If you specify a cube as write-enabled, client applications can record changes to the cube’s data. These changes are called “write-back” data and are stored in a table separate from the cube and its underlying data, but are incorporated into query results as if they were part of the cube data. Write-enabled cubes allow end users to explore scenarios by changing cell values and analyzing the effects of the changes on cube data.
An end user’s change is stored in the write-back table as a difference from the currently displayed value. For example, if an end user changes a cell value from 90 to 100, the value +10 is stored in the write-back table, along with the time of the change and information about the end user who made it. The net effect of accumulated changes is displayed to client applications. The original value in the cube is preserved and an audit trail of changes is recorded in the write-back table.
Changes can only be made to cells at the lowest level, that is, cells that do not contain aggregated information. For example, an end user can change the value of an individual sale, but not the total sales for a store, quarter, or other summarized value. Changes are applied to summarized values when queries are evaluated so end users can view the effects of the change throughout the cube.
End user changes are kept in a separate write-back table that you can:
Note Converting to a partition is available only if you install Microsoft® SQL Server™ OLAP Services, Enterprise Edition.
For more information about write-enabling a cube, browsing write-back data, and converting write-back tables to partitions, see Maintaining Write-Enabled Cubes and Write-Back Data and its subtopics.
An end user is permitted to record changes in a cube’s write-back table only if the user belongs to a role with read/write permissions assigned to the cube. For more information, see Creating Security Roles.