Increase the default value of cpu_index_tuple_cost from 0.001 to 0.005.

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.

doc/src/sgml/config.sgml

-<!-- $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>

src/backend/utils/misc/postgresql.conf.sample

@@ -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
 

src/include/optimizer/cost.h

@@ -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 */