Re: [GD-General] Re: asset & document management

[J C L. <cl...@ka...>]

On Sun, 18 May 2003 00:26:40 +0200 
Anders Nilsson <br...@ho...> wrote:

> Why aren't they storing the most recent file and then doing the binary
> diffs backwards? So they store the diff of how to get from the newest
> file to the next newest file. That way the newest file would be fast
> to use, you can save full files every time you branch etc. Might be
> slower to get old versions but that's mostly for backup/safety anyway.

The reverse diffs are one of the many reasons I generally won't use CVS
or any of the other RCS based repositories.  Very large chunks of the
historical versions of the IRIX and HP-UX source trees are no longer
accessible in any form due to undetected corruption of the ,v files in
the backups.  In one way or another the ,v file was corrupted, the
corrupted file was backed up, time passed, and no uncorrupted versions
exist.

Forward diff based systems, like BitKeeper and SCCS are necessarily more
expensive, but have the advantage of checking the logical consistency of
the files on every operation.  Ergo, corruption and other problems are
revealed essentially instantly.  In practice the added expense when
compared to the overhead of open(2)/close(2) is generally minimal, even
for files with >2^16 changesets (which I have).

-- 
J C Lawrence                
---------(*)                Satan, oscillate my metallic sonatas. 
cl...@ka...               He lived as a devil, eh?		  
http://www.kanga.nu/~claw/  Evil is a name of a foeman, as I live.