Add a new section to canonically explain how remote reference pruning works, and how users should be careful about using it in conjunction with tag refspecs in particular. A subsequent commit will update the git-remote documentation to refer to this section, and details the motivation for writing this in the first place. Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@xxxxxxxxx> --- Documentation/git-fetch.txt | 49 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 49 insertions(+) diff --git a/Documentation/git-fetch.txt b/Documentation/git-fetch.txt index b153aefa68..18fac0da2e 100644 --- a/Documentation/git-fetch.txt +++ b/Documentation/git-fetch.txt @@ -99,6 +99,55 @@ The latter use of the `remote.<repository>.fetch` values can be overridden by giving the `--refmap=<refspec>` parameter(s) on the command line. +PRUNING +------- + +Git has a default disposition of keeping data unless it's explicitly +thrown away; this extends to holding onto local references to branches +on remotes that have themselves deleted those branches. + +If left to accumulate, these stale references might make performance +worse on big and busy repos that have a lot of branch churn, and +e.g. make the output of commands like `git branch -a --contains +<commit>` needlessly verbose, as well as impacting anything else +that'll work with the complete set of known references. + +These remote tracking references can be deleted as a one-off with +either of: + +------------------------------------------------ +# While fetching +$ git fetch --prune <name> + +# Only prune, don't fetch +$ git remote prune <name> +------------------------------------------------ + +To prune references as part of your normal workflow without needing to +remember to run that set `fetch.prune` globally, or +`remote.<name>.prune` per-remote in the config. See +linkgit:git-config[1]. + +Here's where things get tricky and more specific. The pruning feature +doesn't actually care about branches, instead it'll prune local <-> +remote references as a function of the refspec of the remote (see +`<refspec>` and <<CRTB,CONFIGURED REMOTE-TRACKING BRANCHES>> above). + +Therefore if the refspec for the remote includes +e.g. `refs/tags/*:refs/tags/*`, or you manually run e.g. `git fetch +--prune <name> "refs/tags/*:refs/tags/*"` it won't be stale remote +tracking branches that are deleted, but any local tag that doesn't +exist on the remote. + +This might not be what you expect, i.e. you want to prune remote +`<name>`, but also explicitly fetch tags from it, so when you fetch +from it you delete all your local tags, most of which may not have +come from the `<name>` remote in the first place. + +So be careful when using this with a refspec like +`refs/tags/*:refs/tags/*`, or any other refspec which might map +references from multiple remotes to the same local namespace. + OUTPUT ------ -- 2.15.1.424.g9478a66081
