I have another potential strategy.. and maybe Mysql isn't the best choice for a site with
such a huge number of inserts going on. If you
use PostgreSql you might be able to produce your own
trigger code that increments a number represented
using say base 62 (0..9,a..z,A..Z) or maybe just hexadecimal (0..9,a..f). You should be able to
hit some pretty high numbers with that (of course you need
more than 8 bytes since bitz iz bitz), and no worries
about DBI internal code as you store in the database as
a string. PostreSql.org has some
about writing triggers in PL/SQL or PL/Perl,
don't know how fast this is but looks interesting. They do recommend writing triggers in C if you are worried about performance..