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Re: [PATCH] Replace vdelta with xdelta variant

From: Niels Werensteijn <n.werensteijn_at_student.utwente.nl>
Date: Sat, 19 Jan 2008 12:07:34 +0100

Daniel Berlin schreef:
> On Jan 18, 2008 1:54 PM, Niels Werensteijn
> <n.werensteijn_at_student.utwente.nl> wrote:
>>> Is this an implementation of any particular algorithm?
>> No. I just looked at XDelta as it was implemented. I saw how it would be
>> faster than vdelta, and adjusted the XDelta algorithm so it could make a
>> diff against itself.
> So, my question becomes does this do better than running zlib's
> compress over the stream?

I suspect not. Xdelta is not optimally diffing, when looking at the
output size, so it definitely is not optimal for compression. I have
thought about implementing this as 1 insert command that inserts the
whole stream(chunk). This would speed things up considerably on the cpu
side, and when send between client and server, zlib will compress it (I
only looked at svnserve, I am not sure DAV would use zlib). The down
side would be that the files would also be stored this way in the
repository. And there, as far as I know, no zlib compression is applied.

I don't know what the policy is on repository size. I think repository
size has been sacrificed when the switch from vdelta to xdelta was made.
So if that is no problem, we could explore the "single insert" option.

Niels Werensteijn

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Received on 2008-01-19 12:07:42 CET

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