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From: "Jon Smirl" <jonsmirl@gmail.com>
To: "Git Mailing List" <git@vger.kernel.org>
Subject: Git's database structure
Date: Tue, 4 Sep 2007 11:23:02 -0400	[thread overview]
Message-ID: <9e4733910709040823k731f0ffchba1f93bdb4a8373d@mail.gmail.com> (raw)

Let's back up a little bit from "Caclulating tree node".  What are the
elements of git's data structures?

Right now we have an index structure (tree nodes) integrated in to a
base table. Integrating indexing into the data is not normally done in
a database. Doing a normalization analysis like this may expose flaws
in the way the data is structured. Of course we may also decide to
leave everything the way it is.

What about the special status of a rename? In the current model we
effectively have three tables.

commit - a set of all SHAs in the commit, previous commit, comment, author, etc
blob - a file, permissions, etc.
file names - name, SHA

The file name table is encoded as an index and it has been
intermingled with the commit table.

Looking at this from a set theory angle brings up the question, do we
really have three tables and file names are an independent variable
from the blobs, or should file names be an attribute of the blob?

How this gets structured in the db is an independent question about
how renames get detected on a commit. The current scheme for detecting
renames by comparing diffs is working fine. The question is, once we
detect a rename how should it be stored?

Ignoring the performance impacts and looking at the problem from the
set theory view point, should:
the pathnames be in their own table with a row for each alias
the pathnames be stored as an attribute of the blob

Both of these are the same information, we're just looking at how
things are normalized.

-- 
Jon Smirl
jonsmirl@gmail.com

             reply	other threads:[~2007-09-04 15:23 UTC|newest]

Thread overview: 39+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-09-04 15:23 Jon Smirl [this message]
2007-09-04 15:55 ` Git's database structure Andreas Ericsson
2007-09-04 16:07   ` Mike Hommey
2007-09-04 16:10     ` Andreas Ericsson
2007-09-04 16:19   ` Jon Smirl
2007-09-04 16:29     ` Andreas Ericsson
2007-09-04 17:09     ` Jeff King
2007-09-04 20:17     ` David Tweed
2007-09-04 17:21   ` Junio C Hamano
2007-09-04 16:28 ` Jon Smirl
2007-09-04 16:31   ` Andreas Ericsson
2007-09-04 16:47     ` Jon Smirl
2007-09-04 16:51       ` Andreas Ericsson
2007-09-04 17:25   ` Junio C Hamano
2007-09-04 17:44     ` Jon Smirl
2007-09-04 18:04       ` Mike Hommey
2007-09-04 19:44         ` Reece Dunn
2007-09-04 18:06       ` Junio C Hamano
2007-09-04 21:25       ` Theodore Tso
2007-09-04 21:54         ` Jon Smirl
2007-09-05  7:18           ` Andreas Ericsson
2007-09-05 13:41             ` Jon Smirl
2007-09-05 14:51               ` Andreas Ericsson
2007-09-05 15:37                 ` Jon Smirl
2007-09-05 15:54                   ` Julian Phillips
2007-09-05 16:12                     ` Jon Smirl
2007-09-05 17:31                       ` Julian Phillips
2007-09-06  1:27                         ` Kyle Moffett
2007-09-05 17:39                       ` Mike Hommey
2007-09-06  8:49                       ` Andreas Ericsson
2007-09-06  9:09                         ` Junio C Hamano
2007-09-06 11:03                           ` Wincent Colaiuta
2007-09-06 12:56                       ` Johannes Schindelin
2007-09-06 18:14                         ` Steven Grimm
2007-09-07  0:33                       ` Martin Langhoff
2007-09-05 19:52               ` Andy Parkins
2007-09-04 17:19 ` Julian Phillips
2007-09-04 17:30   ` Jon Smirl
2007-09-04 18:51     ` Andreas Ericsson

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