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IT24193: INTERMITTENT WRONG RESULTS ARE POSSIBLE WITH A PLAN WHERE COLUMNAR EARLY OUT NLJN IS PRESENT

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APAR status

  • Closed as program error.

Error description

  • If Columnar tables are involved in the query,
    and Plan has Nested Loop Join,
    and NLJN is  done in Columnar processing (under CTQ lolepop),
    and Nested Loop Join is marked EARLYOUT, then
    
    it is possible, intermittently, to lose some of the rows in the
    result set.
    
    example of the early-out NLJN in the plan:
    
            12) NLJOIN: (Nested Loop Join)
    ....
                    Arguments:
                    ---------
                    EARLYOUT: (Early Out flag)
                            LEFT
    

Local fix

  • change the plan to move NLJN from Columnar processing (under CTQ
    lolepop) to Rowstore processing(above CTQ lolepops)
    using OPTGUIDELINES
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * ALL                                                          *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * See Error Description                                        *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Upgrade to Db2 11.1 Mod 4 Fixpack 4 or higher                *
    ****************************************************************
    

Problem conclusion

  • First fixed in Db2 11.1 Mod 4 Fixpack 4
    

Temporary fix

Comments

APAR Information

  • APAR number

    IT24193

  • Reported component name

    DB2 FOR LUW

  • Reported component ID

    DB2FORLUW

  • Reported release

    B10

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    YesHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2018-02-23

  • Closed date

    2018-11-27

  • Last modified date

    2018-11-27

  • 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

  • RB10 PSN

       UP

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

Document Information

Modified date:
27 November 2018