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Re: What's the difference between `git show branch:file | diff -u - file` vs `git diff branch file`?

From
Junio C Hamano <gitster@pobox.com>
Date
Aug 29, 2011, 17:18 UTC
Message-ID
<7v1uw46srf.fsf@alter.siamese.dyndns.org>
In-Reply-To
<CACsJy8Dar5i3Fn+rhOq78vdsqRL4D+RNUc5G64BM-6DvKC=L5w@mail.gmail.com>
Nguyen Thai Ngoc Duy <pclouds@gmail.com> writes:
> That may explain it. "git diff <ref>" walks through the index, unpacks
> tree objects along the way, matches up entries with the same path from
> the branch, the index then feeds matching entries to diff function.

Yeah, that would explain it. The implementation of diff-index has changed a few times and the latest incarnation is based on unpack-trees, _merging_ the tree and the index, introduced by d1f2d7e (Make run_diff_index() use unpack_trees(), not read_tree(), 2008-01-19).

Of course the merge machinery does not know anything about pruning with pathspec, so it is understandable (not justifiable) it would walk the full tree.

Will try to find time this week to cook up something.
Previous: Nguyen Thai Ngoc DuyNext: Junio C Hamano
Message 16 of 56 in “What's the difference between `git show branch:file | diff -u - file` vs `git diff branch file`?”
  1. Marat RadchenkoAug 23, 2011
  2. Michael J GruberAug 23, 2011
  3. Marat RadchenkoAug 23, 2011
  4. Michael WittenAug 23, 2011
  5. Michael J GruberAug 23, 2011
  6. Marat RadchenkoAug 23, 2011
  7. Junio C HamanoAug 23, 2011
  8. Marat RadchenkoAug 23, 2011
  9. Michael J GruberAug 23, 2011
  10. Marat RadchenkoAug 25, 2011
  11. Junio C HamanoAug 25, 2011
  12. Marat RadchenkoAug 26, 2011
  13. Nguyen Thai Ngoc DuyAug 29, 2011
  14. Marat RadchenkoAug 29, 2011
  15. Nguyen Thai Ngoc DuyAug 29, 2011
  16. Junio C HamanoAug 29, 2011
  17. Junio C HamanoAug 29, 2011
  18. Junio C HamanoAug 29, 2011
  19. Junio C HamanoAug 29, 2011
  20. 0/3 Un-pessimize "diff-index $commit -- $pathspec"Junio C Hamano, Aug 29, 2011
  21. 1/3 traverse_trees(): allow pruning with pathspecJunio C Hamano, Aug 29, 2011
  22. Nguyen Thai Ngoc DuyAug 30, 2011
  23. Junio C HamanoAug 30, 2011
  24. Nguyen Thai Ngoc DuyAug 31, 2011
  25. Michael HaggertyOct 9, 2011
  26. Nguyen Thai Ngoc DuyOct 9, 2011
  27. Michael HaggertyOct 10, 2011
  28. 2/3 unpack-trees: allow pruning with pathspecJunio C Hamano, Aug 29, 2011
  29. Nguyen Thai Ngoc DuyAug 30, 2011
  30. Junio C HamanoAug 30, 2011
  31. David Michael BarrAug 30, 2011
  32. 3/3 diff-index: pass pathspec down to unpack-trees machineryJunio C Hamano, Aug 29, 2011
  33. Jonathan NiederJan 11, 2012
  34. Junio C HamanoJan 11, 2012
  35. Nguyen Thai Ngoc DuyJan 11, 2012
  36. Nguyen Thai Ngoc DuyJan 11, 2012
  37. Junio C HamanoJan 11, 2012
  38. tree_entry_interesting: make recursive mode defaultNguyễn Thái Ngọc Duy, Jan 12, 2012
  39. Junio C HamanoJan 12, 2012
  40. Nguyen Thai Ngoc DuyJan 12, 2012
  41. 1/2 Document limited recursion pathspec matching with wildcardsNguyễn Thái Ngọc Duy, Jan 14, 2012
  42. 2/2 tree_entry_interesting: make recursive mode defaultNguyễn Thái Ngọc Duy, Jan 14, 2012
  43. Junio C HamanoJan 15, 2012
  44. Nguyen Thai Ngoc DuyJan 15, 2012
  45. Junio C HamanoJan 16, 2012
  46. Nguyen Thai Ngoc DuyJan 18, 2012
  47. Junio C HamanoJan 15, 2012
  48. Nguyen Thai Ngoc DuyJan 15, 2012
  49. Linus TorvaldsAug 29, 2011
  50. Junio C HamanoAug 29, 2011
  51. Linus TorvaldsAug 29, 2011
  52. Junio C HamanoAug 29, 2011
  53. Marat RadchenkoAug 30, 2011
  54. Junio C HamanoAug 31, 2011
  55. Michael J GruberAug 30, 2011
  56. Junio C HamanoAug 30, 2011

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