Re: [PATCH 0/7] gitweb: Trying to improve history view speed

From: Linus Torvalds <torvalds@osdl.org>
Date: Sep 6, 2006, 18:30 UTC
Message-ID: <Pine.LNX.4.64.0609061125000.27779@g5.osdl.org>
In-Reply-To: <edmv57$lt7$1@sea.gmane.org>

On Wed, 6 Sep 2006, Jakub Narebski wrote:

Show 11 quoted lines

> Linus Torvalds wrote:
> 
> > So the rule is:
> > 
> >  - using "--full-history" + "--parents" means that you want (surprise 
> >    surprise) full history with parenthood, which means that you get all 
> >    the connecting merges too. And since you asked for the _full_ history, 
> >    that means EVERY SINGLE MERGE.
> 
> I just don't quite understand where <pathspec> filtering takes place 
> in this case.

Well, since you asked for full history, by definition it doesn't take place for merges, since you'll be wanting to follow both sides of the merge (to see the full history) regardless of whether the parents of that merge seem interesting or not.

> Every single merge is for parents to be connected, or what?

Well, "--parents" on its own means that we want a connected graph. It's just that if you don't ask for full history, then the connected graph result is obviously much smaller.

Think "graphical visualizer", and you'll see what's going on. Do a

	gitk git.c
	gitk --full-history git.c

and see the difference, and you'll understand (gitk already asks for "--parents" on its own).

Basically, "--full-history" means that we traverse every parent of a merge, whether it looks interesting or not.

> When I though about it, git_history needs not parents of a commit; from
> parsed commit it needs only date, author and title/summary (and of course
> commit sha1), so we can skip '--parents' option to git-rev-list, and have
> nice _history of a file_, using only one call to git-rev-list to make it.

Yes. Once you get rid of "--parents", git-rev-list should indeed do exactly what you want (because it no longer tries to keep things connected, and thus happily drops uninteresting merges).

Of course, there could well be a bug _there_, since "--full-history" isn't used very much (but "git whatchanged" uses it, so it should have gotten _some_ testing).

			Linus