Re: git reset for index restoration?

From: Jeff King <peff@peff.net>
Date: May 22, 2014, 16:46 UTC
Message-ID: <20140522164634.GB30419@sigill.intra.peff.net>
In-Reply-To: <1400775763.1933.5.camel@stross>

On Thu, May 22, 2014 at 12:22:43PM -0400, David Turner wrote:

Show 9 quoted lines

> If I have a git repository with a clean working tree, and I delete the
> index, then I can use git reset (with no arguments) to recreate it.
> However, when I do recreate it, it doesn't come back the same.  I have
> not analyzed this in detail, but the effect is that commands like git
> status take much longer because they must read objects out of a pack
> file.  In other words, the index seems to not realize that the index (or
> at least most of it) represents the same state as HEAD.  If I do git
> reset --hard, the index is restored to the original state (it's
> byte-for-byte identical), and the pack file is no longer read.

Are you sure it's reading a packfile? I would expect that it is rather reading the files in the working tree. One of the functions of the index is to maintain a cache of the sha1 of the working tree file content and the stat information. Once that is populated, a subsequent "git status" can then just lstat() the files to see that its sha1 cache is up to date.

-Peff