BUG: Processing a Cube Fails Without a Specific Error Message

• Microsoft SQL Server OLAP Services version 7.0

SYMPTOMS

Processing a cube with an aggregation containing more than 64 thousand records fails without a specific error message while creating aggregations after reading in a segment's worth.

CAUSE

SQL Server 7.0 OLAP Services calculates aggregations for a cube from the fact table. The initial aggregations designed are at the top level members (All, All, All, All, and so on). As more aggregations are designed, OLAP Services looks lower in the dimension hierarchies. For example, OLAP starts using ([Produce], [WA], and so on).

In this way, aggregations can have a great deal of records, and this number usually increases as the aggregations get deeper. In fact, you can think of the fact table as the largest aggregation. This problem surfaces if the number of records in an aggregation is greater than 64 thousand and the storage type is not ROLAP.

The Process Buffer Size value in the Properties dialog box affects the likelihood of encountering this problem. Increasing the Process Buffer Size value increases the temporary buffer that OLAP Services uses for storing facts and determining the number of records that can fit in a segment. Because aggregations are calculated on a segment-by-segment basis, there is a higher probability of running into this problem if the Process Buffer Size value is higher.

This problem has been seen in cubes with one or more of the following characteristics:

• The fact table has more than one million rows.



• The number of aggregations affords a performance gain greater than 30 percent, as indicated in the Storage Design Wizard or the Usage-Based Optimization Wizard.



• The cube is on a server where the Process Buffer Size value has been changed.



• Each record in the fact table (<= 3 dimensions, ~2 measures).

WORKAROUND

To work around this problem, do any of the following:

• Reduce the Process Buffer Size value in the Properties dialog box (note that 4 MB is the default value after a new installation). You must stop and then restart the server for this change to take effect.
  
  -or-



• Design fewer aggregations for the cube.
  
  -or-



• Change the storage type to ROLAP.

STATUS

Microsoft has confirmed this to be a problem in SQL Server OLAP Services version 7.0.

Additional query words: plato 64K K 30% %

Keywords          : SSOSdso SSOSmgr kbbug7.00 
Version           : winnt:7.0
Platform          : winnt 
Issue type        : kbbug 

Last Reviewed: February 16, 1999