pixz/README.md

pixz

Pixz (pronounced pixie) is a parallel, indexing version of xz.

Repository: https://github.com/vasi/pixz

Downloads: https://github.com/vasi/pixz/releases

pixz vs xz

The existing XZ Utils provide great compression in the .xz file format, but they have two significant problems:

• they are single-threaded, while most users nowadays have multi-core computers
• the .xz files they produce are just one big block of compressed data, rather than a collection of smaller blocks which makes random access to the original data impossible

With pixz, both these problems are solved.

Building pixz

General help about the building process's configuration step can be acquired via:

./configure --help

Dependencies

• pthreads
• liblzma 4.999.9-beta-212 or later (from the xz distribution)
• libarchive 2.8 or later
• AsciiDoc to generate the man page

Build from Release Tarball

./configure
make
make install

You many need sudo permissions to run make install.

Build from GitHub

git clone https://github.com/vasi/pixz.git
cd pixz
./autogen.sh
./configure
make
make install

You many need sudo permissions to run make install.

Usage

Single Files

Compress a single file (no tarball, just compression), multi-core:

pixz bar bar.xz

Decompress it, multi-core:

pixz -d bar.xz bar

Tarballs

Compress and index a tarball, multi-core:

pixz foo.tar foo.tpxz

Very quickly list the contents of the compressed tarball:

pixz -l foo.tpxz

Decompress the tarball, multi-core:

pixz -d foo.tpxz foo.tar

Very quickly extract a single file, multi-core, also verifies that contents match index:

pixz -x dir/file < foo.tpxz | tar x

Create a tarball using pixz for multi-core compression:

tar -Ipixz -cf foo.tpxz foo/

Specifying Input and Output

These are the same (also work for -x, -d and -l as well):

pixz foo.tar foo.tpxz
pixz < foo.tar > foo.tpxz
pixz -i foo.tar -o foo.tpxz

Extract the files from foo.tpxz into foo.tar:

pixz -x -i foo.tpxz -o foo.tar file1 file2 ...

Compress to foo.tpxz, removing the original:

pixz foo.tar

Extract to foo.tar, removing the original:

pixz -d foo.tpxz

Other Flags

Faster, worse compression:

pixz -1 foo.tar

Better, slower compression:

pixz -9 foo.tar

Use exactly 2 threads:

pixz -p 2 foo.tar

Compress, but do not treat it as a tarball, i.e. do not index it:

pixz -t foo.tar

Decompress, but do not check that contents match index:

pixz -d -t foo.tpxz

List the xz blocks instead of files:

pixz -l -t foo.tpxz

For even more tuning flags, check the manual page:

man pixz

Comparison to other Tools

plzip

• about equally complex and efficient
• lzip format seems less-used
• version 1 is theoretically indexable, I think

ChopZip

• written in Python, much simpler
• more flexible, supports arbitrary compression programs
• uses streams instead of blocks, not indexable
• splits input and then combines output, much higher disk usage

pxz

• simpler code
• uses OpenMP instead of pthreads
• uses streams instead of blocks, not indexable
• uses temporary files and does not combine them until the whole file is compressed, high disk and memory usage

pbzip2

• not indexable
• appears slow
• bzip2 algorithm is non-ideal

pigz

• not indexable

dictzip, idzip

• not parallel