Having done a search of the list lately, there seems to be a real bias
away from mod_gzip toward mod_deflate. For reasons that I have just been
informed of, there is no "approved" mod_gzip for Apache/2.0.x. Instead,
mod_deflate is being touted as a "suitable" alternative for content
compression.

Well, it's not. It's ok, but mod_gzip -- and this will get me into
trouble with the Apache Core team -- has a far better content
compression algorithm than mod_deflate.

Best examples I can give are from my own servers. One is Apache/1.3.27
with mod_gzip and the current production one is Apache/2.0.44 with
mod_deflate

***

http://www.pierzchala.com/compress/homepage2.html
No Compression 56380 bytes

http://www.pierzchala.com/compress/homepage2.html
mod_deflate 19818 bytes
-- DeflateMemLevel 8

http://www.pierzchala.com:9280/compress/homepage2.html
mod_gzip 16333 bytes
-- Default configuration
-- No source hack to increase gzip compression level applied

***

As well, mod_deflate appears to have a bug when you modify the
DeflateMemLevel setting. A "9" is supposed to give maximum compression.
Unfortunately, this is not the case.

***

Example #1
----------
http://www.pierzchala.com/resume.html -- 10924 bytes

Deflate Level Byte Size
----------------------------------
1 5520
2 4993
3 4719
4 4589
5 4521
6 4500
7 4488
8 4473
9 4483


Example #2
----------
http://www.pierzchala.com/compress/homepage2.html -- 56380 bytes

Deflate Level Byte Size
----------------------------------
1 25411
2 22503
3 21649
4 20568
5 20129
6 20009
7 19914
8 19818
9 19898

***

Could a setting of "9" adds so much more header information that it
actually increases the file size?

I am throwing this out there to perhaps stir some open and frank
discussion about the merits of the GZIP approach of mod_gzip versus the
ZLIB approach of mod_deflate. I would like this to be discussed in the
open, as the benefits of an improved compression module that is a part
of the core Apache far outweighs the differences that separate the ZLIB
from the GZIP camp.

smp

--

****

Stephen Pierzchala
stephen@pierzchala.com
http://www.pierzchala.com/


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