Re: [GSoC] Designing a faster index format

From: david@lang.hm
To: Thomas Gummerer <italyhockeyfeed@gmail.com>
Cc: Michael Haggerty <mhagger@alum.mit.edu>,
	Nguyen Thai Ngoc Duy <pclouds@gmail.com>,
	Junio C Hamano <gitster@pobox.com>,
	Thomas Rast <trast@student.ethz.ch>,
	git@vger.kernel.org
Subject: Re: [GSoC] Designing a faster index format
Date: Tue, 3 Apr 2012 13:15:50 -0700 (PDT)	[thread overview]
Message-ID: <alpine.DEB.2.02.1204031313170.10782@asgard.lang.hm> (raw)
In-Reply-To: <C15BAB9A-EAFA-4EA4-85B2-0E0C5FF473E9@gmail.com>

On Tue, 3 Apr 2012, Thomas Gummerer wrote:

> Lets take another scenario. Someone changes a lot of files and then executes
> some commands which would usually only read the index. In that case either you
> would need the load time (O(n)) plus the time for merging (O(k*log(n)), as
> described above plus the time for writing the index (O(n)) which usually wouldn't
> be necessary.

note that in a large repository you are not that likely to change a very 
large percentage of the files with one update. yes, there are some use 
cases where this happens, but in general, the number of files changed in a 
changeset grows at a much slower rate than the total number of files in a 
repository. As projects get big they tend to get fewer across-the-board 
changes.

David Lang