Sender: smw@sabre.com
Message-ID: <38035ECB.A89A13E8@sabre.com>
Date: Tue, 12 Oct 1999 11:16:11 -0500
From: "Steven M. Wheeler" <swheeler@sabre.com>
Organization: Mid-range UNIX Engineering, The SABRE Group
MIME-Version: 1.0
To: Tom Lane <tgl@sss.pgh.pa.us>
CC: pgsql-sql@hub.org
Subject: Re: [SQL] Questions about vacuum analyze
References: <3104.939393781@sss.pgh.pa.us>
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit

Space taken up by entire DB:  6.7GB
Space available on filesystem: 9.2GB

Space taken by currnt table: 3.7GB
Space taken by currnt index: 2.5GB

Fluctuation of available space during a select distinct on the currnt table:
max: 9.2GB, min: 4.1GB

--
Steven Wheeler
Mid-Range UNIX Engineering
Sabre Inc.
(918) 292-4119

Tom Lane wrote:

> "Steven M. Wheeler" <swheeler@sabre.com> writes:
> > I am now running into another problem.  I need to do select distinct from the
> > currnt to get dates for maintenance activity (rows to summarize and move to
> > history).  When ever I do I get this message in my server.log file:
>
> > NOTICE:  BufFileRead: should have flushed after writing
>
> > And I get 0 records selected.
>
> After some code browsing I have come up with a theory: is it possible
> that you are running out of disk space during the sort?  I see psort.c
> neglects to check for write failure :-(, although I am not entirely
> clear on why that particular message and nothing else would come out
> after it bulled ahead with an incomplete temporary file.
>
> Sorting a large table seems to require temp disk space equal to several
> times the size of the table.  Since you said your table is 40M rows,
> I can easily believe you don't have that much free space...
>
> I don't believe anyone has taken a hard look at psort.c in a long time.
> I will try to dive into it and see if its resource consumption can't
> be reduced.  Mergesort inherently requires 2X the original data space,
> but it seems that psort is using even more than that, and perhaps this
> can be improved.
>
>                         regards, tom lane