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

6       git-pack-objects - Create a packed archive of objects
7

SYNOPSIS

9       git pack-objects [-q | --progress | --all-progress] [--all-progress-implied]
10               [--no-reuse-delta] [--delta-base-offset] [--non-empty]
11               [--local] [--incremental] [--window=<n>] [--depth=<n>]
12               [--revs [--unpacked | --all]] [--keep-pack=<pack-name>]
13               [--stdout [--filter=<filter-spec>] | base-name]
14               [--shallow] [--keep-true-parents] [--[no-]sparse] < object-list
15

DESCRIPTION

17       Reads list of objects from the standard input, and writes either one or
18       more packed archives with the specified base-name to disk, or a packed
19       archive to the standard output.
20
21       A packed archive is an efficient way to transfer a set of objects
22       between two repositories as well as an access efficient archival
23       format. In a packed archive, an object is either stored as a compressed
24       whole or as a difference from some other object. The latter is often
25       called a delta.
26
27       The packed archive format (.pack) is designed to be self-contained so
28       that it can be unpacked without any further information. Therefore,
29       each object that a delta depends upon must be present within the pack.
30
31       A pack index file (.idx) is generated for fast, random access to the
32       objects in the pack. Placing both the index file (.idx) and the packed
33       archive (.pack) in the pack/ subdirectory of $GIT_OBJECT_DIRECTORY (or
34       any of the directories on $GIT_ALTERNATE_OBJECT_DIRECTORIES) enables
35       Git to read from the pack archive.
36
37       The git unpack-objects command can read the packed archive and expand
38       the objects contained in the pack into "one-file one-object" format;
39       this is typically done by the smart-pull commands when a pack is
40       created on-the-fly for efficient network transport by their peers.
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OPTIONS

43       base-name
44           Write into pairs of files (.pack and .idx), using <base-name> to
45           determine the name of the created file. When this option is used,
46           the two files in a pair are written in
47           <base-name>-<SHA-1>.{pack,idx} files. <SHA-1> is a hash based on
48           the pack content and is written to the standard output of the
49           command.
50
51       --stdout
52           Write the pack contents (what would have been written to .pack
53           file) out to the standard output.
54
55       --revs
56           Read the revision arguments from the standard input, instead of
57           individual object names. The revision arguments are processed the
58           same way as git rev-list with the --objects flag uses its commit
59           arguments to build the list of objects it outputs. The objects on
60           the resulting list are packed. Besides revisions, --not or
61           --shallow <SHA-1> lines are also accepted.
62
63       --unpacked
64           This implies --revs. When processing the list of revision arguments
65           read from the standard input, limit the objects packed to those
66           that are not already packed.
67
68       --all
69           This implies --revs. In addition to the list of revision arguments
70           read from the standard input, pretend as if all refs under refs/
71           are specified to be included.
72
73       --include-tag
74           Include unasked-for annotated tags if the object they reference was
75           included in the resulting packfile. This can be useful to send new
76           tags to native Git clients.
77
78       --window=<n>, --depth=<n>
79           These two options affect how the objects contained in the pack are
80           stored using delta compression. The objects are first internally
81           sorted by type, size and optionally names and compared against the
82           other objects within --window to see if using delta compression
83           saves space. --depth limits the maximum delta depth; making it too
84           deep affects the performance on the unpacker side, because delta
85           data needs to be applied that many times to get to the necessary
86           object.
87
88           The default value for --window is 10 and --depth is 50. The maximum
89           depth is 4095.
90
91       --window-memory=<n>
92           This option provides an additional limit on top of --window; the
93           window size will dynamically scale down so as to not take up more
94           than <n> bytes in memory. This is useful in repositories with a mix
95           of large and small objects to not run out of memory with a large
96           window, but still be able to take advantage of the large window for
97           the smaller objects. The size can be suffixed with "k", "m", or
98           "g".  --window-memory=0 makes memory usage unlimited. The default
99           is taken from the pack.windowMemory configuration variable.
100
101       --max-pack-size=<n>
102           In unusual scenarios, you may not be able to create files larger
103           than a certain size on your filesystem, and this option can be used
104           to tell the command to split the output packfile into multiple
105           independent packfiles, each not larger than the given size. The
106           size can be suffixed with "k", "m", or "g". The minimum size
107           allowed is limited to 1 MiB. This option prevents the creation of a
108           bitmap index. The default is unlimited, unless the config variable
109           pack.packSizeLimit is set.
110
111       --honor-pack-keep
112           This flag causes an object already in a local pack that has a .keep
113           file to be ignored, even if it would have otherwise been packed.
114
115       --keep-pack=<pack-name>
116           This flag causes an object already in the given pack to be ignored,
117           even if it would have otherwise been packed.  <pack-name> is the
118           pack file name without leading directory (e.g.  pack-123.pack). The
119           option could be specified multiple times to keep multiple packs.
120
121       --incremental
122           This flag causes an object already in a pack to be ignored even if
123           it would have otherwise been packed.
124
125       --local
126           This flag causes an object that is borrowed from an alternate
127           object store to be ignored even if it would have otherwise been
128           packed.
129
130       --non-empty
131           Only create a packed archive if it would contain at least one
132           object.
133
134       --progress
135           Progress status is reported on the standard error stream by default
136           when it is attached to a terminal, unless -q is specified. This
137           flag forces progress status even if the standard error stream is
138           not directed to a terminal.
139
140       --all-progress
141           When --stdout is specified then progress report is displayed during
142           the object count and compression phases but inhibited during the
143           write-out phase. The reason is that in some cases the output stream
144           is directly linked to another command which may wish to display
145           progress status of its own as it processes incoming pack data. This
146           flag is like --progress except that it forces progress report for
147           the write-out phase as well even if --stdout is used.
148
149       --all-progress-implied
150           This is used to imply --all-progress whenever progress display is
151           activated. Unlike --all-progress this flag doesn’t actually force
152           any progress display by itself.
153
154       -q
155           This flag makes the command not to report its progress on the
156           standard error stream.
157
158       --no-reuse-delta
159           When creating a packed archive in a repository that has existing
160           packs, the command reuses existing deltas. This sometimes results
161           in a slightly suboptimal pack. This flag tells the command not to
162           reuse existing deltas but compute them from scratch.
163
164       --no-reuse-object
165           This flag tells the command not to reuse existing object data at
166           all, including non deltified object, forcing recompression of
167           everything. This implies --no-reuse-delta. Useful only in the
168           obscure case where wholesale enforcement of a different compression
169           level on the packed data is desired.
170
171       --compression=<n>
172           Specifies compression level for newly-compressed data in the
173           generated pack. If not specified, pack compression level is
174           determined first by pack.compression, then by core.compression, and
175           defaults to -1, the zlib default, if neither is set. Add
176           --no-reuse-object if you want to force a uniform compression level
177           on all data no matter the source.
178
179       --[no-]sparse
180           Toggle the "sparse" algorithm to determine which objects to include
181           in the pack, when combined with the "--revs" option. This algorithm
182           only walks trees that appear in paths that introduce new objects.
183           This can have significant performance benefits when computing a
184           pack to send a small change. However, it is possible that extra
185           objects are added to the pack-file if the included commits contain
186           certain types of direct renames. If this option is not included, it
187           defaults to the value of pack.useSparse, which is true unless
188           otherwise specified.
189
190       --thin
191           Create a "thin" pack by omitting the common objects between a
192           sender and a receiver in order to reduce network transfer. This
193           option only makes sense in conjunction with --stdout.
194
195           Note: A thin pack violates the packed archive format by omitting
196           required objects and is thus unusable by Git without making it
197           self-contained. Use git index-pack --fix-thin (see git-index-
198           pack(1)) to restore the self-contained property.
199
200       --shallow
201           Optimize a pack that will be provided to a client with a shallow
202           repository. This option, combined with --thin, can result in a
203           smaller pack at the cost of speed.
204
205       --delta-base-offset
206           A packed archive can express the base object of a delta as either a
207           20-byte object name or as an offset in the stream, but ancient
208           versions of Git don’t understand the latter. By default, git
209           pack-objects only uses the former format for better compatibility.
210           This option allows the command to use the latter format for
211           compactness. Depending on the average delta chain length, this
212           option typically shrinks the resulting packfile by 3-5 per-cent.
213
214           Note: Porcelain commands such as git gc (see git-gc(1)), git repack
215           (see git-repack(1)) pass this option by default in modern Git when
216           they put objects in your repository into pack files. So does git
217           bundle (see git-bundle(1)) when it creates a bundle.
218
219       --threads=<n>
220           Specifies the number of threads to spawn when searching for best
221           delta matches. This requires that pack-objects be compiled with
222           pthreads otherwise this option is ignored with a warning. This is
223           meant to reduce packing time on multiprocessor machines. The
224           required amount of memory for the delta search window is however
225           multiplied by the number of threads. Specifying 0 will cause Git to
226           auto-detect the number of CPU’s and set the number of threads
227           accordingly.
228
229       --index-version=<version>[,<offset>]
230           This is intended to be used by the test suite only. It allows to
231           force the version for the generated pack index, and to force 64-bit
232           index entries on objects located above the given offset.
233
234       --keep-true-parents
235           With this option, parents that are hidden by grafts are packed
236           nevertheless.
237
238       --filter=<filter-spec>
239           Requires --stdout. Omits certain objects (usually blobs) from the
240           resulting packfile. See git-rev-list(1) for valid <filter-spec>
241           forms.
242
243       --no-filter
244           Turns off any previous --filter= argument.
245
246       --missing=<missing-action>
247           A debug option to help with future "partial clone" development.
248           This option specifies how missing objects are handled.
249
250           The form --missing=error requests that pack-objects stop with an
251           error if a missing object is encountered. If the repository is a
252           partial clone, an attempt to fetch missing objects will be made
253           before declaring them missing. This is the default action.
254
255           The form --missing=allow-any will allow object traversal to
256           continue if a missing object is encountered. No fetch of a missing
257           object will occur. Missing objects will silently be omitted from
258           the results.
259
260           The form --missing=allow-promisor is like allow-any, but will only
261           allow object traversal to continue for EXPECTED promisor missing
262           objects. No fetch of a missing object will occur. An unexpected
263           missing object will raise an error.
264
265       --exclude-promisor-objects
266           Omit objects that are known to be in the promisor remote. (This
267           option has the purpose of operating only on locally created
268           objects, so that when we repack, we still maintain a distinction
269           between locally created objects [without .promisor] and objects
270           from the promisor remote [with .promisor].) This is used with
271           partial clone.
272
273       --keep-unreachable
274           Objects unreachable from the refs in packs named with --unpacked=
275           option are added to the resulting pack, in addition to the
276           reachable objects that are not in packs marked with *.keep files.
277           This implies --revs.
278
279       --pack-loose-unreachable
280           Pack unreachable loose objects (and their loose counterparts
281           removed). This implies --revs.
282
283       --unpack-unreachable
284           Keep unreachable objects in loose form. This implies --revs.
285
286       --delta-islands
287           Restrict delta matches based on "islands". See DELTA ISLANDS below.
288

DELTA ISLANDS

290       When possible, pack-objects tries to reuse existing on-disk deltas to
291       avoid having to search for new ones on the fly. This is an important
292       optimization for serving fetches, because it means the server can avoid
293       inflating most objects at all and just send the bytes directly from
294       disk. This optimization can’t work when an object is stored as a delta
295       against a base which the receiver does not have (and which we are not
296       already sending). In that case the server "breaks" the delta and has to
297       find a new one, which has a high CPU cost. Therefore it’s important for
298       performance that the set of objects in on-disk delta relationships
299       match what a client would fetch.
300
301       In a normal repository, this tends to work automatically. The objects
302       are mostly reachable from the branches and tags, and that’s what
303       clients fetch. Any deltas we find on the server are likely to be
304       between objects the client has or will have.
305
306       But in some repository setups, you may have several related but
307       separate groups of ref tips, with clients tending to fetch those groups
308       independently. For example, imagine that you are hosting several
309       "forks" of a repository in a single shared object store, and letting
310       clients view them as separate repositories through GIT_NAMESPACE or
311       separate repos using the alternates mechanism. A naive repack may find
312       that the optimal delta for an object is against a base that is only
313       found in another fork. But when a client fetches, they will not have
314       the base object, and we’ll have to find a new delta on the fly.
315
316       A similar situation may exist if you have many refs outside of
317       refs/heads/ and refs/tags/ that point to related objects (e.g.,
318       refs/pull or refs/changes used by some hosting providers). By default,
319       clients fetch only heads and tags, and deltas against objects found
320       only in those other groups cannot be sent as-is.
321
322       Delta islands solve this problem by allowing you to group your refs
323       into distinct "islands". Pack-objects computes which objects are
324       reachable from which islands, and refuses to make a delta from an
325       object A against a base which is not present in all of A's islands.
326       This results in slightly larger packs (because we miss some delta
327       opportunities), but guarantees that a fetch of one island will not have
328       to recompute deltas on the fly due to crossing island boundaries.
329
330       When repacking with delta islands the delta window tends to get clogged
331       with candidates that are forbidden by the config. Repacking with a big
332       --window helps (and doesn’t take as long as it otherwise might because
333       we can reject some object pairs based on islands before doing any
334       computation on the content).
335
336       Islands are configured via the pack.island option, which can be
337       specified multiple times. Each value is a left-anchored regular
338       expressions matching refnames. For example:
339
340           [pack]
341           island = refs/heads/
342           island = refs/tags/
343
344       puts heads and tags into an island (whose name is the empty string; see
345       below for more on naming). Any refs which do not match those regular
346       expressions (e.g., refs/pull/123) is not in any island. Any object
347       which is reachable only from refs/pull/ (but not heads or tags) is
348       therefore not a candidate to be used as a base for refs/heads/.
349
350       Refs are grouped into islands based on their "names", and two regexes
351       that produce the same name are considered to be in the same island. The
352       names are computed from the regexes by concatenating any capture groups
353       from the regex, with a - dash in between. (And if there are no capture
354       groups, then the name is the empty string, as in the above example.)
355       This allows you to create arbitrary numbers of islands. Only up to 14
356       such capture groups are supported though.
357
358       For example, imagine you store the refs for each fork in
359       refs/virtual/ID, where ID is a numeric identifier. You might then
360       configure:
361
362           [pack]
363           island = refs/virtual/([0-9]+)/heads/
364           island = refs/virtual/([0-9]+)/tags/
365           island = refs/virtual/([0-9]+)/(pull)/
366
367       That puts the heads and tags for each fork in their own island (named
368       "1234" or similar), and the pull refs for each go into their own
369       "1234-pull".
370
371       Note that we pick a single island for each regex to go into, using
372       "last one wins" ordering (which allows repo-specific config to take
373       precedence over user-wide config, and so forth).
374

SEE ALSO

376       git-rev-list(1) git-repack(1) git-prune-packed(1)
377

GIT

379       Part of the git(1) suite
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383Git 2.30.2                        2021-03-08               GIT-PACK-OBJECTS(1)
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