OLAP memory management

The OLAP database requires memory in order to store data, run calculations, and answer requests. Depending on the kind of requests and calculations, the amount of memory required to perform such an operation varies greatly.

OLAP checks the available memory on a regular basis. This is done to avoid a memory allocation that overwhelms the system. If a request requires more memory than configured for OLAP, the request is canceled with an out-of-memory exception.

These memory checks are in the MDX Engine and the OLAP Kernel.

These are just a few reasons for large memory consumption:

Very large cross-joins
Sorting very large sets
Returning a very large amount of data
Value-generating rules.
Operations that create a large number of cell values.

In EPM Administration, the Free system memory limit option defines the limit that is checked by the OLAP Kernel memory manager. To disable the memory check, run the disable-memory-manager command. To enable the memory check, run the enable-memory-manager command.

In the MDX Engine, the memory check is always enabled. In EPM Administration, the Free system memory limit and Memory limit per request options define the limits that are checked by the MDX Engine. These options are available on the Service Specific tab of the OLAP Service Settings dialog box. See the "Service-specific properties" topic under EPM Administration.