Microsoft KB Archive/931292

= You may experience decreased performance when you run queries against a cube that contains linked dimensions in SQL Server 2005 Analysis Services =

Article ID: 931292

Article Last Modified on 2/2/2007

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APPLIES TO


 * Microsoft SQL Server 2005 Analysis Services

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SYMPTOMS
You may experience decreased performance when you run queries against a cube that contains linked dimensions in Microsoft SQL Server 2005 Analysis Services. This issue may occur if the following conditions are true:
 * You created a linked dimension in a SQL Server 2005 Analysis Services (SSAS) database (database A). The dimension is linked from another SSAS database (database B).
 * The fact table for the linked dimension of database A contains more than 4,096 unique values.
 * You processed database B by using the Process Full option and then processed database A by using the Process Update option.

Additionally, you may find that the index bitmap files (.map files) of the linked dimension in database A are discarded.



CAUSE
This issue occurs because SQL Server 2005 Analysis Services detects a change in the link dimension structure but cannot determine whether the linked dimension was fully processed. Therefore, SQL Server 2005 Analysis Services makes the conservative choice to discard the index bitmap files to avoid wrong results. Query performances are downgraded when you run queries against a cube that contains linked dimensions.

These index bitmap files are used to quickly retrieve the fact and aggregation data that is used by a dimension member. The index bitmap files are created when there are more than 4,096 unique values in the fact table. This feature can be set up by using the IndexBuildThreshold property that is defined in the Msmrsrv.ini file. For more information about the IndexBuildThreshold property, visit the following Microsoft Developer Network (MSDN) Web site:

http://msdn2.microsoft.com/en-us/library/ms174469.aspx



RESOLUTION
To resolve this issue, process the cube that contains the linked dimension by using the Process Index option. The index bitmap files are reestablished. If you process the cube before the first query discards the index bitmap files, the index bitmap files are maintained, and the processing is completed quickly.



STATUS
This behavior is by design.

Keywords: kbtshoot kbexpertiseadvanced kbsql2005bi kbsql2005as kbprb KB931292

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