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:
$ time unsort file
real 0m1.388s
$ unsort --version
unsort 1.1.2
$ time perl -e 'print sort { rand() <=> rand() } <>' file
real 0m6.621s
$ time sort -R file
real 4m8.403s
$ sort --version
sort (GNU coreutils) 8.5
What is even scarier: sort without -R is faster than sort -R:
$ time sort file
real 0m53.553s
I would expect sort -R to be faster than sort and faster than Perl if
not as fast as unsort.
/Ole
