Message-ID: <4BA6DA08.4010201@postnewspapers.com.au>
Date: Mon, 22 Mar 2010 10:46:32 +0800
From: Craig Ringer <craig@postnewspapers.com.au>
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To: Dave Crooke <dcrooke@gmail.com>
CC: David Newall <postgresql@davidnewall.com>,
	pgsql-performance@postgresql.org, robertmhaas@gmail.com,
	Tom Lane <tgl@sss.pgh.pa.us>
Subject: Re: GZIP of pre-zipped output
References: <ca24673e1003211004l68237f72r101eb04082f8e288@mail.gmail.com>
In-Reply-To: <ca24673e1003211004l68237f72r101eb04082f8e288@mail.gmail.com>
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On 22/03/2010 1:04 AM, Dave Crooke wrote:
> 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.

bzip2 doesn't work very well on gzip'd (deflated) data, though. For good 
results, you'd want to feed it uncompressed data, which is a bit of a 
pain when the compression is part of the PDF document structure and when 
you otherwise want the PDFs to remain compressed.

Anyway, if you're going for extreme compression, these days 7zip is 
often a better option than bzip2.

--
Craig Ringer