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[RFC PATCH v4 11/19] Introduce "sparse checkout"

From
Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Date
Aug 20, 2009, 13:47 UTC
Message-ID
<1250776033-12395-12-git-send-email-pclouds@gmail.com>
In-Reply-To
<1250776033-12395-11-git-send-email-pclouds@gmail.com>

With skip-worktree bit, you can manually set it to unwanted files, then remove them: you would have the so-called sparse checkout. The disadvantages are:

 - Porcelain tools are not aware of this. Everytime you do an
   operation that may update working directory, skip-worktree may be
   cleared out. You have to set them again.
 - You still have to remove skip-worktree'd files manually, which is
   boring and ineffective.

These will be addressed in the following patches. This patch gives an idea what is "sparse checkout" in Documentation/git-read-tree.txt. This file is chosen instead of git-checkout.txt because it is quite technical and user-unfriendly. I'd expect git-checkout.txt to have something when Porcelain support is done.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 Documentation/git-read-tree.txt |   44 +++++++++++++++++++++++++++++++++++++++
 1 files changed, 44 insertions(+), 0 deletions(-)
diff --git a/Documentation/git-read-tree.txt b/Documentation/git-read-tree.txt
index 4a932b0..8b39716 100644
--- a/Documentation/git-read-tree.txt
+++ b/Documentation/git-read-tree.txt
@@ -360,6 +360,50 @@ middle of doing, and when your working tree is ready (i.e. you
 have finished your work-in-progress), attempt the merge again.
 
 
+Sparse checkout
+---------------
+
+"Sparse checkout" allows to sparsely populate working directory.
+It uses skip-worktree bit (see linkgit:git-update-index[1]) to tell
+Git whether a file on working directory is worth looking at.
+
+"git read-tree" and other merge-based commands ("git merge", "git
+checkout"...) can help maintaining skip-worktree bitmap and working
+directory update. `$GIT_DIR/info/sparse-checkout` is used to
+define the skip-worktree reference bitmap. When "git read-tree" needs
+to update working directory, it will reset skip-worktree bit in index
+based on this file, which uses the same syntax as .gitignore files.
+If an entry matches a pattern in this file, skip-worktree will be
+set on that entry. Otherwise, skip-worktree will be unset.
+
+Then it compares the new skip-worktree value with the previous one. If
+skip-worktree turns from unset to set, it will add the corresponding
+file back. If it turns from set to unset, that file will be removed.
+
+While `$GIT_DIR/info/sparse-checkout` is usually used to specify what
+files are in. You can also specify what files are _not_ in, using
+negate patterns. For example, to remove file "unwanted":
+
+----------------
+*
+!unwanted
+----------------
+
+Another tricky thing is fully repopulating working directory when you
+no longer want sparse checkout. You cannot just disable "sparse
+checkout" because skip-worktree are still in the index and you working
+directory is still sparsely populated. You should re-populate working
+directory with the `$GIT_DIR/info/sparse-checkout` file content as
+follows:
+
+----------------
+*
+----------------
+
+Then you can disable sparse checkout. Sparse checkout support in "git
+read-tree" and similar commands is disabled by default.
+
+
 SEE ALSO
 --------
 linkgit:git-write-tree[1]; linkgit:git-ls-files[1];
-- 
1.6.3.GIT
Previous: Nguyễn Thái Ngọc DuyNext: Nguyễn Thái Ngọc Duy
Message 12 of 27 in “Sparse checkout”
  1. 00/19 Sparse checkoutNguyễn Thái Ngọc Duy, Aug 20, 2009
  2. 01/19 update-index: refactor mark_valid() in preparation for new optionsNguyễn Thái Ngọc Duy, Aug 20, 2009
  3. 02/19 Add test-index-versionNguyễn Thái Ngọc Duy, Aug 20, 2009
  4. 03/19 Introduce "skip-worktree" bit in index, teach Git to get/set this bitNguyễn Thái Ngọc Duy, Aug 20, 2009
  5. 04/19 Teach Git to respect skip-worktree bit (reading part)Nguyễn Thái Ngọc Duy, Aug 20, 2009
  6. 05/19 Teach Git to respect skip-worktree bit (writing part)Nguyễn Thái Ngọc Duy, Aug 20, 2009
  7. 06/19 Avoid writing to buffer in add_excludes_from_file_1()Nguyễn Thái Ngọc Duy, Aug 20, 2009
  8. 07/19 Read .gitignore from index if it is skip-worktreeNguyễn Thái Ngọc Duy, Aug 20, 2009
  9. 08/19 unpack-trees(): carry skip-worktree bit over in merged_entry()Nguyễn Thái Ngọc Duy, Aug 20, 2009
  10. 09/19 excluded_1(): support exclude files in indexNguyễn Thái Ngọc Duy, Aug 20, 2009
  11. 10/19 dir.c: export excluded_1() and add_excludes_from_file_1()Nguyễn Thái Ngọc Duy, Aug 20, 2009
  12. 11/19 Introduce "sparse checkout"Nguyễn Thái Ngọc Duy, Aug 20, 2009
  13. 12/19 unpack-trees(): add CE_WT_REMOVE to remove on worktree aloneNguyễn Thái Ngọc Duy, Aug 20, 2009
  14. 13/19 unpack-trees.c: generalize verify_* functionsNguyễn Thái Ngọc Duy, Aug 20, 2009
  15. 14/19 unpack-trees(): "enable" sparse checkout and load $GIT_DIR/info/sparse-checkoutNguyễn Thái Ngọc Duy, Aug 20, 2009
  16. 15/19 unpack_trees(): apply $GIT_DIR/info/sparse-checkout to the final indexNguyễn Thái Ngọc Duy, Aug 20, 2009
  17. 16/19 unpack-trees(): ignore worktree check outside checkout areaNguyễn Thái Ngọc Duy, Aug 20, 2009
  18. 17/19 read-tree: add --no-sparse-checkout to disable sparse checkout supportNguyễn Thái Ngọc Duy, Aug 20, 2009
  19. 18/19 Add tests for sparse checkoutNguyễn Thái Ngọc Duy, Aug 20, 2009
  20. 19/19 sparse checkout: inhibit empty worktreeNguyễn Thái Ngọc Duy, Aug 20, 2009
  21. Nguyen Thai Ngoc DuyAug 21, 2009
  22. Junio C HamanoAug 21, 2009
  23. Nguyen Thai Ngoc DuyAug 22, 2009
  24. Jakub NarebskiAug 20, 2009
  25. Matthieu MoyAug 20, 2009
  26. Junio C HamanoAug 21, 2009
  27. Nguyen Thai Ngoc DuyAug 21, 2009

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