti);
 	READ_BOOL_FIELD(forUpdate);
 	READ_BOOL_FIELD(noWait);
+	READ_BOOL_FIELD(isParent);
 
 	READ_DONE();
 }

src/backend/optimizer/path/allpaths.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/path/allpaths.c,v 1.176 2008/11/11 18:13:32 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/path/allpaths.c,v 1.177 2008/11/15 19:43:46 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -283,17 +283,6 @@ set_append_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
 	int			nattrs;
 	ListCell   *l;
 
-	/*
-	 * XXX for now, can't handle inherited expansion of FOR UPDATE/SHARE; can
-	 * we do better?  (This will take some redesign because the executor
-	 * currently supposes that every rowMark relation is involved in every row
-	 * returned by the query.)
-	 */
-	if (get_rowmark(root->parse, parentRTindex))
-		ereport(ERROR,
-				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-				 errmsg("SELECT FOR UPDATE/SHARE is not supported for inheritance queries")));
-
 	/*
 	 * Initialize to compute size estimates for whole append relation.
 	 *

src/backend/optimizer/prep/preptlist.c

@@ -16,7 +16,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/prep/preptlist.c,v 1.93 2008/11/02 01:45:28 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/prep/preptlist.c,v 1.94 2008/11/15 19:43:46 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -138,6 +138,11 @@ preprocess_targetlist(PlannerInfo *root, List *tlist)
 			char	   *resname;
 			TargetEntry *tle;
 
+			/* ignore child rels */
+			if (rc->rti != rc->prti)
+				continue;
+
+			/* always need the ctid */
 			var = makeVar(rc->rti,
 						  SelfItemPointerAttributeNumber,
 						  TIDOID,
@@ -153,6 +158,26 @@ preprocess_targetlist(PlannerInfo *root, List *tlist)
 								  true);
 
 			tlist = lappend(tlist, tle);
+
+			/* if parent of inheritance tree, need the tableoid too */
+			if (rc->isParent)
+			{
+				var = makeVar(rc->rti,
+							  TableOidAttributeNumber,
+							  OIDOID,
+							  -1,
+							  0);
+
+				resname = (char *) palloc(32);
+				snprintf(resname, 32, "tableoid%u", rc->rti);
+
+				tle = makeTargetEntry((Expr *) var,
+									  list_length(tlist) + 1,
+									  resname,
+									  true);
+
+				tlist = lappend(tlist, tle);
+			}
 		}
 	}
 

src/backend/optimizer/prep/prepunion.c

@@ -22,7 +22,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/prep/prepunion.c,v 1.161 2008/11/11 18:13:32 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/prep/prepunion.c,v 1.162 2008/11/15 19:43:46 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1169,6 +1169,7 @@ expand_inherited_rtentry(PlannerInfo *root, RangeTblEntry *rte, Index rti)
 {
 	Query	   *parse = root->parse;
 	Oid			parentOID;
+	RowMarkClause *oldrc;
 	Relation	oldrelation;
 	LOCKMODE	lockmode;
 	List	   *inhOIDs;
@@ -1208,6 +1209,15 @@ expand_inherited_rtentry(PlannerInfo *root, RangeTblEntry *rte, Index rti)
 		return;
 	}
 
+	/*
+	 * Find out if parent relation is selected FOR UPDATE/SHARE.  If so,
+	 * we need to mark its RowMarkClause as isParent = true, and generate
+	 * a new RowMarkClause for each child.
+	 */
+	oldrc = get_rowmark(parse, rti);
+	if (oldrc)
+		oldrc->isParent = true;
+
 	/*
 	 * Must open the parent relation to examine its tupdesc.  We need not lock
 	 * it since the rewriter already obtained at least AccessShareLock on each
@@ -1221,14 +1231,15 @@ expand_inherited_rtentry(PlannerInfo *root, RangeTblEntry *rte, Index rti)
 	 * in the parse/rewrite/plan pipeline.
 	 *
 	 * If the parent relation is the query's result relation, then we need
-	 * RowExclusiveLock.  Otherwise, check to see if the relation is accessed
-	 * FOR UPDATE/SHARE or not.  We can't just grab AccessShareLock because
-	 * then the executor would be trying to upgrade the lock, leading to
-	 * possible deadlocks.	(This code should match the parser and rewriter.)
+	 * RowExclusiveLock.  Otherwise, if it's accessed FOR UPDATE/SHARE, we
+	 * need RowShareLock; otherwise AccessShareLock.  We can't just grab
+	 * AccessShareLock because then the executor would be trying to upgrade
+	 * the lock, leading to possible deadlocks.  (This code should match the
+	 * parser and rewriter.)
 	 */
 	if (rti == parse->resultRelation)
 		lockmode = RowExclusiveLock;
-	else if (get_rowmark(parse, rti))
+	else if (oldrc)
 		lockmode = RowShareLock;
 	else
 		lockmode = AccessShareLock;
@@ -1283,6 +1294,22 @@ expand_inherited_rtentry(PlannerInfo *root, RangeTblEntry *rte, Index rti)
 		appinfo->parent_reloid = parentOID;
 		appinfos = lappend(appinfos, appinfo);
 
+		/*
+		 * Build a RowMarkClause if parent is marked FOR UPDATE/SHARE.
+		 */
+		if (oldrc)
+		{
+			RowMarkClause *newrc = makeNode(RowMarkClause);
+
+			newrc->rti = childRTindex;
+			newrc->prti = rti;
+			newrc->forUpdate = oldrc->forUpdate;
+			newrc->noWait = oldrc->noWait;
+			newrc->isParent = false;
+
+			parse->rowMarks = lappend(parse->rowMarks, newrc);
+		}
+
 		/* Close child relations, but keep locks */
 		if (childOID != parentOID)
 			heap_close(newrelation, NoLock);

src/backend/parser/analyze.c

@@ -17,7 +17,7 @@
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- *	$PostgreSQL: pgsql/src/backend/parser/analyze.c,v 1.382 2008/10/07 01:47:54 tgl Exp $
+ *	$PostgreSQL: pgsql/src/backend/parser/analyze.c,v 1.383 2008/11/15 19:43:46 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -2049,8 +2049,10 @@ applyLockingClause(Query *qry, Index rtindex, bool forUpdate, bool noWait)
 	/* Make a new RowMarkClause */
 	rc = makeNode(RowMarkClause);
 	rc->rti = rtindex;
+	rc->prti = rtindex;
 	rc->forUpdate = forUpdate;
 	rc->noWait = noWait;
+	rc->isParent = false;
 	qry->rowMarks = lappend(qry->rowMarks, rc);
 }
 

src/backend/rewrite/rewriteManip.c

@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/rewrite/rewriteManip.c,v 1.117 2008/10/22 20:17:52 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/rewrite/rewriteManip.c,v 1.118 2008/11/15 19:43:46 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -352,6 +352,7 @@ OffsetVarNodes(Node *node, int offset, int sublevels_up)
 				RowMarkClause *rc = (RowMarkClause *) lfirst(l);
 
 				rc->rti += offset;
+				rc->prti += offset;
 			}
 		}
 		query_tree_walker(qry, OffsetVarNodes_walker,
@@ -536,6 +537,8 @@ ChangeVarNodes(Node *node, int rt_index, int new_index, int sublevels_up)
 
 				if (rc->rti == rt_index)
 					rc->rti = new_index;
+				if (rc->prti == rt_index)
+					rc->prti = new_index;
 			}
 		}
 		query_tree_walker(qry, ChangeVarNodes_walker,

src/include/catalog/catversion.h

@@ -37,7 +37,7 @@
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/catalog/catversion.h,v 1.507 2008/11/14 02:09:51 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/catalog/catversion.h,v 1.508 2008/11/15 19:43:46 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	200811133
+#define CATALOG_VERSION_NO	200811151
 
 #endif

src/include/nodes/execnodes.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/nodes/execnodes.h,v 1.194 2008/10/31 19:37:56 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/nodes/execnodes.h,v 1.195 2008/11/15 19:43:46 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -368,14 +368,19 @@ typedef struct EState
 } EState;
 
 
-/* es_rowMarks is a list of these structs: */
+/*
+ * es_rowMarks is a list of these structs.  See RowMarkClause for details
+ * about rti and prti.  toidAttno is not used in a "plain" rowmark.
+ */
 typedef struct ExecRowMark
 {
 	Relation	relation;		/* opened and RowShareLock'd relation */
 	Index		rti;			/* its range table index */
+	Index		prti;			/* parent range table index, if child */
 	bool		forUpdate;		/* true = FOR UPDATE, false = FOR SHARE */
 	bool		noWait;			/* NOWAIT option */
 	AttrNumber	ctidAttNo;		/* resno of its ctid junk attribute */
+	AttrNumber	toidAttNo;		/* resno of tableoid junk attribute, if any */
 } ExecRowMark;
 
 

src/include/nodes/parsenodes.h

@@ -13,7 +13,7 @@
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/nodes/parsenodes.h,v 1.377 2008/10/31 08:39:22 heikki Exp $
+ * $PostgreSQL: pgsql/src/include/nodes/parsenodes.h,v 1.378 2008/11/15 19:43:46 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -700,14 +700,23 @@ typedef struct SortGroupClause
  * RowMarkClause -
  *	   representation of FOR UPDATE/SHARE clauses
  *
- * We create a separate RowMarkClause node for each target relation
+ * We create a separate RowMarkClause node for each target relation.  In the
+ * output of the parser and rewriter, all RowMarkClauses have rti == prti and
+ * isParent == false.  When the planner discovers that a target relation
+ * is the root of an inheritance tree, it sets isParent true, and adds an
+ * additional RowMarkClause to the list for each child relation (including
+ * the target rel itself in its role as a child).  The child entries have
+ * rti == child rel's RT index, prti == parent's RT index, and can therefore
+ * be recognized as children by the fact that prti != rti.
  */
 typedef struct RowMarkClause
 {
 	NodeTag		type;
 	Index		rti;			/* range table index of target relation */
+	Index		prti;			/* range table index of parent relation */
 	bool		forUpdate;		/* true = FOR UPDATE, false = FOR SHARE */
 	bool		noWait;			/* NOWAIT option */
+	bool		isParent;		/* set by planner when expanding inheritance */
 } RowMarkClause;
 
 /*

src/test/regress/expected/portals.out

@@ -1118,7 +1118,7 @@ SELECT * FROM uctest;
 (3 rows)
 
 BEGIN;
-DECLARE c1 CURSOR FOR SELECT * FROM uctest;
+DECLARE c1 CURSOR FOR SELECT * FROM uctest FOR UPDATE;
 FETCH 1 FROM c1;
  f1 |  f2   
 ----+-------

src/test/regress/sql/portals.sql

@@ -393,7 +393,7 @@ INSERT INTO ucchild values(100, 'hundred');
 SELECT * FROM uctest;
 
 BEGIN;
-DECLARE c1 CURSOR FOR SELECT * FROM uctest;
+DECLARE c1 CURSOR FOR SELECT * FROM uctest FOR UPDATE;
 FETCH 1 FROM c1;
 UPDATE uctest SET f1 = f1 + 10 WHERE CURRENT OF c1;
 FETCH 1 FROM c1;