Re: How Blobs Work ( Blobs Vs. Deltas)

From: Johannes Sixt <j.sixt@viscovery.net>
Date: Sep 30, 2008, 15:29 UTC
Message-ID: <48E245C4.7030003@viscovery.net>
In-Reply-To: <16946e800809300814v134a42dft37becdbd8aa7669a@mail.gmail.com>

Feanil Patel schrieb:

Show 10 quoted lines

> I was reading about git objects on The Git
> Book(http://book.git-scm.com/1_the_git_object_model.html) which was
> posted on the mailing list a while back and I was wondering something
> about blobs and how files are stored in any particular version.  If
> file A is changed from version one to version two there are two
> different blobs that exist for the two versions of the file, is that
> correct?  The Book was saying Git does not use delta storage so does
> this mean that there are two almost identical copies of the file with
> the difference being the change that was put in from version one to
> version two?

At the conceptual level, yes. An entire file (== blob) is the smallest unit that you can address. Even git's internals do not work with smaller units.

But there is, of course, a mechanism that stores the database in a more compact format, the so-called pack files, that basically store differences between files as much as possible.

-- Hannes