Compressing packages with bzip2 instead gzip?

John C. McCabe-Dansted gmatht at
Thu Jan 19 01:24:29 GMT 2006

On Thursday 19 January 2006 09:42, Phillip Susi wrote:
> Rather than generate the .zsync file against the .deb, it would be
> generated against the uncompressed .tars inside the deb.  This of
> course, would require the server to either store the decompressed tars,
> or decompress them on the fly and serve them to the clients on request.

This does *not* require that the uncompressed tar be stored on the server. In 
fact the zsync manual recommends that you do not decompress the tar, so that 
zsync can read the smaller compressed data.

Zsync uses a clever trick which I think goes basically like this:

$gzip_opts=detect which options were used to create data.tar.gz
tail -f data.tar data.tar | gzip $gzip_opts > data.tar.gz &
if next block b matches
	cat b >> data.tar
	read data from http://server/data.tar.gz until there is enough data in the 
local copy of data.tar.gz to reconstruct block b. 

John C. McCabe-Dansted
Masters Student

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