public inbox for [email protected]help / color / mirror / Atom feed
streaming replication confusion 5+ messages / 2 participants [nested] [flat]
* streaming replication confusion @ 2012-11-09 02:56 Josh Kupershmidt <[email protected]> 0 siblings, 1 reply; 5+ messages in thread From: Josh Kupershmidt @ 2012-11-09 02:56 UTC (permalink / raw) To: pgsql-docs I think there is at least[4] one confusing documentation leftover from the 9.0 days at: http://www.postgresql.org/docs/devel/static/warm-standby.html First, we claim: | Streaming replication is asynchronous, so there is still a small delay | between committing a transaction in the primary and for the changes | to become visible in the standby. This unqualified statement, which has remained the same since 9.0, suggests synchronous replication is not possible using streaming replication. Further down we are closer to the truth: | PostgreSQL streaming replication is asynchronous by default. Proposed fix for this gripe attached. I'd be pleased to see this particular doc patch backpatched to 9.2 and 9.1, given that the replication docs are both important and fairly confusing. The Streaming Replication wiki page[1] contains similar out-of-date claims[2]; I can fix some of the egregious errors myself, though help is welcome. The "Synchronous Replication" wiki page[3] is in even worse shape, containing mostly info about a patch different than what was committed... and it's currently the first Google search result for "postgresql synchronous replication" :-( Josh [1] http://wiki.postgresql.org/wiki/Streaming_Replication [2] such as "Currently SR supports only asynchronous log-shipping", or already-released functionality described under the "Future release section". [3] http://wiki.postgresql.org/wiki/Synchronous_replication [4] I have a larger gripe about the way this entire page is laid out, with streaming rep. info bolted onto a page which is still named and was intended to be about warm standby, but I'll try to make a separate thread about that. Attachments: [application/octet-stream] streaming_rep.docfix.diff (1.4K, 2-streaming_rep.docfix.diff) download | inline diff: diff --git a/doc/src/sgml/high-availability.sgml b/doc/src/sgml/high-availability.sgml new file mode 100644 index 62f72b4..c29fe82 *** a/doc/src/sgml/high-availability.sgml --- b/doc/src/sgml/high-availability.sgml *************** archive_cleanup_command = 'pg_archivecle *** 738,750 **** </para> <para> ! Streaming replication is asynchronous, so there is still a small delay ! between committing a transaction in the primary and for the changes to ! become visible in the standby. The delay is however much smaller than with ! file-based log shipping, typically under one second assuming the standby ! is powerful enough to keep up with the load. With streaming replication, ! <varname>archive_timeout</> is not required to reduce the data loss ! window. </para> <para> --- 738,751 ---- </para> <para> ! Streaming replication is asynchronous by default ! (see <xref linkend="synchronous-replication">), in which case there is ! a small delay between committing a transaction in the primary and the ! changes becoming visible in the standby. This delay is however much ! smaller than with file-based log shipping, typically under one second ! assuming the standby is powerful enough to keep up with the load. With ! streaming replication, <varname>archive_timeout</> is not required to ! reduce the data loss window. </para> <para> ^ permalink raw reply [nested|flat] 5+ messages in thread
* Re: streaming replication confusion @ 2013-01-05 18:26 Josh Kupershmidt <[email protected]> parent: Josh Kupershmidt <[email protected]> 0 siblings, 1 reply; 5+ messages in thread From: Josh Kupershmidt @ 2013-01-05 18:26 UTC (permalink / raw) To: pgsql-docs On Thu, Nov 8, 2012 at 7:56 PM, Josh Kupershmidt <[email protected]> wrote: > The Streaming Replication wiki page[1] contains similar out-of-date > claims[2]; I can fix some of the egregious errors myself, though help > is welcome. The "Synchronous Replication" wiki page[3] is in even > worse shape, containing mostly info about a patch different than what > was committed... and it's currently the first Google search result for > "postgresql synchronous replication" :-( I've shuffled around the Synchronous replication page, and made some changes to Streaming Replication, though the latter could probably use some further pruning. Could someone take a look at the small documentation patch? -- Sent via pgsql-docs mailing list ([email protected]) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-docs ^ permalink raw reply [nested|flat] 5+ messages in thread
* Re: streaming replication confusion @ 2013-01-17 13:54 Magnus Hagander <[email protected]> parent: Josh Kupershmidt <[email protected]> 0 siblings, 1 reply; 5+ messages in thread From: Magnus Hagander @ 2013-01-17 13:54 UTC (permalink / raw) To: Josh Kupershmidt <[email protected]>; +Cc: pgsql-docs On Sat, Jan 5, 2013 at 7:26 PM, Josh Kupershmidt <[email protected]> wrote: > On Thu, Nov 8, 2012 at 7:56 PM, Josh Kupershmidt <[email protected]> wrote: > >> The Streaming Replication wiki page[1] contains similar out-of-date >> claims[2]; I can fix some of the egregious errors myself, though help >> is welcome. The "Synchronous Replication" wiki page[3] is in even >> worse shape, containing mostly info about a patch different than what >> was committed... and it's currently the first Google search result for >> "postgresql synchronous replication" :-( > > I've shuffled around the Synchronous replication page, and made some > changes to Streaming Replication, though the latter could probably use > some further pruning. Could someone take a look at the small > documentation patch? Was that message supposed to contain a second patch, or were you just referring to the one you sent back in November? -- Magnus Hagander Me: http://www.hagander.net/ Work: http://www.redpill-linpro.com/ -- Sent via pgsql-docs mailing list ([email protected]) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-docs ^ permalink raw reply [nested|flat] 5+ messages in thread
* Re: streaming replication confusion @ 2013-01-17 15:04 Josh Kupershmidt <[email protected]> parent: Magnus Hagander <[email protected]> 0 siblings, 1 reply; 5+ messages in thread From: Josh Kupershmidt @ 2013-01-17 15:04 UTC (permalink / raw) To: Magnus Hagander <[email protected]>; +Cc: pgsql-docs On Thu, Jan 17, 2013 at 6:54 AM, Magnus Hagander <[email protected]> wrote: >> I've shuffled around the Synchronous replication page, and made some >> changes to Streaming Replication, though the latter could probably use >> some further pruning. Could someone take a look at the small >> documentation patch? > > Was that message supposed to contain a second patch, or were you just > referring to the one you sent back in November? I was referring to the initial patch sent in November. Josh -- Sent via pgsql-docs mailing list ([email protected]) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-docs ^ permalink raw reply [nested|flat] 5+ messages in thread
* Re: streaming replication confusion @ 2013-01-20 15:13 Magnus Hagander <[email protected]> parent: Josh Kupershmidt <[email protected]> 0 siblings, 0 replies; 5+ messages in thread From: Magnus Hagander @ 2013-01-20 15:13 UTC (permalink / raw) To: Josh Kupershmidt <[email protected]>; +Cc: pgsql-docs On Thu, Jan 17, 2013 at 4:04 PM, Josh Kupershmidt <[email protected]> wrote: > On Thu, Jan 17, 2013 at 6:54 AM, Magnus Hagander <[email protected]> wrote: >>> I've shuffled around the Synchronous replication page, and made some >>> changes to Streaming Replication, though the latter could probably use >>> some further pruning. Could someone take a look at the small >>> documentation patch? >> >> Was that message supposed to contain a second patch, or were you just >> referring to the one you sent back in November? > > I was referring to the initial patch sent in November. Ok, thanks for confirming. Applied and backpatched. -- Magnus Hagander Me: http://www.hagander.net/ Work: http://www.redpill-linpro.com/ -- Sent via pgsql-docs mailing list ([email protected]) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-docs ^ permalink raw reply [nested|flat] 5+ messages in thread
end of thread, other threads:[~2013-01-20 15:13 UTC | newest] Thread overview: 5+ messages (download: mbox mbox.gz follow: Atom feed) -- links below jump to the message on this page -- 2012-11-09 02:56 streaming replication confusion Josh Kupershmidt <[email protected]> 2013-01-05 18:26 ` Josh Kupershmidt <[email protected]> 2013-01-17 13:54 ` Magnus Hagander <[email protected]> 2013-01-17 15:04 ` Josh Kupershmidt <[email protected]> 2013-01-20 15:13 ` Magnus Hagander <[email protected]>
This inbox is served by agora; see mirroring instructions for how to clone and mirror all data and code used for this inbox