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IT34049: NEW BCD DIVISION IMPLEMENTATION FOR ROW BASED DECIMAL

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APAR status

  • Closed as fixed if next.

Error description

  • Starting with v11.1m1fp2 the BCD DECIMAL division algorithm got
    replaced on AIX by an implementation based on decimal floating
    point instructions available on Power6 and above.
    This has made the row based DECIMAL division much faster. As a
    side effect users might experience an increased accuracy.
    
    This change now introduces a new and faster BCD DECIMAL division
    implementation for the other platforms that provides increased
    accuracy for the other platforms.
    
    Without the change on non-AIX
    
    db2
    "values(Decimal('9056550.000',19,3)/Decimal('20125666.660',19,3)
    )"
    
    will return 0.450000000000 while the expected result is
    0.450000000149.
    
    In most cases this tiny difference does not play a role as the
    result typically gets written back to DECIMAL(19,3) and then the
    difference in the last digits get truncated.
    
    To return to the old DECIMAL division implementation, use:
    
    db2set DB2_RUNTIME_DEBUG_FLAGS=DECIMAL_DIVIDE_COMPAT
    

Local fix

  • Perform division using DECFLOAT data type.
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * non-AIX or <= Db2 v11.1 m1fp2 or not Power6                  *
    * row based division with large scale                          *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * See Error Description                                        *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Upgrade to next fixpack.                                     *
    ****************************************************************
    

Problem conclusion

Temporary fix

Comments

APAR Information

  • APAR number

    IT34049

  • Reported component name

    DB2 FOR LUW

  • Reported component ID

    DB2FORLUW

  • Reported release

    B10

  • Status

    CLOSED FIN

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2020-08-30

  • Closed date

    2021-02-23

  • Last modified date

    2021-02-23

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

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

Fix information

Applicable component levels

[{"Line of Business":{"code":"LOB10","label":"Data and AI"},"Business Unit":{"code":"BU053","label":"Cloud & Data Platform"},"Product":{"code":"SSEPGG","label":"Db2 for Linux, UNIX and Windows"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"11.1"}]

Document Information

Modified date:
27 February 2021