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Re: Backward or forward deltas, backend, FSX

From: Julian Foad <julianfoad_at_apache.org>
Date: Thu, 15 Feb 2018 19:57:10 +0000

Péter wrote:
> [I am not a list member]
>
> In the proposed FSX backend,
> [ https://subversion.apache.org/docs/release-notes/1.9.html#fsx ]
> what type of deltas is planned? Deltas against an older - or newer
> revision?
> [ http://svn.apache.org/repos/asf/subversion/trunk/notes/skip-deltas ]
> FSFS-like way, or BDB-like way?
>
> Please explain it, why was that chosen. Why is optimal. Or, if not quite
> decided/fixed, please consider carefully.
>
>
> I know almost nothing (nor want to) about the internals ("fulltext and
> txdelta caching" etc.), but:
> I would (as everybody :) prefer the variant which uses less space (less
> cache, maybe only one - the last revision), and at the same time less
> time for extracting revision, with strong weight to the last (just
> added) revision, and the last few revisions.
>
> With say, 100000 revisions, when someone checks out the last revision:
> svn starts (would start, with the FSX backend) with the 30 years old,
> "fossile" ancient revision? (It would be case with the "FSFS-like way".)
> Which has nothing common with the recent revisions? And applies (at
> least) 17 deltas (patches)? Of which many deltas are very "heavy" (huge
> changings, complete rewritings)?.. I would marvel at that and do not
> understand the reasons..
>
>
> Peter
>
>
>
>
>
Received on 2018-02-15 20:57:16 CET

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