Re: [PATCH v2 0/4] [RFC] repack: add --filter=

[Robert Coup <robert.coup@koordinates.com>]

Hi John,

On Wed, 9 Feb 2022 at 02:41, John Cai via GitGitGadget
<gitgitgadget@gmail.com> wrote:
>
> This patch series makes partial clone more useful by making it possible to
> run repack to remove objects from a repository (replacing it with promisor
> objects). This is useful when we want to offload large blobs from a git
> server onto another git server, or even use an http server through a remote
> helper.
>
> In [A], a --refilter option on fetch and fetch-pack is being discussed where
> either a less restrictive or more restrictive filter can be used. In the
> more restrictive case, the objects that already exist will not be deleted.
> But, one can imagine that users might want the ability to delete objects
> when they apply a more restrictive filter in order to save space, and this
> patch series would also allow that.

This all makes sense to me, and the implementation is remarkably short -
gluing together capabilities that are already there, and writing tests.

*But*, running `repack --filter` drops objects from the object db.
That seems like
a capability Git shouldn't idly expose without people understanding the
consequences - mostly that they really have another copy elsewhere or they
will lose data, and it won't necessarily be obvious for a long time. Otherwise
it is a footgun.

I don't know whether that is just around naming (--delete-filter /
--drop-filter /
--expire-filter ?), and/or making the documentation very explicit that
this isn't so
much "omitting certain objects from a packfile" as irretrievably
deleting objects.

Rob :)