SAS/MDDB Server Administrator's Guide

MDDB Memory Optimization

The primary factors affecting reporting performance using SAS/MDDB Server software are population of crossings and the storing of totals, but you can also optimize performance and tune the server to your particular environment by specifying how much memory the MDDB should be able to use during creation and reporting. This capability allows you to limit the resources that an individual MDDB request will take. You specify the memory limitations using the VMEMSIZE= and PKTSIZE= options in the MDDB procedure for creation of and reporting from MDDBs. See Building an MDDB with the MDDB Procedure for details on MDDB procedure syntax.

The PKTSIZE= parameter determines the size of an internal heap that is used for storing analysis and statistic data nodes for the MDDB. The size of this internal heap also determines the maximum number of data nodes that can be written to disk at any one time. Ideally, this parameter should be set to a size that allows 1 to 10% of the total nodes in the NWAY cube to be stored in a single heap.

The VMEMSIZE= parameter determines the maximum amount of memory that is used for storing analysis and statistic data in memory; data that cannot be maintained in memory is written to temporary space in the WORK library. When you specify a non-zero value for the VMEMSIZE= parameter, analysis and statistical data is written to temporary disk space in a first in/first out fashion, as necessary to keep data memory usage at or below the specified value. Specifying a value for the VMEMSIZE= parameter could adversely affect performance for building and reading MDDBs, but in most cases, it will allow you to build and access larger data cubes than would be possible using the default value of 0.

Chapter Contents
Previous
Next
Top of Page