Hi Henson,
Currently we do not account the cost of RPR while planning. Attached
is the first attempt to try to estimate the RPR costs. The cost model
is very simple:
expression cost per PATTERN variable * number of input tuples
Any idea to make this estimation better?
Best regards,
--
Tatsuo Ishii
SRA OSS K.K.
English: http://www.sraoss.co.jp/index_en/
Japanese:http://www.sraoss.co.jp
diff --git a/src/backend/optimizer/path/costsize.c
b/src/backend/optimizer/path/costsize.c
index 89ca4e08bf1..5a221214b21 100644
--- a/src/backend/optimizer/path/costsize.c
+++ b/src/backend/optimizer/path/costsize.c
@@ -103,6 +103,7 @@
#include "optimizer/placeholder.h"
#include "optimizer/plancat.h"
#include "optimizer/restrictinfo.h"
+#include "optimizer/rpr.h"
#include "parser/parsetree.h"
#include "utils/lsyscache.h"
#include "utils/selfuncs.h"
@@ -3227,12 +3228,16 @@ cost_windowagg(Path *path, PlannerInfo *root,
* many rows the window function will fetch, it's hard to do better. In
* any case, it's a good estimate for all the built-in window functions,
* so we'll just do this for now.
+ *
+ * Moreover, if DEFINE/PATTERN clause exists, we charge their
expressions
+ * per tuple.
*/
foreach(lc, windowFuncs)
{
WindowFunc *wfunc = lfirst_node(WindowFunc, lc);
Cost wfunccost;
QualCost argcosts;
+ QualCost defcosts;
argcosts.startup = argcosts.per_tuple = 0;
add_function_cost(root, wfunc->winfnoid, (Node *) wfunc,
@@ -3245,6 +3250,37 @@ cost_windowagg(Path *path, PlannerInfo *root,
startup_cost += argcosts.startup;
wfunccost += argcosts.per_tuple;
+ /* also add DEFINE clause expressions' cost to per-input-row
costs */
+ if (winclause->rpPattern)
+ {
+ List *pattern_vars; /* list of pattern
variable names */
+ ListCell *lc2;
+
+ pattern_vars =
collectPatternVariables(winclause->rpPattern);
+
+ /* iterate according to the pattern variable */
+ foreach(lc2, pattern_vars)
+ {
+ char *ptname = strVal((char *)
lfirst(lc2));
+
+ /* iterate according to the DEFINE clause */
+ foreach_node(TargetEntry, def,
winclause->defineClause)
+ {
+ if (!strcmp(ptname, def->resname))
+ {
+ /*
+ * varname found. Add DEFINE
clause expressions' cost
+ * to per-input-row costs.
+ */
+ cost_qual_eval_node(&defcosts,
(Node *) def->expr, root);
+ startup_cost +=
defcosts.startup;
+ wfunccost += defcosts.per_tuple;
+ }
+ }
+ }
+ list_free_deep(pattern_vars);
+ }
+
/*
* Add the filter's cost to per-input-row costs. XXX We should
reduce
* input expression costs according to filter selectivity.
