Qmail-sql can handle multiple databases. It will try another database if
- the current database is unreachable or takes too much time to connect
- the database returned a query-error
- the database didn't reply fast enough
The configuration is quite simple:
connection_timeout and query_timeout default to 0: wait
forever (or until the database-client library aborts due to a socketerror)
- Define a 'connectionstring' for each database you want in your pool.
- Define connection_timeout to X seconds if you want qmail-sql to try a new
database if qmail-sql couldn't connect within X seconds.
- Define query_timeout to X seconds if you want qmail-sql to try a new
database if the database didn't reply within X seconds.