1GIT-PACK-OBJECTS(1) Git Manual GIT-PACK-OBJECTS(1)
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6 git-pack-objects - Create a packed archive of objects
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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
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 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 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 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 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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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 --stdout
52 Write the pack contents (what would have been written to .pack
53 file) out to the standard output.
54 --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 --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 --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 --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 --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 The default value for --window is 10 and --depth is 50. The maximum
89 depth is 4095.
90 --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 --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 --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 --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 --incremental
122 This flag causes an object already in a pack to be ignored even if
123 it would have otherwise been packed.
124 --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 --non-empty
131 Only create a packed archive if it would contain at least one
132 object.
133 --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 --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 --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 -q
155 This flag makes the command not to report its progress on the
156 standard error stream.
157 --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 --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 --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 --[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 --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 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 --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 --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 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 --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 --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 --keep-true-parents
235 With this option, parents that are hidden by grafts are packed
236 nevertheless.
237 --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 --no-filter
244 Turns off any previous --filter= argument.
245 --missing=<missing-action>
247 A debug option to help with future "partial clone" development.
248 This option specifies how missing objects are handled.
249 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 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 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 --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 --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 --pack-loose-unreachable
280 Pack unreachable loose objects (and their loose counterparts
281 removed). This implies --revs.
282 --unpack-unreachable
284 Keep unreachable objects in loose form. This implies --revs.
285 --delta-islands
287 Restrict delta matches based on "islands". See DELTA ISLANDS below.
288
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 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 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 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 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 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 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 [pack]
341 island = refs/heads/
342 island = refs/tags/
343 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 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 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 [pack]
363 island = refs/virtual/([0-9]+)/heads/
364 island = refs/virtual/([0-9]+)/tags/
365 island = refs/virtual/([0-9]+)/(pull)/
366 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 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
376 Various configuration variables affect packing, see git-config(1)
377 (search for "pack" and "delta").
378 Notably, delta compression is not used on objects larger than the
380 core.bigFileThreshold configuration variable and on files with the
381 attribute delta set to false.
382
384 git-rev-list(1) git-repack(1) git-prune-packed(1)
385
387 Part of the git(1) suite
388Git 2.31.1 2021-03-26 GIT-PACK-OBJECTS(1)