DB2 FOR LUW / DB2FORLUW / 970 - DB2

The index manager attempts to keep up-to-date values for full 
key 
cardinality and the number of leaf pages for the optimizer's 
 
Just-In-Time statistics feature.  When we issue a CREATE or 
REORG 
INDEX command, we get accurate values and then we keep them 
up to date during insert/update/delete activities.  When 
RUNSTATS is executed we update these values with accurate values 
-- this is important as these values can degrade over time as 
they are only hardened to disk periodically.  The code to update 
the values during RUNSTATS was broken for partitioned indexes. 
Without this fix, instead of having correct values in each index 
partition's control block, we have 0 for each partition, but 
correct 
summarized values stored in the last index partition's control 
block.  When the optimizer gets the Just-In-Time statistics from 
the index manager for a partitioned index, it will choose a 
partition 
that is not the last partition and instead of getting valid 
values 
for these stats, it will get zeros and will think that the index 
scan will perform much faster than it actually will.

**************************************************************** 
* USERS AFFECTED:                                              * 
* All users                                                    * 
**************************************************************** 
* PROBLEM DESCRIPTION:                                         * 
* For the optimizer's Just-In-Time statistics feature, the     * 
* index manager attempts to keep up-to-date values for full    * 
* key cardinality and the number of leaf pages.  When we issue * 
* a CREATE or REORG INDEX command, we get accurate values and  * 
* then we keep them up to date during insert/update/delete     * 
* activities.  When RUNSTATS is executed we update these       * 
* values with accurate values -- this is important as these    * 
* values can degrade over time as they are only hardened to    * 
* disk periodically.  The code to update the values during     * 
* RUNSTATS was broken for partitioned indexes.  Without this   * 
* fix, instead of having correct values in each index          * 
* partition's control block, we have 0 for each partition, but * 
* correct summarized values stored in the last index           * 
* partition's control block.  When the optimizer gets the      * 
* Just-In-Time statistics from the index manager for a         * 
* partitioned index, it will choose a partition that is not    * 
* the last partition and instead of getting valid values for   * 
* these stats, it will get zeros and will think that the index * 
* scan will perform much faster than it actually will.         * 
**************************************************************** 
* RECOMMENDATION:                                              * 
* Upgrade to DB2 9.7.0.4.                                      * 
****************************************************************

DB2 Version 9.7 Fix Pack 4 for Linux, UNIX, and Windows
 DB2 Version 9.7 Fix Pack 5 for Linux, UNIX, and Windows
 DB2 Version 9.7 Fix Pack 6 for Linux, UNIX, and Windows
 DB2 Version 9.7 Fix Pack 7 for Linux, UNIX, and Windows
 DB2 Version 9.7 Fix Pack 8 for Linux, UNIX, and Windows
 DB2 Version 9.7 Fix Pack 9 for Linux, UNIX, and Windows
 DB2 Version 9.7 Fix Pack 9a for Linux, UNIX, and Windows
 DB2 Version 9.7 Fix Pack 10 for Linux, UNIX, and Windows
 

The problem is fixed in DB2 9.7.0.4.

not known / see Local fix

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

11.01.2011
29.04.2011
29.04.2011

9.7.0.4