IC90500: QUERY WITH NOT EXISTS PREDICATES MIGHT HAVE PERFORMANCE DEGRADATION

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You can track all active APARs for this component.

APAR status

  • Closed as program error.

Error description

  • Under rare scenarios, DB2 might produce a sub-optimal query plan
    if the following conditions are satisfied:
    1. There are 3 or more inner joined tables in the query (say T1,
    T2, T3)
    2. The query contains a Not Exists or Not In subquery
    3. One of the tables (T1) in the inner join is also the source
    for the subquery.
    4. There is only a single join predicate between Table T1 and
    one of the other tables (T2)
    5. There are local predicates on tables not directly connect to
    T1.
    
    eg. select * from t1, t2, t3 where
    t1.c1 = t2.c1 and t2.c2 = t3.c2 and t3.c1 = 1 and
    not exists (select c1 from T4 where t1.c2 = t4.c2);
    

Local fix

  • db2set DB2_ANTIJOIN=NO -im
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * Users prior to V10.1 FP3                                     *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * See Error Description                                        *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Upgrade to DB2 V10.1 Fixpack 3                               *
    ****************************************************************
    

Problem conclusion

  • First Fixed in V10.1 FP3
    

Temporary fix

Comments

APAR Information

  • APAR number

    IC90500

  • Reported component name

    DB2 FOR LUW

  • Reported component ID

    DB2FORLUW

  • Reported release

    A10

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2013-02-27

  • Closed date

    2013-10-01

  • Last modified date

    2013-10-01

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

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

    IC95261 IC95490 IC95491

Fix information

  • Fixed component name

    DB2 FOR LUW

  • Fixed component ID

    DB2FORLUW

Applicable component levels

  • RA10 PSY

       UP



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Document information


More support for:

DB2 for Linux, UNIX and Windows

Software version:

10.1

Reference #:

IC90500

Modified date:

2013-10-01

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