Defining OLAP Cube Partitions
After the stored procedures have been processed, cube partitions must be defined. Cubes can be configured to be automatically partitioned by the Report preparation task as described below, or manually partitioned by a system administrator. This functionality is designed to meet the needs of sites with large-scale data warehousing requirements, while minimizing the amount of systems management overhead necessary to manage the partitioned data.
All cubes that ship with Commerce Server 2002 are enabled for automatic partitioning. This means that each time the Report preparation task runs, it will examine the data in the fact table and, if necessary, create cube partitions to hold the data.
Automatic partitioning requires that the fact table conform to certain rules. If a user adds new nonconforming cubes, automatic partitioning can be disabled on a cube-by-cube basis and the cube can be processed manually by adding entries in the CubePartitionInfo table.
Multiple OLAP partitions
To automatically create and process multiple OLAP partitions, you must use Commerce Server 2002 Enterprise Edition and Analysis Services 2000 Enterprise Edition. Multiple OLAP partitions are only supported by Analysis Services Enterprise Edition, and creating and processing multiple OLAP partitions is supported by Commerce Server 2002 Enterprise Edition.
In Commerce Server 2002 Enterprise Edition, the Report preparation task by default creates a partition with an OLAP cube for every 20 million key column values in the cube's fact table. This value is intended to minimize the number of partitions on large-scale sites, while ensuring that those cubes can be efficiently processed and queried.
Single OLAP partitions
Commerce Server 2002 Standard Edition supports automatically creating and processing a single partition per cube. If you are using Commerce Server 2002 Standard Edition, and you are creating a new cube to be processed automatically by the Report preparation DTS task, set the partition size to cover all possible partitioning key values.
In Commerce Server 2002 Standard Edition, the cube definition in the CubeProcInfo table by default defines a single partition that covers approximately 17 trillion key values in the cube's fact table.
csdw_spDefineOLAPPartitions stored procedure
As part of the stored procedure phase, the Report preparation task runs the stored procedure csdw_spDefineOLAPPartitions. This stored procedure is the core of the auto-partitioning support and is responsible for examining the various fact tables and determining if new partitions are needed to hold data that might have been added since the last processing run.
The stored procedure phase includes the following steps:
- If new partitions are needed, the stored procedure adds partitions to the CubePartitionInfo table that will hold the new data.
- The Report preparation task then runs the csdw_spEnumOLAPPartitions stored procedure, which returns a list of all the cube partitions that should be applied to the cubes before processing.
- These partitions are then applied to the OLAP database and processed in subsequent phases of the Report preparation task.
- If partition filtering is changed, the cube will be truncated and all data for all partitions will be refreshed.
See Also
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