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Date: Sun, 21 Mar 2010 12:04:00 -0500
Message-ID: <ca24673e1003211004l68237f72r101eb04082f8e288@mail.gmail.com>
Subject: GZIP of pre-zipped output
From: Dave Crooke <dcrooke@gmail.com>
To: David Newall <postgresql@davidnewall.com>
Cc: pgsql-performance@postgresql.org, robertmhaas@gmail.com,
	Tom Lane <tgl@sss.pgh.pa.us>, Craig Ringer <craig@postnewspapers.com.au>
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If you are really so desparate to save a couple of GB that you are resorting
to -Z9 then I'd suggest using bzip2 instead.

bzip is designed for things like installer images where there will be
massive amounts of downloads, so it uses a ton of cpu during compression,
but usually less than -Z9 and makes a better result.

Cheers
Dave

On Mar 21, 2010 10:50 AM, "David Newall" <postgresql@davidnewall.com> wrote:

Tom Lane wrote:
>
> I would bet that the reason for the slow throughput is that gzip
> is fruitlessl...
Indeed, I didn't expect much reduction in size, but I also didn't expect a
four-order of magnitude increase in run-time (i.e. output at 10MB/second
going down to 500KB/second), particularly as my estimate was based on
gzipping a previously gzipped file.  I think it's probably pathological
data, as it were.  Might even be of interest to gzip's maintainers.

--0016e6d9728a22269a04825291e7
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<p>If you are really so desparate to save a couple of GB that you are resor=
ting to -Z9 then I&#39;d suggest using bzip2 instead.</p>
<p>bzip is designed for things like installer images where there will be ma=
ssive amounts of downloads, so it uses a ton of cpu during compression, but=
 usually less than -Z9 and makes a better result.</p>
<p>Cheers<br>
Dave </p>
<p><blockquote type=3D"cite">On Mar 21, 2010 10:50 AM, &quot;David Newall&q=
uot; &lt;<a href=3D"mailto:postgresql@davidnewall.com">postgresql@davidnewa=
ll.com</a>&gt; wrote:<br><br><p><font color=3D"#500050">Tom Lane wrote:<br>=
&gt;<br>
&gt; I would bet that the reason for the slow throughput is that gzip<br>&g=
t; is fruitlessl...</font></p>
Indeed, I didn&#39;t expect much reduction in size, but I also didn&#39;t e=
xpect a four-order of magnitude increase in run-time (i.e. output at 10MB/s=
econd going down to 500KB/second), particularly as my estimate was based on=
 gzipping a previously gzipped file. =A0I think it&#39;s probably pathologi=
cal data, as it were. =A0Might even be of interest to gzip&#39;s maintainer=
s.<br>

</blockquote></p>

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