IT35384: Private memory leak during DDL on column-organized tables in DPFenvironment

Db2 Version 11.1 Mod 4 Fix Pack 7 for Linux, UNIX, and Windows

APAR status

• Closed as program error.

Error description

• Symptoms are typical of excessive memory usage problems. In a
  fixed instance_memory environment, out of memory errors may
  occur in various memory areas attempting to grow (SQL0973,
  SQL0954, SQL0101, etc.). The memory leak only occurs in a DPF
  environment, and it will only occur on non-coordinator
  partitions (i.e. if member 0 always serves as the coordinator,
  the leak will not occur there).
  
  The private memory leak can be seen either in DB2 monitoring
  tools (MON_GET_MEMORY_SET, db2pd -memsets, db2pd -dbptnmem
  etc.). In order to identify that this APAR is applicable, the
  scenario should apply (DDL on columnar tables in a DPF
  environment), and the specific memory area/source should match
  per below.
  
  Scenarios:
  a) db_migrate tool to migrate data from Netezza to IIAS
  b) any DPF system with frequent DDL on columnar-based tables
  
  Memory monitoring data details (on non-coordinator partitions):
  
  1. The MON_GET_MEMORY_POOL routine will show the memory usage
  growth in the "PERSISTENT_PRIVATE" memory pool
    db2 "select MEMBER, MEMORY_POOL_USED from
  table(mon_get_memory_pool('PRIVATE',null,-2)) where
  MEMORY_POOL_TYPE='PERSISTENT_PRIVATE'"
  
  2. memory block data will show a large number of allocations
  from files starting with "sqqg":
  db2pd -memblocks pid=`db2pd -edus | awk '/db2sysc PID/ {print
  $3}'` sort
  Total set Memory blocks sorted by size:
  PoolID     PoolName   TotalSize(Bytes)     TotalCount LOC   File
  0                     170160264            4833       88
  sqlqg_memory.C
  0                     52036632             9279       1412
  sqlqg_misc.C
  0                     29584360             677        536
  sqlqg_memory.C
  0                     6185624              1103       713
  sqlqg_misc.C
  0                     3529600              4149       452
  sqlqg_misc.C
  ...
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * ALL                                                          *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * See Error Description                                        *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * Upgrade to Db2 version 11.1.4.7                              *
  ****************************************************************
  

Problem conclusion

• First fixed in Db2 version 11.1.4.7
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

  IT32523

• APAR is sysrouted TO one or more of the following:

Fix information

• Fixed component name

  DB2 FOR LUW

• Fixed component ID

  DB2FORLUW

Applicable component levels

• RB10 PSN

     UP