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IC70557: REWRITE OR PREDICATE TO UNION IN NOT IN/IN SUBQUERY MAY CAUSE PERFORMANCE REGRESSION

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You can track all active APARs for this component.

APAR status

  • Closed as program error.

Error description

  • When DB2 rewrites OR predicate to UNION to utilize an index scan
    access in the context of a NOT IN or IN subquery and the
    subquery has no reference to any column of the tables outside
    the subquery. The result of the rewrite may cause DB2 to select
    a suboptimal plan by choosing an access plan that repeats the
    processing of the subquery for each row of the tables outside
    the subquery.
    

Local fix

Problem summary

  • REWRITE OR PREDICATE TO UNION IN NOT IN/IN SUBQUERY MAY CAUSE
    PERFORMANCE REGRESSION
    

Problem conclusion

  • Problem was first fixed in Version 9.7 FixPack 4
    

Temporary fix

Comments

APAR Information

  • APAR number

    IC70557

  • 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

    2010-08-13

  • Closed date

    2011-05-02

  • Last modified date

    2011-05-02

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

    IZ74290

  • 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

  • R970 PSY

       UP



Document information

More support for: DB2 for Linux, UNIX and Windows

Software version: 9.7

Reference #: IC70557

Modified date: 02 May 2011