running maintenance tasks on DB

Hello,

Approaching completion of an online auction system based on Postgres and
mod_perl/Apache I yet have to devise a good way of running certain
maintenance tasks on the DB like closing auctions, notifying winners,
transferring old records to archive tables, etc.

What is the usual way of programming such tasks? Write a backend
function (in pl/sql or C) and call it from a cron job? From a mod_perl
handler?

Thanks in advance for any insight, cheers,

--
Louis-David Mitterrand - ldm@apartia.org - http://www.apartia.org