On Fri, Feb 10, 2012 at 04:34, Fujii Masao <[email protected]> wrote: > On Fri, Feb 10, 2012 at 8:14 AM, Magnus Hagander <[email protected]> wrote: >> On Thu, Feb 9, 2012 at 17:35, Heikki Linnakangas >> <[email protected]> wrote: >>> On 09.02.2012 15:14, Magnus Hagander wrote: >>>> >>>> Have pg_receivexlog always send an invalid log position in status messages >>>> >>>> This prevents pg_basebackup and pg_receivexlog from becoming a synchronous >>>> standby in case 'write' is used for synchronous_commit. >>> >>> >>> It's not completely crazy to use pg_receivexlog as a synchronous standby. It >>> provides the zero-loss property like a real standby does, ie. if the master >>> dies after sending the WAL to pg_receivexlog, that transaction is safe in >>> the archive. >> >> Yes, but as I stated in the email in the thread that the patch was >> posted in, I think this should not be the default behaviour, but it >> should be available as a commandline option, or something along that >> line. > > Even if we make that the default behavior, pg_receivexlog doesn't work as > a sync standby unless synchronous_standby_names is set to "pg_receivexlog" > or "*". There is little risk that we make that the default, I think... No?
We discussed this at some previous time, and since it's fairly common for people to use "*" - in fact, I believe it's what most people do. Which would lead to unintended consequences. I guess we could document that very clearly in the docs of that parameter... > Anyway, to consider pg_receivexlog as a sync standby, we need to change it > so that its status report includes the valid write and flush > positions, and so that > it replies as soon as it writes or flushes the received WAL, like real > sync standby > does. Otherwise, the master has to wait for the status report interval (which > is > specified in -s or --statusint option of pg_receivexlog). Yes, that's what I suggested be controled by a separate parameter. Having it sync standby and only send status reports every now and then seems like a really bad idea. > The proposed change would increase the frequency for pg_receivexlog to send > back the report very much. Which might be a problem. For people who want to > avoid such frequent reports, we might need to introduce the option > which specifies > whether frequent report is allowed or not. Exactly my point... -- Magnus Hagander Me: http://www.hagander.net/ Work: http://www.redpill-linpro.com/ -- Sent via pgsql-committers mailing list ([email protected]) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-committers
