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IT01085: SQL STATEMENT WITH UNCORRELATED SUBQUERY PREDICATE MIGHT RETURN INCORRECT RESULTS WHEN INTRA_PARALLEL IS ENABLED

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You can track all active APARs for this component.

APAR status

  • Closed as program error.

Error description

  • An SQL statement that satisfies the following conditions might
    return an incorrect result set containing values that do not
    qualify the clauses in the WHERE clause when INTRA_PARALLEL is
    enabled:
    - the statement contains an uncorrelated subquery predicate
    nested within an uncorrelated EXISTS subquery predicate
    - the query optimizer converts the EXISTS subquery to a join
    - the access plan generated by the optimizer is parallelized
    
    The following is an example of a statement that satisfies the
    above conditions
    
    SELECT DISTINCT A1 FROM T1
    WHERE EXISTS (SELECT A2 FROM T2 WHERE B2 <> ALL (SELECT B3 FROM
    T3 WHERE A3 BETWEEN 1 and 10);
    

Local fix

  • Disable INTRA_PARALLEL for the problematic statement by setting
    the CURRENT DEGREE special register to 1.
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * All users                                                    *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * See Error Description                                        *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Upgrade to DB2 version 9.7.0.10.                             *
    ****************************************************************
    

Problem conclusion

  • The problem is first fixed in DB2 version 9.7.0.10.
    

Temporary fix

Comments

APAR Information

  • APAR number

    IT01085

  • Reported component name

    DB2 FOR LUW

  • Reported component ID

    DB2FORLUW

  • Reported release

    970

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    YesHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2014-04-16

  • Closed date

    2014-12-08

  • Last modified date

    2015-02-17

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

    IC99818

  • 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 PSN

       UP



Document information

More support for: DB2 for Linux, UNIX and Windows

Software version: 9.7

Reference #: IT01085

Modified date: 17 February 2015