What are the pros & concs of using multiple different types of database connections (e.g. sql server, adw, oracle db ee) in a single semantic model, assuming tables from different types of connections will be joined or sourced to each other — as opposed to pulling all these sources connections into a single database connection (merging adw, oracle db into sql server) & then using a single database connection? If we can avoid integration / syncronising between databases that would be good, but don't want to use multiple connections if say joins are going to run longer if table A in sql server is being joined to table B in adw as opposed to table A in adw being joined to table B in the same adw.
