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Re: [PATCH] Replace vdelta with xdelta variant

From: Malcolm Rowe <malcolm-svn-dev_at_farside.org.uk>
Date: Mon, 21 Jan 2008 13:32:28 +0000

On Mon, Jan 21, 2008 at 12:01:30PM +0100, =?ISO-8859-2?Q?Branko_=C8ibej_ wrote:
> Please note that we currently expect things to be either plaintext, or
> svndiff; and that we can always combine svndiffs. Introducing a
> zlib-compressed thing would affect the delta combiner and a lot of other
> things.
>

Sure; I meant "can we use the output from zlib to produce an
svndiff-compatible stream". Thinking about it some more, it might be
more productive to just switch off vdelta entirely, and product a
plaintext svndiff output (i.e. ADD <bytes>, ADD <bytes>, ...) for deltas
against the empty stream, relying on an upper-level protocol to compress
the data section of the output (i.e. svndiff1).

If I remember correctly, that would disadvantage pre-1.4 clients and
'svnadmin dump --deltas', but would help in all other cases (in that
vdelta self-compression+zlib is almost guaranteed to be slower/bigger
than zlib alone).

Or perhaps communicate the existence of the secondary compressor to the
delta engine, and make it switch between vdelta/plaintext based on that.
I've looked at doing that previously, though, and it's not very clean.

Regards,
Malcolm

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Received on 2008-01-21 14:32:46 CET

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