DB2 FOR LUW / DB2FORLUW / A50 - DB2

Index builds, including during reorg, reserve the full sortheap 
from sort memory.  Most index builds are done in parallel with 6 
subagents, so most reserve 6 full sortheaps.  Much of this 
memory may never be allocated for smaller index builds.  Since 
STMM tuning is based on the sort reservation, STMM may react by 
increasing the sort configuration, which may cause a subsequent 
index build to reserve even more memory. 
 
Generally there is no adverse symptom from this other than an 
STMM-tuned configuration may seem to set SHEAPTHRES_SHR and 
SORTHEAP unnecessarily high.  In extreme cases other STMM 
consumers may be decreased, causing some performance 
degradation. 
 
One method of determining this issue exists is by examining a 
database snapshot.  The high water mark for reserved shared sort 
usage: 
Shared Sort heap high water mark           = 70129 ( 4K pages ) 
 
May be much higher than the actual shared sort pool usage : 
    Memory Pool Type                           = Shared Sort 
Heap 
       Current size (bytes)                    = 0 
       High water mark (bytes)                 = 20512768 
       Configured size (bytes)                 = 307200000 
 
In this case, the highest reserved sort memory was 280 Mb (70129 
4K pages), but the actual allocated memory only reached 20MB 
(20512768 bytes).

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* USERS AFFECTED:                                              * 
* All systems                                                  * 
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* PROBLEM DESCRIPTION:                                         * 
* See Error Description                                        * 
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* RECOMMENDATION:                                              * 
* Upgrade to DB2 Version 10.5 Fix Pack 4                       * 
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configure sortheap, sheapthres_shr to fixed values

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
 

Problem first fixed in DB2 Version 10.5 Fix Pack 4

see Local Fix

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

29.01.2014
22.09.2014
10.06.2016