DB2 - Problem description
Problem IC94861 | Status: Closed |
MERGE STATEMENT WITH ONLY MATCHED CONDITION AND DISTINCT MIGHT LEAD TO PERFORMANCE DEGRADATION | |
product: | |
DB2 CONNECT / DB2CONNCT / 970 - 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: * * Users using Merge statement * **************************************************************** * PROBLEM DESCRIPTION: * * See Error Description * **************************************************************** * RECOMMENDATION: * * Upgrade to DB2 V9.7 Fix pack 9 or higher. * **************************************************************** | |
Local Fix: | |
available fix packs: | |
DB2 Version 9.7 Fix Pack 9 for Linux, UNIX, and Windows | |
Solution | |
Problem fixed in DB2 V9.7 Fix pack 9 and above. | |
Workaround | |
not known / see Local fix | |
BUG-Tracking | |
forerunner : APAR is sysrouted TO one or more of the following: IC95130 follow-up : | |
Timestamps | |
Date - problem reported : Date - problem closed : Date - last modified : | 13.08.2013 18.12.2013 18.12.2013 |
Problem solved at the following versions (IBM BugInfos) | |
9.7.FP9 | |
Problem solved according to the fixlist(s) of the following version(s) | |
9.7.0.9 | |
9.7.0.9 |