|
Problem IC95526
|
Status: Closed |
MERGE STATEMENT WITH ONLY MATCHED CONDITION AND DISTINCT MIGHT LEAD TO PERFORMANCE DEGRADATION |
| product: |
DB2 FOR LUW / DB2FORLUW / A50 - DB2 |
| Problem description: |
Some queries might see performance degradation starting DB2
version 970 fix pack 6 if the following conditions are true:
1. The query is a merge statement with only the matched
condition
2. The Source of the merge is a distinct join between two or
more tables, alias
3. (Optional) One of the tables in this join is the same as the
target table
eg. MERGE INTO MYALIAS.TAB1 AS TGT USING <----------- condition
1
(SELECT DISTINCT A.TRN, A.SYS, A.LANG <-----------
condition 2
FROM MYALIAS.TAB2 A, MYALIAS.TAB1 B <-----------
condition 3
WHERE A.TRN = B.TRN AND NULLIF(B.TRN , '') IS NOT NULL
AND A.SYS = B.SYS AND A.LANG = B.LANG) AS STG
ON STG.TRN = TGT.TRN
WHEN MATCHED THEN
UPDATE SET TGT.TRN = STG.TRN; |
| Problem Summary: |
****************************************************************
* USERS AFFECTED: *
* All *
****************************************************************
* PROBLEM DESCRIPTION: *
* See Error Description *
****************************************************************
* RECOMMENDATION: *
* Upgrade to DB2 version 105 fix pack 3 *
**************************************************************** |
| Local Fix: |
|
| 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 |
The problem is fixed in DB2 version 105 fix pack 3 |
| Workaround |
not known / see Local fix |
| Timestamps |
Date - problem reported :
Date - problem closed :
Date - last modified :
| 27.08.2013
27.02.2014
27.02.2014 |
| 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
|
|
