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PI36847: A LONG RUNNING REMOTE OFFLOADED QUERY FROM CONGNOS APPLICATION ENVIRONMENT

A fix is available

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You can track all active APARs for this component.

APAR status

  • Closed as program error.

Error description

  • A remote offloaded query to the accelerator from Congnos
    application. The query ran for hours.
    ***************************************************************
    Additional Symptoms and Keywords:
     IDAA IDAAV4R1/K
     Performance PERF WAIT DELAY ELAPSED TIME
     ABEND0C4 AB0C4 S00C4 0C4
      0C4-00000010 00000010 RC00000010
       DSNLCKDS DSNLCKDS+1848 1848 OFFSET1848
     IFCID180 QWHS0180 IFCID 180
    

Local fix

  • Increase DRDA query block size to 256K.
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED: All DB2 users of the IBM Data Analytics      *
    *                 Accelerator (IDAA).                          *
    ****************************************************************
    * PROBLEM DESCRIPTION: This APAR addresses two unrelated       *
    *                      symptoms:                               *
    *                      1. A remote query that is offloaded to  *
    *                         an accelerator exhibits a greater    *
    *                         elapsed time compared to the same    *
    *                         query executed on DB2.               *
    *                      2. When IFCID 180 trace is enabled,     *
    *                         DB2 encounters ABEND0C4-00000010 at  *
    *                         LOC=DSNLILLM.DSNLCKDS+1848           *
    ****************************************************************
    * RECOMMENDATION:                                              *
    ****************************************************************
    The following two unrelated conditions are reported:
    1. An application, using the IBM Data Server Driver, connects
       to a DB2 for z/OS server and issues a query which DB2
       offloads to an accelerator.  The number of rows returned
       from the query is limited by the IBM Data Server Driver
       ROWSET attribute.  However, DB2 returns the entire query
       result set instead of only the number of rows needed to
       satisfy the request.  The excess rows returned results in
       greater elapsed time compared to the same query executed
       on DB2.
    2. Abend ABEND0C4-00000010 at LOC=DSNLILLM.DSNLCKDS+1848 may
       occur while writing an IFCID 180 trace record.  This abend
       results from an internal logic error during processing of a
       partial DRDA DSS header.
       This abend is not limited to query offload processing, and
       can occur for any remote request whenever IFCID 180 tracing
       is enabled.
    

Problem conclusion

  • DB2 has been changed as follows:
    1. Instead of returning the entire result set during a remote
       query offload, DB2 will now return only the rows needed to
       satisfy the request.
    2. DB2 will now correctly process partial DRDA DSS headers when
       writing an IFCID 180 trace record.
    

Temporary fix

Comments

APAR Information

  • APAR number

    PI36847

  • Reported component name

    DB2 OS/390 & Z/

  • Reported component ID

    5740XYR00

  • Reported release

    A10

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2015-03-12

  • Closed date

    2015-04-30

  • Last modified date

    2015-06-01

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

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

    UI27247 UI27248

Modules/Macros

  •    DSNLCKDS DSNLZHC1
    

Fix information

  • Fixed component name

    DB2 OS/390 & Z/

  • Fixed component ID

    5740XYR00

Applicable component levels

  • RA10 PSY UI27247

       UP15/05/15 P F505

  • RB10 PSY UI27248

       UP15/05/15 P F505

Fix is available

  • Select the PTF appropriate for your component level. You will be required to sign in. Distribution on physical media is not available in all countries.



Document information

More support for: DB2 for z/OS

Software version: A10

Reference #: PI36847

Modified date: 01 June 2015


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