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Re: GSoC - Some questions on the idea of

From
Nguyen Thai Ngoc Duy <pclouds@gmail.com>
Date
Apr 2, 2012, 01:00 UTC
Message-ID
<CACsJy8CJK4gZwnrqkhq2DUqErS94X=99kvB9z=x9TefG=MrE4A@mail.gmail.com>
In-Reply-To
<CA+M5ThTnd+TST6WsAn-Jd=Gb=1EWaJ+QbLMxXgtAVFNVqnRcMw@mail.gmail.com>
On Mon, Apr 2, 2012 at 6:30 AM, Bo Chen <chen@chenirvine.org> wrote:
Show 6 quoted lines
> One question,  can anyone help me clear?
>
> My .git/objects has 3 blobs, a, b, and c. a is a unique file, b and c
> two sequential versions of the same file. When I run "git gc", what
> exactly happens here, e.g., how exactly git (in the latest version)
> delta compresses-the blobs here?

See Documentation/technical/pack-heuristics.txt for how pack-objects (called by"git gc") decides to delta either b or c based on the other one. Once it chooses, say, b to be delta against c, it generates delta using diff-delta.c, then store the delta in either ref-delta or ofs-delta format. The former stores sha-1 of c, the latter the offset of c in the pack.

-- 
Duy
Previous: Bo ChenNext: Bo Chen
Message 36 of 43 in “GSoC - Some questions on the idea of "Better big-file support".”
  1. Bo ChenMar 28, 2012
  2. Nguyen Thai Ngoc DuyMar 28, 2012
  3. SergioMar 28, 2012
  4. Bo ChenMar 30, 2012
  5. Bo ChenMar 30, 2012
  6. Jeff KingMar 30, 2012
  7. Bo ChenMar 30, 2012
  8. Sergio CallegariMar 31, 2012
  9. Neal KreitzingerMar 31, 2012
  10. Jeff KingApr 2, 2012
  11. Sergio CallegariApr 3, 2012
  12. Neal KreitzingerApr 11, 2012
  13. Jonathan NiederApr 11, 2012
  14. Neal KreitzingerApr 11, 2012
  15. Jeff KingApr 11, 2012
  16. Neal KreitzingerApr 11, 2012
  17. Neal KreitzingerApr 11, 2012
  18. Jonathan NiederApr 11, 2012
  19. Junio C HamanoApr 11, 2012
  20. Jonathan NiederApr 11, 2012
  21. Neal KreitzingerApr 11, 2012
  22. Jeff KingApr 11, 2012
  23. Neal KreitzingerApr 12, 2012
  24. Jeff KingApr 12, 2012
  25. Neal KreitzingerApr 12, 2012
  26. Bo ChenApr 13, 2012
  27. Neal KreitzingerMar 31, 2012
  28. Jeff KingApr 2, 2012
  29. Junio C HamanoApr 2, 2012
  30. Jeff KingApr 3, 2012
  31. Neal KreitzingerMar 31, 2012
  32. Neal KreitzingerMar 31, 2012
  33. Bo ChenMar 31, 2012
  34. Nguyen Thai Ngoc DuyApr 1, 2012
  35. Bo ChenApr 1, 2012
  36. Nguyen Thai Ngoc DuyApr 2, 2012
  37. Bo ChenMar 30, 2012
  38. Jeff KingMar 30, 2012
  39. Jeff KingApr 15, 2012
  40. Neal KreitzingerApr 15, 2012
  41. Jeff KingApr 16, 2012
  42. Neal KreitzingerMay 10, 2012
  43. Jeff KingMay 10, 2012

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