Monday, March 12, 2012

Problem with ROLAP dimension updates

Simple scenario:
Cube based on a single table. (FactContacts)
One HOLAP count of rows measure.
One ROLAP fact dimension with an attribute based on a nullable string column. (Status)

Everything works fine as long as I process the cube manually through VS. However, I often get the following error if I rely on the cube to update automatically as my source table changes. (Interestingly the error doesn't always occur.)

The query could not be processed:
o Errors in the OLAP storage engine: The attribute key cannot be found: Table: dbo_FactContacts, Column: Status, Value:aaaa.
o Errors in the OLAP storage engine: The process operation ended because the number of errors encountered during processing reached the defined limit of allowable errors for the operation.

My first guess was that things are getting updated in the wrong sequence (measure before dimension), so I've tried changing the ProcessingPriority properties on the dimension and on the measure group but that didn't have any effect.

Any ideas?
I should probably also clarify I have proactive caching enabled, both on the dimension and on the measure group. My notification method is SQL Server.

I'd really like to know if this could possibly be a bug of SSAS, or if I'm just missing something. This problem is pretty much a showstopper for my project, as real-time data is a requirement.

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