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PM54681: DB2 MAY CHOOSE AN INEFFECTIVE ACCESS PATH FOR THE PREDICATES REFERENCING A COLUMN WITH FREQUENCY, HISTOGRAM.

A fix is available

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APAR status

  • Closed as program error.

Error description

  • DB2 may choose an ineffective access path for the
    predicates referencing a column with frequency, histogram.
    

Local fix

  • N/A
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED: DB2 for z/OS users with queries containing   *
    *                 predicates on columns where frequency or     *
    *                 histogram statistics have been collected.    *
    ****************************************************************
    * PROBLEM DESCRIPTION: DB2 may choose an inefficient access    *
    *                      path for query with predicates          *
    *                      referencing a column or columns where   *
    *                      frequency or histogram statistics have  *
    *                      been collected.                         *
    ****************************************************************
    * RECOMMENDATION:                                              *
    ****************************************************************
    DB2 may choose an inefficient access path for query with
    predicates referencing a column where frequency or histogram
    statistics have been collected.  When the problem occurs, it
    might result in a poorly performing access path being selected
    by the optimizer.
    

Problem conclusion

  • The problems mentioned above are fixed so that DB2 will not
    give incorrect filter factor estimation in that situation.
    
    ADDITIONAL KEYWORDS:
    
    SQLACCESSPATH SQLPERFORMANCE
    

Temporary fix

Comments

APAR Information

  • APAR number

    PM54681

  • Reported component name

    DB2 OS/390 & Z/

  • Reported component ID

    5740XYR00

  • Reported release

    A10

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    YesHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2011-12-20

  • Closed date

    2012-01-13

  • Last modified date

    2012-02-02

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

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

    UK75450

Modules/Macros

  •    DSNXODFB DSNXODFE DSNXODFR DSNXODFT DSNXODFX
    

Fix information

  • Fixed component name

    DB2 OS/390 & Z/

  • Fixed component ID

    5740XYR00

Applicable component levels

  • RA10 PSY UK75450

       UP12/01/31 P F201

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 #: PM54681

Modified date: 02 February 2012


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