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



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

SYNOPSIS
       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>]
	       [--cruft] [--cruft-expiration=<time>]
	       [--stdout [--filter=<filter-spec>] | <base-name>]
	       [--shallow] [--keep-true-parents] [--[no-]sparse] < <object-list>


DESCRIPTION
       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 pack.

       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 archive.

       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
       base-name
	   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
	   command.

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

       --revs
	   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.

       --unpacked
	   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.

       --all
	   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-tag
	   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.

       --stdin-packs
	   Read the basenames of packfiles (e.g., pack-1234abcd.pack) from the
	   standard input, instead of object names or revision arguments. The
	   resulting pack contains all objects listed in the included packs
	   (those not beginning with ^), excluding any objects listed in the
	   excluded packs (beginning with ^).

	   Incompatible with --revs, or options that imply --revs (such as
	   --all), with the exception of --unpacked, which is compatible.

       --cruft
	   Packs unreachable objects into a separate "cruft" pack, denoted by
	   the existence of a .mtimes file. Typically used by git repack
	   --cruft. Callers provide a list of pack names and indicate which
	   packs will remain in the repository, along with which packs will be
	   deleted (indicated by the - prefix). The contents of the cruft pack
	   are all objects not contained in the surviving packs which have not
	   exceeded the grace period (see --cruft-expiration below), or which
	   have exceeded the grace period, but are reachable from an other
	   object which hasn't.

	   When the input lists a pack containing all reachable objects (and
	   lists all other packs as pending deletion), the corresponding cruft
	   pack will contain all unreachable objects (with mtime newer than
	   the --cruft-expiration) along with any unreachable objects whose
	   mtime is older than the --cruft-expiration, but are reachable from
	   an unreachable object whose mtime is newer than the
	   --cruft-expiration).

	   Incompatible with --unpack-unreachable, --keep-unreachable,
	   --pack-loose-unreachable, --stdin-packs, as well as any other
	   options which imply --revs. Also incompatible with --max-pack-size;
	   when this option is set, the maximum pack size is not inferred from
	   pack.packSizeLimit.

       --cruft-expiration=<approxidate>
	   If specified, objects are eliminated from the cruft pack if they
	   have an mtime older than <approxidate>. If unspecified (and given
	   --cruft), then no objects are eliminated.

       --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.

       --window-memory=<n>
	   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.

       --max-pack-size=<n>
	   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. The default is unlimited, unless the
	   config variable pack.packSizeLimit is set. Note that this option
	   may result in a larger and slower repository; see the discussion in
	   pack.packSizeLimit.

       --honor-pack-keep
	   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 packed.

       --keep-pack=<pack-name>
	   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
	   pack file name without leading directory (e.g.  pack-123.pack). The
	   option could be specified multiple times to keep multiple packs.

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

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

       --non-empty
	   Only create a packed archive if it would contain at least one
	   object.

       --progress
	   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.

       --all-progress
	   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.

       --all-progress-implied
	   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.

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

       --no-reuse-delta
	   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.

       --no-reuse-object
	   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.

       --compression=<n>
	   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.

       --[no-]sparse
	   Toggle the "sparse" algorithm to determine which objects to include
	   in the pack, when combined with the "--revs" option. This algorithm
	   only walks trees that appear in paths that introduce new objects.
	   This can have significant performance benefits when computing a
	   pack to send a small change. However, it is possible that extra
	   objects are added to the pack-file if the included commits contain
	   certain types of direct renames. If this option is not included, it
	   defaults to the value of pack.useSparse, which is true unless
	   otherwise specified.

       --thin
	   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.

       --shallow
	   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.

       --delta-base-offset
	   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.

       --threads=<n>
	   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
	   accordingly.

       --index-version=<version>[,<offset>]
	   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.

       --keep-true-parents
	   With this option, parents that are hidden by grafts are packed
	   nevertheless.

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

       --no-filter
	   Turns off any previous --filter= argument.

       --missing=<missing-action>
	   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. If the repository is a
	   partial clone, an attempt to fetch missing objects will be made
	   before declaring them missing. This is the default action.

	   The form --missing=allow-any will allow object traversal to
	   continue if a missing object is encountered. No fetch of a missing
	   object will occur. 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. No fetch of a missing object will occur. An unexpected
	   missing object will raise an error.

       --exclude-promisor-objects
	   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.

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

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

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

DELTA ISLANDS
       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 boundaries.

       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:

	   [pack]
	   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/heads/.

       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
       configure:

	   [pack]
	   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
       "1234-pull".

       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).

CONFIGURATION
       Various configuration variables affect packing, see git-config(1)
       (search for "pack" and "delta").

       Notably, delta compression is not used on objects larger than the
       core.bigFileThreshold configuration variable and on files with the
       attribute delta set to false.

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

GIT
       Part of the git(1) suite



Git 2.38.4			  05/16/2024		   GIT-PACK-OBJECTS(1)