path: root/Documentation
diff options
Diffstat (limited to 'Documentation')
2 files changed, 39 insertions, 0 deletions
diff --git a/Documentation/gitrepository-layout.txt b/Documentation/gitrepository-layout.txt
index 17d2ea6..79653f3 100644
--- a/Documentation/gitrepository-layout.txt
+++ b/Documentation/gitrepository-layout.txt
@@ -155,6 +155,10 @@ index::
The current index file for the repository. It is
usually not found in a bare repository.
+ The shared index part, to be referenced by $GIT_DIR/index and
+ other temporary index files. Only valid in split index mode.
Additional information about the repository is recorded
in this directory.
diff --git a/Documentation/technical/index-format.txt b/Documentation/technical/index-format.txt
index f352a9b..fe6f316 100644
--- a/Documentation/technical/index-format.txt
+++ b/Documentation/technical/index-format.txt
@@ -129,6 +129,9 @@ Git index format
(Version 4) In version 4, the padding after the pathname does not
+ Interpretation of index entries in split index mode is completely
+ different. See below for details.
== Extensions
=== Cached tree
@@ -198,3 +201,35 @@ Git index format
- At most three 160-bit object names of the entry in stages from 1 to 3
(nothing is written for a missing stage).
+=== Split index
+ In split index mode, the majority of index entries could be stored
+ in a separate file. This extension records the changes to be made on
+ top of that to produce the final index.
+ The signature for this extension is { 'l', 'i, 'n', 'k' }.
+ The extension consists of:
+ - 160-bit SHA-1 of the shared index file. The shared index file path
+ is $GIT_DIR/sharedindex.<SHA-1>. If all 160 bits are zero, the
+ index does not require a shared index file.
+ - An ewah-encoded delete bitmap, each bit represents an entry in the
+ shared index. If a bit is set, its corresponding entry in the
+ shared index will be removed from the final index. Note, because
+ a delete operation changes index entry positions, but we do need
+ original positions in replace phase, it's best to just mark
+ entries for removal, then do a mass deletion after replacement.
+ - An ewah-encoded replace bitmap, each bit represents an entry in
+ the shared index. If a bit is set, its corresponding entry in the
+ shared index will be replaced with an entry in this index
+ file. All replaced entries are stored in sorted order in this
+ index. The first "1" bit in the replace bitmap corresponds to the
+ first index entry, the second "1" bit to the second entry and so
+ on. Replaced entries may have empty path names to save space.
+ The remaining index entries after replaced ones will be added to the
+ final index. These added entries are also sorted by entry namme then
+ stage.