gc: automatically write commit-graph files
[git/git.git] / Documentation / git-gc.txt
1 git-gc(1)
2 =========
3
4 NAME
5 ----
6 git-gc - Cleanup unnecessary files and optimize the local repository
7
8
9 SYNOPSIS
10 --------
11 [verse]
12 'git gc' [--aggressive] [--auto] [--quiet] [--prune=<date> | --no-prune] [--force] [--keep-largest-pack]
13
14 DESCRIPTION
15 -----------
16 Runs a number of housekeeping tasks within the current repository,
17 such as compressing file revisions (to reduce disk space and increase
18 performance), removing unreachable objects which may have been
19 created from prior invocations of 'git add', packing refs, pruning
20 reflog, rerere metadata or stale working trees.
21
22 Users are encouraged to run this task on a regular basis within
23 each repository to maintain good disk space utilization and good
24 operating performance.
25
26 Some git commands may automatically run 'git gc'; see the `--auto` flag
27 below for details. If you know what you're doing and all you want is to
28 disable this behavior permanently without further considerations, just do:
29
30 ----------------------
31 $ git config --global gc.auto 0
32 ----------------------
33
34 OPTIONS
35 -------
36
37 --aggressive::
38 Usually 'git gc' runs very quickly while providing good disk
39 space utilization and performance. This option will cause
40 'git gc' to more aggressively optimize the repository at the expense
41 of taking much more time. The effects of this optimization are
42 persistent, so this option only needs to be used occasionally; every
43 few hundred changesets or so.
44
45 --auto::
46 With this option, 'git gc' checks whether any housekeeping is
47 required; if not, it exits without performing any work.
48 Some git commands run `git gc --auto` after performing
49 operations that could create many loose objects. Housekeeping
50 is required if there are too many loose objects or too many
51 packs in the repository.
52 +
53 If the number of loose objects exceeds the value of the `gc.auto`
54 configuration variable, then all loose objects are combined into a
55 single pack using `git repack -d -l`. Setting the value of `gc.auto`
56 to 0 disables automatic packing of loose objects.
57 +
58 If the number of packs exceeds the value of `gc.autoPackLimit`,
59 then existing packs (except those marked with a `.keep` file
60 or over `gc.bigPackThreshold` limit)
61 are consolidated into a single pack by using the `-A` option of
62 'git repack'.
63 If the amount of memory is estimated not enough for `git repack` to
64 run smoothly and `gc.bigPackThreshold` is not set, the largest
65 pack will also be excluded (this is the equivalent of running `git gc`
66 with `--keep-base-pack`).
67 Setting `gc.autoPackLimit` to 0 disables automatic consolidation of
68 packs.
69 +
70 If houskeeping is required due to many loose objects or packs, all
71 other housekeeping tasks (e.g. rerere, working trees, reflog...) will
72 be performed as well.
73
74
75 --prune=<date>::
76 Prune loose objects older than date (default is 2 weeks ago,
77 overridable by the config variable `gc.pruneExpire`).
78 --prune=all prunes loose objects regardless of their age and
79 increases the risk of corruption if another process is writing to
80 the repository concurrently; see "NOTES" below. --prune is on by
81 default.
82
83 --no-prune::
84 Do not prune any loose objects.
85
86 --quiet::
87 Suppress all progress reports.
88
89 --force::
90 Force `git gc` to run even if there may be another `git gc`
91 instance running on this repository.
92
93 --keep-largest-pack::
94 All packs except the largest pack and those marked with a
95 `.keep` files are consolidated into a single pack. When this
96 option is used, `gc.bigPackThreshold` is ignored.
97
98 CONFIGURATION
99 -------------
100
101 The optional configuration variable `gc.reflogExpire` can be
102 set to indicate how long historical entries within each branch's
103 reflog should remain available in this repository. The setting is
104 expressed as a length of time, for example '90 days' or '3 months'.
105 It defaults to '90 days'.
106
107 The optional configuration variable `gc.reflogExpireUnreachable`
108 can be set to indicate how long historical reflog entries which
109 are not part of the current branch should remain available in
110 this repository. These types of entries are generally created as
111 a result of using `git commit --amend` or `git rebase` and are the
112 commits prior to the amend or rebase occurring. Since these changes
113 are not part of the current project most users will want to expire
114 them sooner. This option defaults to '30 days'.
115
116 The above two configuration variables can be given to a pattern. For
117 example, this sets non-default expiry values only to remote-tracking
118 branches:
119
120 ------------
121 [gc "refs/remotes/*"]
122 reflogExpire = never
123 reflogExpireUnreachable = 3 days
124 ------------
125
126 The optional configuration variable `gc.rerereResolved` indicates
127 how long records of conflicted merge you resolved earlier are
128 kept. This defaults to 60 days.
129
130 The optional configuration variable `gc.rerereUnresolved` indicates
131 how long records of conflicted merge you have not resolved are
132 kept. This defaults to 15 days.
133
134 The optional configuration variable `gc.packRefs` determines if
135 'git gc' runs 'git pack-refs'. This can be set to "notbare" to enable
136 it within all non-bare repos or it can be set to a boolean value.
137 This defaults to true.
138
139 The optional configuration variable `gc.commitGraph` determines if
140 'git gc' should run 'git commit-graph write'. This can be set to a
141 boolean value. This defaults to false.
142
143 The optional configuration variable `gc.aggressiveWindow` controls how
144 much time is spent optimizing the delta compression of the objects in
145 the repository when the --aggressive option is specified. The larger
146 the value, the more time is spent optimizing the delta compression. See
147 the documentation for the --window option in linkgit:git-repack[1] for
148 more details. This defaults to 250.
149
150 Similarly, the optional configuration variable `gc.aggressiveDepth`
151 controls --depth option in linkgit:git-repack[1]. This defaults to 50.
152
153 The optional configuration variable `gc.pruneExpire` controls how old
154 the unreferenced loose objects have to be before they are pruned. The
155 default is "2 weeks ago".
156
157 Optional configuration variable `gc.worktreePruneExpire` controls how
158 old a stale working tree should be before `git worktree prune` deletes
159 it. Default is "3 months ago".
160
161
162 NOTES
163 -----
164
165 'git gc' tries very hard not to delete objects that are referenced
166 anywhere in your repository. In
167 particular, it will keep not only objects referenced by your current set
168 of branches and tags, but also objects referenced by the index,
169 remote-tracking branches, refs saved by 'git filter-branch' in
170 refs/original/, or reflogs (which may reference commits in branches
171 that were later amended or rewound).
172 If you are expecting some objects to be deleted and they aren't, check
173 all of those locations and decide whether it makes sense in your case to
174 remove those references.
175
176 On the other hand, when 'git gc' runs concurrently with another process,
177 there is a risk of it deleting an object that the other process is using
178 but hasn't created a reference to. This may just cause the other process
179 to fail or may corrupt the repository if the other process later adds a
180 reference to the deleted object. Git has two features that significantly
181 mitigate this problem:
182
183 . Any object with modification time newer than the `--prune` date is kept,
184 along with everything reachable from it.
185
186 . Most operations that add an object to the database update the
187 modification time of the object if it is already present so that #1
188 applies.
189
190 However, these features fall short of a complete solution, so users who
191 run commands concurrently have to live with some risk of corruption (which
192 seems to be low in practice) unless they turn off automatic garbage
193 collection with 'git config gc.auto 0'.
194
195 HOOKS
196 -----
197
198 The 'git gc --auto' command will run the 'pre-auto-gc' hook. See
199 linkgit:githooks[5] for more information.
200
201
202 SEE ALSO
203 --------
204 linkgit:git-prune[1]
205 linkgit:git-reflog[1]
206 linkgit:git-repack[1]
207 linkgit:git-rerere[1]
208
209 GIT
210 ---
211 Part of the linkgit:git[1] suite