IBM Support

IT38832: DB2 QUERY MAY PERFORM POORLY WHEN NULL PRODUCING SIDE OF OUTER JOIN IS ON BASE TABLE.

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You can track all active APARs for this component.

 

APAR status

  • Closed as program error.

Error description

  • Db2 query may perform poorly when the following conditions are
    met:
    - The query has an outer join
    - The null producing side is select on base table.
    - There is local predicate on the table in null producing side.
    - The row preserving side used in join predicate is small
    compared to the null producing side.
    

Local fix

  • DB2COMPOPT=NOOJSJ registry can be used as workaround.
    
    This can have some negative impact on queries in which case it
    can also be applied only for the specific queries with
    optimization guideline:
    
    <query>
    /*<OPTGUIDELINES> <REGISTRY> <OPTION NAME='DB2COMPOPT'
    VALUE='NOOJSJ'/> </REGISTRY> </OPTGUIDELINES>*/
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * all                                                          *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * See Error Description                                        *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Upgrade to 11.5 FP7 or later                                 *
    ****************************************************************
    

Problem conclusion

  • Upgrade to 11.5 FP7 or later
    

Temporary fix

Comments

APAR Information

  • APAR number

    IT38832

  • Reported component name

    DB2 FOR LUW

  • Reported component ID

    DB2FORLUW

  • Reported release

    B50

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2021-10-27

  • Closed date

    2021-11-22

  • Last modified date

    2021-11-22

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

    IT31211

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

Fix information

  • Fixed component name

    DB2 FOR LUW

  • Fixed component ID

    DB2FORLUW

Applicable component levels

  • RB50 PSN

       UP

[{"Business Unit":{"code":"BU058","label":"IBM Infrastructure w\/TPS"},"Product":{"code":"SSEPGG","label":"DB2 for Linux- UNIX and Windows"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"11.5","Line of Business":{"code":"LOB10","label":"Data and AI"}}]

Document Information

Modified date:
17 December 2021