Large SSAS Partition

 
Earlier this week I had to take ownership of a new SSAS system due to one of our offices shutting down. I’ve heard of it exisiting but never was able to take a look at it until just a few days ago.
  
I had heard there were performance problems and when I opened up the cube in BIDS, I came across this…
 
 

 

A single partition with a size of over 40GB. I initially thought it was due to too many aggregations (60% indicated), however after a closer look, the entire 40GB lies in the leaf fact data. All the dimension attributes are set to a RelationshipType of Flexible, and since the dimensions are being processed  by a ProcessUpdate without ProcessAffectedObjects set to true, all the aggregations have never been rebult. My best guess is there are around 3-6 billion fact rows contained in the partition. Wow.

Personally I always try to keep disk size under 1GB – row wise under 100 million. I know MS best practices says to keep it around 20 million, however after talking to others it seems like you can go a fair amount over that 20 million. All depends on how many dimensions/aggregations are associated with a row of course…

What’s the largest partition size you guys have seen?

 

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