Re: Calculating tree nodes

From: Shawn O. Pearce <spearce@spearce.org>
Date: Sep 4, 2007, 02:51 UTC
Message-ID: <20070904025153.GS18160@spearce.org>
In-Reply-To: <9e4733910709031913q278cb9dbp441756afb28607c6@mail.gmail.com>

Jon Smirl <jonsmirl@gmail.com> wrote:

Show 6 quoted lines

> When I change a file it creates a new object with a new SHA. This new
> SHA causes the tree node pointing to it to change. Changing the tree
> node forces its parent to change and so on. Of course git batches all
> of the changes together into a commit so that this ripple effect
> doesn't happen for every file. But every commit causes a new root tree
> node to be created, right?

Only if at least one file (or tree) differed. This may not be the case if you do a merge with the ours merge strategy, but these are very rare. So you can pretty much just say that yes, every commit causes a new root tree to be created.

Usually the smallest number of objects created per commit is 3:

  - the new commit
  - the new root tree
  - the new blob for a file in the root directory

The number increases as more files are modified or if they are in subdirectories of the root.

-- 
Shawn.