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  1. #1
    Join Date
    Oct 2004
    Posts
    28

    Unanswered: Low Package Cache Hitratio

    We cannot seem to get our package cache hitratio up to 90% hitratio, we have configured it with different sizes but just not seem to climb higher than 29% package cache size is configured with size 384000 (+-1.2gb)
    increased from 19200 but hitratio still stays at 29%

    Anybody have any ideas how to get the package cache hitratio up

  2. #2
    Join Date
    Oct 2004
    Posts
    28
    Hi Everybody,

    Any help with this problem, urgent please.

    thanks

  3. #3
    Join Date
    Apr 2005
    Posts
    41
    I would recommend you review the Pakcage Cache Sections in:

    http://www.redbooks.ibm.com/abstract...6432.html?Open

    It is unlikely you would need to have a Package Cache as large as you have stated (384000 ???), this seems excessive (Note: there is a performance penalty in setting this too high).

    I have seen customers with the need for up to 40000 - and this was exceptional, as they had vast numbers of packages.

    It sounds to me that you may not get reading the Hit Rate correctly. The above Redbook details how to capture the correct reading.

    Does your application have many static pacakges + dynamic SQL calls, as there aren't that many then something doesn't add up.

    Graham Martin
    http://www.ibm.com/software/data/db2/migration/

  4. #4
    Join Date
    Mar 2004
    Location
    Toronto, ON, Canada
    Posts
    513
    How are the queries being assembled? I've seen some applications that don't use parameter markers, ie. instead of :

    SELECT * FROM a WHERE ID = ?

    They use

    SELECT * FROM a WHERE ID = 'A';
    SELECT * FROM a WHERE ID = 'B';

    To DB2, those are two different statements that are each prep'd with their own access plan.
    --
    Jonathan Petruk
    DB2 Database Consultant

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