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