Placeholders are emulated by the DBD::pg module. Check out the docs. I don't know if that'll solve your speed problems, but your table really isn't that big. I don't have experience with PostgreSQL, but I've done multiple updates on 500,000 row tables in mySQL and it's only taken about 10 minutes on decent hardware.

Your poor performance may also be a function of the excessive amount of cols in your table. Maybe you should consider redesigning your database to use multiple tables and foreign keys. That might make things better.

Gary Blackburn
Trained Killer