On Wed, 2019-07-10 at 17:04 +0900, Michael Paquier wrote: > Hmm. synchronous_commit is user-settable, which means that it is > possible to enforce a value in the connection string doing the > connection. Isn't that something we had better enforce directly in > the tool? In this case what could be fixed is GetConnection() which > builds the connection string parameters.
I don't follow. Are you talking about the replication connection from pg_receivewal to the PostgreSQL server? That wouldn't do anything, because it is the setting of "synchronous_commit" for an independent client connection that is the problem: - pg_receivewal starts a replication connection. - It is added to "synchronous_standby_names" on the server. - A client connects. It sets "synchronous_commit" to "remote_apply". - If the client modifies data, COMMIT will hang indefinitely, because pg_receivewal will never send confirmation that it has applied the changes. One alternative option I see is for pg_receivewal to confirm that it has applied the changes as soon as it flushed them. It would be cheating somewhat, but it would work around the problem in a way that few people would find surprising. Yours, Laurenz Albe
