From: Steven M. Wheeler <swheeler@sabre.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: pgsql-sql@hub.org
Subject: Re: [SQL] Questions about vacuum analyze
Date: Tue, 12 Oct 1999 11:16:11 -0500
Message-ID: <38035ECB.A89A13E8@sabre.com> (raw)
References: <3104.939393781@sss.pgh.pa.us>
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
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To: pgsql-sql@postgresql.org
Cc: swheeler@sabre.com, tgl@sss.pgh.pa.us, pgsql-sql@hub.org
Subject: Re: [SQL] Questions about vacuum analyze
In-Reply-To: <38035ECB.A89A13E8@sabre.com>
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