Author Topic: Read Cache Size for Power Cubes  (Read 1198 times)

Offline vivek_vdc

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Read Cache Size for Power Cubes
« on: 09 Jan 2015 10:14:13 am »
I wanted to get some opinions from the group on read cache size settings for power cubes to be used in powerplay studio.
I have read the guideline given (see below) on this topic. I have a year time based partitioned cube5. 5 cubes for 5 years each 1 GB. Pointer File MDC to the yearly cubes is 128 KB. What should the read cache size be - 1 GB?

IBM Guideline:

The default read cache size for published PowerCubes is 80 MB. You can set this parameter to a value between 1 MB and 1 GB, as required for optimal query performance.

The optimal read cache size may be higher or lower than the default value of 80 MB. This is to be expected, as PowerCubes in production vary widely in type and query characteristics.

Note that the read cache size has no effect on the initial time required to open a cube.

The typical profile for query performance, or processing time, follows a pattern whereby performance increases with the read cache size and then levels off beyond the optimal setting. To determine the optimal setting, we recommend that you lower the default by 10 MB (or 5 MB, or 1 MB, depending on the level of fine tuning desired) and use the resulting query performance results as a guide for establishing whether further reductions, or increases, are required.

The optimal read cache size will change as the cube grows and changes in the production environment. As a result, you should review the optimal read cache size when changes to the user’s query performance pattern, or changes in the PowerCube characteristics, occur.