|
Problem IT38832
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Status: Closed |
DB2 QUERY MAY PERFORM POORLY WHEN NULL PRODUCING SIDE OF OUTER JOIN IS ON BASE TABLE.
|
| product: |
DB2 FOR LUW / DB2FORLUW / B50 - DB2 |
| Problem description: |
Db2 query may perform poorly when the following conditions are
met:
- The query has an outer join
- The null producing side is select on base table.
- There is local predicate on the table in null producing side.
- The row preserving side used in join predicate is small
compared to the null producing side. |
| Problem Summary: |
****************************************************************
* USERS AFFECTED: *
* all *
****************************************************************
* PROBLEM DESCRIPTION: *
* See Error Description *
****************************************************************
* RECOMMENDATION: *
* Upgrade to 11.5 FP7 or later *
**************************************************************** |
| Local Fix: |
DB2COMPOPT=NOOJSJ registry can be used as workaround.
This can have some negative impact on queries in which case it
can also be applied only for the specific queries with
optimization guideline:
/* */ |
| Solution |
|
| Workaround |
****************************************************************
* USERS AFFECTED: *
* all *
****************************************************************
* PROBLEM DESCRIPTION: *
* See Error Description *
****************************************************************
* RECOMMENDATION: *
* Upgrade to 11.5 FP7 or later *
**************************************************************** |
| Comment |
Upgrade to 11.5 FP7 or later |
| Timestamps |
Date - problem reported :
Date - problem closed :
Date - last modified :
| 27.10.2021
22.11.2021
22.11.2021 |
| Problem solved at the following versions (IBM BugInfos) |
|
| Problem solved according to the fixlist(s) of the following version(s) |
