What about getting the job done in less than a half of second? (no DBMs, no Hashes):

use strict;
use warnings;

my ($file1, $file2) = @ARGV;

my $ids = 1000000;  # last id
my $bin=0;
substr($bin,$_,1,pack ("c",0)) for (0..$ids);

# Create the index
open my $fh1, "<", $file1 or die $!;
while (my $id = <$fh1>){
  chomp $id;
  substr($bin, $id,1,pack ("c",1));
}
close $fh1;

# Search $ids from file 2
open my $fh2, "<", $file2 or die $!;
while (my $id2 = <$fh2>){
  chomp $id2;
  print "$id2\n" if ((unpack "c",substr ($bin,$id2,1)) == 1);
}
close $fh2;

[download]

file1 contains 400000 numbers between 0 and 1000000. file2 contains 10000 numbers in the same range. Processing both takes less than half a second.

time perl sp.pl file1 file2 > /dev/null
real    0m0.448s
user    0m0.448s
sys     0m0.000s

[download]

A bit of explanation: The program constructs an scalar ($bin) containing 1000000 of 0s. While processing the index (the first list of ids), it substitutes every 0 at position $id with a 1.

Then, it reads the second file of ids and checks if at position $id2, the $bin scalar has a 0 (not seen previously) or a 1 ($id already seen in the first file).

Hope this helps

citromatik

In reply to Re: searching through data by citromatik
in thread searching through data by baxy77bax

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