BI Setup Guidance

I am using PostgreSQL. I have a slave server that I want to use data from for a PostgreSQL staging area which will be separate from the slave. My question is I want to build OLAP cubes and where do the OLAP cubes reside? In another database? Partitioned space? In the repository? Can it be in the same area as my staging area? I am thinking that it is in two areas because of the nature of the two functions the staging area is and what the cubes are.

I appreciate your help.