Re: Questions about the hash function transition

From: Johannes Schindelin <johannes.schindelin@gmx.de>
Date: Aug 28, 2018, 12:04 UTC
Message-ID: <nycvar.QRO.7.76.6.1808281402510.73@tvgsbejvaqbjf.bet>
In-Reply-To: <20180824014703.GE99542@aiede.svl.corp.google.com>

Hi,

On Thu, 23 Aug 2018, Jonathan Nieder wrote:

Show 16 quoted lines

> Ævar Arnfjörð Bjarmason wrote:
> 
> [...]
> >> Since all operations that make new objects (e.g., "git commit") add
> >> the new objects to the corresponding index, this mapping is possible
> >> for all objects in the object store.
> >
> > Are we going to need a midx version of these mapping files? How does
> > midx fit into this picture? Perhaps it's too obscure to worry about...
> 
> That's a great question!  I think the simplest answer is to have a
> midx only for the primary object format and fall back to using
> ordinary idx files for the others.
> 
> The midx format already has a field for hash function (thanks,
> Derrick!).

Related: I wondered whether we could simply leverage the midx code for the
bidirectional SHA-1 <-> SHA-256 mapping, as it strikes me as very similar
in concept and challenges.

Ciao, Dscho