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

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You can track all active APARs for this component.

 

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 number

    IT35384

  • Reported component name

    DB2 FOR LUW

  • Reported component ID

    DB2FORLUW

  • Reported release

    B10

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2020-12-30

  • Closed date

    2022-04-17

  • Last modified date

    2022-04-17

  • 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

[{"Business Unit":{"code":"BU058","label":"IBM Infrastructure w\/TPS"},"Product":{"code":"SSEPGG","label":"DB2 for Linux- UNIX and Windows"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"11.1","Line of Business":{"code":"LOB10","label":"Data and AI"}}]

Document Information

Modified date:
03 May 2022