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Re: [RFC] Inheritable Properties

From: Branko Čibej <brane_at_apache.org>
Date: Mon, 13 Feb 2012 17:52:01 +0100

On 13.02.2012 17:09, Daniel Shahaf wrote:
> Thanks for your thoughts. One comment:
>
> Branko Čibej wrote on Sun, Feb 12, 2012 at 21:52:16 +0100:
>> The idea is that we'd always maintain the complete index, i.e., in order
>> to determine if path_at_15 exists, one only needs to search the index for
>> (path, rev <= 15, !deleted) -- which is trivial in a properly ordered
>> index. (Yes, this assumes that we record deletions in the index as well
>> as insertions.)
>>
>> All of this can be done with an append-only index representation. What
>> you can't do with append-only is represent forward history links, but --
>> we're not representing them very well right now, are we. :)
> Within the append-only constraint one can implement forward links if one
> has, say, a separate file per revision. (So asking "where was foo_at_15
> copied to" involves a linear scan of $REPOS/db/forward-links/15.)
>
> stsp and I even started on such a design on some branch somewhere ---
> but that branch has been abandoned as the motivation for it was rename
> tracking, which stsp figured he could solve better without the new FS
> feature.

A separate file per revision has other problems, too. You'd quickly run
out of inodes on ext-derived file systems, for example.

-- Brane
Received on 2012-02-13 17:52:42 CET

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