IBM Support

IT31200: IN-PLACE ALTER CAN TAKE LONG, CONSUMING A FULL CPU VP, WHEN CLEANING UP MANY (AND SOME LARGE) OLD ALTERS

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APAR status

  • Closed as program error.

Error description

  • An ALTER TABLE, when executed as an in-place alter (IPA), is the
    point in time where oldest in-place alter versions get cleaned
    up if there are no more rows for these versions.  Such clean-up
    can be time and cpu consuming if there are many such old
    versions to remove and esp. some later versions in the IPA
    history involve large alters (e.g. multiple hundreds of columns
    added in one version).  With fragmented tables this process had
    to occur for every fragment's IPA history, and while processing
    one partition, no other thread could be running on the current
    cpu vp.
    
    This is independent from any rows in such table and also has
    nothing to do with 'outstanding in-place alters' (rows still in
    old versions' schemas). No table data is being modified in this
    process.
    

Local fix

  • To anticipate and avoid this problem, find tables with very high
    (> couple thousands) sysmaster.sysptnhdr.pta_opems_filled values
    and rebuild them before their next ALTER TABLE.
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * Users of Informix Server prior to 12.10.xC15 and 14.10.xC5.  *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * See Error Description                                        *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Upgrade to Informix Server 12.10.xC15 (when available) or    *
    * 14.10.xC5.                                                   *
    ****************************************************************
    

Problem conclusion

  • Fixed in Informix Server 12.10.xC15 and 14.10.xC5.
    

Temporary fix

Comments

APAR Information

  • APAR number

    IT31200

  • Reported component name

    INFORMIX SERVER

  • Reported component ID

    5725A3900

  • Reported release

    C10

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2019-12-09

  • Closed date

    2020-12-10

  • Last modified date

    2020-12-10

  • 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

    INFORMIX SERVER

  • Fixed component ID

    5725A3900

Applicable component levels

[{"Line of Business":{"code":null,"label":null},"Business Unit":{"code":"BU053","label":"Cloud & Data Platform"},"Product":{"code":"SSGU8G","label":"Informix Servers"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"C10"}]

Document Information

Modified date:
11 December 2020