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Re: CVSNT and Subversion binary file handling comparison

From: Ryan Schmidt <subversion-2006Q1_at_ryandesign.com>
Date: 2006-03-18 14:11:40 CET

On Mar 18, 2006, at 01:54, Kevin Grover wrote:

>> Comparing binary files handling, we've found that CVSNT seems to
>> be much more efficient than Subversion.
>>
>> We tested with the file mysql-noinstall-5.0.18-win32.zip
>> (38.401.269 bytes) , downloaded from www.mysql.com
>>
>> The next table shows the file system space used by subversion and
>> CVSNT after operations 1, 2, 3 y 4.
>>
>> 1 2
>> 3 4
>> SVN: 37.932.031 37.983.254 46.071.560
>> 72.523.597
>> CVS: 38.535.677 38.587.299 38.779.655
>> 38.990.102
>>
>> 1: zip file added to the repository
>> 2: access.cfg file was eliminated from the .zip and the change
>> was commited
>> 3: mysqlclient.lib file was eliminated from the .zip and the
>> change was commited
>> 4: mysqld-debug.exe file was eliminated from the .zip and the
>> change was commited
>
> However, keep in mind that Subversion keeps a local 'clean' copy of
> files. When you commit those clean copies must be updated also.
> If you where to test updates on a very slow or dialup connection
> (or with vary large binary files), I'd guess that you'd find
> Subversion faster: It creates the deltas locally and only transmits
> that data. Also, because of the local clean copies, you can do
> comparisions and reverts on your working copy while not having
> access to the repository (while on a plane for example).

Kevin, he wasn't talking about how long anything takes, and he wasn't
talking about disk space used on the client; he was talking about
disk space used on the server. True, there are other considerations
which might should be more important, given how cheap disks are now.

Alfredo, Subversion works best with text files and other files
(generally uncompressed files) where the difference between one
revision of a file and the next can be efficiently expressed as a
diff. Try your test again with uncompressed files and see if
Subversion performs any better in regard to this metric. Also, note
that some compression formats, like gzip, offer an option that makes
them work better for programs that want to compute differences; gzip
calls this the "rsyncable" option because it's commonly used with the
rsync program. I found this page which describes that option:

http://glasnost.beeznest.org/articles/206

If you can compress your files with gzip and the rsyncable option
instead of zip, you may see better disk space usage in the repository.

bzip2 compresses better than gzip; Google may be able to help you
discover whether bzip2 offers a similar "rsyncable" option.

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Received on Sat Mar 18 14:12:58 2006

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