We have been using golang's database/sql and github.com/lib/pq with a PostgreSQL cluster, meaning that a certain database server that was a replication master might be a read-only replica after the previous master has failed.
Recently, our low-usage service managed to keep a single connection in its connection pool (there were no concurrent requests that would have opened a second connection), and its target had been demoted to a read-only replica. As a result, each write operation to the service failed until it was restarted. That would not have happened, if a new connection was made to the cluster.
The problem is I can't find a documented way to discard a connection on certain kinds of errors. The only public method in database/sql that sounds correct is Conn.Close which returns the connection to the pool without closing it. Not calling it will cause a resource leak which will eventually make the pool unusable. Is there a sustainable way to get rid of a connection when the application wants to?
