DB2 FOR LUW / DB2FORLUW / A10 - DB2

Problem description 
When RUNSTATS is executed with the TABLESAMPLE option, the 
NUMNULLS statistics might be inaccurate for columns that do not 
appear as a leading column in an index.  The problem is 
encountered under some circumstances which is dependent on the 
distribution of NULL and non-NULL values of the column in the 
table.  When the problem occurs, you will likely observe that 
increasing the sampling rate does not help to improve the 
accuracy. 
 
This problem was first introduced in DB2 V10.1.

**************************************************************** 
* USERS AFFECTED:                                              * 
* ALL                                                          * 
**************************************************************** 
* PROBLEM DESCRIPTION:                                         * 
* See Error Description                                        * 
**************************************************************** 
* RECOMMENDATION:                                              * 
* Upgrade to DB2 version v10.1 Fix Pack 3                      * 
****************************************************************

Workarounds for this problem are: 
- Execute runstats without the TABLESAMPLE option. 
- Create an index with the column as the lead column, and 
collect table and index statistics for the table; if the column 
is extensively used in predicates, such an index will also be 
beneficial for query performance. 
- Manually update SYSSTAT.COLUMNS.NUMNULLS with a more accurate 
value; if AUTO_RUNSTATS is enabled, the table is excluded from 
automatic statistics collection until you execute a RUNSTATS on 
the table, which serves to indicate to DB2 that the manual 
update is no longer needed.

DB2 Version 10.1 Fix Pack 3 for Linux, UNIX, and Windows
 DB2 Version 10.1 Fix Pack 4 for Linux, UNIX, and Windows
 DB2 Version 10.1 Fix Pack 3a for Linux, UNIX, and Windows
 DB2 Version 10.1 Fix Pack 6 for Linux, UNIX, and Windows
 

First fixed in version v10.1 Fix Pack 3

not known / see Local fix

forerunner  : APAR is sysrouted TO one or more of the following: IC97414 
follow-up : 

Date  - problem reported    :
Date  - problem closed      :
Date  - last modified       :

22.02.2013
04.11.2013
04.11.2013