What options do I have for creating OLAP cubes with Postgres and making it accessible via .net webservices/wcf? [closed]
We came across a similar type of an issue and used Modrian (Pentahoe BI) as the OLAP server. This is free and open source. It should provide you access to the OLAP cube from your VB code since Mondrian is also based on XMLA. Front end, as far as browsing the cube and running live mdx queries are concerned, you will need to come up with some solution (actually we are currently developing and integrating the capability to our own BI tool). But we were successful using Mondrian on a web based solution.
We (www.icCube.com) got a customer with similar setup regarding the data (volume and postgres).
Regarding the front-end and access via .Net: we're not specialist (we're from JAVA) but the OLAP driver (actually the same used by Excel) should be ok to access our cube via XMLA (and transparent for your programmers).
We're not free but I guess quite affordable compared to the big names in the BI market.