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Diffstat (limited to 'Documentation/technical')
| -rw-r--r-- | Documentation/technical/index-format.txt | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/Documentation/technical/index-format.txt b/Documentation/technical/index-format.txt index f352a9b22e..fe6f31667d 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 exist. + 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. |