IC80663: POOR QUERY PERFORMANCE WHEN STRING HOST VARIABLE OR PARAMETER MARKER IS CAST TO ANOTHER STRING TYPE

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You can track all active APARs for this component.

APAR status

  • Closed as program error.

Error description

  • This APAR improves performance for queries that cast string host
    variable or parameter marker to another string type.  The result
    only needs to be evaluated once, before this fix, it was
    evaluated for every row.  For example:
    
      SELECT * FROM T WHERE GRAPHICCOL = cast( ? as char(10) )
    
    The parameter marker has type CHAR(10), there is an implicit
    cast to GRAPHIC type.  Before this fix, the CHAR to GRAPHIC cast
    was evaluated for every row of the table instead of once at the
    beginning of the query.
    
    Note that the same thing can occur without explicit host
    variables or parameter markers when the statement concentrator
    is enabled, e.g.:
    
      SELECT * FROM T WHERE GRAPHICCOL = 'literal'
    
    The statement concentrator replaces the string literal with a
    host variable of type VARCHAR.  As above, the VARCHAR host
    variable is internally cast to GRAPHIC type to match the left
    hand side of the predicate.
    

Local fix

  • N/A
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * ALL                                                          *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * See Error Description                                        *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Upgrade to DB2 Version 9.7 Fix Pack 6 or later.              *
    ****************************************************************
    

Problem conclusion

  • The problem has been fixed in DB2 Version 9.7 Fix Pack 6.
    

Temporary fix

Comments

APAR Information

  • APAR number

    IC80663

  • 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

    2012-01-04

  • Closed date

    2013-03-04

  • Last modified date

    2013-03-04

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

  • 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



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Document information


More support for:

DB2 for Linux, UNIX and Windows

Software version:

9.7

Reference #:

IC80663

Modified date:

2013-03-04

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