DB2 FOR LUW / DB2FORLUW / A50 - DB2

DB2 may trap and generate core file during runtime of SQL 
queries having stacked MDTQs. 
 
A stacked MDTQ is an access plan that features 2 merge TQ's on 
top of one another without having any damming operations like a 
SORT or a TEMP in between them.  The Bottom of the 2 merge TQ's 
is a merge directed TQ (MDTQ). The top one can be either 
directed or broadcast, but must still be a merging TQ (MDTQ, or 
MBTQ) 
 
for example: 
 
   ... 
   MBTQ 
      | 
  GRPBY 
      | 
   MDTQ 
     | 
 ... 
 
but: 
 
   MBTQ 
      | 
   SCAN 
      | 
   SORT 
      | 
   MDTQ 
 
..is not a stack MDTQ because there is a damming operation 
(SORT) in between them. 
 
The trap is timing-dependent, and the 
failure is seen during some runs of the query. 
 
Stack looks similar to IC95108 -- but has different cause. 
 
Stack #1             Signal #11        Timestamp 
2014-10-02-12.22.42.214367 
0        sqlkqsnd 
1        sqlktsnd 
2        sqlkt_pack_tuple 
3        sqlktins 
4        sqlritqb 
5        sqlriSectInvoke 
6        sqlrr_dss_router 
7        sqlrr_subagent_router 
8        sqleSubRequestRouter 
9        sqleProcessSubRequest 
10       sqeAgent::RunEDU 
11       sqzEDUObj::EDUDriver 
12       sqlzRunEDU 
13       sqloEDUEntry 
 
The problem is seen intermittently due to dependence on timing 
and presence of certain aggravating factors. Factors that work 
in combination to precipitate this error include -- 
1)Fetch first N rows - resulting in 'early-out' in access plan 
2)Stacked Merge table queue MDTQ 
3)Spilling table queue 
4)Flow of control messages 
5)Partition layout, and patterns in data

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* USERS AFFECTED:                                              * 
* All                                                          * 
**************************************************************** 
* PROBLEM DESCRIPTION:                                         * 
* See Error Description                                        * 
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* RECOMMENDATION:                                              * 
* Upgrade to DB2 LUW v10.5 Fixpack 7                           * 
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Not available

not known / see Local fix

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

19.01.2015
01.02.2016
01.02.2016