Re: pg_multixact not getting truncated - Mailing list pgsql-hackers

From Andres Freund
Subject Re: pg_multixact not getting truncated
Date
Msg-id 20141108115246.GD4510@alap3.anarazel.de
Whole thread Raw
In response to Re: pg_multixact not getting truncated  (Josh Berkus <josh@agliodbs.com>)
List pgsql-hackers
On 2014-11-07 16:09:44 -0800, Josh Berkus wrote:
> On 11/05/2014 11:15 AM, Josh Berkus wrote:
> > On 11/05/2014 10:40 AM, Jim Nasby wrote:
> >> Can you post the contents of pg_multixact/members/?
> > 
> > Well, not as of last week, obviously.
> > 
> > https://gist.github.com/jberkus/d05db3629e8c898664c4
> > 
> > I haven't pasted all the filenames, because, well, look at the count.  I
> > also added the contents of the /offsets directory, for full information.
> > 
> > Note that we've added 400 multixact files since my first email.
> 
> So, just did a quick survey of our managed services customers.  4 out of
> 6 have pg_multixact bloat.  Basically it looks like this:
> 
> User1 (the one above): 1.1GB
> User2: 64K
> User3: 929MB
> User4: 1.3GB
> User5: 301MB
> User6: 48K
> 
> Nobody (out of 6 more) running a version older than 9.3 had a
> pg_multixact larger than 128K.
> 
> None of these users used pg_upgrade, so that's not the source of this
> problem.  Instead, as demonstrated earlier, we are simply not truncating
> pg_multixact sufficiently.
> 
> So this looks like a pretty serious bug.

I've not seen actual evidence of a bug here. What's their multixact
related settings? How large is pg_clog?

Greetings,

Andres Freund

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



pgsql-hackers by date:

Previous
From: Petr Jelinek
Date:
Subject: Re: Sequence Access Method WIP
Next
From: Andres Freund
Date:
Subject: Re: pg_multixact not getting truncated