Issue: Import DB Might Clear Current DB from Memory

Under certain server configurations, e.g. one db uses a prefix and another does not, or two different database engines are used, the current database pointer might be lost from memory when connecting to the source database during an import operation. This makes it impossible to perform imports in such a setup.

Update the DB controller to support multiple instances of a DB controller, i.e. 1 per connection rather than 1 that is shared across all connections.