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DB2 - Problem description

Problem IC69294 Status: Closed

ENHANCE QUERY PERFORMANCE THROUGH PUSHDOWN OF JOIN(S)
THROUGH DISJOINT UNION ALL VIEW(S)

product:
DB2 FOR LUW / DB2FORLUW / 950 - DB2
Problem description:
DB2 Query ReWrite may be able to improve the performance of a 
query by optimizing it during compilation if it satisfies the 
following conditions: 
- The query refers to 3 or more UNION ALL views (UAV) 
- Each UAV branch or operand is a select over a base table or 
nickname 
- The UAVs all have the same number of branches or operands 
- The UAVs are all joined to each other 
- The joins between the UAVs are either all inner joins or joins 
on columns that source from row-preserving sides of any outer 
joins 
- At least one join column from each branch or operand of each 
UAV has the same local predicate as corresponding branches from 
other UAVs 
- A one-to-one join mapping can be derived from all of the 
previous conditions 
 
This enhancement is only available under registry variable 
control. To enable it, issue: 
db2set 
DB2_UNION_OPTIMIZATION=[<other-values>,]COMPLEX_DISJOINT_UA_JPPD 
[,<other-values>] 
and restart the database manager for settings to take effect.
Problem Summary:
**************************************************************** 
* USERS AFFECTED:                                              * 
* NA                                                           * 
**************************************************************** 
* PROBLEM DESCRIPTION:                                         * 
* DB2 Query ReWrite may be able to improve the performance of  * 
* a                                                            * 
* query by optimizing it during compilation                    * 
**************************************************************** 
* RECOMMENDATION:                                              * 
* Upgrade to FP7                                               * 
****************************************************************
Local Fix:
Manually rewrite any applicable queries to be of the form 
derived through this enhancement.
available fix packs:
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
Upgrade to FP7
Workaround
not known / see Local fix
BUG-Tracking
forerunner  : APAR is sysrouted TO one or more of the following: IC71543 
follow-up : 
Timestamps
Date  - problem reported    :
Date  - problem closed      :
Date  - last modified       :
16.06.2010
10.01.2011
10.01.2011
Problem solved at the following versions (IBM BugInfos)
Problem solved according to the fixlist(s) of the following version(s)
9.1.0.7 FixList
9.5.0.7 FixList
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