[Mondrian] per query memory limit?

Wright, Jeff (Truven Health) jeff.s.wright at truvenhealth.com
Thu Jul 11 16:49:09 EDT 2013

Has anybody else every thought about implementing some kind of per query memory limit?

In our application, users can create ad hoc queries against a large schema with many medium-to-high cardinality dimensions. For that to work, it's important to be able to stop a query from taking over the Mondrian instance and using all memory. We've tried the memory threshold property and that's not a good solution.

I think in general there are two possible approaches:

1) Try to estimate the memory that will be required ahead of time, abort if too high.
2) Monitor some data structure that is a proxy for memory as you evaluate the query, and abort it out when you cross the threshold.

We've done some work with cell limits that is sort of like #1. But we find that a naive cell estimate is likely to miss some intermediate memory usage.

Any thoughts?

--Jeff Wright

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