|
Problem IC89364
|
Status: Closed |
OPTIMIZER MIGHT CHOOSE NON-OPTIMAL JOIN IN PRESENCE OF CYCLES WHEN DB2_REDUCED_OPTIMIZATION=JOIN IS SET |
| product: |
DB2 FOR LUW / DB2FORLUW / 970 - DB2 |
| Problem description: |
When the DB2_REDUCED_OPTIMIZATION registry variable setting
includes the JOIN value, the optimizer might choose a
non-optimal join order or join alternative, such as a hash join
over a nested loop join, for star join eligible queries that
include join cycles. This is more likely to occur in Version
9.7 Fix Pack 7. |
| Problem Summary: |
****************************************************************
* USERS AFFECTED: *
* Environments with DB2_REDUCED_OPTIMIZATION registry variable *
* setting that includes the JOIN value is affected. *
****************************************************************
* PROBLEM DESCRIPTION: *
* See Error Description *
****************************************************************
* RECOMMENDATION: *
* Upgrade to DB2 Version 9.7 Fix Pack 8. *
**************************************************************** |
| Local Fix: |
|
| available fix packs: |
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 first fixed in DB2 Version 9.7 Fix Pack 8. |
| Workaround |
not known / see Local fix |
| BUG-Tracking |
forerunner : APAR is sysrouted TO one or more of the following: IC91751 IC93698
follow-up : |
| Timestamps |
Date - problem reported :
Date - problem closed :
Date - last modified :
| 03.01.2013
01.04.2013
01.04.2013 |
| Problem solved at the following versions (IBM BugInfos) |
9.7.FP8
|
| Problem solved according to the fixlist(s) of the following version(s) |
| 9.7.0.8
|
 |
