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Date: Mon, 19 Oct 2015 22:20:22 +0300
From: Lars Wirzenius <liw@liw.fi>
To: Henri Sivonen <hsivonen@hsivonen.fi>
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Cc: obnam-dev@obnam.org
Subject: Re: Enhancement: Avoid storing compressed data when compression
would expand data
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Applied, thanks.
On Sat, Oct 17, 2015 at 08:54:50PM +0300, Henri Sivonen wrote:
> I have made a minor improvement to avoid storing compressed data even
> when compression has been enabled in cases where compression (plus
> tagging) would end up expanding the data. This avoids space waste upon
> transfer and storage and compute waste upon reading.
>
> The change is available for pulling from the "no-expansion" branch of
> the repo https://github.com/hsivonen/obnam.git (the branch contains
> nothing else). Web view of the changeset:
> https://github.com/hsivonen/obnam/commit/5002965ad28c89a08c370efa880a060cf7835dbd
> Patch format:
> https://github.com/hsivonen/obnam/commit/5002965ad28c89a08c370efa880a060cf7835dbd.patch
>
> I have tested the patch manually with a directory containing two files
> generated with
> $ head -c 1024 /dev/urandom > rand
> $ head -c 1024 /dev/zero > zero
> (rand doesn't compress and zero compresses very well.)
>
> However, I'm currently unfamiliar with the workings of yarn, so I
> haven't added automated tests. If the patch isn't acceptable without
> tests, I'd appreciate advice on how to do the kind of testing that
> looks inside the chunk data stored in the repo.
>
> --
> Henri Sivonen
> hsivonen@hsivonen.fi
> https://hsivonen.fi/
>
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undefined until a restore is attempted. -- andrewsh
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