Git's database structure

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To: Git Mailing List <git@...>
Date: Tuesday, September 4, 2007 - 11:23 am

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
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Messages in current thread:
Git's database structure, Jon Smirl, (Tue Sep 4, 11:23 am)
Re: Git's database structure, Julian Phillips, (Tue Sep 4, 1:19 pm)
Re: Git's database structure, Jon Smirl, (Tue Sep 4, 1:30 pm)
Re: Git's database structure, Andreas Ericsson, (Tue Sep 4, 2:51 pm)
Re: Git's database structure, Jon Smirl, (Tue Sep 4, 12:28 pm)
Re: Git's database structure, Junio C Hamano, (Tue Sep 4, 1:25 pm)
Re: Git's database structure, Jon Smirl, (Tue Sep 4, 1:44 pm)
Re: Git's database structure, Theodore Tso, (Tue Sep 4, 5:25 pm)
Re: Git's database structure, Jon Smirl, (Tue Sep 4, 5:54 pm)
Re: Git's database structure, Andreas Ericsson, (Wed Sep 5, 3:18 am)
Re: Git's database structure, Jon Smirl, (Wed Sep 5, 9:41 am)
Re: Git's database structure, Andy Parkins, (Wed Sep 5, 3:52 pm)
Re: Git's database structure, Andreas Ericsson, (Wed Sep 5, 10:51 am)
Re: Git's database structure, Jon Smirl, (Wed Sep 5, 11:37 am)
Re: Git's database structure, Julian Phillips, (Wed Sep 5, 11:54 am)
Re: Git's database structure, Jon Smirl, (Wed Sep 5, 12:12 pm)
Re: Git's database structure, Martin Langhoff, (Thu Sep 6, 8:33 pm)
Re: Git's database structure, Johannes Schindelin, (Thu Sep 6, 8:56 am)
Re: Git's database structure, Steven Grimm, (Thu Sep 6, 2:14 pm)
Re: Git's database structure, Andreas Ericsson, (Thu Sep 6, 4:49 am)
Re: Git's database structure, Junio C Hamano, (Thu Sep 6, 5:09 am)
Re: Git's database structure, Wincent Colaiuta, (Thu Sep 6, 7:03 am)
Re: Git's database structure, Mike Hommey, (Wed Sep 5, 1:39 pm)
Re: Git's database structure, Julian Phillips, (Wed Sep 5, 1:31 pm)
Re: Git's database structure, Kyle Moffett, (Wed Sep 5, 9:27 pm)
Re: Git's database structure, Junio C Hamano, (Tue Sep 4, 2:06 pm)
Re: Git's database structure, Mike Hommey, (Tue Sep 4, 2:04 pm)
Re: Git's database structure, Reece Dunn, (Tue Sep 4, 3:44 pm)
Re: Git's database structure, Andreas Ericsson, (Tue Sep 4, 12:31 pm)
Re: Git's database structure, Jon Smirl, (Tue Sep 4, 12:47 pm)
Re: Git's database structure, Andreas Ericsson, (Tue Sep 4, 12:51 pm)
Re: Git's database structure, Andreas Ericsson, (Tue Sep 4, 11:55 am)
Re: Git's database structure, Junio C Hamano, (Tue Sep 4, 1:21 pm)
Re: Git's database structure, Jon Smirl, (Tue Sep 4, 12:19 pm)
Re: Git's database structure, David Tweed, (Tue Sep 4, 4:17 pm)
Re: Git's database structure, Jeff King, (Tue Sep 4, 1:09 pm)
Re: Git's database structure, Andreas Ericsson, (Tue Sep 4, 12:29 pm)
Re: Git's database structure, Mike Hommey, (Tue Sep 4, 12:07 pm)
Re: Git's database structure, Andreas Ericsson, (Tue Sep 4, 12:10 pm)