1GIT-GC(1) Git Manual GIT-GC(1)
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6 git-gc - Cleanup unnecessary files and optimize the local repository
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9 git gc [--aggressive] [--auto] [--quiet] [--prune=<date> | --no-prune] [--force] [--keep-largest-pack]
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12 Runs a number of housekeeping tasks within the current repository, such
13 as compressing file revisions (to reduce disk space and increase
14 performance), removing unreachable objects which may have been created
15 from prior invocations of git add, packing refs, pruning reflog, rerere
16 metadata or stale working trees. May also update ancillary indexes such
17 as the commit-graph.
18 When common porcelain operations that create objects are run, they will
20 check whether the repository has grown substantially since the last
21 maintenance, and if so run git gc automatically. See gc.auto below for
22 how to disable this behavior.
23 Running git gc manually should only be needed when adding objects to a
25 repository without regularly running such porcelain commands, to do a
26 one-off repository optimization, or e.g. to clean up a suboptimal
27 mass-import. See the "PACKFILE OPTIMIZATION" section in git-fast-
28 import(1) for more details on the import case.
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31 --aggressive
32 Usually git gc runs very quickly while providing good disk space
33 utilization and performance. This option will cause git gc to more
34 aggressively optimize the repository at the expense of taking much
35 more time. The effects of this optimization are mostly persistent.
36 See the "AGGRESSIVE" section below for details.
37 --auto
39 With this option, git gc checks whether any housekeeping is
40 required; if not, it exits without performing any work.
41 See the gc.auto option in the "CONFIGURATION" section below for how
43 this heuristic works.
44 Once housekeeping is triggered by exceeding the limits of
46 configuration options such as gc.auto and gc.autoPackLimit, all
47 other housekeeping tasks (e.g. rerere, working trees, reflog...)
48 will be performed as well.
49 --[no-]cruft
51 When expiring unreachable objects, pack them separately into a
52 cruft pack instead of storing them as loose objects. --cruft is on
53 by default.
54 --max-cruft-size=<n>
56 When packing unreachable objects into a cruft pack, limit the size
57 of new cruft packs to be at most <n> bytes. Overrides any value
58 specified via the gc.maxCruftSize configuration. See the
59 --max-cruft-size option of git-repack(1) for more.
60 --prune=<date>
62 Prune loose objects older than date (default is 2 weeks ago,
63 overridable by the config variable gc.pruneExpire). --prune=now
64 prunes loose objects regardless of their age and increases the risk
65 of corruption if another process is writing to the repository
66 concurrently; see "NOTES" below. --prune is on by default.
67 --no-prune
69 Do not prune any loose objects.
70 --quiet
72 Suppress all progress reports.
73 --force
75 Force git gc to run even if there may be another git gc instance
76 running on this repository.
77 --keep-largest-pack
79 All packs except the largest non-cruft pack, any packs marked with
80 a .keep file, and any cruft pack(s) are consolidated into a single
81 pack. When this option is used, gc.bigPackThreshold is ignored.
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84 When the --aggressive option is supplied, git-repack(1) will be invoked
85 with the -f flag, which in turn will pass --no-reuse-delta to git-pack-
86 objects(1). This will throw away any existing deltas and re-compute
87 them, at the expense of spending much more time on the repacking.
88 The effects of this are mostly persistent, e.g. when packs and loose
90 objects are coalesced into one another pack the existing deltas in that
91 pack might get re-used, but there are also various cases where we might
92 pick a sub-optimal delta from a newer pack instead.
93 Furthermore, supplying --aggressive will tweak the --depth and --window
95 options passed to git-repack(1). See the gc.aggressiveDepth and
96 gc.aggressiveWindow settings below. By using a larger window size we’re
97 more likely to find more optimal deltas.
98 It’s probably not worth it to use this option on a given repository
100 without running tailored performance benchmarks on it. It takes a lot
101 more time, and the resulting space/delta optimization may or may not be
102 worth it. Not using this at all is the right trade-off for most users
103 and their repositories.
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106 Everything below this line in this section is selectively included from
107 the git-config(1) documentation. The content is the same as what’s
108 found there:
109 gc.aggressiveDepth
111 The depth parameter used in the delta compression algorithm used by
112 git gc --aggressive. This defaults to 50, which is the default for
113 the --depth option when --aggressive isn’t in use.
114 See the documentation for the --depth option in git-repack(1) for
116 more details.
117 gc.aggressiveWindow
119 The window size parameter used in the delta compression algorithm
120 used by git gc --aggressive. This defaults to 250, which is a much
121 more aggressive window size than the default --window of 10.
122 See the documentation for the --window option in git-repack(1) for
124 more details.
125 gc.auto
127 When there are approximately more than this many loose objects in
128 the repository, git gc --auto will pack them. Some Porcelain
129 commands use this command to perform a light-weight garbage
130 collection from time to time. The default value is 6700.
131 Setting this to 0 disables not only automatic packing based on the
133 number of loose objects, but also any other heuristic git gc --auto
134 will otherwise use to determine if there’s work to do, such as
135 gc.autoPackLimit.
136 gc.autoPackLimit
138 When there are more than this many packs that are not marked with
139 *.keep file in the repository, git gc --auto consolidates them into
140 one larger pack. The default value is 50. Setting this to 0
141 disables it. Setting gc.auto to 0 will also disable this.
142 See the gc.bigPackThreshold configuration variable below. When in
144 use, it’ll affect how the auto pack limit works.
145 gc.autoDetach
147 Make git gc --auto return immediately and run in the background if
148 the system supports it. Default is true.
149 gc.bigPackThreshold
151 If non-zero, all non-cruft packs larger than this limit are kept
152 when git gc is run. This is very similar to --keep-largest-pack
153 except that all non-cruft packs that meet the threshold are kept,
154 not just the largest pack. Defaults to zero. Common unit suffixes
155 of k, m, or g are supported.
156 Note that if the number of kept packs is more than
158 gc.autoPackLimit, this configuration variable is ignored, all packs
159 except the base pack will be repacked. After this the number of
160 packs should go below gc.autoPackLimit and gc.bigPackThreshold
161 should be respected again.
162 If the amount of memory estimated for git repack to run smoothly is
164 not available and gc.bigPackThreshold is not set, the largest pack
165 will also be excluded (this is the equivalent of running git gc
166 with --keep-largest-pack).
167 gc.writeCommitGraph
169 If true, then gc will rewrite the commit-graph file when git-gc(1)
170 is run. When using git gc --auto the commit-graph will be updated
171 if housekeeping is required. Default is true. See git-commit-
172 graph(1) for details.
173 gc.logExpiry
175 If the file gc.log exists, then git gc --auto will print its
176 content and exit with status zero instead of running unless that
177 file is more than gc.logExpiry old. Default is "1.day". See
178 gc.pruneExpire for more ways to specify its value.
179 gc.packRefs
181 Running git pack-refs in a repository renders it unclonable by Git
182 versions prior to 1.5.1.2 over dumb transports such as HTTP. This
183 variable determines whether git gc runs git pack-refs. This can be
184 set to notbare to enable it within all non-bare repos or it can be
185 set to a boolean value. The default is true.
186 gc.cruftPacks
188 Store unreachable objects in a cruft pack (see git-repack(1))
189 instead of as loose objects. The default is true.
190 gc.maxCruftSize
192 Limit the size of new cruft packs when repacking. When specified in
193 addition to --max-cruft-size, the command line option takes
194 priority. See the --max-cruft-size option of git-repack(1).
195 gc.pruneExpire
197 When git gc is run, it will call prune --expire 2.weeks.ago (and
198 repack --cruft --cruft-expiration 2.weeks.ago if using cruft packs
199 via gc.cruftPacks or --cruft). Override the grace period with this
200 config variable. The value "now" may be used to disable this grace
201 period and always prune unreachable objects immediately, or "never"
202 may be used to suppress pruning. This feature helps prevent
203 corruption when git gc runs concurrently with another process
204 writing to the repository; see the "NOTES" section of git-gc(1).
205 gc.worktreePruneExpire
207 When git gc is run, it calls git worktree prune --expire
208 3.months.ago. This config variable can be used to set a different
209 grace period. The value "now" may be used to disable the grace
210 period and prune $GIT_DIR/worktrees immediately, or "never" may be
211 used to suppress pruning.
212 gc.reflogExpire, gc.<pattern>.reflogExpire
214 git reflog expire removes reflog entries older than this time;
215 defaults to 90 days. The value "now" expires all entries
216 immediately, and "never" suppresses expiration altogether. With
217 "<pattern>" (e.g. "refs/stash") in the middle the setting applies
218 only to the refs that match the <pattern>.
219 gc.reflogExpireUnreachable, gc.<pattern>.reflogExpireUnreachable
221 git reflog expire removes reflog entries older than this time and
222 are not reachable from the current tip; defaults to 30 days. The
223 value "now" expires all entries immediately, and "never" suppresses
224 expiration altogether. With "<pattern>" (e.g. "refs/stash") in the
225 middle, the setting applies only to the refs that match the
226 <pattern>.
227 These types of entries are generally created as a result of using
229 git commit --amend or git rebase and are the commits prior to the
230 amend or rebase occurring. Since these changes are not part of the
231 current project most users will want to expire them sooner, which
232 is why the default is more aggressive than gc.reflogExpire.
233 gc.recentObjectsHook
235 When considering whether or not to remove an object (either when
236 generating a cruft pack or storing unreachable objects as loose),
237 use the shell to execute the specified command(s). Interpret their
238 output as object IDs which Git will consider as "recent",
239 regardless of their age. By treating their mtimes as "now", any
240 objects (and their descendants) mentioned in the output will be
241 kept regardless of their true age.
242 Output must contain exactly one hex object ID per line, and nothing
244 else. Objects which cannot be found in the repository are ignored.
245 Multiple hooks are supported, but all must exit successfully, else
246 the operation (either generating a cruft pack or unpacking
247 unreachable objects) will be halted.
248 gc.repackFilter
250 When repacking, use the specified filter to move certain objects
251 into a separate packfile. See the --filter=<filter-spec> option of
252 git-repack(1).
253 gc.repackFilterTo
255 When repacking and using a filter, see gc.repackFilter, the
256 specified location will be used to create the packfile containing
257 the filtered out objects. WARNING: The specified location should
258 be accessible, using for example the Git alternates mechanism,
259 otherwise the repo could be considered corrupt by Git as it migh
260 not be able to access the objects in that packfile. See the
261 --filter-to=<dir> option of git-repack(1) and the
262 objects/info/alternates section of gitrepository-layout(5).
263 gc.rerereResolved
265 Records of conflicted merge you resolved earlier are kept for this
266 many days when git rerere gc is run. You can also use more
267 human-readable "1.month.ago", etc. The default is 60 days. See git-
268 rerere(1).
269 gc.rerereUnresolved
271 Records of conflicted merge you have not resolved are kept for this
272 many days when git rerere gc is run. You can also use more
273 human-readable "1.month.ago", etc. The default is 15 days. See git-
274 rerere(1).
275
277 git gc tries very hard not to delete objects that are referenced
278 anywhere in your repository. In particular, it will keep not only
279 objects referenced by your current set of branches and tags, but also
280 objects referenced by the index, remote-tracking branches, reflogs
281 (which may reference commits in branches that were later amended or
282 rewound), and anything else in the refs/* namespace. Note that a note
283 (of the kind created by git notes) attached to an object does not
284 contribute in keeping the object alive. If you are expecting some
285 objects to be deleted and they aren’t, check all of those locations and
286 decide whether it makes sense in your case to remove those references.
287 On the other hand, when git gc runs concurrently with another process,
289 there is a risk of it deleting an object that the other process is
290 using but hasn’t created a reference to. This may just cause the other
291 process to fail or may corrupt the repository if the other process
292 later adds a reference to the deleted object. Git has two features that
293 significantly mitigate this problem:
294 1. Any object with modification time newer than the --prune date is
296 kept, along with everything reachable from it.
297 2. Most operations that add an object to the database update the
299 modification time of the object if it is already present so that #1
300 applies.
301 However, these features fall short of a complete solution, so users who
303 run commands concurrently have to live with some risk of corruption
304 (which seems to be low in practice).
305
307 The git gc --auto command will run the pre-auto-gc hook. See
308 githooks(5) for more information.
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311 git-prune(1) git-reflog(1) git-repack(1) git-rerere(1)
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314 Part of the git(1) suite
315Git 2.43.0 11/20/2023 GIT-GC(1)