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![Jeff King](/assets/img/avatar_default.png)
The usual way to do a full repack (and what is done by git-gc) is to run "repack -Ad --unpack-unreachable=<when>", which will loosen any unreachable objects newer than "<when>", and drop any older ones. This is a safer alternative to "repack -ad", because "<when>" becomes a grace period during which we will not drop any new objects that are about to be referenced. However, it isn't perfectly safe. It's always possible that a process is about to reference an old object. Even if that process were to take care to update the timestamp on the object, there is no atomicity with a simultaneously running "repack" process. So while unlikely, there is a small race wherein we may drop an object that is in the process of being referenced. If you do automated repacking on a large number of active repositories, you may hit it eventually, and the result is a corrupted repository. It would be nice to fix that race in the long run, but it's complicated. In the meantime, there is a much simpler strategy for automated repository maintenance: do not drop objects at all. We already have a "--keep-unreachable" option in pack-objects; we just need to plumb it through from git-repack. Note that this _isn't_ plumbed through from git-gc, so at this point it's strictly a tool for people doing their own advanced repository maintenance strategy. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
164 lines
5.7 KiB
Plaintext
164 lines
5.7 KiB
Plaintext
git-repack(1)
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=============
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NAME
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----
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git-repack - Pack unpacked objects in a repository
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SYNOPSIS
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--------
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[verse]
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'git repack' [-a] [-A] [-d] [-f] [-F] [-l] [-n] [-q] [-b] [--window=<n>] [--depth=<n>]
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DESCRIPTION
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-----------
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This command is used to combine all objects that do not currently
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reside in a "pack", into a pack. It can also be used to re-organize
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existing packs into a single, more efficient pack.
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A pack is a collection of objects, individually compressed, with
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delta compression applied, stored in a single file, with an
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associated index file.
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Packs are used to reduce the load on mirror systems, backup
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engines, disk storage, etc.
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OPTIONS
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-------
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-a::
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Instead of incrementally packing the unpacked objects,
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pack everything referenced into a single pack.
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Especially useful when packing a repository that is used
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for private development. Use
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with '-d'. This will clean up the objects that `git prune`
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leaves behind, but `git fsck --full --dangling` shows as
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dangling.
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+
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Note that users fetching over dumb protocols will have to fetch the
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whole new pack in order to get any contained object, no matter how many
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other objects in that pack they already have locally.
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-A::
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Same as `-a`, unless '-d' is used. Then any unreachable
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objects in a previous pack become loose, unpacked objects,
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instead of being left in the old pack. Unreachable objects
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are never intentionally added to a pack, even when repacking.
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This option prevents unreachable objects from being immediately
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deleted by way of being left in the old pack and then
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removed. Instead, the loose unreachable objects
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will be pruned according to normal expiry rules
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with the next 'git gc' invocation. See linkgit:git-gc[1].
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-d::
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After packing, if the newly created packs make some
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existing packs redundant, remove the redundant packs.
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Also run 'git prune-packed' to remove redundant
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loose object files.
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-l::
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Pass the `--local` option to 'git pack-objects'. See
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linkgit:git-pack-objects[1].
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-f::
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Pass the `--no-reuse-delta` option to `git-pack-objects`, see
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linkgit:git-pack-objects[1].
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-F::
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Pass the `--no-reuse-object` option to `git-pack-objects`, see
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linkgit:git-pack-objects[1].
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-q::
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Pass the `-q` option to 'git pack-objects'. See
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linkgit:git-pack-objects[1].
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-n::
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Do not update the server information with
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'git update-server-info'. This option skips
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updating local catalog files needed to publish
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this repository (or a direct copy of it)
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over HTTP or FTP. See linkgit:git-update-server-info[1].
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--window=<n>::
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--depth=<n>::
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These two options affect how the objects contained in the pack are
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stored using delta compression. The objects are first internally
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sorted by type, size and optionally names and compared against the
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other objects within `--window` to see if using delta compression saves
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space. `--depth` limits the maximum delta depth; making it too deep
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affects the performance on the unpacker side, because delta data needs
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to be applied that many times to get to the necessary object.
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The default value for --window is 10 and --depth is 50.
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--window-memory=<n>::
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This option provides an additional limit on top of `--window`;
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the window size will dynamically scale down so as to not take
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up more than '<n>' bytes in memory. This is useful in
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repositories with a mix of large and small objects to not run
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out of memory with a large window, but still be able to take
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advantage of the large window for the smaller objects. The
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size can be suffixed with "k", "m", or "g".
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`--window-memory=0` makes memory usage unlimited, which is the
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default.
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--max-pack-size=<n>::
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Maximum size of each output pack file. The size can be suffixed with
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"k", "m", or "g". The minimum size allowed is limited to 1 MiB.
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If specified, multiple packfiles may be created, which also
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prevents the creation of a bitmap index.
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The default is unlimited, unless the config variable
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`pack.packSizeLimit` is set.
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-b::
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--write-bitmap-index::
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Write a reachability bitmap index as part of the repack. This
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only makes sense when used with `-a` or `-A`, as the bitmaps
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must be able to refer to all reachable objects. This option
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overrides the setting of `repack.writeBitmaps`. This option
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has no effect if multiple packfiles are created.
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--pack-kept-objects::
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Include objects in `.keep` files when repacking. Note that we
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still do not delete `.keep` packs after `pack-objects` finishes.
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This means that we may duplicate objects, but this makes the
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option safe to use when there are concurrent pushes or fetches.
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This option is generally only useful if you are writing bitmaps
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with `-b` or `repack.writeBitmaps`, as it ensures that the
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bitmapped packfile has the necessary objects.
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--unpack-unreachable=<when>::
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When loosening unreachable objects, do not bother loosening any
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objects older than `<when>`. This can be used to optimize out
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the write of any objects that would be immediately pruned by
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a follow-up `git prune`.
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-k::
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--keep-unreachable::
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When used with `-ad`, any unreachable objects from existing
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packs will be appended to the end of the packfile instead of
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being removed.
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Configuration
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-------------
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By default, the command passes `--delta-base-offset` option to
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'git pack-objects'; this typically results in slightly smaller packs,
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but the generated packs are incompatible with versions of Git older than
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version 1.4.4. If you need to share your repository with such ancient Git
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versions, either directly or via the dumb http protocol, then you
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need to set the configuration variable `repack.UseDeltaBaseOffset` to
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"false" and repack. Access from old Git versions over the native protocol
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is unaffected by this option as the conversion is performed on the fly
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as needed in that case.
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SEE ALSO
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--------
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linkgit:git-pack-objects[1]
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linkgit:git-prune-packed[1]
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GIT
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---
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Part of the linkgit:git[1] suite
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