Managing the Aggregate Storage Cache

Aggregate storage cache facilitates memory usage during data loads, aggregations, and retrievals. The cache memory locking feature is used only with block storage applications.

When an aggregate storage outline is started, a small area in memory is allocated as the aggregate storage cache for the relevant application. As additional cache area is needed, the cache size incrementally increases until the maximum cache size is used or the operating system denies additional allocations.

Note:

Denial of aggregate cache memory allocations does not deny increased use of existing memory.

You can view the current aggregate cache memory allocation and the maximum aggregate cache size setting. Changing the setting may optimize memory use. The default maximum cache size, 32 MB, is the minimum setting size. You can use the size of input-level data to determine when to increase the maximum size for the cache. Administration Services and MaxL display the size of input-level data as the aggregate storage database property: Size of level 0 values.

A 32 MB cache setting supports a database with approximately 2 GB of input-level data. If the input-level data size is greater than 2 GB by some factor, the aggregate storage cache can be increased by the square root of the factor. For example, if the input-level data size is 3 GB (2 GB * 1.5), multiply the aggregate storage cache size of 32 MB by the square root of 1.5, and set the aggregate cache size to the result: 39.04 MB.

For aggregation materialization performance, consider the number of threads set for parallel calculation. The aggregation materialization process uses multiple threads that divide the aggregate storage cache. Increasing the number of threads specified in the CALCPARALLEL configuration setting for aggregate storage applications or databases may require an increase in aggregate storage cache size. See the CALCPARALLEL configuration setting in the Oracle Essbase Technical Reference.

Note:

Setting the number of threads higher than the number of processors may improve aggregate storage application performance.

Do not increase the maximum size of the aggregate storage cache beyond what is needed.

  To set aggregate storage cache size, use a tool:

Tool

Topic

Location

Administration Services

Sizing the Aggregate Storage Cache

Oracle Essbase Administration Services Online Help

MaxL

query application

alter application

Oracle Essbase Technical Reference

Note:

A changed aggregate storage cache setting becomes effective when the application is restarted.