DB2 FOR LUW / DB2FORLUW / A50 - DB2

Partial Aggregation operators (PED, PEA) may cause DB2 to abend 
due to a trap from invalid memory access and/or memory 
corruption.  This occurs due to writing past the end of an 
assigned memory range when either of the following occurs : 
- SORTHEAP has been dynamically reduced since the SQL statement 
was initially compiled, such as in an environment where STMM 
automatically tunes SORTHEAP 
- The sort reservation available to the operator is reduced due 
to throttling, i.e. the total sort reservation is approaching or 
exceeding SHEAPTHRES_SHR 
 
DB2 versions 10.1 and higher are vulnerable 
 
The db2diag.log will indicate that available memory is reduced 
as in the message below, though note that this alone is not 
enough to indicate the problem will definitely occur.  There 
must be an additional rare/specific shortage range resulting 
from the reduction which causes a logic error. 
 
XXXXXXXXXXXXXXXXXXXXXXXXXXXX        LEVEL: Warning 
EDUID   : XXXXX                EDUNAME: db2agent (XXXXX) 0 
FUNCTION: DB2 UDB, runtime interpreter, sqlriPEXInitHashTable, 
probe:3229 
MESSAGE : Partial Early Aggregation/Distinct running with 
reduced memory 
 
The trap symptoms can vary greatly due to the various 
side-effects resulting from memory corruption.  A common trap 
will have "Pea" in the function stack, such as: 
_intel_fast_memcpy 
sqlri_hsjnUnFormatPayload 
sqlriPeaPassAggValues 
sqlriPeaPassNonEmptyRec 
sqlriPeaEOF 
sqlripea

**************************************************************** 
* USERS AFFECTED:                                              * 
* All systems are vulnerable                                   * 
**************************************************************** 
* PROBLEM DESCRIPTION:                                         * 
* See Error Description                                        * 
**************************************************************** 
* RECOMMENDATION:                                              * 
* Upgrade to DB2 Version 10.5 Fix Pack 7                       * 
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Disable partial aggregation by the following : 
  db2set DB2_REDUCED_OPTIMIZATION="NO_PEA,NO_PED" 
  recycle the instance 
 
This is an internal registry variable setting to workaround this 
problem.  The setting should be removed upon upgrade to the Fix 
pack level containing this fix : 
   db2set DB2_REDUCED_OPTIMIZATION= 
   recycle the instance

Problem first fixed in DB2 Version 10.5 Fix Pack 7

see Local Fix

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

24.03.2015
16.02.2016
16.02.2016