From: David Steele <david@pgmasters.net>
To: pgsql-hackers@lists.postgresql.org
Subject: Re: PATCH: Exclude unlogged tables from base backups
Date: Tue, 12 Dec 2017 18:24:23 -0500
Message-ID: <b5b63d5c-2552-4b13-0fe5-844901eefeea@pgmasters.net> (raw)
In-Reply-To: <CAB7nPqRW=rk_i8q1UhfDcNGvYpMVm4oTqwRacWHG=+5uRLi9UQ@mail.gmail.com>
References: <04791bab-cb04-ba43-e9c0-664a4c1ffb2c@pgmasters.net>
<20171212225234.jqdwd4sp663l4znp@alap3.anarazel.de>
<5e428ad7-f37f-6479-aabf-2c8b9318fb79@pgmasters.net>
<CAB7nPqRW=rk_i8q1UhfDcNGvYpMVm4oTqwRacWHG=+5uRLi9UQ@mail.gmail.com>
Hi Michael,
On 12/12/17 6:08 PM, Michael Paquier wrote:
>
>> If the forks are written out of order (i.e. main before init), which is
>> definitely possible, then I think worst case is some files will be backed up
>> that don't need to be. The main fork is unlikely to be very large at that
>> point so it doesn't seem like a big deal.
>
> As far as I recall the init forks are logged before the main forks. I
> don't think that we should rely on that assumption though to be always
> satisfied.
Indeed, nothing is sure until a checkpoint. Until then we must assume
writes are random.
>> Well, I would be happy if you had a look!
>
> You can count me in. I think that this patch has value for some
> dedicated workloads.
Thanks!
> It is a waste to backup stuff that will be
> removed at recovery anyway.
It also causes confusion when the recovered database is smaller than the
backup. I can't tell you how many times I have answered this question...
--
-David
david@pgmasters.net
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-hackers@postgresql.org
Cc: david@pgmasters.net, pgsql-hackers@lists.postgresql.org
Subject: Re: PATCH: Exclude unlogged tables from base backups
In-Reply-To: <b5b63d5c-2552-4b13-0fe5-844901eefeea@pgmasters.net>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox