Re: Hash algorithm choice

From: Matthieu Moy <matthieu.moy@imag.fr>
Date: Aug 9, 2009, 18:44 UTC
Message-ID: <vpq1vnkddy2.fsf@bauges.imag.fr>
In-Reply-To: <f448a46a0908090917s102b4c83pbad6f298a8e127cc@mail.gmail.com>

Jerome Baum <jerome@jeromebaum.com> writes:

> How difficult would it be to allow users to choose a hash function
> during git-init which is then globally used in the repo?

There's at least one really difficult thing: how do you merge two projects using two different hash functions? The Git repository, for example, has several (I don't remember how many) root repository, and was originally made of several projects (git, gitk, git gui, ...). If these projects had started using different hash functions, then, either:

* Git would have needed to learn how to merge, and record the merge
  history, of projects using different hash functions.

* One of the projects would have been forced to be converted to
  another hash function, which means changing all its identifiers (so,
  for example, finding a message on gmane telling that commit 1ab23cde
  fixes your problem wouldn't help much anymore ...).

-- 
Matthieu