When working with multiple databases, it seems not possible to switch between database connections (DSNs).

A typical use case would be in situations where you have two databases which are differently tuned; for the kind of data they deal with. One for configuration lookup, i.e high performance, almost all coming from memory, and the other database server for huge tables, say for example logs or financial transaction history.

If one needs to write a test that would talk to multiple databases, it would be handy to be able to switch between DSNs at will during the test.