GIT-PACK-OBJECTS(1)              Git Manual              GIT-PACK-OBJECTS(1)

NAME         top

       git-pack-objects - Create a packed archive of objects

SYNOPSIS         top

       git pack-objects [-q | --progress | --all-progress] [--all-progress-implied]
               [--no-reuse-delta] [--delta-base-offset] [--non-empty]
               [--local] [--incremental] [--window=<n>] [--depth=<n>]
               [--revs [--unpacked | --all]] [--keep-pack=<pack-name>]
               [--stdout [--filter=<filter-spec>] | base-name]
               [--shallow] [--keep-true-parents] < object-list

DESCRIPTION         top

       Reads list of objects from the standard input, and writes either one
       or more packed archives with the specified base-name to disk, or a
       packed archive to the standard output.

       A packed archive is an efficient way to transfer a set of objects
       between two repositories as well as an access efficient archival
       format. In a packed archive, an object is either stored as a
       compressed whole or as a difference from some other object. The
       latter is often called a delta.

       The packed archive format (.pack) is designed to be self-contained so
       that it can be unpacked without any further information. Therefore,
       each object that a delta depends upon must be present within the

       A pack index file (.idx) is generated for fast, random access to the
       objects in the pack. Placing both the index file (.idx) and the
       packed archive (.pack) in the pack/ subdirectory of
       $GIT_OBJECT_DIRECTORY (or any of the directories on
       $GIT_ALTERNATE_OBJECT_DIRECTORIES) enables Git to read from the pack

       The git unpack-objects command can read the packed archive and expand
       the objects contained in the pack into "one-file one-object" format;
       this is typically done by the smart-pull commands when a pack is
       created on-the-fly for efficient network transport by their peers.

OPTIONS         top

           Write into pairs of files (.pack and .idx), using <base-name> to
           determine the name of the created file. When this option is used,
           the two files in a pair are written in
           <base-name>-<SHA-1>.{pack,idx} files. <SHA-1> is a hash based on
           the pack content and is written to the standard output of the

           Write the pack contents (what would have been written to .pack
           file) out to the standard output.

           Read the revision arguments from the standard input, instead of
           individual object names. The revision arguments are processed the
           same way as git rev-list with the --objects flag uses its commit
           arguments to build the list of objects it outputs. The objects on
           the resulting list are packed. Besides revisions, --not or
           --shallow <SHA-1> lines are also accepted.

           This implies --revs. When processing the list of revision
           arguments read from the standard input, limit the objects packed
           to those that are not already packed.

           This implies --revs. In addition to the list of revision
           arguments read from the standard input, pretend as if all refs
           under refs/ are specified to be included.

           Include unasked-for annotated tags if the object they reference
           was included in the resulting packfile. This can be useful to
           send new tags to native Git clients.

       --window=<n>, --depth=<n>
           These two options affect how the objects contained in the pack
           are stored using delta compression. The objects are first
           internally sorted by type, size and optionally names and compared
           against the other objects within --window to see if using delta
           compression saves space. --depth limits the maximum delta depth;
           making it too deep affects the performance on the unpacker side,
           because delta data needs to be applied that many times to get to
           the necessary object.

           The default value for --window is 10 and --depth is 50. The
           maximum depth is 4095.

           This option provides an additional limit on top of --window; the
           window size will dynamically scale down so as to not take up more
           than <n> bytes in memory. This is useful in repositories with a
           mix of large and small objects to not run out of memory with a
           large window, but still be able to take advantage of the large
           window for the smaller objects. The size can be suffixed with
           "k", "m", or "g".  --window-memory=0 makes memory usage
           unlimited. The default is taken from the pack.windowMemory
           configuration variable.

           In unusual scenarios, you may not be able to create files larger
           than a certain size on your filesystem, and this option can be
           used to tell the command to split the output packfile into
           multiple independent packfiles, each not larger than the given
           size. The size can be suffixed with "k", "m", or "g". The minimum
           size allowed is limited to 1 MiB. This option prevents the
           creation of a bitmap index. The default is unlimited, unless the
           config variable pack.packSizeLimit is set.

           This flag causes an object already in a local pack that has a
           .keep file to be ignored, even if it would have otherwise been

           This flag causes an object already in the given pack to be
           ignored, even if it would have otherwise been packed.
           <pack-name> is the the pack file name without leading directory
           (e.g.  pack-123.pack). The option could be specified multiple
           times to keep multiple packs.

           This flag causes an object already in a pack to be ignored even
           if it would have otherwise been packed.

           This flag causes an object that is borrowed from an alternate
           object store to be ignored even if it would have otherwise been

           Only create a packed archive if it would contain at least one

           Progress status is reported on the standard error stream by
           default when it is attached to a terminal, unless -q is
           specified. This flag forces progress status even if the standard
           error stream is not directed to a terminal.

           When --stdout is specified then progress report is displayed
           during the object count and compression phases but inhibited
           during the write-out phase. The reason is that in some cases the
           output stream is directly linked to another command which may
           wish to display progress status of its own as it processes
           incoming pack data. This flag is like --progress except that it
           forces progress report for the write-out phase as well even if
           --stdout is used.

           This is used to imply --all-progress whenever progress display is
           activated. Unlike --all-progress this flag doesn’t actually force
           any progress display by itself.

           This flag makes the command not to report its progress on the
           standard error stream.

           When creating a packed archive in a repository that has existing
           packs, the command reuses existing deltas. This sometimes results
           in a slightly suboptimal pack. This flag tells the command not to
           reuse existing deltas but compute them from scratch.

           This flag tells the command not to reuse existing object data at
           all, including non deltified object, forcing recompression of
           everything. This implies --no-reuse-delta. Useful only in the
           obscure case where wholesale enforcement of a different
           compression level on the packed data is desired.

           Specifies compression level for newly-compressed data in the
           generated pack. If not specified, pack compression level is
           determined first by pack.compression, then by core.compression,
           and defaults to -1, the zlib default, if neither is set. Add
           --no-reuse-object if you want to force a uniform compression
           level on all data no matter the source.

           Create a "thin" pack by omitting the common objects between a
           sender and a receiver in order to reduce network transfer. This
           option only makes sense in conjunction with --stdout.

           Note: A thin pack violates the packed archive format by omitting
           required objects and is thus unusable by Git without making it
           self-contained. Use git index-pack --fix-thin (see
           git-index-pack(1)) to restore the self-contained property.

           Optimize a pack that will be provided to a client with a shallow
           repository. This option, combined with --thin, can result in a
           smaller pack at the cost of speed.

           A packed archive can express the base object of a delta as either
           a 20-byte object name or as an offset in the stream, but ancient
           versions of Git don’t understand the latter. By default, git
           pack-objects only uses the former format for better
           compatibility. This option allows the command to use the latter
           format for compactness. Depending on the average delta chain
           length, this option typically shrinks the resulting packfile by
           3-5 per-cent.

           Note: Porcelain commands such as git gc (see git-gc(1)), git
           repack (see git-repack(1)) pass this option by default in modern
           Git when they put objects in your repository into pack files. So
           does git bundle (see git-bundle(1)) when it creates a bundle.

           Specifies the number of threads to spawn when searching for best
           delta matches. This requires that pack-objects be compiled with
           pthreads otherwise this option is ignored with a warning. This is
           meant to reduce packing time on multiprocessor machines. The
           required amount of memory for the delta search window is however
           multiplied by the number of threads. Specifying 0 will cause Git
           to auto-detect the number of CPU’s and set the number of threads

           This is intended to be used by the test suite only. It allows to
           force the version for the generated pack index, and to force
           64-bit index entries on objects located above the given offset.

           With this option, parents that are hidden by grafts are packed

           Requires --stdout. Omits certain objects (usually blobs) from the
           resulting packfile. See git-rev-list(1) for valid <filter-spec>

           Turns off any previous --filter= argument.

           A debug option to help with future "partial clone" development.
           This option specifies how missing objects are handled.

           The form --missing=error requests that pack-objects stop with an
           error if a missing object is encountered. This is the default

           The form --missing=allow-any will allow object traversal to
           continue if a missing object is encountered. Missing objects will
           silently be omitted from the results.

           The form --missing=allow-promisor is like allow-any, but will
           only allow object traversal to continue for EXPECTED promisor
           missing objects. Unexpected missing object will raise an error.

           Omit objects that are known to be in the promisor remote. (This
           option has the purpose of operating only on locally created
           objects, so that when we repack, we still maintain a distinction
           between locally created objects [without .promisor] and objects
           from the promisor remote [with .promisor].) This is used with
           partial clone.

           Objects unreachable from the refs in packs named with --unpacked=
           option are added to the resulting pack, in addition to the
           reachable objects that are not in packs marked with *.keep files.
           This implies --revs.

           Pack unreachable loose objects (and their loose counterparts
           removed). This implies --revs.

           Keep unreachable objects in loose form. This implies --revs.

           Restrict delta matches based on "islands". See DELTA ISLANDS

DELTA ISLANDS         top

       When possible, pack-objects tries to reuse existing on-disk deltas to
       avoid having to search for new ones on the fly. This is an important
       optimization for serving fetches, because it means the server can
       avoid inflating most objects at all and just send the bytes directly
       from disk. This optimization can’t work when an object is stored as a
       delta against a base which the receiver does not have (and which we
       are not already sending). In that case the server "breaks" the delta
       and has to find a new one, which has a high CPU cost. Therefore it’s
       important for performance that the set of objects in on-disk delta
       relationships match what a client would fetch.

       In a normal repository, this tends to work automatically. The objects
       are mostly reachable from the branches and tags, and that’s what
       clients fetch. Any deltas we find on the server are likely to be
       between objects the client has or will have.

       But in some repository setups, you may have several related but
       separate groups of ref tips, with clients tending to fetch those
       groups independently. For example, imagine that you are hosting
       several "forks" of a repository in a single shared object store, and
       letting clients view them as separate repositories through
       GIT_NAMESPACE or separate repos using the alternates mechanism. A
       naive repack may find that the optimal delta for an object is against
       a base that is only found in another fork. But when a client fetches,
       they will not have the base object, and we’ll have to find a new
       delta on the fly.

       A similar situation may exist if you have many refs outside of
       refs/heads/ and refs/tags/ that point to related objects (e.g.,
       refs/pull or refs/changes used by some hosting providers). By
       default, clients fetch only heads and tags, and deltas against
       objects found only in those other groups cannot be sent as-is.

       Delta islands solve this problem by allowing you to group your refs
       into distinct "islands". Pack-objects computes which objects are
       reachable from which islands, and refuses to make a delta from an
       object A against a base which is not present in all of A's islands.
       This results in slightly larger packs (because we miss some delta
       opportunities), but guarantees that a fetch of one island will not
       have to recompute deltas on the fly due to crossing island

       When repacking with delta islands the delta window tends to get
       clogged with candidates that are forbidden by the config. Repacking
       with a big --window helps (and doesn’t take as long as it otherwise
       might because we can reject some object pairs based on islands before
       doing any computation on the content).

       Islands are configured via the pack.island option, which can be
       specified multiple times. Each value is a left-anchored regular
       expressions matching refnames. For example:

           island = refs/heads/
           island = refs/tags/

       puts heads and tags into an island (whose name is the empty string;
       see below for more on naming). Any refs which do not match those
       regular expressions (e.g., refs/pull/123) is not in any island. Any
       object which is reachable only from refs/pull/ (but not heads or
       tags) is therefore not a candidate to be used as a base for

       Refs are grouped into islands based on their "names", and two regexes
       that produce the same name are considered to be in the same island.
       The names are computed from the regexes by concatenating any capture
       groups from the regex, with a - dash in between. (And if there are no
       capture groups, then the name is the empty string, as in the above
       example.) This allows you to create arbitrary numbers of islands.
       Only up to 14 such capture groups are supported though.

       For example, imagine you store the refs for each fork in
       refs/virtual/ID, where ID is a numeric identifier. You might then

           island = refs/virtual/([0-9]+)/heads/
           island = refs/virtual/([0-9]+)/tags/
           island = refs/virtual/([0-9]+)/(pull)/

       That puts the heads and tags for each fork in their own island (named
       "1234" or similar), and the pull refs for each go into their own

       Note that we pick a single island for each regex to go into, using
       "last one wins" ordering (which allows repo-specific config to take
       precedence over user-wide config, and so forth).

SEE ALSO         top

       git-rev-list(1) git-repack(1) git-prune-packed(1)

GIT         top

       Part of the git(1) suite

COLOPHON         top

       This page is part of the git (Git distributed version control system)
       project.  Information about the project can be found at 
       ⟨⟩.  If you have a bug report for this manual page,
       see ⟨⟩.  This page was obtained from the
       project's upstream Git repository ⟨⟩ on
       2018-10-29.  (At that time, the date of the most recent commit that
       was found in the repository was 2018-10-26.)  If you discover any
       rendering problems in this HTML version of the page, or you believe
       there is a better or more up-to-date source for the page, or you have
       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to

Git           10/28/2018              GIT-PACK-OBJECTS(1)

Pages that refer to this page: git(1)git-config(1)git-index-pack(1)git-pack-redundant(1)git-prune-packed(1)git-repack(1)git-rev-list(1)git-show-index(1)