On Tue, Mar 29, 2016 at 9:43 PM, Michael Paquier <michael.paqu...@gmail.com> wrote: > On Wed, Mar 30, 2016 at 10:39 AM, Robert Haas <robertmh...@gmail.com> wrote: >> On Tue, Mar 29, 2016 at 9:37 PM, Michael Paquier >> <michael.paqu...@gmail.com> wrote: >>> On Wed, Mar 30, 2016 at 10:31 AM, Robert Haas <rh...@postgresql.org> wrote: >>>> Add new replication mode synchronous_commit = 'remote_apply'. >>>> >>>> In this mode, the master waits for the transaction to be applied on >>>> the remote side, not just written to disk. That means that you can >>>> count on a transaction started on the standby to see all commits >>>> previously acknowledged by the master. >>>> >>>> To make this work, the standby sends a reply after replaying each >>>> commit record generated with synchronous_commit >= 'remote_apply'. >>>> This introduces a small inefficiency: the extra replies will be sent >>>> even by standbys that aren't the current synchronous standby. But >>>> previously-existing synchronous_commit levels make no attempt at all >>>> to optimize which replies are sent based on what the primary cares >>>> about, so this is no worse, and at least avoids any extra replies for >>>> people not using the feature at all. >>>> >>>> Thomas Munro, reviewed by Michael Paquier and by me. Some additional >>>> tweaks by me. >>> >>> The commit message does not directly mention that the spec of >>> walrcv_receive has been changed in a backward-incompatible way so as >>> the wait control can be done with a latch directly in walreceiver.c >>> and not in libpqwalreceiver.c. That's not worth a mention in the >>> release notes as this is really low-level and compilation on any code >>> using this hook would simply fail on 9.6, so I am just mentioning it >>> for the sake of the archives. >> >> Yeah, I didn't really think that mattered much. I'm not really sure >> what you even mean by backward-incompatible -- AFAIK, that's a private >> interface which we can whack around whenever we like. > > By "Backward-incompatible", I mean that any custom library using this > walrcv hook is not going to compile anymore and we don't provide a > pre-9.5 equivalent. I don't think that's worth worrying though, I have > yet to see this interface being used for something else than > libpqwalreceiver to be honest.
Yeah, I'd be very surprised if anyone did that. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-committers mailing list (pgsql-committers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-committers
