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 info 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..