Re: [PATCH v2 0/5] Fsck for lazy objects, and (now) actual invocation of loader

[Junio C Hamano <gitster@pobox.com>]

Jonathan Tan <jonathantanmy@google.com> writes:

> One possibility to conceptually have the same thing without the overhead
> of the list is to put the obtained-from-elsewhere objects into its own
> alternate object store, so that we can distinguish the two.

Now you are talking.  Either a separate object store, or a packfile
that is specially marked as such, would work.  "Maintaining a list
of object names in a flat file is too costly" is not a valid excuse
to discard the integrity of locally created objects, without which
Git will no longer be a version control system, and your "We have to
trust the sender of objects on the other side anyway when operating
in lazy-objects mode, so devise a way that we can use to tell which
objects we _know_ the other side has" that leads to the above idea
is a good line of thought.

> I mentioned
> this in my e-mail but rejected it, but after some more thought, this
> might be sufficient - we might still need to iterate through every
> object to know exactly what we can assume the remote to have, but the
> "frontier" solution also needs this iteration, so we are no worse off.

Most importantly, this is allowed to be costly---we are doing this
not at runtime all the time, but when the user says "make sure that
I haven't lost objects and it is safe for me to build further on
what I created locally so far" by running "git fsck".