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PI92586: AE PI86134 FIX COMPLETION

A fix is available

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APAR status

  • Closed as program error.

Error description

Local fix

  • n/a
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * AE PI86134 FIX COMPLETION                                    *
    * All users of DB2 11 or 12 for z/OS                           *
    * who run queries with an OPTIMIZE FOR                         *
    * 1 ROW or FETCH FIRST 1 ROW ONLY clause.                      *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * AE PI86134 FIX COMPLETION                                    *
    * For queries with an OPTIMIZE FOR 1 ROW                       *
    * or FETCH FIRST 1 ROW ONLY clause, DB2                        *
    * may choose sparse index to access                            *
    * the inner table when there are index                         *
    * plans available with good matching                           *
    * predicates. It may cause a query                             *
    * performance problem.                                         *
    *                                                              *
    * SQLACCESSPATH SQLFFNR                                        *
    * SQLOFNR SQLSPARSEINDEX                                       *
    * SPARSEINDEX SQLPERFORMANCE                                   *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Apply corrective PTF when available                          *
    ****************************************************************
    AE PI86134 FIX COMPLETION
    For queries with an OPTIMIZE FOR 1 ROW or FETCH FIRST 1 ROW
    ONLY clause, DB2 may choose sparse index to access the inner
    table when there are index plans available with good matching
    predicates.
    
    Compared with an index plan with good matching predicates, the
    sparse index plan cannot fetch the first several rows
    as efficiently. Therefore it should not get a cost reduction
    for the OPTIMIZE FOR 1 ROW or FETCH FIRST 1 ROW ONLY
    clause.
    

Problem conclusion

  • AE PI86134 FIX COMPLETION
    The problem of the incorrect cost reduction for a sparse index
    plan is fixed by recognizing that the index plan with good
    matching predicates exists.
    

Temporary fix

Comments

APAR Information

  • APAR number

    PI92586

  • Reported component name

    DB2 OS/390 & Z/

  • Reported component ID

    5740XYR00

  • Reported release

    B10

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2018-01-17

  • Closed date

    2018-02-27

  • Last modified date

    2018-04-03

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

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

    UI54123 UI54124

Modules/Macros

  • DSNXOCSC
    

Fix information

  • Fixed component name

    DB2 OS/390 & Z/

  • Fixed component ID

    5740XYR00

Applicable component levels

  • RC10 PSY UI54123

       UP18/03/16 P F803

  • RB10 PSY UI54124

       UP18/03/17 P F803

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: B10

Reference #: PI92586

Modified date: 03 April 2018


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