Documentation / git-gc.txton commit wt-status.h: drop stdio.h include (7a06fb0)
   1git-gc(1)
   2=========
   3
   4NAME
   5----
   6git-gc - Cleanup unnecessary files and optimize the local repository
   7
   8
   9SYNOPSIS
  10--------
  11[verse]
  12'git gc' [--aggressive] [--auto] [--quiet] [--prune=<date> | --no-prune] [--force] [--keep-largest-pack]
  13
  14DESCRIPTION
  15-----------
  16Runs a number of housekeeping tasks within the current repository,
  17such as compressing file revisions (to reduce disk space and increase
  18performance), removing unreachable objects which may have been
  19created from prior invocations of 'git add', packing refs, pruning
  20reflog, rerere metadata or stale working trees. May also update ancillary
  21indexes such as the commit-graph.
  22
  23When common porcelain operations that create objects are run, they
  24will check whether the repository has grown substantially since the
  25last maintenance, and if so run `git gc` automatically. See `gc.auto`
  26below for how to disable this behavior.
  27
  28Running `git gc` manually should only be needed when adding objects to
  29a repository without regularly running such porcelain commands, to do
  30a one-off repository optimization, or e.g. to clean up a suboptimal
  31mass-import. See the "PACKFILE OPTIMIZATION" section in
  32linkgit:git-fast-import[1] for more details on the import case.
  33
  34OPTIONS
  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        mostly persistent. See the "AGGRESSIVE" section below for details.
  43
  44--auto::
  45        With this option, 'git gc' checks whether any housekeeping is
  46        required; if not, it exits without performing any work.
  47+
  48See the `gc.auto` option in the "CONFIGURATION" section below for how
  49this heuristic works.
  50+
  51Once housekeeping is triggered by exceeding the limits of
  52configuration options such as `gc.auto` and `gc.autoPackLimit`, all
  53other housekeeping tasks (e.g. rerere, working trees, reflog...) will
  54be performed as well.
  55
  56
  57--prune=<date>::
  58        Prune loose objects older than date (default is 2 weeks ago,
  59        overridable by the config variable `gc.pruneExpire`).
  60        --prune=now prunes loose objects regardless of their age and
  61        increases the risk of corruption if another process is writing to
  62        the repository concurrently; see "NOTES" below. --prune is on by
  63        default.
  64
  65--no-prune::
  66        Do not prune any loose objects.
  67
  68--quiet::
  69        Suppress all progress reports.
  70
  71--force::
  72        Force `git gc` to run even if there may be another `git gc`
  73        instance running on this repository.
  74
  75--keep-largest-pack::
  76        All packs except the largest pack and those marked with a
  77        `.keep` files are consolidated into a single pack. When this
  78        option is used, `gc.bigPackThreshold` is ignored.
  79
  80AGGRESSIVE
  81----------
  82
  83When the `--aggressive` option is supplied, linkgit:git-repack[1] will
  84be invoked with the `-f` flag, which in turn will pass
  85`--no-reuse-delta` to linkgit:git-pack-objects[1]. This will throw
  86away any existing deltas and re-compute them, at the expense of
  87spending much more time on the repacking.
  88
  89The effects of this are mostly persistent, e.g. when packs and loose
  90objects are coalesced into one another pack the existing deltas in
  91that pack might get re-used, but there are also various cases where we
  92might pick a sub-optimal delta from a newer pack instead.
  93
  94Furthermore, supplying `--aggressive` will tweak the `--depth` and
  95`--window` options passed to linkgit:git-repack[1]. See the
  96`gc.aggressiveDepth` and `gc.aggressiveWindow` settings below. By
  97using a larger window size we're more likely to find more optimal
  98deltas.
  99
 100It's probably not worth it to use this option on a given repository
 101without running tailored performance benchmarks on it. It takes a lot
 102more time, and the resulting space/delta optimization may or may not
 103be worth it. Not using this at all is the right trade-off for most
 104users and their repositories.
 105
 106CONFIGURATION
 107-------------
 108
 109The below documentation is the same as what's found in
 110linkgit:git-config[1]:
 111
 112include::config/gc.txt[]
 113
 114NOTES
 115-----
 116
 117'git gc' tries very hard not to delete objects that are referenced
 118anywhere in your repository. In
 119particular, it will keep not only objects referenced by your current set
 120of branches and tags, but also objects referenced by the index,
 121remote-tracking branches, refs saved by 'git filter-branch' in
 122refs/original/, reflogs (which may reference commits in branches
 123that were later amended or rewound), and anything else in the refs/* namespace.
 124If you are expecting some objects to be deleted and they aren't, check
 125all of those locations and decide whether it makes sense in your case to
 126remove those references.
 127
 128On the other hand, when 'git gc' runs concurrently with another process,
 129there is a risk of it deleting an object that the other process is using
 130but hasn't created a reference to. This may just cause the other process
 131to fail or may corrupt the repository if the other process later adds a
 132reference to the deleted object. Git has two features that significantly
 133mitigate this problem:
 134
 135. Any object with modification time newer than the `--prune` date is kept,
 136  along with everything reachable from it.
 137
 138. Most operations that add an object to the database update the
 139  modification time of the object if it is already present so that #1
 140  applies.
 141
 142However, these features fall short of a complete solution, so users who
 143run commands concurrently have to live with some risk of corruption (which
 144seems to be low in practice).
 145
 146HOOKS
 147-----
 148
 149The 'git gc --auto' command will run the 'pre-auto-gc' hook.  See
 150linkgit:githooks[5] for more information.
 151
 152
 153SEE ALSO
 154--------
 155linkgit:git-prune[1]
 156linkgit:git-reflog[1]
 157linkgit:git-repack[1]
 158linkgit:git-rerere[1]
 159
 160GIT
 161---
 162Part of the linkgit:git[1] suite