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Help optimizing sort of large files

 
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Old 11-07-2014
Wrench Help optimizing sort of large files
I'm doing a hobby project that has me sorting huge files with sort of monotonous keys. It's very slow -- the current file is about 300 GB and has been sorting for a day. I know that sort has this --batch-size and --buffer-size parameters, but I'd like a jump start if possible to limit the number of days I have to fool around finding what works. The man page doesn't even tell me what the default values are.

I have a 4-core 64-bit AMD processor, 32 GB RAM and plenty of hard drive space.

I would normally do a preliminary radix sort on files this size, but it's a bit awkward with these keys. The keys represent positions in a game and consist of 64 bytes of just 3 values: x, o and -, always beginning with x. They tend to form clusters that are similar at the beginning, and vary from run to run. It's not clear how to form the radix. Here are records from various spots in a typical run....

Code:
xo-xoooox---x-------ooox------------xxo--x----------o-xx-------- -45 20 -1 1
xo-xo-oox---x-------ooox------------xxo--x----------o-xx-------- +45 19 05 1
xo-xo-oox---x-------ooox------------x-o--x----------o-xx-------- -45 18 37 2
xo-xo-o-x---x-------ooox------------x-o--x----------o-xx-------- +45 17 07 3
xo-xo-o-x---x-------ooox--------------o--x----------o-xx-------- -45 16 36 4

xxxooxx-oooxo-------ooo--xo-----------o--xxo-----------x----xoxx -31 26 23 8
xxxooxx-oooxo--------oo--xo-----------o--xxo-----------x----xoxx +31 25 20 9
xxxoo-x-oooxo--------oo--xo-----------o--xxo-----------x----xoxx +35 24 20 457
xxxoo-x-oooxo--------o---xo-----------o--xxo-----------x----xoxx -35 23 22 458
xx-oo-x-oooxo--------ox--xo-----------o--xxo-------o---x---xxoxx -35 25 02 0


xx-ooxx-oooxo--------o---x------------o--xxo-------------------x +34 18 55 5344
xx-ooxx-oooxo--------o---x---------------xxo-------------------x -34 17 38 5345
xx-ooxx-ooo-o--------o---x---------------xxo-------------------x +34 16 11 5346
xx-ooxx-oo--o--------o---x---------------xxo-------------------x -34 15 10 5347
xx-oo-x-oo--o--------o---x---------------xxo-------------------x +34 14 26 1237242

 
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