Date: Fri, 30 May 2014 23:03:53 +0200
From: Andres Freund <andres@2ndquadrant.com>
To: Bruce Momjian <bruce@momjian.us>
Cc: PostgreSQL Bugs <pgsql-bugs@postgresql.org>,
 Alvaro Herrera <alvherre@2ndquadrant.com>
Subject: Re: pg_upgrade < 9.3 -> >=9.3 misses a step around multixacts
Message-ID: <20140530210353.GI30516@awork2.anarazel.de>
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On 2014-05-30 16:35:15 -0400, Bruce Momjian wrote:
> On Fri, May 30, 2014 at 05:13:17PM +0200, Andres Freund wrote:
> > It'd need to be clusters that used more multixacts than fit onto two
> > slru offsets/ segments in < 9.2. Otherwise things will probably just
> > continue to work because there's no hole.
> 
> Do you mean <= 9.2 here for the old cluster?

yes.

> Multi-xacts were added in 9.3:

That's not really correct. They were added in 8.2 or something...

>         commit 0ac5ad5134f2769ccbaefec73844f8504c4d6182
>         Author: Alvaro Herrera <alvherre@alvh.no-ip.org>
>         Date:   Wed Jan 23 12:04:59 2013 -0300
> 
>             Improve concurrency of foreign key locking

That just expanded the usage to also be able to track updated rows.

Greetings,

Andres Freund

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


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