|
Problem IC95335
|
Status: Closed |
PERFORMANCE DEGRADATION MIGHT BE NOTICED WITH NOT EXISTS SUBQUERY WITH MULTIPLE TABLES. |
| product: |
DB2 FOR LUW / DB2FORLUW / A50 - DB2 |
| Problem description: |
Under some scenarios, DB2 might choose a suboptimal plan if the
following conditions are true:
1. The query has a not exists subquery
2. The subquery contains 2 or more base tables
3. The correlated join predicate in the subquery has an index on
the join column. |
| Problem Summary: |
Under some scenarios, DB2 might choose a suboptimal plan if the
following conditions are true:
1. The query has a not exists subquery
2. The subquery contains 2 or more base tables
3. The correlated join predicate in the subquery has an index on
the join column. |
| Local Fix: |
Disable AntiJoin by either :
1> db2set DB2_ANTIJOIN=NO -im
2> set up an optimization guideline to disable the antijoin for
this specific query only. |
| available fix packs: |
DB2 Version 10.5 Fix Pack 3 for Linux, UNIX, and Windows
DB2 Version 10.5 Fix Pack 3a for Linux, UNIX, and Windows
DB2 Cancun Release 10.5.0.4 (also known as Fix Pack 4) for Linux, UNIX, and Windows
DB2 Version 10.5 Fix Pack 9 for Linux, UNIX, and Windows
|
| Solution |
Disable AntiJoin by either :
1> db2set DB2_ANTIJOIN=NO -im
2> set up an optimization guideline to disable the antijoin for
this specific query only. |
| Workaround |
not known / see Local fix |
| Timestamps |
Date - problem reported :
Date - problem closed :
Date - last modified :
| 27.08.2013
09.04.2014
09.04.2014 |
| Problem solved at the following versions (IBM BugInfos) |
|
| Problem solved according to the fixlist(s) of the following version(s) |
| 10.5.0.3
|
 |
| 10.5.0.3
|
|
| 10.5.0.4
|
|
