You might want to consider using a round robin database, which are great for aggregating 'buckets' of data from varying degrees of resolution; it would be up to you to specify the minimal bucket size and how long it takes them to coalesce into larger buckets.

RRDtool is a well known example. They do provide perl bindings as well as ones for ruby and python.

Cheers,
Matt

P.S. The RRDtool site provides a nice tutorial for beginners if you haven't messed with RRD's before.