> On 09/29/2014 01:13 PM, furu...@pm.nttdata.co.jp wrote: > >> I don't understand what this patch does. When would you want to use > >> the new --reply-fsync option? Is there any reason *not* to use it? > >> In other words, do we need an option for this, couldn't you just > >> always send the feedback message after fsync? > > > > Thanks for the comment. > > > > --reply-fsync option is intended for use in synchronous mode. > > > > By specifying -F option and --slot option, process calls fsync() when > > it received the WAL, and flush location would be set in feedback > > message. > > > > Interval of sending feedback message depends on -s option in this > > state, so in the case of synchronous mode, waiting for feedback > > message would occure. > > > > therefore, --reply-fsync option is necessary. because it can send the > > feedback message after fsync without waiting for the interval of -s > > option. > > > > The reason for not sending the feedback message after fsync without > > waiting for the interval of -s option always, is to answer the needs > > who want to use fsync only (NOT using synchronous mode). > > I still don't get it. AFAICS there are two ways to use pg_receivexlog. > Either you use it as a synchronous standby, or not. > > What set of options would you pass if you want to use it as a synchronous > standby? And if you don't? Could we just have a single "--synchronous" > flag, instead of -F and --reply-fsync?
Thanks for comment. If you set "synchronous_commit" as "remote_write", the options would be different . The set of options in each case, see the following. Synchronous standby(synchronous_commit=on) --fsync-interval=-1 --reply-fsync --slot=slotname Synchronous standby(synchronous_commit=remote_write) --fsync-interval=-1 --reply-fsync Asynchronous There are no relative options. Well, if the response time delay(value of "--status-interval=interval") is acceptable, "--reply-fsync" is unnecessary. Instead of "--reply-fsync", using "--synchronous"(which summarizes the "--reply-fsync" and "fsync-interval = -1") might be easy to understand. Although, in that case, "--fsync-interval=interval" would be fixed value. Isn't there any problem ? Regards, -- Furuya Osamu -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
