From: Alvaro Herrera <alvherre@2ndquadrant.com>
To: Bruce Momjian <bruce@momjian.us>
Cc: Andres Freund <andres@2ndquadrant.com>
Cc: PostgreSQL Bugs <pgsql-bugs@postgresql.org>
Subject: Re: pg_upgrade < 9.3 -> >=9.3 misses a step around multixacts
Date: Fri, 27 Jun 2014 17:15:58 -0400
Message-ID: <20140627211558.GQ7340@eldon.alvh.no-ip.org> (raw)
In-Reply-To: <20140627210520.GP7340@eldon.alvh.no-ip.org>
References: <20140619020633.GA20469@momjian.us>
<20140619015205.GD3806@momjian.us>
<20140619014034.GC3806@momjian.us>
<20140619220425.GQ18688@eldon.alvh.no-ip.org>
<20140620010653.GS18688@eldon.alvh.no-ip.org>
<20140620180725.GD29143@momjian.us>
<20140624201346.GB17110@momjian.us>
<20140627210520.GP7340@eldon.alvh.no-ip.org>
List-Unsubscribe: <mailto:majordomo@postgresql.org?body=unsub%20pgsql-bugs>
Alvaro Herrera wrote:
> I think the query above is correct. One possible quibble is a FFFF
> segment that isn't allocated in full. I don't think this is a problem,
> because although the 0000 file would survive deletion, it would be
> overwritten with zeroes as soon as the counter wraps around. Since 0000
> is seen as "in the future" as soon as file 8000 starts being used, it
> shouldn't be a problem there.
... that said, there is a wraparound check in SimpleLruTruncate: if you
are using file 8000 and above, slru.c refuses to remove the old files
because it believes you may have already suffered wraparound, and you
would get a WARNING message every time the truncation was attempted.
The warnings would probably be pretty much invisible because of their
low frequency. This might be improved by my commit this afternoon,
which should cause multixact truncations to be attempted much more
often. In any case, just removing the offending offsets/0000 file
should clear it up.
--
Álvaro Herrera http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
--
Sent via pgsql-bugs mailing list (pgsql-bugs@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-bugs
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-bugs@postgresql.org
Cc: alvherre@2ndquadrant.com, bruce@momjian.us, andres@2ndquadrant.com
Subject: Re: pg_upgrade < 9.3 -> >=9.3 misses a step around multixacts
In-Reply-To: <20140627211558.GQ7340@eldon.alvh.no-ip.org>
* 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