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The main reason to continue to use gzip is speed: it's an order of magnitude faster than bzip2 for compression / decompression, for a relatively small compression ratio hit. It's fast enough to us inline in web servers, SSH sessions, etc, and if you're just moving data around a single time, often the amount of time for compress / transfer / decompress is much faster than with bzip2.

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I've found that on many types of data, xz -2 is twice as fast and compresses better than gzip -9. Of course gzip -1 kicks the pants off xz but there's absolutely no reason to use gzip at its higher levels, nor to use bzip2 at all. And if you want fast, LZO does it better -- the lzop tool provides a typical unix compress interface.

Using 50MiB from a tarball I had lying around, best of 3:

     prog    time(s)   size(%)
    gzip  -1  1.703    38.7
    gzip  -9 14.670    35.1    (worse than xz -1)
    bzip2 -1  7.714    34.0
    bzip2 -9  8.035    31.4    (worse than xz -1)
    xz    -1  6.278    31.3
    xz    -9 42.445    22.7    (best compression)
    lzop  -1  0.670    46.1    (fastest)
    lzop  -9 18.144    38.0

Out of curiousity, can you run this tarball through paq (say, paq8hp12)?

http://en.wikipedia.org/wiki/PAQ

It segfaulted at the end, after taking 7m28s. I don't know how big the result was because it got truncated to 35 bytes.

Ugh. Can you try with a lighter compression level? There is a command line switch for that, and it should also show the memory requirements for each compression level.

I'm insisting because PAQ is a really incredible collection of compressors. Far more intelligence in it than in the LZ* bunch.

If anyone is still reading this thread, I made a chart overnight using a better corpus:

http://partiallystapled.com/~gxti/misc/2010/06/25-shootout.p...

http://partiallystapled.com/~gxti/misc/2010/06/25-linux-2.6....

Yes, the new compression algorithms (BWT and LZ77-based) are slower and require a lot more memory than DEFLATE (*zip) in most cases.

This guy did a not so rigorous analysis but it is mostly OK: http://changelog.complete.org/archives/931-how-to-think-abou...

A little bird told me there's a better algorithm in speed/compression rate coming soon ;)

Another feature of gzip which may be your life-saver is that it keeps a record of the original size so you can know it without decompression.

xz format seems to have this feature, but: $ xz --list xz: --list is not implemented yet.

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