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Increase the default value of cpu_index_tuple_cost from 0.001 to 0.005.

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This shouldn't affect simple indexscans much, while for bitmap scans that
are touching a lot of index rows, this seems to bring the estimates more
in line with reality.  Per recent discussion.
This commit is contained in:
Tom Lane 2006-06-05 03:03:42 +00:00
parent eed6c9ed7e
commit e4de635a2b
3 changed files with 5 additions and 5 deletions
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4
doc/src/sgml/config.sgml
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@ -1,4 +1,4 @@
<!-- $PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.60 2006/06/05 02:49:58 tgl Exp $ -->
<!-- $PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.61 2006/06/05 03:03:42 tgl Exp $ -->
<chapter Id="runtime-config">
<title>Server Configuration</title>
@ -1831,7 +1831,7 @@ archive_command = 'copy "%p" /mnt/server/archivedir/"%f"' # Windows
<para>
Sets the planner's estimate of the cost of processing
each index entry during an index scan.
The default is 0.001.
The default is 0.005.
</para>
</listitem>
</varlistentry>

2
src/backend/utils/misc/postgresql.conf.sample
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@ -178,7 +178,7 @@
#seq_page_cost = 1.0 # measured on an arbitrary scale
#random_page_cost = 4.0 # same scale as above
#cpu_tuple_cost = 0.01 # same scale as above
#cpu_index_tuple_cost = 0.001 # same scale as above
#cpu_index_tuple_cost = 0.005 # same scale as above
#cpu_operator_cost = 0.0025 # same scale as above
#effective_cache_size = 1000 # typically 8KB each

4
src/include/optimizer/cost.h
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@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/optimizer/cost.h,v 1.74 2006/06/05 02:49:58 tgl Exp $
* $PostgreSQL: pgsql/src/include/optimizer/cost.h,v 1.75 2006/06/05 03:03:42 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -24,7 +24,7 @@
#define DEFAULT_SEQ_PAGE_COST 1.0
#define DEFAULT_RANDOM_PAGE_COST 4.0
#define DEFAULT_CPU_TUPLE_COST 0.01
#define DEFAULT_CPU_INDEX_TUPLE_COST 0.001
#define DEFAULT_CPU_INDEX_TUPLE_COST 0.005
#define DEFAULT_CPU_OPERATOR_COST 0.0025
#define DEFAULT_EFFECTIVE_CACHE_SIZE 1000.0 /* measured in pages */