Today I was playing around with stacking SSAS on top of Teradata. Essentially I have AdventureWorks DW moved over into Teradata and I’m trying to build a dumbed-down version of the AdventureWorks cube against it.
Things went fairly well while my partitions were MOLAP. But when I started changing some of them to ROLAP, SSAS threw the following exception when I tried to process:
Errors in the high-level relational engine. The following exception occurred while the managed IDbConnection interface was being used: The isolation level is not supported by this version of Teradata Database.
After a bit of playing, I found that the issue had to do with including aggregations on these partitions – you can’t. When I set the aggs to 0%, everything worked perfectly. Shortly afterwards, a colleague forwarded me additional information on the subject, which will be included in a soon-to-be released Teradata/SSAS whitepaper:
ROLAP aggregations: An Analysis Services cube partition that uses ROLAP partition storage with the Teradata Database, must be defined with zero aggregations. This issue is discussed in Designing Partition Storage and Aggregations section. Recommendation to use AJI for performance