Date: Tue, 3 Dec 2013 20:00:16 +0100
From: Andres Freund <andres@2ndquadrant.com>
To: Robert Haas <robertmhaas@gmail.com>
Cc: =?iso-8859-1?Q?Fabr=EDzio?= Mello <fabriziomello@gmail.com>,
 Christian Kruse <christian@2ndquadrant.com>,
 Pgsql Hackers <pgsql-hackers@postgresql.org>
Subject: Re: Time-Delayed Standbys
Message-ID: <20131203190016.GG19016@awork2.anarazel.de>
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On 2013-12-03 13:46:28 -0500, Robert Haas wrote:
> On Tue, Dec 3, 2013 at 12:36 PM, Fabr=EDzio de Royes Mello
> <fabriziomello@gmail.com> wrote:
> > On Tue, Dec 3, 2013 at 2:33 PM, Christian Kruse <christian@2ndquadrant.=
com>
> > wrote:
> >>
> >> Hi Fabrizio,
> >>
> >> looks good to me. I did some testing on 9.2.4, 9.2.5 and HEAD. It
> >> applies and compiles w/o errors or warnings. I set up a master and two
> >> hot standbys replicating from the master, one with 5 minutes delay and
> >> one without delay. After that I created a new database and generated
> >> some test data:
> >>
> >> CREATE TABLE test (val INTEGER);
> >> INSERT INTO test (val) (SELECT * FROM generate_series(0, 1000000));
> >>
> >> The non-delayed standby nearly instantly had the data replicated, the
> >> delayed standby was replicated after exactly 5 minutes. I did not
> >> notice any problems, errors or warnings.
> >>
> >
> > Thanks for your review Christian...
>=20
> So, I proposed this patch previously and I still think it's a good
> idea, but it got voted down on the grounds that it didn't deal with
> clock drift.  I view that as insufficient reason to reject the
> feature, but others disagreed.

I really fail to see why clock drift should be this patch's
responsibility. It's not like the world would go under^W data corruption
would ensue if the clocks drift. Your standby would get delayed
imprecisely. Big deal. From what I know of potential users of this
feature, they would set it to at the very least 30min - that's WAY above
the range for acceptable clock-drift on servers.

Greetings,

Andres Freund

--=20
 Andres Freund	                   http://www.2ndQuadrant.com/
 PostgreSQL Development, 24x7 Support, Training & Services


--=20
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