|
Problem IC84454
|
Status: Closed |
EQUALITY JOIN PREDICATES PUSHED DOWN THRU OLAP FUNCTION FORMING A CORRELATION MAY CAUSE A PERFORMANCE DEGRADATION. |
| product: |
DB2 FOR LUW / DB2FORLUW / A10 - 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 10.1 *
****************************************************************
* PROBLEM DESCRIPTION: *
* See Error Description *
****************************************************************
* RECOMMENDATION: *
* Upgrade to Version 10.1 FixPack 1. *
**************************************************************** |
| Local Fix: |
|
| available fix packs: |
DB2 Version 10.1 Fix Pack 1 for Linux, UNIX, and Windows
DB2 Version 10.1 Fix Pack 2 for Linux, UNIX, and Windows
DB2 Version 10.1 Fix Pack 3 for Linux, UNIX, and Windows
DB2 Version 10.1 Fix Pack 4 for Linux, UNIX, and Windows
DB2 Version 10.1 Fix Pack 3a for Linux, UNIX, and Windows
DB2 Version 10.1 Fix Pack 6 for Linux, UNIX, and Windows
|
| Solution |
Problem was first fixed in DB2 UDB Version 10.1 FixPack 1. |
| Workaround |
not known / see Local fix |
| Timestamps |
Date - problem reported :
Date - problem closed :
Date - last modified :
| 14.06.2012
03.11.2012
03.11.2012 |
| Problem solved at the following versions (IBM BugInfos) |
|
| Problem solved according to the fixlist(s) of the following version(s) |
| 10.1.0.1
|
 |
| 10.5.0.1
|
|
