DB2 FOR LUW / DB2FORLUW / A50 - DB2

A query with joins and subquery predicates may hang with 
intraquery parallelism enabled. Whether the hang occurs depends 
on the access plan chosen by the optimizer and the table data 
the query is acting on. 
 
Vulnerable access plans can be identified by examining formatted 
EXPLAIN output. If an access plan has the following pattern it 
might be vulnerable: an NLJOIN or ZZJOIN operator with at least 
one NLJOIN, MSJOIN or ZZJOIN operator somewhere within its inner 
plan subtree, and then a subquery predicate subplan somewhere 
within the inner subtree of the nested join.

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* USERS AFFECTED:                                              * 
* Users with intra-query parallelism enabled                   * 
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* PROBLEM DESCRIPTION:                                         * 
* See Error Description                                        * 
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* RECOMMENDATION:                                              * 
* Upgrade to DB2 Cancun Release 10.5.0.4.                      * 
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Disable intraquery parallelism for the specific query by setting 
the CURRENT DEGREE special register to 1 prior to issuing the 
query, or, for static SQL, by setting the DEGREE bind option to 
1. Alternatively, set the DFT_DEGREE database configuration 
parameter to 1 to disable intraquery parallelism by default for 
the database (and for static SQL, BIND again).

Problem first fixed in DB2 Cancun Release 10.5.0.4.

See local fix

Date  - problem reported    :
Date  - problem closed      :
Date  - last modified       :

27.03.2014
08.09.2014
08.09.2014