|
Problem IT15854
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Status: Closed |
POOR PERFORMANCE IN A FEDERATED ENVIRONMENT WHEN LOCAL PREDICATEON COLUMNS WITH SMALL NUMBER OF DISTINCT VALUES, <=3. |
| product: |
DB2 FOR LUW / DB2FORLUW / A50 - DB2 |
| Problem description: |
Poor performance may be seen with a federated query due to a
poor access plan selection due to the lack of statistics for the
federated data.
This is due to the high2key and low2key values not be retrieved
where the column cardinality (colcard) <=3
This will only be enabled when the following DB2 Registry
parameter is set:
DB2_SELECTIVITY=EXTDIST_CC1 |
| Problem Summary: |
****************************************************************
* USERS AFFECTED: *
* All DB2 LUW Federated users *
****************************************************************
* PROBLEM DESCRIPTION: *
* See Error Description *
****************************************************************
* RECOMMENDATION: *
* Upgrade to DB2 LUW 10.5 Fix Pack 9 or later *
**************************************************************** |
| Local Fix: |
Use Optimizer Profile to ensure that a good access plan is used
for the query. |
| Solution |
Fix fixed in DB2 LUW 10.5 Fix Pack 9 |
| Workaround |
not known / see Local fix |
| Timestamps |
Date - problem reported :
Date - problem closed :
Date - last modified :
| 24.06.2016
18.07.2017
18.07.2017 |
| Problem solved at the following versions (IBM BugInfos) |
9.0.
|
| Problem solved according to the fixlist(s) of the following version(s) |
