Sunday, February 12, 2012

Autoslicing not working

I have around 36 partitions in the 2005 cube. Each partition is roughly 20M fact rows.

The partitions are differentiated by a date member dimension.

When I run a query which selects by a distinct date, SSAS tries to scan all partitions (for inclusions?). This introduces a huge performance impact. It takes many seconds to run a single query.

I have aggregations designed specifically for relevant dimensions. The Profiler shows that SSAS reads from aggregations. It does not read from facts.

The storage mode is MOLAP.

Do I need to use the partition slice property ? I am seeing on forums from time to time that this attribute is not used in MOLAP.

I just need to make sure that my queries are fast.

I don't see where it could hurt to set this property, though BOL indicates this is only used by SSAS for ROLAP partitions. I thought I had heard that with MOLOP and/or HOLAP, that SSAS maintained an internal set of information regarding the contents of a slice that would handle this function for you. Maybe someone else out there could chime in on this one.

Regarding the query you specify above, are you specifying a date member from the specific cube dimension used to partition your cube? You probably are but it wasn't explicitly stated. Date dimensions are often used in a role-playing capacity which introduces some confusion.

Thanks,
Bryan

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can anyone clarify if the Slice property on Partition is used in MOLAP or not?

I checked info....xml files for my slicing dimension min/max values and they seem correct, however with explicit queries, SSAS still reads a bunch of partitions...

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