From: Rafael Martinez <r.m.guerrero@usit.uio.no>
To: Robert Haas <robertmhaas@gmail.com>
Cc: pgsql-docs@postgresql.org
Subject: Re: Information about WAL Configuration needs an update
Date: Mon, 13 Jun 2011 20:25:11 +0200
Message-ID: <1307989511.2862.810.camel@core2> (raw)
In-Reply-To: <BANLkTikCxvg9J4ZbGPXt8PrSxiptjkEdeQ@mail.gmail.com>
References: <4DE89072.7070305@usit.uio.no>
<BANLkTikCxvg9J4ZbGPXt8PrSxiptjkEdeQ@mail.gmail.com>
On Mon, 2011-06-13 at 13:24 -0400, Robert Haas wrote:
> On Fri, Jun 3, 2011 at 3:42 AM, Rafael Martinez
> >
> > You can see the graph with the generation of WAL files + some extra
> > information for this test here: http://folk.uio.no/rafael/total_wal/
> >
> > What do you think? Shouldn't we update the documentation with some
> > information about this?
>
> Perhaps, but we'd have to think of something intelligent to say about
> it first. We can't remove the old WAL files until we successfully
> checkpoint, and so I think if checkpoints are taking a very long to
> complete or failing altogether, there's actually no upper bound. I
> don't think we have any kind of "hard stop" where, if no log space is
> available, we just refuse to process write transactions - such a thing
> would seem to be rather dangerous.
>
Well, a good start will be to try to identify or describe the situations
where checkpoints can take very long to complete or fail altogether.
I have the first one: Creating a large GIN index on a tsvector column. I
don't know why, maybe somebody who knows postgres internals can explain
why a creation of an index can create this situation.
regards,
--
Rafael Martinez Guerrero
Center for Information Technology
University of Oslo, Norway
PGP Public Key: http://folk.uio.no/rafael/Attachments:
signature.asc (application/pgp-signature, 197B) download
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To: pgsql-docs@postgresql.org
Cc: r.m.guerrero@usit.uio.no, robertmhaas@gmail.com
Subject: Re: Information about WAL Configuration needs an update
In-Reply-To: <1307989511.2862.810.camel@core2>
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