Re: [Q] assume unchanged?

From: Andreas Ericsson <ae@op5.se>
Date: Mar 13, 2008, 07:27 UTC
Message-ID: <47D8D77D.8070908@op5.se>
In-Reply-To: <20080227222243.6117@nanako3.bluebottle.com>

しらいしななこ wrote:

Show 17 quoted lines

> I was looking at the documentation of git-update-index because I
> thought git-add is the preferred way to do what the command was used
> for in the old versions of git, and wanted to see if the old command
> has more features that are missing from git-add.
> 
> I noticed that there is --assume-unchanged option, and I read its
> description three times, but I do not understand it.  What is it good
> for?  Version control systems are used in order to keep track
> changes, and if using that option makes my changes ignored, how can
> it be a good thing?
> 
> The manual says "This is sometimes helpful when working with a big
> project on a filesystem that has very slow lstat(2) system call", but
> unfortunately it does not answer my question.
> 
> Could somebody explain, please?
>

If you're hacking on, oh, let's say the openoffice repo (or something similarly huge), and the files you're actually testing are located on an NFS-mounted network disk, you can use "--assume-unchanged java --assume-unchanged writer" to make git not walk through those directories and lstat(2) everything in it to see if there are changes. For huge projects, doing the lstat() walk can take a couple of seconds on a quick filesystem sitting on a local disk, and several minutes on a really slow network disk.

-- 
Andreas Ericsson                   andreas.ericsson@op5.se
OP5 AB                             www.op5.se
Tel: +46 8-230225                  Fax: +46 8-230231