a few tar.xz packages are bigger than their uncompressed tar

Kaz Kylheku 920-082-4242@kylheku.com
Thu Oct 5 18:56:00 GMT 2017


On 24.09.2017 11:46, Jérôme Bouat wrote:
> Hello,
> 
> I looked into the local folder where the downloaded packages are saved
> before they are installed. I noticed that a few compressed archives
> files are using more size than their uncompressed form. For example,
> the libstdc++6-6.4.0-1.tar.xz file uses more space than its
> uncompressed tar file (on cygwin x86_64).
> 
> That is not surprising. All compression methods may sometimes inflate
> the final amount of data.

No compression method need ever increase the
size of the datum by more than one bit.

The compressed representation can begin with a header
bit which is 1 to indicate "compressed" and 0 to indicate
"stored without compression".


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