X-Git-Url: http://git.osdn.net/view?a=blobdiff_plain;f=src%2Fbackend%2Foptimizer%2Fpath%2Fcostsize.c;h=7f30dde869f31faa0c98c08fee27752364d94fac;hb=95b07bc7f5010233f52f9d11da74e2e5b653b0a7;hp=0b9c5819820274de0fc52a30487de106c7f6c05f;hpb=38e9348282e9d078487147ba8a85aebec54e3a08;p=pg-rex%2Fsyncrep.git

diff --git a/src/backend/optimizer/path/costsize.c b/src/backend/optimizer/path/costsize.c
index 0b9c581982..7f30dde869 100644
--- a/src/backend/optimizer/path/costsize.c
+++ b/src/backend/optimizer/path/costsize.c
@@ -54,7 +54,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/path/costsize.c,v 1.201 2008/11/22 22:47:05 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/path/costsize.c,v 1.202 2008/12/28 18:53:56 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1284,6 +1284,40 @@ cost_agg(Path *path, PlannerInfo *root,
 }
 
 /*
+ * cost_windowagg
+ *		Determines and returns the cost of performing a WindowAgg plan node,
+ *		including the cost of its input.
+ *
+ * Input is assumed already properly sorted.
+ */
+void
+cost_windowagg(Path *path, PlannerInfo *root,
+			   int numWindowFuncs, int numPartCols, int numOrderCols,
+			   Cost input_startup_cost, Cost input_total_cost,
+			   double input_tuples)
+{
+	Cost		startup_cost;
+	Cost		total_cost;
+
+	startup_cost = input_startup_cost;
+	total_cost = input_total_cost;
+
+	/*
+	 * We charge one cpu_operator_cost per window function per tuple (often a
+	 * drastic underestimate, but without a way to gauge how many tuples the
+	 * window function will fetch, it's hard to do better).  We also charge
+	 * cpu_operator_cost per grouping column per tuple for grouping
+	 * comparisons, plus cpu_tuple_cost per tuple for general overhead.
+	 */
+	total_cost += cpu_operator_cost * input_tuples * numWindowFuncs;
+	total_cost += cpu_operator_cost * input_tuples * (numPartCols + numOrderCols);
+	total_cost += cpu_tuple_cost * input_tuples;
+
+	path->startup_cost = startup_cost;
+	path->total_cost = total_cost;
+}
+
+/*
  * cost_group
  *		Determines and returns the cost of performing a Group plan node,
  *		including the cost of its input.
@@ -2155,6 +2189,11 @@ cost_qual_eval_walker(Node *node, cost_qual_eval_context *context)
 	 * Vars and Consts are charged zero, and so are boolean operators (AND,
 	 * OR, NOT). Simplistic, but a lot better than no model at all.
 	 *
+	 * Note that Aggref and WindowFunc nodes are (and should be) treated
+	 * like Vars --- whatever execution cost they have is absorbed into
+	 * plan-node-specific costing.  As far as expression evaluation is
+	 * concerned they're just like Vars.
+	 *
 	 * Should we try to account for the possibility of short-circuit
 	 * evaluation of AND/OR?  Probably *not*, because that would make the
 	 * results depend on the clause ordering, and we are not in any position