>- Data isolation by either physical separation (i.e. separate database) or logical separation (i.e. separate schema, table, or column association) depending on requirements

It's interesting to me that you and @abraae seem to take the exact opposite view on the topic of data isolation where he/she has a much... harsher opinion:

>We took the decision to use separate databases (schemas in the Oracle world) ... I now think of this approach as maybe getting into heroin (no direct experience). Feels great, powerful, you can do anything. But ultimately it will kill you.

Of course this doesn't apply to the case of column association, but I'm interested on your take on this.