Re: Git's database structure

From: Mike Hommey <mh@glandium.org>
Date: Sep 5, 2007, 17:39 UTC
Message-ID: <20070905173912.GB3396@glandium.org>
In-Reply-To: <9e4733910709050912i57ed7137o6abb02ee741d394b@mail.gmail.com>

On Wed, Sep 05, 2007 at 12:12:28PM -0400, Jon Smirl <jonsmirl@gmail.com> wrote:

Show 24 quoted lines

> On 9/5/07, Julian Phillips <julian@quantumfyre.co.uk> wrote:
> > On Wed, 5 Sep 2007, Jon Smirl wrote:
> >
> > > On 9/5/07, Andreas Ericsson <ae@op5.se> wrote:
> > >> Jon Smirl wrote:
> > >>>
> > >>> The path name field needs to be moved back into the blobs to support
> > >>> alternative indexes. For example I want an index on the Signed-off-by
> > >>> field. I use this index to give me the SHAs for the blobs
> > >>> Signed-off-by a particular person. In the current design I have no way
> > >>> of recovering the path name for these blobs other than a brute force
> > >>> search following every path looking for the right SHA.
> > >>>
> > >>
> > >> Ah, there we go. A use-case at last :)
> >
> > But not a brilliant one.  You sign off on commits not blobs.  So you go
> > from the sign-off to paths, then to blobs.  There is no need to go from
> > blob to path unless you deliberately introduce such a need.
> 
> Use blame for an example. Blame has to crawl every commit to see if it
> touched the file. It keeps doing this until it figures out the last
> author for every line in the file. Worse case blame has to crawl every
> commit in the data store.

And why exactly would you need to change blobs to contain path for blame to be faster ?

Or more generally, what, in the current way of git doing things, prevents you from adding an index to $THE_DATA_YOU_LIKE, exactly ?

>From the very few use cases you've given, I see nothing preventing to

create an additional index from the data git currently uses.

Mike