On Fri, 2010-09-03 at 12:50 +0900, Fujii Masao wrote: > On Thu, Sep 2, 2010 at 11:32 PM, Heikki Linnakangas > <heikki.linnakan...@enterprisedb.com> wrote: > > I understand what you're after, the idea of being able to set > > synchronization level on a per-transaction basis is cool. But I haven't seen > > a satisfactory design for it. I don't understand how it would work in > > practice. Even though it's cool, having different kinds of standbys > > connected is a more common scenario, and the design needs to accommodate > > that too. I'm all ears if you can sketch a design that can do that. > > That design would affect what the standby should reply. If we choose > async/recv/fsync/replay on a per-transaction basis, the standby > should send multiple LSNs and the master needs to decide when > replication has been completed. OTOH, if we choose just sync/async, > the standby has only to send one LSN. > > The former seems to be more useful, but triples the number of ACK > from the standby. I'm not sure whether its overhead is ignorable, > especially when the distance between the master and the standby is > very long.
No, it doesn't. There is no requirement for additional messages. It just adds 16 bytes onto the reply message, maybe 24. If there is a noticeable overhead from that, shoot me. -- Simon Riggs www.2ndQuadrant.com PostgreSQL Development, 24x7 Support, Training and Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
