Re: [PATCH v2] rev-list --disk-usage

Jeff King [off-list ref] writes:

But in practice, we've found this kind of naive --disk-usage useful for
answering questions like:

  - do I need all of these objects? Comparing "rev-list --disk-usage
    --objects --all", "rev-list --disk-usage --objects --all --reflog",
    and "du objects/pack/*.pack" will tell you if a prune/repack might
    help, and whether expiring reflogs makes a difference.

  - the size of the shared alternates repo for a set of forks has
    jumped. Comparing "rev-list --disk-usage --objects --remotes=$base
    --not --remotes=$fork" will tell you what's reachable from a fork
    but not from the base (we use "refs/remotes/$id/*" to keep track of
    fork refs in our alternates repo). This can be junk like somebody
    forking git/git and then uploading a bunch of pirated video files.
    :)

  - likewise, the size of cloning a single repo may jump. Comparing
    "rev-list --disk-usage --objects HEAD..$branch" for each branch
    might show that one branch is an outlier (e.g., because somebody
    accidentally committed a bunch of build artifacts).

In those kinds of cases, it's not usually "oh, this version is twice as
big as this other one". It's more like "wow, this branch is 100x as big
as the other branches", and little decisions like delta direction are
just noise. I imagine that in those cases the uncompressed object sizes
would probably produce similar patterns and answers. But it's actually
faster to produce the on-disk sizes. :)

Thanks.

I kind of feel sad to have a nice write-up like this only in the
list archive.  Is there a section in our documentation set to keep
collection of such a real-life use cases?  Perhaps the examples
section of manpages is the closest thing, but it looks a bit too
narrowly scoped for the example section of "rev-list" manpage.

THanks.