On Fri, 2008-11-14 at 19:23 +0200, Heikki Linnakangas wrote: > Simon Riggs wrote: > > On Fri, 2008-11-14 at 19:00 +0200, Heikki Linnakangas wrote: > >> Why do we need a separate XLogsndRqst variable in shared memory? Don't > >> we always want to send the WAL up to the same point as we flush it? > > > > If we're doing synch rep and we're committing. > > You flush and send the WAL, up to the same point?
Yes, but you may make progress towards it in different size steps. > > What happens when we're > > doing async rep or running something like a large load. > > You don't flush, and you don't request the WAL to be sent? The > background writer and WAL sender can still wake up periodically, and > write and send the WAL as they find convenient. With WAL writes we write and flush at the same time. With WAL sending that doesn't sound such a good plan. -- Simon Riggs www.2ndQuadrant.com PostgreSQL Training, Services and Support -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
