|
Problem IC98750
|
Status: Closed |
SUBQUERIES REFERENCING AN ALWAYS FALSE PREDICATE MIGHT NOTICE BAD PERFORMANCE |
| product: |
DB2 FOR LUW / DB2FORLUW / A50 - DB2 |
| Problem description: |
Under rare scenarios, a query executing on DB2 might take a long
time if the following conditions are true:
1) The query contains one or more subqueries of the type NOT
EXISTS/NOT IN.
2) The subqueries contains predicates which can be proven to be
ALWAYS FALSE and
produce an empty result set.
eg. Select * from T1
Where Not Exists (select * from T2
where T1.c1 = T2.c1 and
1=0) |
| Problem Summary: |
****************************************************************
* USERS AFFECTED: *
* ALL *
****************************************************************
* PROBLEM DESCRIPTION: *
* See Error Description *
****************************************************************
* RECOMMENDATION: *
* Please update to DB2 Cancun Release 10.5.0.4 *
**************************************************************** |
| Local Fix: |
Workaround:
1) Manually rewrite the query to remove the subquery
2) db2set -im DB2_ANTIJOIN=NO |
| available fix packs: |
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 Cancun Release 10.5.0.4 |
| Workaround |
not known / see Local fix |
| Timestamps |
Date - problem reported :
Date - problem closed :
Date - last modified :
| 15.01.2014
06.10.2014
06.10.2014 |
| Problem solved at the following versions (IBM BugInfos) |
|
| Problem solved according to the fixlist(s) of the following version(s) |
| 10.5.0.4
|
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