Is mv preferable to delete/add from a space standpoint?

[Talden]

On Fri, May 7, 2010 at 10:35 AM, Robert Collins
<robertc at robertcollins.net> wrote:
> jar files are zips; unless you're a) using the rsyncable patch to make
> them and b) lucky, you'll get almost no cross compression anyway.

Actually, from experience in Subversion, you can get quite a lot of
benefit.  Assuming they've used the same 'zip' tool with the same
settings each time and since zip compresses each file individually (as
opposed to say 7zips solid LZMA), unchanged files will have the same
compressed representation.  I've frequently have good improvements
from

CMD> svn mv working-copy/a-1.0.jar working-copy/a-1.1,jar
CMD> copy reference-copy/a-1.1.jar working-copy/1.1.jar

(and yes I was surprised and compared it in a test repo with just an
rm of 1.0 and an add of 1.1.

Of course you'd save more up-front if the jar format was more
efficient but since it's not it's good that Subversion was able to
take advantage (with hand-holding)...  Bazaar should achieve the same.

Of course when a library recompiled the lot with a newer class-file
format that benefit became a cost with subversion adding some
overhead...

YMMV

--
Talden