IC92524: COLLECTING INDEX-ONLY STATISTICS CAN INCORRECTLY UPDATE SYSCAT.COLUMNS.NQUANTILES AND SYSCAT.COLUMNS.NMOSTFREQ TO -1.

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APAR status

  • Closed as program error.

Error description

  • If a column has distribution statistics and it is the leading
    column in an index, collecting index-only statistics for the
    index will incorrectly update SYSCAT.COLUMNS.NQUANTILES and
    SYSCAT.COLUMNS.NMOSTFREQ to -1, suggesting the column does not
    have distribution statistics.  However, the column's
    distribution statistics are not affected in the
    SYSCAT.SYSCOLDIST catalog.  Also not affected are the
    distribution statistics in the table's packed descriptor which
    is used by the query optimizer.
    
    The problem therefore affects applications that query
    SYSCAT.COLUMNS.NQUANTILES and SYSCAT.COLUMNS.NMOSTFREQ, instead
    of SYSCAT.SYSCOLDIST, to determine if a column has distribution
    statistics.  The db2look tool is affected by this problem.  When
    the problem has occurred, db2look mimic output will not contain
    distribution statistics information for the affected columns.
    

Local fix

  • Perform a table and indexes statistics collection on the
    affected tables.
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * ALL                                                          *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * See Error Description                                        *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Upgrade to DB2 V9.7 FP9                                      *
    ****************************************************************
    

Problem conclusion

  • Fixed in DB2 V9.7 FP9
    

Temporary fix

Comments

APAR Information

  • APAR number

    IC92524

  • Reported component name

    DB2 FOR LUW

  • Reported component ID

    DB2FORLUW

  • Reported release

    970

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2013-05-23

  • Closed date

    2013-12-17

  • Last modified date

    2013-12-17

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

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

    IC95347 IC98550

Fix information

  • Fixed component name

    DB2 FOR LUW

  • Fixed component ID

    DB2FORLUW

Applicable component levels

  • R970 PSN

       UP

  • R980 PSN

       UP

  • RA10 PSN

       UP

  • RA50 PSN

       UP



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Document information


More support for:

DB2 for Linux, UNIX and Windows

Software version:

9.7

Reference #:

IC92524

Modified date:

2013-12-17

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