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On Mon, 18 Nov 2002, James Clark wrote:
>
> > A variety
> > of small-scale studies have shown that general-purpose compression is
> > generally as good as, or better than, some scheme that knows it's
> > compressing XML.
>
> Hmmm. What about
>
> http://www.research.att.com/sw/tools/xmill/
Nice try - but no cigar.
Using a real file from my office (I chose a nice big one at random to
test):
-rw-rw---- 1 snowhare snowhare 7267803 Nov 18 07:15 recipes.xml
xmill returned:
-rw-rw-r-- 1 snowhare snowhare 1993131 Nov 18 07:15 recipes.xmi
but a simple bzip2 returned:
-rw-rw---- 1 snowhare snowhare 1922919 Nov 18 07:15 recipes.xml.bz2
So, the _optimized_ XML compressor did more poorly than a default general
purpose compressor by a few percentage points (at least for this data).
Their description sounds remarkably similiar to a block sort compressor -
which is _precisely_ what bzip2 is (minus the 'patent rights' language
from AT&T ;) ). Which is probably why the end sizes are fairly close for
both.
Its _DAMNED HARD_ to improve on a modern general purpose compression
program for textual data.
--
Jerry
I should either have been less specific or more correct ...
---Andy Armstrong <andy@wonderworks.co.uk>
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