Your logfiles could even be written to databases, though that's probably less important than being careful to not try to slurp too much in at a time from your logfiles as you parse them. The key is to parse, and write out to the database without building up gigantic hashes of usernames and other data.

To this end, DBI and DBD::SQLite are very good options. They will require that you learn some SQL. But DBD::SQLite is such a powerful (albiet lightweight) database that you are likely to not need anything heavier (such as Oracle) for a long time. DBD::SQLite is the database driver, and the database server wrapped into one module. DBI.pm is the "Database Interface" which allows you to write code in a database independant way, rather than getting down to the nitty-gritty of dealing directly with a low level database driver. You use the two together: DBI as the API to DBD::SQLite. I do consider them to be very good options if you're looking for ways to scale your project beyond its current capacity.