update-index: list supported idx versions and their features
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/Documentation/git-update-index.txt b/Documentation/git-update-index.txt
index 9d0b151..dd36d13 100644
--- a/Documentation/git-update-index.txt
+++ b/Documentation/git-update-index.txt
@@ -145,7 +145,15 @@
--index-version <n>::
Write the resulting index out in the named on-disk format version.
- The current default version is 2.
+ Supported versions are 2, 3 and 4. The current default version is 2
+ or 3, depending on whether extra features are used, such as
+ `git add -N`.
++
+Version 4 performs a simple pathname compression that reduces index
+size by 30%-50% on large repositories, which results in faster load
+time. Version 4 is relatively young (first released in in 1.8.0 in
+October 2012). Other Git implementations such as JGit and libgit2
+may not support it yet.
-z::
Only meaningful with `--stdin` or `--index-info`; paths are
