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IT20634: INCORRECT RESSULT WHEN AT LEAST 3 COLUMNAR TABLES ARE JOINED THROUGH CDE NLJNS AND TOP NLJN IS EARLY OUT

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APAR status

  • Closed as program error.

Error description

  • - If at least 3 COLUMNAR TABLES ARE JOINED THROUGH CDE NLJNS AND
    TOP NLJN IS EARLY OUT, then it is possible to get wrong plan
    where a predicate is evaluated too late in the plan, above early
    out join. In this case we could loose rows.
    
    - An example of a query that might generate a wrong plan:
    SELECT DISTINCT C1 FROM T1, T2, T3 WHERE (T1.C1 <> T2.C1) AND
    (T3.C2 <= T2.C2) AND (T1.C3 <= T3.C3)
    

Local fix

  • Setting the following undocumented join support registry
    variable will solve the issue:
    db2set -im DB2_CDE_ILLEGAL_JOIN_SUPPORT=1
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * Columnar tables only                                         *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * Please, See Error Description and install this fix.          *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Please, See Error Description and install this fix.          *
    ****************************************************************
    

Problem conclusion

  • Please, See Error Description and install this fix.
    

Temporary fix

Comments

APAR Information

  • APAR number

    IT20634

  • 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

    2017-05-17

  • Closed date

    2018-05-22

  • Last modified date

    2018-05-22

  • 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 PSY

       UP

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Document Information

Modified date:
22 May 2018