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 When common porcelain operations that create objects are run, they
  24 will check whether the repository has grown substantially since the
  25 last maintenance, and if so run `git gc` automatically. See `gc.auto`
  26 below for how to disable this behavior.
  27
  28 Running `git gc` manually should only be needed when adding objects to
  29 a repository without regularly running such porcelain commands, to do
  30 a one-off repository optimization, or e.g. to clean up a suboptimal
  31 mass-import. See the "PACKFILE OPTIMIZATION" section in
  32 linkgit:git-fast-import[1] for more details on the import case.
  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 +
  49 See the `gc.auto` option in the "CONFIGURATION" section below for how
  50 this heuristic works.
  51 +
  52 Once housekeeping is triggered by exceeding the limits of
  53 configuration options such as `gc.auto` and `gc.autoPackLimit`, all
  54 other housekeeping tasks (e.g. rerere, working trees, reflog...) will
  55 be performed as well.
  56
  57
  58 --prune=<date>::
  59         Prune loose objects older than date (default is 2 weeks ago,
  60         overridable by the config variable `gc.pruneExpire`).
  61         --prune=now prunes loose objects regardless of their age and
  62         increases the risk of corruption if another process is writing to
  63         the repository concurrently; see "NOTES" below. --prune is on by
  64         default.
  65
  66 --no-prune::
  67         Do not prune any loose objects.
  68
  69 --quiet::
  70         Suppress all progress reports.
  71
  72 --force::
  73         Force `git gc` to run even if there may be another `git gc`
  74         instance running on this repository.
  75
  76 --keep-largest-pack::
  77         All packs except the largest pack and those marked with a
  78         `.keep` files are consolidated into a single pack. When this
  79         option is used, `gc.bigPackThreshold` is ignored.
  80
  81 CONFIGURATION
  82 -------------
  83
  84 The below documentation is the same as what's found in
  85 linkgit:git-config[1]:
  86
  87 include::config/gc.txt[]
  88
  89 NOTES
  90 -----
  91
  92 'git gc' tries very hard not to delete objects that are referenced
  93 anywhere in your repository. In
  94 particular, it will keep not only objects referenced by your current set
  95 of branches and tags, but also objects referenced by the index,
  96 remote-tracking branches, refs saved by 'git filter-branch' in
  97 refs/original/, or reflogs (which may reference commits in branches
  98 that were later amended or rewound).
  99 If you are expecting some objects to be deleted and they aren't, check
 100 all of those locations and decide whether it makes sense in your case to
 101 remove those references.
 102
 103 On the other hand, when 'git gc' runs concurrently with another process,
 104 there is a risk of it deleting an object that the other process is using
 105 but hasn't created a reference to. This may just cause the other process
 106 to fail or may corrupt the repository if the other process later adds a
 107 reference to the deleted object. Git has two features that significantly
 108 mitigate this problem:
 109
 110 . Any object with modification time newer than the `--prune` date is kept,
 111   along with everything reachable from it.
 112
 113 . Most operations that add an object to the database update the
 114   modification time of the object if it is already present so that #1
 115   applies.
 116
 117 However, these features fall short of a complete solution, so users who
 118 run commands concurrently have to live with some risk of corruption (which
 119 seems to be low in practice) unless they turn off automatic garbage
 120 collection with 'git config gc.auto 0'.
 121
 122 HOOKS
 123 -----
 124
 125 The 'git gc --auto' command will run the 'pre-auto-gc' hook.  See
 126 linkgit:githooks[5] for more information.
 127
 128
 129 SEE ALSO
 130 --------
 131 linkgit:git-prune[1]
 132 linkgit:git-reflog[1]
 133 linkgit:git-repack[1]
 134 linkgit:git-rerere[1]
 135
 136 GIT
 137 ---
 138 Part of the linkgit:git[1] suite