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 --cruft
51 When expiring unreachable objects, pack them separately into a
52 cruft pack instead of storing them as loose objects.
53 --prune=<date>
55 Prune loose objects older than date (default is 2 weeks ago,
56 overridable by the config variable gc.pruneExpire). --prune=now
57 prunes loose objects regardless of their age and increases the risk
58 of corruption if another process is writing to the repository
59 concurrently; see "NOTES" below. --prune is on by default.
60 --no-prune
62 Do not prune any loose objects.
63 --quiet
65 Suppress all progress reports.
66 --force
68 Force git gc to run even if there may be another git gc instance
69 running on this repository.
70 --keep-largest-pack
72 All packs except the largest pack and those marked with a .keep
73 files are consolidated into a single pack. When this option is
74 used, gc.bigPackThreshold is ignored.
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77 When the --aggressive option is supplied, git-repack(1) will be invoked
78 with the -f flag, which in turn will pass --no-reuse-delta to git-pack-
79 objects(1). This will throw away any existing deltas and re-compute
80 them, at the expense of spending much more time on the repacking.
81 The effects of this are mostly persistent, e.g. when packs and loose
83 objects are coalesced into one another pack the existing deltas in that
84 pack might get re-used, but there are also various cases where we might
85 pick a sub-optimal delta from a newer pack instead.
86 Furthermore, supplying --aggressive will tweak the --depth and --window
88 options passed to git-repack(1). See the gc.aggressiveDepth and
89 gc.aggressiveWindow settings below. By using a larger window size we’re
90 more likely to find more optimal deltas.
91 It’s probably not worth it to use this option on a given repository
93 without running tailored performance benchmarks on it. It takes a lot
94 more time, and the resulting space/delta optimization may or may not be
95 worth it. Not using this at all is the right trade-off for most users
96 and their repositories.
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99 Everything below this line in this section is selectively included from
100 the git-config(1) documentation. The content is the same as what’s
101 found there:
102 gc.aggressiveDepth
104 The depth parameter used in the delta compression algorithm used by
105 git gc --aggressive. This defaults to 50, which is the default for
106 the --depth option when --aggressive isn’t in use.
107 See the documentation for the --depth option in git-repack(1) for
109 more details.
110 gc.aggressiveWindow
112 The window size parameter used in the delta compression algorithm
113 used by git gc --aggressive. This defaults to 250, which is a much
114 more aggressive window size than the default --window of 10.
115 See the documentation for the --window option in git-repack(1) for
117 more details.
118 gc.auto
120 When there are approximately more than this many loose objects in
121 the repository, git gc --auto will pack them. Some Porcelain
122 commands use this command to perform a light-weight garbage
123 collection from time to time. The default value is 6700.
124 Setting this to 0 disables not only automatic packing based on the
126 number of loose objects, but any other heuristic git gc --auto will
127 otherwise use to determine if there’s work to do, such as
128 gc.autoPackLimit.
129 gc.autoPackLimit
131 When there are more than this many packs that are not marked with
132 *.keep file in the repository, git gc --auto consolidates them into
133 one larger pack. The default value is 50. Setting this to 0
134 disables it. Setting gc.auto to 0 will also disable this.
135 See the gc.bigPackThreshold configuration variable below. When in
137 use, it’ll affect how the auto pack limit works.
138 gc.autoDetach
140 Make git gc --auto return immediately and run in background if the
141 system supports it. Default is true.
142 gc.bigPackThreshold
144 If non-zero, all packs larger than this limit are kept when git gc
145 is run. This is very similar to --keep-largest-pack except that all
146 packs that meet the threshold are kept, not just the largest pack.
147 Defaults to zero. Common unit suffixes of k, m, or g are supported.
148 Note that if the number of kept packs is more than
150 gc.autoPackLimit, this configuration variable is ignored, all packs
151 except the base pack will be repacked. After this the number of
152 packs should go below gc.autoPackLimit and gc.bigPackThreshold
153 should be respected again.
154 If the amount of memory estimated for git repack to run smoothly is
156 not available and gc.bigPackThreshold is not set, the largest pack
157 will also be excluded (this is the equivalent of running git gc
158 with --keep-largest-pack).
159 gc.writeCommitGraph
161 If true, then gc will rewrite the commit-graph file when git-gc(1)
162 is run. When using git gc --auto the commit-graph will be updated
163 if housekeeping is required. Default is true. See git-commit-
164 graph(1) for details.
165 gc.logExpiry
167 If the file gc.log exists, then git gc --auto will print its
168 content and exit with status zero instead of running unless that
169 file is more than gc.logExpiry old. Default is "1.day". See
170 gc.pruneExpire for more ways to specify its value.
171 gc.packRefs
173 Running git pack-refs in a repository renders it unclonable by Git
174 versions prior to 1.5.1.2 over dumb transports such as HTTP. This
175 variable determines whether git gc runs git pack-refs. This can be
176 set to notbare to enable it within all non-bare repos or it can be
177 set to a boolean value. The default is true.
178 gc.cruftPacks
180 Store unreachable objects in a cruft pack (see git-repack(1))
181 instead of as loose objects. The default is false.
182 gc.pruneExpire
184 When git gc is run, it will call prune --expire 2.weeks.ago (and
185 repack --cruft --cruft-expiration 2.weeks.ago if using cruft packs
186 via gc.cruftPacks or --cruft). Override the grace period with this
187 config variable. The value "now" may be used to disable this grace
188 period and always prune unreachable objects immediately, or "never"
189 may be used to suppress pruning. This feature helps prevent
190 corruption when git gc runs concurrently with another process
191 writing to the repository; see the "NOTES" section of git-gc(1).
192 gc.worktreePruneExpire
194 When git gc is run, it calls git worktree prune --expire
195 3.months.ago. This config variable can be used to set a different
196 grace period. The value "now" may be used to disable the grace
197 period and prune $GIT_DIR/worktrees immediately, or "never" may be
198 used to suppress pruning.
199 gc.reflogExpire, gc.<pattern>.reflogExpire
201 git reflog expire removes reflog entries older than this time;
202 defaults to 90 days. The value "now" expires all entries
203 immediately, and "never" suppresses expiration altogether. With
204 "<pattern>" (e.g. "refs/stash") in the middle the setting applies
205 only to the refs that match the <pattern>.
206 gc.reflogExpireUnreachable, gc.<pattern>.reflogExpireUnreachable
208 git reflog expire removes reflog entries older than this time and
209 are not reachable from the current tip; defaults to 30 days. The
210 value "now" expires all entries immediately, and "never" suppresses
211 expiration altogether. With "<pattern>" (e.g. "refs/stash") in the
212 middle, the setting applies only to the refs that match the
213 <pattern>.
214 These types of entries are generally created as a result of using
216 git commit --amend or git rebase and are the commits prior to the
217 amend or rebase occurring. Since these changes are not part of the
218 current project most users will want to expire them sooner, which
219 is why the default is more aggressive than gc.reflogExpire.
220 gc.rerereResolved
222 Records of conflicted merge you resolved earlier are kept for this
223 many days when git rerere gc is run. You can also use more
224 human-readable "1.month.ago", etc. The default is 60 days. See git-
225 rerere(1).
226 gc.rerereUnresolved
228 Records of conflicted merge you have not resolved are kept for this
229 many days when git rerere gc is run. You can also use more
230 human-readable "1.month.ago", etc. The default is 15 days. See git-
231 rerere(1).
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234 git gc tries very hard not to delete objects that are referenced
235 anywhere in your repository. In particular, it will keep not only
236 objects referenced by your current set of branches and tags, but also
237 objects referenced by the index, remote-tracking branches, reflogs
238 (which may reference commits in branches that were later amended or
239 rewound), and anything else in the refs/* namespace. Note that a note
240 (of the kind created by git notes) attached to an object does not
241 contribute in keeping the object alive. If you are expecting some
242 objects to be deleted and they aren’t, check all of those locations and
243 decide whether it makes sense in your case to remove those references.
244 On the other hand, when git gc runs concurrently with another process,
246 there is a risk of it deleting an object that the other process is
247 using but hasn’t created a reference to. This may just cause the other
248 process to fail or may corrupt the repository if the other process
249 later adds a reference to the deleted object. Git has two features that
250 significantly mitigate this problem:
251 1. Any object with modification time newer than the --prune date is
253 kept, along with everything reachable from it.
254 2. Most operations that add an object to the database update the
256 modification time of the object if it is already present so that #1
257 applies.
258 However, these features fall short of a complete solution, so users who
260 run commands concurrently have to live with some risk of corruption
261 (which seems to be low in practice).
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264 The git gc --auto command will run the pre-auto-gc hook. See
265 githooks(5) for more information.
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268 git-prune(1) git-reflog(1) git-repack(1) git-rerere(1)
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271 Part of the git(1) suite
272Git 2.39.1 2023-01-13 GIT-GC(1)