RE: FS copy model

My personal opinion is that *copying* implies no need
to maintain prior history, but *linking* implies that
the two files share a common history and future (though
the futures may be divergent (branches, etc)).

Again, personal opinion, but based on 12 years
experience with this sort of thing...

-Peter

--
Peter A. Vogel
Manager, Configuration Management
Arsin Corporation
4800 Great America Parkway Suite 425, Santa Clara, CA 95054
> -----Original Message-----
> From: Greg Stein [mailto:gstein@lyra.org]
> Sent: Tuesday, January 02, 2001 8:47 PM
> To: dev@subversion.tigris.org
> Subject: FS copy model
> 
> 
> Okay... this isn't related to the network layer. Honest!
> 
> :-)
> 
> 
> Let's say that I have the following items of interest in the FS:
> 
>   PATH     ID
>   /        1.37
>   /A       50.7
>   /A/foo   73.4
>   /B       61.8
> 
> Now I make a copy of /A/foo to /B/foo. The IDs are now:
> 
>   /        1.38
>   /A       50.7
>   /A/foo   73.4
>   /B       61.9
>   /B/foo   73.4
> 
> And one more copy to /B/bar:
> 
>   /        1.39
>   /A       50.7
>   /A/foo   73.4
>   /B       61.10
>   /B/foo   73.4
>   /B/bar   73.4
> 
> In each copy, you'll note that only the directory's ID 
> changes because I'm
> not actually making any change to 73.4. We see /B change and 
> the resulting
> bubble-up to /.
> 
> 
> Question: should /B/foo and /B/bar know that they came from 
> /A/foo? To put
> it another way, when somebody pulls up a change log for /B/foo:
> 
>   1) they will see the changes from 73.1 thru 73.4
>   2) will they *also* see that /B/foo was copied from /A/foo?
> 
> In the above handling of node IDs and copying, the answer is 
> "No, they have
> no way of knowing whether /B/foo was copied from /A/foo or 
> from /B/bar. The
> user *might* have a way to see that they are related, but only the
> inspection of parent directory changes will show the actual 
> ordering of
> copies. Even then, the comment for the revision may not 
> specify what was
> copied from where."
> 
> Another alternative is to spin a new revision of 73.4 and insert some
> property / comment / marker saying that it was copied from 
> /A/foo. The final
> ID table would look like:
> 
>   /        1.39
>   /A       50.7
>   /A/foo   73.4
>   /B       61.10
>   /B/foo   73.4.1.1
>   /B/bar   73.4.2.1
> 
> 
> Which approach are we using today? (has it been considered?) 
> Is that the
> preferred approach?
> 
> I think another way to phrase the question is:
> 
>   Do we record a copy from one location to another in the FS? 
> If so, then
>   how is it recorded? Is there a machine-readable marker? (the checkin
>   comment is not machine-readable)
> 
> Cheers,
> -g
> 
> -- 
> Greg Stein, http://www.lyra.org/
>