performance and downtime: adding columns with a not null default

Hi,
I have a 2GB table (1 million rows) with which I need to add a dozen or so columns and set perhaps two dozen defaults values with not nulls (not my design...)

Offpeak it has new rows added every minute or two and so I can't afford to exclusively lock the table for a long time. I could work at one column at a time while the database is in use. Or I could pay the piper and make the changes during downtime - doing all the columns at once.

I will work on estimating the time for those two options more precisely,
but what are peoples experience as to the most optimal way of doing this?

thanks

Greg Received on Mon Nov 26 2001 - 20:13:27 CST