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Problem IT13366
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Status: Closed |
OPTIMIZER FAVOURS HSJOIN OVER A BETTER NLJOIN WHEN JOIN COLUMN HAS LESS THAN 3 DISTINCT VALUES |
| product: |
DB2 FOR LUW / DB2FORLUW / A50 - DB2 |
| Problem description: |
The optimizer might favour a HSJOIN over a better performing
NLJOIN if there are one or more equality join preds where the
join column on the outer input of the NLJOIN has less than 3
distinct values and the other has a large number of distinct
values. |
| Problem Summary: |
****************************************************************
* USERS AFFECTED: *
* DB2 UDB Version 10.5 *
****************************************************************
* PROBLEM DESCRIPTION: *
* See Error Description. *
****************************************************************
* RECOMMENDATION: *
* Upgrade to Version 10.5 FixPack 7. *
**************************************************************** |
| Local Fix: |
You can apply an optimization profile to request the optimizer
to choose a NLJOIN |
| Solution |
Problem was first fixed in DB2 UDB Version 10.5 FixPack 7. |
| Workaround |
not known / see Local fix |
| Timestamps |
Date - problem reported :
Date - problem closed :
Date - last modified :
| 22.01.2016
02.06.2016
02.06.2016 |
| Problem solved at the following versions (IBM BugInfos) |
|
| Problem solved according to the fixlist(s) of the following version(s) |
| 10.5.0.7
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