Re: [PATCH] Add --no-reuse-delta option to git-gc

From: Johannes Schindelin <johannes.schindelin@gmx.de>
Date: Jun 11, 2007, 10:20 UTC
Message-ID: <Pine.LNX.4.64.0706111109430.4059@racer.site>
In-Reply-To: <alpine.LFD.0.99.0706102144080.12885@xanadu.home>

Hi,

On Sun, 10 Jun 2007, Nicolas Pitre wrote:

Show 15 quoted lines

> On Sun, 10 Jun 2007, Sam Vilain wrote:
> 
> > Anyway it's a free world so be my guest to implement it, I guess if 
> > this was selectable it would only be a minor annoyance waiting a bit 
> > longer pulling from from some repositories, and it would be 
> > interesting to see if it did make a big difference with pack file 
> > sizes.
> 
> It won't happen for a simple reason: to be backward compatible with 
> older GIT clients.  If you have your repo compressed with bzip2 and an 
> old client pulls it then the server would have to decompress and 
> recompress everything with gzip.  If instead your repo remains with gzip 
> and a new client asks for bzip2 then you have to recompress as well 
> (slow).  So in practice it is best to remain with a single compression 
> method.

With the extension mechanism we have in place, the client can send what kind of compression it supports, and the server can actually refuse to send anything if it does not want to recompress.

What I am trying to say: you do not necessarily have to allow every client to access that particular repository. I agree that mixed-compression repos are evil, but nothing stands in the way of a flag allowing (or disallowing) recompression in a different format when fetching.

So if you should decide someday to track data with Git (remember: Generic Information Tracker, not just source code), that is particularly unfit for compression with gzip, but that you _need_ to store in a different compressed manner, you can set up a repository which will _only_ _ever_ use that compression.

Of course, you'd need to prepare Git for that, but I could imagine something like a music library, which stores everything as ogg encoded snippets. It might even use some perception-based hash on small chunks of the music, and store the music as tree objects, which concatenate the small chunks. I might even try to do this for fun, some day in the distant future.

It's a wild world, Dscho