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Problem IC65506
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Status: Closed |
DB2 Query-Rewrite may result in expensive repetitions of an expression |
| product: |
DB2 FOR LUW / DB2FORLUW / 950 - DB2 |
| Problem description: |
The query-rewrite phase of DB2 query compiler may replicate an
expression multiple times. DB2 has a registry controlled
facility to avoid this replication, if the execution cost of
replicated expression is very high.
This fix will improve the existing facility by defining a more
granular threshold and comparing the total cost for all
expressions against the threshold. |
| Problem Summary: |
****************************************************************
* USERS AFFECTED: *
* All users *
****************************************************************
* PROBLEM DESCRIPTION: *
* The query-rewrite phase of DB2 query compiler may *
* replicatean expression multiple times. DB2 has a registry *
* controlledfacility to avoid this replication, if the *
* execution cost ofreplicated expression is very high.This fix *
* will improve the existing facility by defining amore *
* granular threshold and comparing the total cost for *
* allexpressions against the threshold. *
****************************************************************
* RECOMMENDATION: *
* Upgrade to Version 9.5 Fix Pack 6 or later releasecontaining *
* the fix. *
**************************************************************** |
| Local Fix: |
|
| available fix packs: |
DB2 Version 9.5 Fix Pack 6a for Linux, UNIX, and Windows
DB2 Version 9.5 Fix Pack 7 for Linux, UNIX, and Windows
DB2 Version 9.5 Fix Pack 8 for Linux, UNIX, and Windows
DB2 Version 9.5 Fix Pack 9 for Linux, UNIX, and Windows
DB2 Version 9.5 Fix Pack 10 for Linux, UNIX, and Windows
|
| Solution |
Problem was first fixed in Version 9.5 Fix Pack 6. |
| Workaround |
not known / see Local fix |
| BUG-Tracking |
forerunner : APAR is sysrouted TO one or more of the following: IC66078
follow-up : |
| Timestamps |
Date - problem reported :
Date - problem closed :
Date - last modified :
| 11.01.2010
31.05.2010
31.05.2010 |
| Problem solved at the following versions (IBM BugInfos) |
9.5.FP6
|
| Problem solved according to the fixlist(s) of the following version(s) |
