IBM Support

IC70468: QUERY RETURNS INCORRECT RESULT WHEN INTRA-PARTITION PARALLELISM IS USED

Subscribe

You can track all active APARs for this component.

APAR status

  • Closed as program error.

Error description

  • A query that used to work fine in V9.1 returns incorrect result
    in V9.7. For example:
    
    SELECT * FROM myschema.tbl1
    WHERE C1 = 'X'
      AND C2 = 'Y'
      AND C3 IN ('A', 'B', 'C', 'D', 'E', 'F', 'G', 'H' )
      AND C4 = 'V'
      AND '2010-01-01' BETWEEN C5 AND C6
      AND C7 = 'Z'
      AND C8 = '0'
    FETCH FIRST 1 ROWS ONLY
    
    The query fails to return any rows even though two rows satisfy
    the predicate criteria. If the "fetch first" option is removed,
    or "fetch first 2 rows only" is used, the query returns two rows
    as expected.
    
    The problem occurs when the following conditions are true:
    
    - Intra-partition parallelism is on
    - Query degree is greater than 1
    - Index scan is used
    - Runstats has been performed against the table and indexes
    

Local fix

  • Disable intra-partition parallelism (may affect performance of
    other queries)
    

Problem summary

  • APAR fix was provided in Fixpack 4.
    

Problem conclusion

  • The fix ensures correct result set is returned for the case in
    question.
    

Temporary fix

Comments

APAR Information

  • APAR number

    IC70468

  • 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

    2010-08-11

  • Closed date

    2011-05-09

  • Last modified date

    2011-05-09

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

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

    IC75107

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 #: IC70468

Modified date: 09 May 2011