|
Problem IC81077
|
Status: Closed |
DB2 QUERY OPTIMIZER MIGHT CHOOSE A NON-OPTIMAL ACCESS PLAN FOR QUERIES INVOLVING JOINS ON SKEWED DATA |
| product: |
DB2 FOR LUW / DB2FORLUW / 950 - DB2 |
| Problem description: |
This is an extension to IC71258. You might encounter this
problem if your SQL statement is not performing optimally, one
or more joins in the query are on columns with significant skew
in one side of the join, one of the columns in the join is
unique, but the non-unique side of the join covers a larger
domain of values. |
| Problem Summary: |
****************************************************************
* USERS AFFECTED: *
* ALL PLATFORMS *
****************************************************************
* PROBLEM DESCRIPTION: *
* See Error Description *
****************************************************************
* RECOMMENDATION: *
* Upgrade to db2 v95fp10 *
**************************************************************** |
| Local Fix: |
As described in IC71258, to solve this problem, a statistical
view can be created on the join, where applicable, to provide
the optimizer the appropriate information to account for the
skew. |
| Solution |
The fix is included in db2 v95fp10 |
| Workaround |
not known / see Local fix |
| BUG-Tracking |
forerunner : APAR is sysrouted TO one or more of the following: IC83850 IC87878
follow-up : |
| Timestamps |
Date - problem reported :
Date - problem closed :
Date - last modified :
| 29.01.2012
27.08.2012
27.08.2012 |
| Problem solved at the following versions (IBM BugInfos) |
9.5.FP10
|
| Problem solved according to the fixlist(s) of the following version(s) |
| 9.5.0.10
|
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