IBM Support

IC78403: DB2 OPTIMIZER CAN CHOOSE A SUB-OPTIMAL PLAN FOR A TABLE THAT HAS A HIGH ROWS-PER-PAGE NUMBER

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APAR status

  • Closed as program error.

Error description

  • When a table has a high rows-per-page number, DB2 optimizer can
    be too conservative with the estimate and as a result,
    prefetching may not occur for a IXSCAN-FETCH operation on such a
    table, even when the index has a high cluster ratio. This can
    result in a sub-optimal query plan.
    

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * All                                                          *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * See Problem Description above.                               *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Upgrade to DB2 Version 9.1 Fix Pack 11.                      *
    ****************************************************************
    

Problem conclusion

  • First Fixed in Version 9.1 Fix Pack 11.
    

Temporary fix

Comments

APAR Information

  • APAR number

    IC78403

  • Reported component name

    DB2 FOR LUW

  • Reported component ID

    DB2FORLUW

  • Reported release

    910

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2011-08-30

  • Closed date

    2011-12-23

  • Last modified date

    2011-12-23

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

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

    IC78430 IC78431

Fix information

  • Fixed component name

    DB2 FOR LUW

  • Fixed component ID

    DB2FORLUW

Applicable component levels

  • R820 PSN

       UP

  • R910 PSN

       UP

  • R950 PSN

       UP

  • R970 PSN

       UP

  • R980 PSN

       UP

[{"Line of Business":{"code":"LOB10","label":"Data and AI"},"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":"9.1"}]

Document Information

Modified date:
18 September 2021