Currently ODBC poller does not have any timeout.
In case of DB server is down, the "ODBC poller" process will stay busy. Since the DB server is completely down, the timeout at DB level cannot help (because the DB server simply does not respond).

One enhancement to this use case can be to allow only 1 concurrent ODBC poller connection per one DB host.

This would be implemented only for "ODBC poller" process, but not for other "pollers".

It should be an option to not allow concurrent connections per one "hostid" or per one "IP" address. Users should have a choice to use this "protection" or not.

A similar implementation has been already done for "IMPI poller".