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Re: issue #1573: fs deltification causes delays

From: <pmarek_at_users.sourceforge.net>
Date: 2003-11-07 07:47:39 CET

> > So we'll get a (data-based) list of (crc, hash, start, length) blocks,
> > which we then compare against the "new" file.
> > In my upcoming perl-module "Digest::Manber" I take another value as well
> > - the crc prior to the boundary.
>
> So, you're proposing that we store block checksums in each
> representation, so that when we diff two representations against each
> other, you can skip past the windows which have matching checksums.
>
> If we stored plaintexts as deltas against the empty source, we could do
> this with (drumroll) window checksums. Which CMike just eliminated from
> the schema. Cue Alanis Morisette song here.
Well, the windows would have to be determined by the rolling crc anyway, so
that they are re-synchronized by inserted characters ... checksums of every X
kB wouldn't work.
And I'd store checksums eventually only for the plain-text files, ie the last
revision - but now that you mention it, they don't exist anymore with
delta-against-empty ... I remember having read this on the list.

But it seems that this is a moot point ...

Regards,

P.Marek

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Received on Fri Nov 7 07:48:34 2003

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