I am talking about the protocol, not a query. What if the state of the connection is not even at ready-for-query state, how do I issue a query? There is no DISCARD ALL in the protocol [0]. You might have only read 3 rows and still have a thousand to flush, or you might have sent a Parse and are awaiting a ParseComplete. This is the type of thing that a Postgres connection pooler has to keep track of. Here's some of their code: https://github.com/yandex/odyssey/blob/master/sources/reset.... (note how it has to get back to ready-for-query state before rolling back).