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Problem IC90465
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Status: Closed |
PERFORMANCE DEGRADATION MIGHT BE NOTICED WITH NOT EXISTS SUBQUERY WITH MULTIPLE TABLES. |
| product: |
DB2 FOR LUW / DB2FORLUW / A10 - 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 10.1 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
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| Solution |
First fixed in DB2 Version 10.1 Fix Pack 3. |
| Workaround |
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. |
| BUG-Tracking |
forerunner : APAR is sysrouted TO one or more of the following: IC95335
follow-up : |
| Timestamps |
Date - problem reported :
Date - problem closed :
Date - last modified :
| 25.02.2013
06.05.2014
06.05.2014 |
| Problem solved at the following versions (IBM BugInfos) |
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| Problem solved according to the fixlist(s) of the following version(s) |
| 10.1.0.3
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| 10.1.0.3
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| 10.1.0.4
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