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IC99818: SQL STATEMENT WITH UNCORRELATED SUBQUERY PREDICATE MIGHT RETURN INCORRECT RESULTS WHEN INTRA_PARALLEL IS ENABLED

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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
    

Problem conclusion

  • Problem is first fixed in DB2 UDB version
    10.1 fix pack 4
    

Temporary fix

Comments

APAR Information

  • APAR number

    IC99818

  • Reported component name

    DB2 FOR LUW

  • Reported component ID

    DB2FORLUW

  • Reported release

    A10

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    YesHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2014-03-04

  • Closed date

    2014-07-18

  • Last modified date

    2014-07-18

Fix information

  • Fixed component name

    DB2 FOR LUW

  • Fixed component ID

    DB2FORLUW

Applicable component levels

  • RA10 PSN

       UP

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Document Information

Modified date:
18 July 2014