IC87802: HOW TO DETERMINE HOW MANY TEMPORARY DBSPACES REQUIRED?

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APAR status

  • Closed as documentation error.

Error description

  • The documentation contains very limited information on
    determining the number of temporary dbspaces.
    
    http://publib.boulder.ibm.com/infocenter/idshelp/v117/topic/com.
    ibm.perf.doc/ids_prf_206.htm
    Where temporary tables are stored
    
    ...
    Important: The DBSPACETEMP configuration parameter is not set in
    the onconfig.std file. For best performance with temporary
    tables and sort files, use DBSPACETEMP to specify two or more
    dbspaces on separate disks.
    ...
    
    It is unclear how to determine based on current workload how
    many temporary dbspaces should be added to DBSPACETEMP onconfig
    parameter for better performance.
    

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * Users of version 11.70xC6 and earlier versions               *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * See Error Description: The documentation contains very       *
    * limited information on determining the number of temporary   *
    * dbspaces.                                                    *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Here are some tips for determining the number of temporary   *
    * dbspaces:                                                    *
    *                                                              *
    * If you work on a small system with a limited number of disks *
    * and cannot place temporary dbspaces on different disk        *
    * drives, you might consider using 1 (or possibly 2) temporary *
    * dbspaces. This can reduce the logging that is associated     *
    * with the temporary dbspaces.                                 *
    *                                                              *
    * If you have many disk drives, you can parallelize many       *
    * operations (such as sorts, joins, and temporary tables)      *
    * without having multiple temporary dbspaces. The number of    *
    * temporary dbspaces that you have relates to how much you     *
    * want to spread the I/O out. A good starting place is 4       *
    * temporary dbspaces. If you create too many small temporary   *
    * dbspaces, you will not have enough space for nonparallel     *
    * creation of large objects.                                   *
    ****************************************************************
    

Problem conclusion

  • Here is some additional information:
    
    If you work on a small system with a limited number of disks and
    cannot place temporary dbspaces on different disk drives, you
    might consider using 1 (or possibly 2) temporary dbspaces. This
    can reduce the logging that is associated with the temporary
    dbspaces.
    
    If you have many disk drives, you can parallelize many
    operations (such as sorts, joins, and temporary tables) without
    having multiple temporary dbspaces. The number of temporary
    dbspaces that you have relates to how much you want to spread
    the I/O out. A good starting place is 4 temporary dbspaces. If
    you create too many small temporary dbspaces, you will not have
    enough space for nonparallel creation of large objects.
    

Temporary fix

Comments

APAR Information

  • APAR number

    IC87802

  • Reported component name

    INFORMIX SERVER

  • Reported component ID

    5725A3900

  • Reported release

    B70

  • Status

    CLOSED DOC

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2012-11-02

  • Closed date

    2014-02-26

  • Last modified date

    2014-02-26

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

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

Fix information

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Document information


More support for:

Informix Servers

Software version:

B70

Reference #:

IC87802

Modified date:

2014-02-26

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