From: Dimitri Fontaine <dimitri@2ndQuadrant.fr>
To: Josh Berkus <josh@agliodbs.com>
Cc: Simon Riggs <simon@2ndQuadrant.com>, Robert Haas <robertmhaas@gmail.com>,
	Greg Stark <gsstark@mit.edu>, Bruce Momjian <bruce@momjian.us>,
	pgsql-hackers@postgresql.org
Subject: Re: Simplifying replication
Organization: 2ndQuadrant
References: <201010220022.o9M0M8Q29438@momjian.us>
	<4CC0DEDE.7060707@agliodbs.com>
	<AANLkTin0RfGOvk20vLYYfCDzdf5Sf94aQ5V-xOBB+Kqx@mail.gmail.com>
	<AANLkTik-L-68UpwgyBh5HtROzkEYQ297fiy7C-c6qRfX@mail.gmail.com>
	<1288096049.1587.253.camel@ebony> <4CC8931D.3040800@agliodbs.com>
User-Mail-Address: dimitri@2ndQuadrant.fr
Date: Sun, 31 Oct 2010 22:12:12 +0100
In-Reply-To: <4CC8931D.3040800@agliodbs.com> (Josh Berkus's message of "Wed,
	27 Oct 2010 14:01:17 -0700")
Message-ID: <m2lj5e83tf.fsf@2ndQuadrant.fr>
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Josh Berkus <josh@agliodbs.com> writes:
>> You have to put the WAL files *somewhere* while you do the base backup.
>
> Agreed.  That's why I like the idea of having a
> max_wal_size/min_wal_time instead of keep_wal_segments or
> checkpoint_segments.  It's relatively simple for a DBA to know how much
> disk space s/he has for WAL, total, before locking up the system.

What if that somewhere is as easy to setup as a PostgreSQL archive
cluster: set a GUC a two, start the server, then in the production
server have archive_mode =3D on and use some internal archive and restore
commands, like 'pg_archivewal -h host -p port =E2=80=A6'?

It's only pushing the problem away, but in my mind the only reason why
we're still talking about the problem is *not* the wal related settings
but the current complexity of setting up a trustworthy archive server,
and the number of external tools required in the operation (shell, scp,
rsync, rm, etc=E2=80=A6).

Or is it just me?

Regards,
--=20
Dimitri Fontaine
http://2ndQuadrant.fr     PostgreSQL : Expertise, Formation et Support