|
Problem IC78431
|
Status: Closed |
DB2 OPTIMIZER CAN CHOOSE A SUB-OPTIMAL PLAN FOR A TABLE THAT HAS A HIGH ROWS-PER-PAGE NUMBER |
| product: |
DB2 FOR LUW / DB2FORLUW / 970 - DB2 |
| Problem description: |
When a table has a high rows-per-page number, DB2 optimizer can
be too conservative with the estimate and as a result,
prefetching may not occur for a IXSCAN-FETCH operation on such a
table, even when the index has a high cluster ratio. This can
result in a sub-optimal query plan. |
| Problem Summary: |
****************************************************************
* USERS AFFECTED: *
* All users. *
****************************************************************
* PROBLEM DESCRIPTION: *
* See Error Description *
****************************************************************
* RECOMMENDATION: *
* Upgrade to version 9.7 Fix Pack 6 or later. *
**************************************************************** |
| Local Fix: |
|
| available fix packs: |
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
|
| Solution |
Problem was first fixed in Version 9.7 Fix Pack 6.
The fix is not enabled by default. To enable it, set the
following registry:
DB2_EXTENDED_OPTIMIZATION=PG_CR |
| Workaround |
not known / see Local fix |
| BUG-Tracking |
forerunner : APAR is sysrouted TO one or more of the following: IC98878
follow-up : |
| Timestamps |
Date - problem reported :
Date - problem closed :
Date - last modified :
| 31.08.2011
05.06.2012
28.01.2014 |
| Problem solved at the following versions (IBM BugInfos) |
9.7.FP6
|
| Problem solved according to the fixlist(s) of the following version(s) |
| 9.7.0.6
|
 |
