Warehouse partition mapping - Microstrategy

Warehouse partition mapping is the mapping of partitions carried out and maintained in the warehouse. You can define a warehouse partition by adding a table with a special structure through the warehouse catalog. This table contains the map for the partition, which is stored in the warehouse.

Warehouse partitions divide tables physically along any number of attributes, though this is not visible to the user. Warehouse partitions must be homogenous, unlike metadata partitions, so that the same amount of data is stored at the same PBT level and the same facts and attributes are defined. Homogenous partitioning divides data of equal levels, like January and February.

The original fact table, which contains all of the data, is not brought into the project. Rather, the database administrator creates multiple smaller physical tables in the data warehouse. Each table contains a subset of the data in the original fact table. The database administrator is responsible for keeping the partitions consistent and up-to-date. He must also create and maintain a partition mapping table (PMT), which is used to identify the partitioned base tables as part of a logical whole.

After the PMT is created, when you run a report in Desktop or Web that requires information from one of the PBTs, the Query Engine first runs a pre-query to the PMT to determine which PBT to access to bring the data back for the report. The pre-query requests the PBT names associated with the attribute IDs from the filtering criteria. When it finds the name of the PBT, it calls the SQL Engine to write the appropriate SQL for the warehouse.

There are no data slices in the warehouse partition.

MicroStrategy supports warehouse partitions on both upgraded and newly created projects. These are added using the Warehouse Catalog Browser.

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