Updating a bazillion rows in SQL

It takes a long time to update 27 million rows.  One strategy I used– bcp Export the table to text, write a .NET program to read each line in, update the relevant column, write back out to a file, BULK import & voila.  Works only if no one is updating your big table during the time between the bcp export and bulk import.

If you have to do it in sql, I recommend doing a UPDATE TOP x, so that the update is done in batches of 50000 or so.