Support data-modifying commands (INSERT/UPDATE/DELETE) in WITH.

This patch implements data-modifying WITH queries according to the
semantics that the updates all happen with the same command counter value,
and in an unspecified order.  Therefore one WITH clause can't see the
effects of another, nor can the outer query see the effects other than
through the RETURNING values.  And attempts to do conflicting updates will
have unpredictable results.  We'll need to document all that.

This commit just fixes the code; documentation updates are waiting on
author.

Marko Tiikkaja and Hitoshi Harada

1 files changed, 14 insertions, 2 deletions

diff --git a/src/backend/optimizer/plan/setrefs.c b/src/backend/optimizer/plan/setrefs.c
index b1c181a1cc5..432d6483be1 100644
--- a/src/backend/optimizer/plan/setrefs.c
+++ b/src/backend/optimizer/plan/setrefs.c
@@ -173,8 +173,9 @@ static bool extract_query_dependencies_walker(Node *node,
  * The return value is normally the same Plan node passed in, but can be
  * different when the passed-in Plan is a SubqueryScan we decide isn't needed.
  *
- * The flattened rangetable entries are appended to glob->finalrtable,
- * and we also append rowmarks entries to glob->finalrowmarks.
+ * The flattened rangetable entries are appended to glob->finalrtable.
+ * Also, rowmarks entries are appended to glob->finalrowmarks, and the
+ * RT indexes of ModifyTable result relations to glob->resultRelations.
  * Plan dependencies are appended to glob->relationOids (for relations)
  * and glob->invalItems (for everything else).
  *
@@ -552,6 +553,17 @@ set_plan_refs(PlannerGlobal *glob, Plan *plan, int rtoffset)
 											  (Plan *) lfirst(l),
 											  rtoffset);
 				}
+
+				/*
+				 * Append this ModifyTable node's final result relation RT
+				 * index(es) to the global list for the plan, and set its
+				 * resultRelIndex to reflect their starting position in the
+				 * global list.
+				 */
+				splan->resultRelIndex = list_length(glob->resultRelations);
+				glob->resultRelations =
+					list_concat(glob->resultRelations,
+								list_copy(splan->resultRelations));
 			}
 			break;
 		case T_Append: