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Optimizing Block Storage Caches - Calculator Cache

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Essbase can create a bitmap to record and track data blocks during a calculation. Sometimes it is faster for Essbase to determine which blocks exist by accessing the bitmap rather than by accessing the disk, particularly when calculating a database for the first time or when calculating a very sparse database.


Essbase uses the calculator cache bitmap if the database that is being calculated has at least two sparse dimensions and either of the following conditions is met: 
  • The database calculation is executed from a calculation script containing the SET CACHE ALL command. 
  • The calculation script fully calculates at least one of the sparse dimensions.
    You control the size of the calculator cache bitmap through CALCCACHE settings in the Essbase configuration file 


    Calculator Cache Maximum and Default Values
    There is no minimum value for the calculator cache. The maximum value is 200 MB and default values is 200 KB 


    Calculator Cache Recommended Values

    The optimum size of the calculator cache depends on the amount of memory that is available in the system; the more memory available, the more memory you can potentially devote to calculator cache.


    The optimal value also depends on the nature and configuration of the database. To make several values available on your server, the Essbase configuration file accepts up to three different level-based values for calculator cache. These values can then be invoked from individual calculation scripts as required.


    Here are the Essbase configuration file statements that are required to activate and set the three levels for the calculator cache:
    CALCCACHE TRUE
    CALCCACHE HIGH High-value
    CALCCACHE LOW Low-value 
    CALCCACHE DEFAULT Default-value

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