index clustering factor

http://richardfoote.wordpress.com/2013/05/08/important-clustering-factor-calculation-improvement-fix-you/

exec dbms_stats.set_table_prefs(ownname=>user, tabname=>'BOWIE',pname=>'TABLE_CACHED_BLOCKS', pvalue=>42);

Bug 13262857  Enh: provide some control over DBMS_STATS index clustering factor computation

 This note gives a brief overview of bug 13262857. 
 The content was last updated on: 08-MAR-2013
 Click here for details of each of the sections below.

Affects:

Product (Component)	Oracle Server (Rdbms)
Range of versions believed to be affected	Versions BELOW 12.1
Versions confirmed as being affected	11.2.0.3 11.2.0.2 11.1.0.7
Platforms affected	Generic (all / most platforms affected)

Fixed:

This issue is fixed in

12.1 (Future Release) 11.2.0.3 Patch 12 on Windows Platforms 11.2.0.2 Patch 18 on Windows Platforms

Symptoms:	Related To:
Code Improvement	Optimizer PL/SQL (DBMS Packages) DBMS_STATS

Description

This is an enhancement to allow a user to specify the number of blocks
that DBMS_STATS package will consider when gathering the index clustering
factor statistics. Prior to this enhancement (also the default with this
enhancement) DBMS_STATS assumed 1. With this enhancement a user will be
able to specify a value between 1 and 255. There is also an AUTO option
which if specified then dbms_stats will use 1% of the table blocks up to
0.1% of the buffer cache size (in blocks).
 
Rediscovery Notes:
 none - this is an enhancement not a bug.
 
Workaround
 None