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Date: Thu, 12 Dec 2013 21:58:44 +0200
From: Daniel Shahaf <d.s@daniel.shahaf.name>
To: Bob Archer <Bob.Archer@amsi.com>
Cc: Branko =?utf-8?B?xIxpYmVq?= <brane@wandisco.com>,
	"users@subversion.apache.org" <users@subversion.apache.org>
Subject: Re: Update-Only Checkout Enhancement
Message-ID: <20131212195844.GA2937@lp-shahaf.local>
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Bob Archer wrote on Wed, Dec 11, 2013 at 21:05:46 +0000:
> There may be some transactional file systems that allow you to get an
> event before the modification is committed to the file system so you
> can access the original copy, but I think they are few and far
> between.

And also would require new code on svn's side to be written.

There are, though, deduplicating filesystems, that store a file just
once if there are several copies of it.  That means a file and its
pristine won't consume twice the platter space, assuming the file
doesn't use either svn:keywords or svn:eol-style=native.

(I'm thinking of zfs.  And BTW, the pristine store also deduplicates, so
if two pristines have the same sha1, they're stored just once.)