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  1. #1
    Join Date
    Apr 2003
    Posts
    3

    Unanswered: Config parms that affect bufferpool usage

    What configuration parameters should be re-evaluated when increasing the size of a bufferpool?

    For example, avg_appls tells the optimizer what percentage of the bufferpool will be available at execution. This can affect the access plan that the optimizer chooses. In one case we observed that the optimizer decided to do tablescans rather than using indexes because it thougt it would have a whole bufferpool to use. avg_appls was set to 1 on that database.

    I'm trying to avoid degrading performance by significantly increasing the size of a bufferpool in order to improve performance.

    Thanks for your help!!
    Plumb

  2. #2
    Join Date
    Apr 2003
    Posts
    191

    Re: Config parms that affect bufferpool usage

    Hi,

    afaik there is no related configuration parameter. Try to estimate total memory consumption and check for swap activity. I believe there is nothing else to consider.

    Johann

    Originally posted by Plumb
    What configuration parameters should be re-evaluated when increasing the size of a bufferpool?

    For example, avg_appls tells the optimizer what percentage of the bufferpool will be available at execution. This can affect the access plan that the optimizer chooses. In one case we observed that the optimizer decided to do tablescans rather than using indexes because it thougt it would have a whole bufferpool to use. avg_appls was set to 1 on that database.

    I'm trying to avoid degrading performance by significantly increasing the size of a bufferpool in order to improve performance.

    Thanks for your help!!
    Plumb

  3. #3
    Join Date
    Mar 2003
    Posts
    343
    You may want ot check out the following things

    num_iocleaners
    num_ioservers

    the prefetchsize of the tablespaces which are assigned to the bufferpool.

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