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IC89682: POOR QUERY PERFORMANCE IF JOIN PREDICATE APPLIED TO THE FIRST AND LAST COLUMNS OF AN INDEX WITH INTERMEDIATE LOCAL PREDICATES

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APAR status

  • Closed as program error.

Error description

  • Query performance may be poor when the query contains at least
    three (3) tables joined together using INNER or OUTER joins and
    there are at least 2 equal join predicates and at least two
    local equality predicate.
    
      The last table in the join sequence must have multicolumn
    index covering the columns involved in the predicates. The
    equality join predicates must be applicable on the first and
    last columns of the index with the local eer quality predicate
    applicable on the intermediate columns of the index.
    
      Under these conditions the optimizer may incorrectly calculate
    the cost of the joins leading to a poorly performing plan.
    

Local fix

  • Use an optimization profile to obtain a better join order
      or
      Change the index definition so that the join predicate are
    applicable to either the leading or trailing columns of the
    index without any intermediate local equality predicates.
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * All                                                          *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * See Error Description                                        *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Upgrade to DB2 version 9.7 fixpack 9                         *
    ****************************************************************
    

Problem conclusion

  • Problem was first fixed in DB2 version 9.7 fixpack 9
    

Temporary fix

Comments

APAR Information

  • APAR number

    IC89682

  • 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

    2013-01-21

  • Closed date

    2013-12-30

  • Last modified date

    2013-12-30

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

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

    IC92082 IC95288

Fix information

  • Fixed component name

    DB2 FOR LUW

  • Fixed component ID

    DB2FORLUW

Applicable component levels

  • R970 PSN

       UP

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Document Information

Modified date:
30 December 2013