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

[Andrey Repin]

Greetings, Jérôme Bouat!

> 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).

$ ls -ld "libstdc++6-6.4.0-1.tar.xz" ; tar tf "libstdc++6-6.4.0-1.tar.xz"  -v
-rw-r--r-- 1 anrdaemon None 282724 сен 18 20:17 libstdc++6-6.4.0-1.tar.xz
-rwxr-xr-x Blue/None   1367059 2017-09-10 01:23 usr/bin/cygstdc++-6.dll

$ sha512sum.exe libstdc++6-6.4.0-1.tar.xz
734f6f91003588c82bccfc016d89414cd25ea6560484391c1424513f053b3e0f3e9932e317740804c10d90e6f9fd99d4d198cf8ea953da22969aab50182f4c74 *libstdc++6-6.4.0-1.tar.xz
# Matches the one in setup.ini

> That is not surprising. All compression methods may sometimes inflate the final amount of data.

> Would it be a way to keep the tar archive file uncompressed if the compressed form needs more space ?

Compression MAY inflate the file, but never by an order of magnitude.
At worst, it will be inflated by the size of metadata describing all blocks in
order.


-- 
With best regards,
Andrey Repin
Wednesday, September 27, 2017 07:43:04

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