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IT22630: Performance Regression might be Observed with Queries ContainingNOT EXISTS or NOT IN Predicates

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APAR status

  • Closed as program error.

Error description

  • Users might observe performance regression when upgrading from
    V9.7 and running queries with the following characteristics:
    1. Queries contain NOT EXISTS or NOT IN predicates
    2. Sub-queries in the NOT EXISTS or NOT IN predicates contain
    correlated sub-queries
    3. The correlation sources of these correlated sub-queries are
    local to the NOT EXISTS or NOT IN sub-queries
    
    An example of such a query is:
    
    select p1
    from   p
    where not exists
    (select *
    -- This NOT EXISTS sub-query contains correlated sub-queries
    from (select *
           from a
          where exists (select 1                              --
    This correlated sub-query has correlation source from Table A
    which is local to the NOT EXISTS sub-query
                               from b
                               where b1=a1 order by b1)
          fetch first 1 row only) q
    where q.a2 = p.p1)
    

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * ALL                                                          *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * See Error Description                                        *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Upgrade to Db2 11.1 Mod 3 Fix Pack 3 or higher               *
    ****************************************************************
    

Problem conclusion

  • First fixed in Db2 11.1 Mod 3 Fix Pack 3
    

Temporary fix

Comments

APAR Information

  • APAR number

    IT22630

  • Reported component name

    DB2 FOR LUW

  • Reported component ID

    DB2FORLUW

  • Reported release

    B10

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2017-10-02

  • Closed date

    2018-03-22

  • Last modified date

    2018-03-22

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

    IT20659

  • 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:
22 March 2018