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

From: Linus Torvalds <torvalds@osdl.org>
Date: Sep 6, 2006, 15:57 UTC
Message-ID: <Pine.LNX.4.64.0609060847521.27779@g5.osdl.org>
In-Reply-To: <200609061504.40725.jnareb@gmail.com>

On Wed, 6 Sep 2006, Jakub Narebski wrote:

Show 7 quoted lines

>
> Unfortunately, git-rev-list is broken: 'git rev-list <commit> 
> --full-history --parents -- <filename>' shows all merges in addition
> to what 'git rev-list <commit> --parents -- <filename>' and 
> 'git rev-list <commit> --full-history -- <filename>' shows, see
> "git-rev-list --full-history --parents doesn't respect path limit 
> and shows all merges" thread

If you ask for "--full-history" and "--parents", then pretty much by _definition_ you need every single merge, because otherwise your history wouldn't be fully connected.

Without that, things like "gitk" and "qgit" wouldn't work.

> So probably those patches should be dropped or put in freezer until
> git-rev-list is corrected.

git-rev-list _is_ correct, and if you want something else, you need to either use a different set of flags (like _only_ using "--full-history") or ask for a totally new flag (like "--most-history").

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.

 - using _just_ "--parents" means that you want a connected history with 
   parenthood information, but since you didn't ask for the _full_ 
   history, it will optimize away the merges that didn't change the file, 
   and only follow the changed side. You still get merges, but now you get 
   only those merges where both (all) sides actually mattered.

 - using _just_ "--full-history" (without asking for parenthood) means 
   that you're not asking for a connected history (since you're not asking 
   for parents), and as such, it will only show individual _commits_ that 
   change the file. That does potentially include merges, but again, it 
   only includes merges that actually _changed_ something.

In other words, "--parents" means a lot more than just "show what the parents" were. In particular, it means (and always has meant, apart from bugs) that we show the _rewritten_ parents after we've done history munging, and that we always output enough commits to actually make sense of that history from the result.

So what you are asking for is pretty nonsensical. You ask for parenthood info, but then you seem to not want to actually connect the dots. So why do you ask for parents in the first place? If you don't want to connect the commits to their parents, you shouldn't ask for it.

		Linus