Forum OpenACS Q&A: Re: Is Postgres/MySQL ready for VLDB solutions?
This isn't much of an answer for you, but if you need
open source OLAP you might want to take a look at Mondrian
I've been checking Mondrian a few days ago and it was quite a hassle to install. Not that much Mondrian itself, but the installer for JPivot is broken, the GUI frontend for Mondrian.
We actually decided to go with a "Pivot-Table" friendly CSV-Export for the moment for Project/Open.
Did you manage to install Mondrian successfully?