Here is what I would do (code snippets untested):
- Open the first file
- Iterate through the file, building a hash making each line a key, eg:
# assumes that duplicates in first file should be ignored.
my %wanted;
open my $in, '<', '$file1' or die "$!\n";
while (my $line = <$in>) {
chomp $line);
$wanted{$line}++;
}
- Open the second file
- Iterate through it line by line
- Extract the second "field" from each line using split
my $foo = (split /|/, $line)[1];
- If this value exists as a key in the hash you built earlier, print the record to your third file
print OUT $line if $wanted{$foo};
This may not be the fastest approach, but it does only open and read each of your input files once. As opposed to 60,000 X 16,000,000 = 960,000,000,000 times - which is what your current code does.
So I'd expect it to be just a tad faster ;)
Hope this helps,
Darren :)
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