git/Documentation/git-gc.txt
Johannes Schindelin 25ee9731c1 gc: call "prune --expire 2.weeks.ago" by default
The only reason we did not call "prune" in git-gc was that it is an
inherently dangerous operation: if there is a commit going on, you will
prune loose objects that were just created, and are, in fact, needed by the
commit object just about to be created.

Since it is dangerous, we told users so.  That led to many users not even
daring to run it when it was actually safe. Besides, they are users, and
should not have to remember such details as when to call git-gc with
--prune, or to call git-prune directly.

Of course, the consequence was that "git gc --auto" gets triggered much
more often than we would like, since unreferenced loose objects (such as
left-overs from a rebase or a reset --hard) were never pruned.

Alas, git-prune recently learnt the option --expire <minimum-age>, which
makes it a much safer operation.  This allows us to call prune from git-gc,
with a grace period of 2 weeks for the unreferenced loose objects (this
value was determined in a discussion on the git list as a safe one).

If you want to override this grace period, just set the config variable
gc.pruneExpire to a different value; an example would be

	[gc]
		pruneExpire = 6.months.ago

or even "never", if you feel really paranoid.

Note that this new behaviour makes "--prune" be a no-op.

While adding a test to t5304-prune.sh (since it really tests the implicit
call to "prune"), also the original test for "prune --expire" was moved
there from t1410-reflog.sh, where it did not belong.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2008-03-12 23:47:01 -07:00

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git-gc(1)
=========
NAME
----
git-gc - Cleanup unnecessary files and optimize the local repository
SYNOPSIS
--------
'git-gc' [--aggressive] [--auto] [--quiet]
DESCRIPTION
-----------
Runs a number of housekeeping tasks within the current repository,
such as compressing file revisions (to reduce disk space and increase
performance) and removing unreachable objects which may have been
created from prior invocations of linkgit:git-add[1].
Users are encouraged to run this task on a regular basis within
each repository to maintain good disk space utilization and good
operating performance. Some git commands may automatically run
`git-gc`; see the `--auto` flag below for details.
OPTIONS
-------
--aggressive::
Usually 'git-gc' runs very quickly while providing good disk
space utilization and performance. This option will cause
git-gc to more aggressively optimize the repository at the expense
of taking much more time. The effects of this optimization are
persistent, so this option only needs to be used occasionally; every
few hundred changesets or so.
--auto::
With this option, `git gc` checks whether any housekeeping is
required; if not, it exits without performing any work.
Some git commands run `git gc --auto` after performing
operations that could create many loose objects.
+
Housekeeping is required if there are too many loose objects or
too many packs in the repository. If the number of loose objects
exceeds the value of the `gc.auto` configuration variable, then
all loose objects are combined into a single pack using
`git-repack -d -l`. Setting the value of `gc.auto` to 0
disables automatic packing of loose objects.
+
If the number of packs exceeds the value of `gc.autopacklimit`,
then existing packs (except those marked with a `.keep` file)
are consolidated into a single pack by using the `-A` option of
`git-repack`. Setting `gc.autopacklimit` to 0 disables
automatic consolidation of packs.
--quiet::
Suppress all progress reports.
Configuration
-------------
The optional configuration variable 'gc.reflogExpire' can be
set to indicate how long historical entries within each branch's
reflog should remain available in this repository. The setting is
expressed as a length of time, for example '90 days' or '3 months'.
It defaults to '90 days'.
The optional configuration variable 'gc.reflogExpireUnreachable'
can be set to indicate how long historical reflog entries which
are not part of the current branch should remain available in
this repository. These types of entries are generally created as
a result of using `git commit \--amend` or `git rebase` and are the
commits prior to the amend or rebase occurring. Since these changes
are not part of the current project most users will want to expire
them sooner. This option defaults to '30 days'.
The optional configuration variable 'gc.rerereresolved' indicates
how long records of conflicted merge you resolved earlier are
kept. This defaults to 60 days.
The optional configuration variable 'gc.rerereunresolved' indicates
how long records of conflicted merge you have not resolved are
kept. This defaults to 15 days.
The optional configuration variable 'gc.packrefs' determines if
`git gc` runs `git-pack-refs`. This can be set to "nobare" to enable
it within all non-bare repos or it can be set to a boolean value.
This defaults to true.
The optional configuration variable 'gc.aggressiveWindow' controls how
much time is spent optimizing the delta compression of the objects in
the repository when the --aggressive option is specified. The larger
the value, the more time is spent optimizing the delta compression. See
the documentation for the --window' option in linkgit:git-repack[1] for
more details. This defaults to 10.
The optional configuration variable 'gc.pruneExpire' controls how old
the unreferenced loose objects have to be before they are pruned. The
default is "2 weeks ago".
See Also
--------
linkgit:git-prune[1]
linkgit:git-reflog[1]
linkgit:git-repack[1]
linkgit:git-rerere[1]
Author
------
Written by Shawn O. Pearce <spearce@spearce.org>
GIT
---
Part of the linkgit:git[7] suite