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Re: RFC: adding xdelta compression to git

From
C. Scott Ananian <cscott@cscott.net>
Date
May 3, 2005, 15:50 UTC
Message-ID
<Pine.LNX.4.61.0505031146130.32767@cag.csail.mit.edu>
In-Reply-To
<Pine.LNX.4.58.0505022131380.3594@ppc970.osdl.org>
On Mon, 2 May 2005, Linus Torvalds wrote:
>> * Changes the repository format.
>
> It wouldn't necessarily. You should be able to do this with _zero_ changes
> to existing objects what-so-ever.

Yes. The 'chunking' code I posted earlier does this, etc. It's kinda odd computing a SHA-1 including the 'blob <size>\0' header, even when your representation doesn't use this type exactly, but it's no big deal. I'm still tinkering with this, btw; I can get modest improvements in 'real' disk space used, but nothing earth-shattering (yet). I'll post the list of things I tried and how well they worked at some point, just to save people the effort of retrying things.

I've been working from the 'no knowledge of commit structure needed' 
perspective; I think Chris Mason has been using the structure of the 
commit object to guide delta-fication and showing more impressive 
space savings.
  --scott
HTAUTOMAT Legion of Doom payment PBPRIME insurgent shortwave AVBUSY 
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                          ( http://cscott.net/ )
Previous: Dan Holmsand
Message 32 of 32 in “RFC: adding xdelta compression to git”
  1. Alon ZivMay 3, 2005
  2. Nicolas PitreMay 3, 2005
  3. Linus TorvaldsMay 3, 2005
  4. Davide LibenziMay 3, 2005
  5. C. Scott AnanianMay 3, 2005
  6. Linus TorvaldsMay 3, 2005
  7. Davide LibenziMay 3, 2005
  8. add the ability to create and retrieve delta objectsNicolas Pitre, May 3, 2005
  9. Chris MasonMay 3, 2005
  10. Nicolas PitreMay 3, 2005
  11. Linus TorvaldsMay 3, 2005
  12. Chris MasonMay 3, 2005
  13. C. Scott AnanianMay 3, 2005
  14. Chris MasonMay 3, 2005
  15. Chris MasonMay 3, 2005
  16. Nicolas PitreMay 3, 2005
  17. Chris MasonMay 3, 2005
  18. Nicolas PitreMay 3, 2005
  19. Chris MasonMay 3, 2005
  20. Linus TorvaldsMay 3, 2005
  21. add the ability to create and retrieve delta objectsNicolas Pitre, May 3, 2005
  22. Chris MasonMay 4, 2005
  23. C. Scott AnanianMay 4, 2005
  24. Chris MasonMay 4, 2005
  25. Linus TorvaldsMay 4, 2005
  26. Chris MasonMay 4, 2005
  27. Nicolas PitreMay 5, 2005
  28. Geert BoschMay 4, 2005
  29. Chris MasonMay 4, 2005
  30. Nicolas PitreMay 5, 2005
  31. Dan HolmsandMay 3, 2005
  32. C. Scott AnanianMay 3, 2005

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