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.

1 files changed, 26 insertions, 1 deletions

diff --git a/src/backend/optimizer/prep/preptlist.c b/src/backend/optimizer/prep/preptlist.c
index 2861125212f..e04e7067664 100644
--- a/src/backend/optimizer/prep/preptlist.c
+++ b/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);
+			}
 		}
 	}