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IT31828: STATISTICS COLLECTED WITH INDEX SAMPLING MAY PRODUCE INACCURATE REAL-TIME INDEX STATISTICS AND MON_GET_INDEX INFORMATION

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APAR status

  • Closed as program error.

Error description

  • This may be due to RUNSTATS .. INDEXSAMPLE, Real-Time Statistics
    (RTS) running with index sampling or AUTO_RUNSTATS running with
    index sampling.
    
    All index statistics sourced from catalog tables are accurate
    and unaffected.
    
    Inaccurate index statistics could be returned by MON_GET_INDEX
    and RTS statistics fabrication.
    
    Non-fabricated/fully collected RTS statistics are not affected.
    
    An example of MON_GET_INDEX providing a different NLEAF count
    relative to that seen in SYSCAT.INDEXES after a RUNSTATS with
    INDEXSAMPLE:
    
        RUNSTATS ON TABLE DB2INST1.TEST AND INDEXES ALL INDEXSAMPLE
    SYSTEM(10)
        DB20000I  The RUNSTATS command completed successfully.
    
        SELECT NLEAF FROM TABLE(MON_GET_INDEX('DB2INST1','TEST',-1))
    
        NLEAF
        --------------------
                          24
    
          1 record(s) selected.
    
    
        SELECT NLEAF FROM SYSCAT.INDEXES WHERE TABNAME='TEST'
    
        NLEAF
        --------------------
                         250
    
          1 record(s) selected.
    

Local fix

  • Avoid use of RUNSTATS with the INDEXSAMPLE clause.
    
    Disable Auto Sampling using the database config parameters,
    AUTO_SAMPLING.
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * ALL                                                          *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * See Error Description                                        *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Apply v11.1 Mod 4 Fixpack 6 to DB2 database server           *
    ****************************************************************
    

Problem conclusion

  • First fixed in v11.1 Mod 4 Fixpack 6
    

Temporary fix

  • SEE LOCAL FIX
    

Comments

APAR Information

  • APAR number

    IT31828

  • 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

    2020-02-11

  • Closed date

    2021-03-29

  • Last modified date

    2021-03-29

  • 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

[{"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:
31 March 2021