|
Problem IC81623
|
Status: Closed |
EQUALITY JOIN PREDICATES PUSHED DOWN THRU OLAP FUNCTION FORMING A CORRELATION MAY CAUSE A PERFORMANCE DEGRADATION. |
| product: |
DB2 FOR LUW / DB2FORLUW / 970 - DB2 |
| Problem description: |
Equality join predicates may be pushed down thru an OLAP
function.
The columns in the join predicates are required to be a superset
of a unique index (or a primary key). The join predicates then
will
form a correlation, resulting in limiting the only join method
eligible
be the NLJOIN. This could cause a performance degradation.
An indicator that a user has hit this problem is to look at the
Optimized Statement of the db2exfmt output.
(SELECT ..., <func>(<col> OVER (PARTITION NY <col>,...), ...
FROM Q#3, ...
WHERE Q#3.<col> = Q#2.<col>
) AS Q#1,
<table> AS Q#2, ...
If a correlated join predicate such as Q#3.<col> = Q#2.<col> is
seen,
this SQL statement may hit this problem. |
| Problem Summary: |
****************************************************************
* USERS AFFECTED: *
* DB2 UDB Version 9.7 *
****************************************************************
* PROBLEM DESCRIPTION: *
* See Error Description *
****************************************************************
* RECOMMENDATION: *
* Upgrade to Version 9.7 FixPack 6. *
**************************************************************** |
| 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 DB2 UDB Version 9.7 FixPack 6. |
| Workaround |
not known / see Local fix |
| BUG-Tracking |
forerunner : APAR is sysrouted TO one or more of the following: IC84454
follow-up : |
| Timestamps |
Date - problem reported :
Date - problem closed :
Date - last modified :
| 23.02.2012
06.06.2012
06.06.2012 |
| 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
|
 |
