while i would definately agree with the other monks that you're going to want to migrate to a real database solution pretty soon, there is an intermediate solution that's likely to help you out if you're on unix.

open your file through grep (or egrep). instead of opening it and searching in perl, let grep do the search and just deal with its results. grep is amazingly more efficient at searching than your perl code will ever be. ie, something like:

my $term = "foobar";
open(INF,"grep $term data.txt|") or die "couldn't open file: $!";
while (<INF>) {
    # do some stuff with $_
}
close INF;
[download]

of course, if you're getting the search term from users, you've got to be careful about taking dangerous shell characters and such.

i had to use this trick once where i had no control over the format of the "database". it will actually scan through a 20MB file in the blink of an eye without using much memory at all whereas the all perl solution might take several minutes and fill your RAM.

once again, this isn't by any means the best solution but if you have no control over the format of the data, it can speed things up a lot.

update: fixed a typo. thanks ChemBoy

anders pearson