another newbie here ... Is hashes the way to go?

It's certainly the way to start and the approaches given by hv and kcott will get you well along that path. As someone new to Perl, the use of hashes is fundamental to so much that the language can do that becoming familiar with them would be very beneficial to you in both the short and long term.

The only problem you might hit for this particular task is if the amount of data to be stored is comparable or greater than the amount of RAM you have available. If that happens then you will see the performance drop off a cliff edge and other tactics or strategies may be required. But only worry about that if/when you hit that limit.

Do consider signing up for an account here. It is free and will make it easier for you to revisit your old posts and for the rest of us to recognise you instead of being lost among all our other anonymous brethren. You've written a very good post for first timer and it would be good to see more of the same.