git-repack - Pack unpacked objects in a repository
git repack [-a] [-A] [-d] [-f] [-F] [-l] [-n] [-q] [-b] [-m] [--window=<n>] [--depth=<n>] [--threads=<n>] [--keep-pack=<pack-name>] [--write-midx]
This command is used to combine all objects that do not currently reside in a "pack", into a pack. It can also be used to re-organize existing packs into a single, more efficient pack.
A pack is a collection of objects, individually compressed, with delta compression applied, stored in a single file, with an associated index file.
Packs are used to reduce the load on mirror systems, backup engines, disk storage, etc.
Note that users fetching over dumb protocols will have to fetch the whole new pack in order to get any contained object, no matter how many other objects in that pack they already have locally.
Promisor packfiles are repacked separately: if there are packfiles that have an associated ".promisor" file, these packfiles will be repacked into another separate pack, and an empty ".promisor" file corresponding to the new separate pack will be written.
The default value for --window is 10 and --depth is 50. The maximum depth is 4095.
git repack ensures this by determining a "cut" of packfiles that need to be repacked into one in order to ensure a geometric progression. It picks the smallest set of packfiles such that as many of the larger packfiles (by count of objects contained in that pack) may be left intact.
Unlike other repack modes, the set of objects to pack is determined uniquely by the set of packs being "rolled-up"; in other words, the packs determined to need to be combined in order to restore a geometric progression.
When --unpacked is specified, loose objects are implicitly included in this "roll-up", without respect to their reachability. This is subject to change in the future. This option (implying a drastically different repack mode) is not guaranteed to work with all other combinations of option to git repack.
When writing a multi-pack bitmap, git repack selects the largest resulting pack as the preferred pack for object selection by the MIDX (see git-multi-pack-index(1)).
Various configuration variables affect packing, see git-config(1) (search for "pack" and "delta").
By default, the command passes --delta-base-offset option to git pack-objects; this typically results in slightly smaller packs, but the generated packs are incompatible with versions of Git older than version 1.4.4. If you need to share your repository with such ancient Git versions, either directly or via the dumb http protocol, then you need to set the configuration variable repack.UseDeltaBaseOffset to "false" and repack. Access from old Git versions over the native protocol is unaffected by this option as the conversion is performed on the fly as needed in that case.
Delta compression is not used on objects larger than the core.bigFileThreshold configuration variable and on files with the attribute delta set to false.
Part of the git(1) suite