Re: [PATCH 37/38] pack v4: introduce "escape hatches" in the name and path indexes

> I think that we've found a way to better support thin packs.
>
> You said:
>
>> What if the sender prepares the sha-1 table to contain missing objects
>> in advance? The sender should know what base objects are missing. Then
>> we only need to append objects at the receiving end and verify that
>> all new objects are also present in the sha-1 table.
>
> So the SHA1 table is covered.
>
> Missing objects in a thin pack cannot themselves be deltas.  We had
> their undeltified form at the end of a pack for the pack to be complete.
> Therefore those missing objects serve only as base objects for other
> deltas.
>
> Although this is possible to have deltified commit objects in pack v2, I
> don't think this happens very often. There is no deltified commit
> objects in pack v4.
>
> Blob objects are the same in pack v2 and pack v4.  No dictionary
> references are needed.
>
> That leaves only tree objects.  And because we've also discussed the
> need to have non transcoded object representations for those odd cases
> such as zero padded file modes, we might as well simply use that for the
> appended tree objects already needed to complete a thin pack.  At least
> the strings in tree entries will be compressed that way.
>
> Problem solved, and one less special case in the code.
>
> What do you think?