0006-Add-cache_page_cost-GUC.patch

From 4bea6a4d150b694f3d16546ec865e4be948745ed Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?C=C3=A9dric=20Villemain?= <cedric@2ndquadrant.fr>
Date: Thu, 2 Jun 2011 02:28:01 +0200
Subject: [PATCH 6/7] Add cache_page_cost GUC

this is used to improve cache estimate and impact in IO cost estimations
---
 doc/src/sgml/config.sgml                      |   13 +++++++++++++
 src/backend/optimizer/path/costsize.c         |    1 +
 src/backend/utils/misc/guc.c                  |   10 ++++++++++
 src/backend/utils/misc/postgresql.conf.sample |    1 +
 src/include/optimizer/cost.h                  |    2 ++
 5 files changed, 27 insertions(+), 0 deletions(-)

diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
new file mode 100644
index e835e4b..8bc5560
*** a/doc/src/sgml/config.sgml
--- b/doc/src/sgml/config.sgml
*************** SET ENABLE_SEQSCAN TO OFF;
*** 2514,2519 ****
--- 2514,2532 ----
        </listitem>
       </varlistentry>
  
+      <varlistentry id="guc-cache-page-cost" xreflabel="cache_page_cost">
+       <term><varname>cache_page_cost</varname> (<type>floating point</type>)</term>
+       <indexterm>
+        <primary><varname>cache_page_cost</> configuration parameter</primary>
+       </indexterm>
+       <listitem>
+        <para>
+         Sets the planner's estimate of the cost of a
+         fetched page from cache.  The default is 0.1.
+        </para>
+       </listitem>
+      </varlistentry>
+ 
       <varlistentry id="guc-cpu-tuple-cost" xreflabel="cpu_tuple_cost">
        <term><varname>cpu_tuple_cost</varname> (<type>floating point</type>)</term>
        <indexterm>
diff --git a/src/backend/optimizer/path/costsize.c b/src/backend/optimizer/path/costsize.c
new file mode 100644
index bb38768..a80dc0c
*** a/src/backend/optimizer/path/costsize.c
--- b/src/backend/optimizer/path/costsize.c
***************
*** 100,105 ****
--- 100,106 ----
  
  double		seq_page_cost = DEFAULT_SEQ_PAGE_COST;
  double		random_page_cost = DEFAULT_RANDOM_PAGE_COST;
+ double		cache_page_cost = DEFAULT_CACHE_PAGE_COST;
  double		cpu_tuple_cost = DEFAULT_CPU_TUPLE_COST;
  double		cpu_index_tuple_cost = DEFAULT_CPU_INDEX_TUPLE_COST;
  double		cpu_operator_cost = DEFAULT_CPU_OPERATOR_COST;
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
new file mode 100644
index 92391ed..7465c08
*** a/src/backend/utils/misc/guc.c
--- b/src/backend/utils/misc/guc.c
*************** static struct config_real ConfigureNames
*** 2392,2397 ****
--- 2392,2407 ----
  		NULL, NULL, NULL
  	},
  	{
+ 		{"cache_page_cost", PGC_USERSET, QUERY_TUNING_COST,
+ 			gettext_noop("Sets the planner's estimate of the cost of a "
+ 			"fetched page from cache."),
+ 			NULL
+ 		},
+ 		&cache_page_cost,
+ 		DEFAULT_CACHE_PAGE_COST, 0, DBL_MAX,
+ 		NULL, NULL, NULL
+ 	},
+ 	{
  		{"cpu_tuple_cost", PGC_USERSET, QUERY_TUNING_COST,
  			gettext_noop("Sets the planner's estimate of the cost of "
  						 "processing each tuple (row)."),
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
new file mode 100644
index 655dad4..82159e1
*** a/src/backend/utils/misc/postgresql.conf.sample
--- b/src/backend/utils/misc/postgresql.conf.sample
***************
*** 233,238 ****
--- 233,239 ----
  
  #seq_page_cost = 1.0			# measured on an arbitrary scale
  #random_page_cost = 4.0			# same scale as above
+ #cache_page_cost = 0.1			# same scale as above
  #cpu_tuple_cost = 0.01			# same scale as above
  #cpu_index_tuple_cost = 0.005		# same scale as above
  #cpu_operator_cost = 0.0025		# same scale as above
diff --git a/src/include/optimizer/cost.h b/src/include/optimizer/cost.h
new file mode 100644
index 2763863..f4babd0
*** a/src/include/optimizer/cost.h
--- b/src/include/optimizer/cost.h
***************
*** 23,28 ****
--- 23,29 ----
  /* If you change these, update backend/utils/misc/postgresql.sample.conf */
  #define DEFAULT_SEQ_PAGE_COST  1.0
  #define DEFAULT_RANDOM_PAGE_COST  4.0
+ #define DEFAULT_CACHE_PAGE_COST  0.1
  #define DEFAULT_CPU_TUPLE_COST	0.01
  #define DEFAULT_CPU_INDEX_TUPLE_COST 0.005
  #define DEFAULT_CPU_OPERATOR_COST  0.0025
*************** typedef enum
*** 45,50 ****
--- 46,52 ----
  /* parameter variables and flags */
  extern PGDLLIMPORT double seq_page_cost;
  extern PGDLLIMPORT double random_page_cost;
+ extern PGDLLIMPORT double cache_page_cost;
  extern PGDLLIMPORT double cpu_tuple_cost;
  extern PGDLLIMPORT double cpu_index_tuple_cost;
  extern PGDLLIMPORT double cpu_operator_cost;
-- 
1.7.5.3