Re: Solving the compression dilema when rsync-ing Debian versions
>>>>> " " == Daniel Burrows <Daniel_Burrows@brown.edu> writes:
> On Sun, Jan 14, 2001 at 01:51:02AM +0100, Goswin Brederlow
> <goswin.brederlow@student.uni-tuebingen.de> was heard to say:
>> This forced flush happens at random places and not too often
>> (increases linux.tar.gz by ~3%). The flush does not depend on
>> the position but on the data compressed. So when two files
>> match for a few K, they will both hit a flush at the same
>> position. When the file is altered at the front gzip will still
>> flush the dictionary at the same places at the end, so the
>> files will match at the end.
> I suspect I'm missing something obvious..if I alter the first
> few bytes of a long file, won't the flushes and dictionaries be
> out of sync for the rest of the file? (since the checksums
> will all be thrown off by those modifications)
The cheksum is calculated over a block of 4K, so 4K after the changes
the block will be identical to the unchaned one.
MfG
Goswin
Reply to: