PM78856: SIGNIFICANT I/O FOR ACCESSING THE XML NODE ID INDEX FROM XMLCLN

A fix is available

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APAR status

  • Closed as program error.

Error description

  • Inefficient index scan for the XML Node ID index could occur
    when a significant number of XML documents in an XML column are
    updated or deleted.
    

Local fix

  • Disable XMLCLN using a USERMOD.
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED: All DB2 10 for z/OS users of XML columns     *
    *                 that support multiple XML versions.          *
    ****************************************************************
    * PROBLEM DESCRIPTION: When there are many deletes or updates  *
    *                      on an XML column that supports multiple *
    *                      XML versions, significant I/O on the    *
    *                      XML Node ID index was caused by the     *
    *                      XMLCLN asynchronous SRB that deletes    *
    *                      unneeded XML rows.                      *
    ****************************************************************
    * RECOMMENDATION:                                              *
    ****************************************************************
    Significant I/O and GetPages were caused by the XMLCLN
    asynchronous SRB that deletes unneeded XML rows from the
    XML table space.  The problem was the search criteria used
    on the XML Node ID index included too many unnecessary pages.
    This problem only occurs when the XML column supports multiple
    XML versions.  The problem is more likely to occur when there
    are a large number of deletes or updates on the XML column.
    

Problem conclusion

  • The search criteria for the XML Node ID index that's used by
    the XMLCLN asynchronous SRB is improved to reduce the number
    of I/O and the number of GetPages.
    
    Additional keywords: XMLALL
    

Temporary fix

Comments

APAR Information

  • APAR number

    PM78856

  • Reported component name

    DB2 OS/390 & Z/

  • Reported component ID

    5740XYR00

  • Reported release

    A10

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2012-12-10

  • Closed date

    2013-07-25

  • Last modified date

    2013-09-03

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

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

    UK96055

Modules/Macros

  • DSNNOCLN DSNNOEXP DSNNOWRT DSNNXCMT DSNNXDLC
    

Fix information

  • Fixed component name

    DB2 OS/390 & Z/

  • Fixed component ID

    5740XYR00

Applicable component levels

  • RA10 PSY UK96055

       UP13/08/10 P F308

Fix is available

  • Select the PTF appropriate for your component level. You will be required to sign in. Distribution on physical media is not available in all countries.



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Document information


More support for:

DB2 for z/OS

Software version:

A10

Reference #:

PM78856

Modified date:

2013-09-03

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