On 2014-02-14 12:55:06 +0000, Greg Stark wrote: > On Fri, Feb 14, 2014 at 12:05 PM, Andres Freund <and...@2ndquadrant.com> > wrote: > > There's no reason not > > to ask for a ping when we're writing.
> Is there a reason to ask for a ping? The point of keepalives is to > ensure there's some traffic on idle connections so that if the > connection is dead it doesn't linger forever and so that any on-demand > links (or more recently NAT routers or stateful firewalls) don't time > out and disconnect and have to reconnect (or more recently just fail > outright). This ain't TCP keepalives. The reason is that we want to kill walsenders if they haven't responded to a ping inside wal_sender_timeout. That's rather important e.g. for sychronous replication, so we can quickly fall over to the next standby. In such scenarios you'll usually want a timeout *far* below anything TCP provides. Greetings, Andres Freund -- Andres Freund http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
