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PI15515: DB2 GENERATES STATISTICS FEEDBACK WITH REASON='CONFLICT' FOR SMALL DISCREPANCIES IN STATISTICS

A fix is available

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APAR status

  • Closed as program error.

Error description

  • DB2 generates records in SYSIBM.SYSSTATFEEDBACK and/or explain
    table DSN_STAT_FEEDBACK with REASON='CONFLICT' when there are
    conflicting statistics.  In some cases, DB2 may note the
    conflict when the discrepancy is small.  Since RUNSTATS can be
    estimated and/or sampled, it is legitimate in some cases that
    statistics may not be exact.
    

Local fix

  • Ignore statistics recommendations with REASON='CONFLICT'.
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED: DB2 11 for z/OS users of                     *
    *                 SYSIBM.SYSSTATFEEDBACK and/or                *
    *                 DSN_STAT_FEEDBACK                            *
    ****************************************************************
    * PROBLEM DESCRIPTION: DB2 may recommend statistics in         *
    *                      SYSIBM.SYSSTATFEEDBACK and/or           *
    *                      DSN_STAT_FEEDBACK with                  *
    *                      REASON='CONFLICT' for small conflicts   *
    *                      in statistics.                          *
    ****************************************************************
    * RECOMMENDATION:                                              *
    ****************************************************************
    DB2 may recommend re-collection of statistics to correct
    conflicts.  These recommendations are marked with
    REASON='CONFLICT'.  In some cases, the conflict is small enough
    that the potential for improvement in DB2's estimates is low.
    In these cases, the conflicting statistics should not be
    recommended.
    
    Additional Keywords:
    SQLPERFORMANCE SQLACCESSPATH SQLSTATS
    

Problem conclusion

  • DB2 code has been modified to only recommend re-collection of
    conflicting statistics when there is a reasonable opportunity
    to improve DB2's estimates.
    

Temporary fix

Comments

APAR Information

  • APAR number

    PI15515

  • Reported component name

    DB2 OS/390 & Z/

  • Reported component ID

    5740XYR00

  • Reported release

    B10

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2014-04-08

  • Closed date

    2014-07-23

  • Last modified date

    2014-09-03

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

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

    UI19894

Modules/Macros

  • DSNXOCCF DSNXOCL  DSNXOPRS DSNXOTL
    

Fix information

  • Fixed component name

    DB2 OS/390 & Z/

  • Fixed component ID

    5740XYR00

Applicable component levels

  • RB10 PSY UI19894

       UP14/08/09 P F408

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.

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Document Information

Modified date:
03 September 2014