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bug#7182: sort -R slow
From: |
Alan Curry |
Subject: |
bug#7182: sort -R slow |
Date: |
Sat, 9 Oct 2010 14:21:00 -0500 (GMT+5) |
Ole Tange writes:
>
> I recently needed to randomize some lines. So I tried using 'sort -R'.
> I was astonished how slow that was. So I tested how slow a competing
> strategies are. GNU sort is two magnitudes slower than unsort and more
> than one magnitude slower than perl:
Never heard of "unsort". Why didn't you try shuf(1)?
Also, your perl is not valid:
>
> $ time perl -e 'print sort { rand() <=> rand() } <>' file
> real 0m6.621s
That comparison function is not consistent (unless very lucky).
> I would expect sort -R to be faster than sort and faster than Perl if
> not as fast as unsort.
How big is your test file? I expect sort(1) to be optimized for big jobs. I
bet it would win the contest if you are shuffling a file that's bigger than
available RAM.