Ask HN: Modern OLAP Cube?

What are startups using as alternatives to Oracle and Microsoft for olap data?

The only decent open source project I can find is Mondrian on top of Postgresql.

I'm investigating cubes because I believe it fits my current problem. We have a star schema that we currently just run tons of different reports on. We take advantage of Postgresql materialized views and abuse the crap out of functions.

One of the larger problems we have is dealing with non-additive metrics. E.g, we might want to see how many distinct ip addresses are in a time frame. And since "distinct" is not additive we currently keep large sets around in the rollups to make them additive. I've investigated HyperLogLog data structures to solve this problem but I couldn't get product management on board with probabilistic data structures.

I'm looking forward to hearing what other people are experimenting with.