C:\test>dir junk.dat
30/03/2012  17:39        53,777,008 junk.dat

C:\test>wc -l junk.dat
1000000 junk.dat

C:\test>head junk.dat
Some random junk 333740 119750 some more random junk
Some random junk 495178 597808 some more random junk
Some random junk 815582 448120 some more random junk
Some random junk 604675 737548 some more random junk
Some random junk 735839 436462 some more random junk
Some random junk 89324 842712 some more random junk
Some random junk 18493 967895 some more random junk
Some random junk 835571 146942 some more random junk
Some random junk 783477 720062 some more random junk
Some random junk 197540 926361 some more random junk

##</code><code>##

#! perl -slw
use strict;
use Time::HiRes qw[ time ];

my $start = time;

my @a; $#a = 1e6;
my $n = 0;
$a[ $n++ ] = pack 'NNA*', m[(\d+) (\d+)], $_ while <>;

printf "%d records\n", scalar @a;

@a = sort @a;

substr( $_, 0, 8, '') for @a;

printf "Took %.6f seconds; check memory? ", time()- $start; <STDIN>;

##</code><code>##

C:\test>t-GRT junk.dat
1000001 records
Took 6.704649 seconds; check memory? 274.1MB

##</code><code>##

#! perl -slw
use strict;
use Time::HiRes qw[ time ];

my @a; $#a = 1e6;
my $n = 0;
$a[ $n++ ] = $_ while <>;

printf "%d records; check memory", scalar @a; <STDIN>;

my $start = time;

my @sorted = @a[
    map { unpack 'N', substr($_,-4) }
    sort
    map { pack 'NNN', $a[ $_ ] =~ m[(\d+) (\d+)], $_ }
    0..$#a
];

printf "Took %.6f seconds; check memory? ", time()- $start; <STDIN>;

##</code><code>##

C:\test>t-TYE junk.dat
1000001 records; check memory 143.8MB
Took 228.533225 seconds; check memory? 649.0 MB