Re: Does content provenance matter?

From: Philip Oakley <philipoakley@iee.org>
Date: May 8, 2012, 09:23 UTC
Message-ID: <F5AF82B3BF334F0A88C8755426C725F0@PhilipOakley>
In-Reply-To: <1336432417.36394.YahooMailClassic@web121504.mail.ne1.yahoo.com>

From: "Kelly Dean" <kellydeanch@yahoo.com> Sent: Tuesday, May 08, 2012 12:13
AM

Show 10 quoted lines

> --- On Mon, 5/7/12, PJ Weisberg <pj@irregularexpressions.net> wrote:
>> But there could be any number of unrelated commits newer than "Bar"
>> but older than "Revert Bar" on other branches.  Even if you could
>> trust the timestamps to be accurate (you can't), you still can't
>> determine a commit's parent unambiguously.
> Therefore, provenance does matter, and it must be explicitly recorded
> because it can't necessarily be correctly and fully deduced from content
> alone. And git does record inter-commit provenance.
> However, git doesn't record intra-commit provenance, as I mentioned in my
> original message. My question is: why this discrepancy?

>  Either provenance matters, or it doesn't;

The logic error is here. There are many other available choices as to deciding the points at which the many provenance quality levels decay. (e.g. see [1]).

People eventually give up caring at some level of detail/history, each in a different place ;-) It's a choice. e.g. Have you noticed all high performance cars (Porche?) need brightly coloured brake cylinders with carefully specified paint jobs - why? At some point we give up caring how someone got a few (how few?) characters into a file... It's not right, but it's not wrong either.

I've worked with systems (e.g. DOORS) that record every keystroke, and recored every hunk at the undo/redo level, but for little benefit.

Git takes the approach of having lightweight (easy) branching with easy commits, with local history re-writing (rebase), to give users the ability to balance between their WIP (work in progress), and their public record. But with strong verification of any given history (e.g. "My Master"). It's a choice as to who and where to blame.

>     why record it in one case but not the other?

Philip [1] Measuring and Managing Technological Knowledge, IEEE Engineering Management Review Winter 1997 p77-88. Reprinted from Sloan Management Review, Fall 1994 http://sloanreview.mit.edu/the-magazine/1994-fall/3615/measuring-and-managing-technological-knowledge/