my $file = shift @ARGV;
my ($fh, $time);

my $filesize = -s $file;
sysopen($fh, $file, 0) or die "\nCant open file!\n";  # Open file for reading only
$time = time;
my $bytes_read = sysread($fh, my $buffer, $filesize);  # Read the whole file into $buffer
close $fh;
defined $bytes_read && $bytes_read == $filesize or die "\nCouldnt read the whole file!\n";

# Do your query thing here
# and see how much faster it is!

printf "%f read lines from disk and do RE.\n", time - $time;