Split the processing of INSERT/UPDATE/DELETE operations out of execMain.c.

They are now handled by a new plan node type called ModifyTable, which is
placed at the top of the plan tree.  In itself this change doesn't do much,
except perhaps make the handling of RETURNING lists and inherited UPDATEs a
tad less klugy.  But it is necessary preparation for the intended extension of
allowing RETURNING queries inside WITH.

Marko Tiikkaja

1 files changed, 71 insertions, 4 deletions

diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index 0bb53d33089..b29b0765919 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -10,7 +10,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/createplan.c,v 1.263 2009/09/17 20:49:29 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/createplan.c,v 1.264 2009/10/10 01:43:49 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -579,7 +579,7 @@ create_append_plan(PlannerInfo *root, AppendPath *best_path)
 		subplans = lappend(subplans, create_plan(root, subpath));
 	}
 
-	plan = make_append(subplans, false, tlist);
+	plan = make_append(subplans, tlist);
 
 	return (Plan *) plan;
 }
@@ -2621,7 +2621,7 @@ make_worktablescan(List *qptlist,
 }
 
 Append *
-make_append(List *appendplans, bool isTarget, List *tlist)
+make_append(List *appendplans, List *tlist)
 {
 	Append	   *node = makeNode(Append);
 	Plan	   *plan = &node->plan;
@@ -2657,7 +2657,6 @@ make_append(List *appendplans, bool isTarget, List *tlist)
 	plan->lefttree = NULL;
 	plan->righttree = NULL;
 	node->appendplans = appendplans;
-	node->isTarget = isTarget;
 
 	return node;
 }
@@ -3712,6 +3711,73 @@ make_result(PlannerInfo *root,
 }
 
 /*
+ * make_modifytable
+ *	  Build a ModifyTable plan node
+ *
+ * Currently, we don't charge anything extra for the actual table modification
+ * work, nor for the RETURNING expressions if any.  It would only be window
+ * dressing, since these are always top-level nodes and there is no way for
+ * the costs to change any higher-level planning choices.  But we might want
+ * to make it look better sometime.
+ */
+ModifyTable *
+make_modifytable(CmdType operation, List *resultRelations,
+				 List *subplans, List *returningLists)
+{
+	ModifyTable *node = makeNode(ModifyTable);
+	Plan	   *plan = &node->plan;
+	double		total_size;
+	ListCell   *subnode;
+
+	Assert(list_length(resultRelations) == list_length(subplans));
+	Assert(returningLists == NIL ||
+		   list_length(resultRelations) == list_length(returningLists));
+
+	/*
+	 * Compute cost as sum of subplan costs.
+	 */
+	plan->startup_cost = 0;
+	plan->total_cost = 0;
+	plan->plan_rows = 0;
+	total_size = 0;
+	foreach(subnode, subplans)
+	{
+		Plan	   *subplan = (Plan *) lfirst(subnode);
+
+		if (subnode == list_head(subplans))	/* first node? */
+			plan->startup_cost = subplan->startup_cost;
+		plan->total_cost += subplan->total_cost;
+		plan->plan_rows += subplan->plan_rows;
+		total_size += subplan->plan_width * subplan->plan_rows;
+	}
+	if (plan->plan_rows > 0)
+		plan->plan_width = rint(total_size / plan->plan_rows);
+	else
+		plan->plan_width = 0;
+
+	node->plan.lefttree = NULL;
+	node->plan.righttree = NULL;
+	node->plan.qual = NIL;
+
+	/*
+	 * Set up the visible plan targetlist as being the same as the first
+	 * RETURNING list.  This is for the use of EXPLAIN; the executor won't
+	 * pay any attention to the targetlist.
+	 */
+	if (returningLists)
+		node->plan.targetlist = copyObject(linitial(returningLists));
+	else
+		node->plan.targetlist = NIL;
+
+	node->operation = operation;
+	node->resultRelations = resultRelations;
+	node->plans = subplans;
+	node->returningLists = returningLists;
+
+	return node;
+}
+
+/*
  * is_projection_capable_plan
  *		Check whether a given Plan node is able to do projection.
  */
@@ -3727,6 +3793,7 @@ is_projection_capable_plan(Plan *plan)
 		case T_Unique:
 		case T_SetOp:
 		case T_Limit:
+		case T_ModifyTable:
 		case T_Append:
 		case T_RecursiveUnion:
 			return false;