at my company i just inherited a 20,000 record contact database that i'm trying to make relational (in a many-to-many way). of course, no one ever gave primary keys to each record in this db. is there a way to assign unique primary keys retroactively? i've created a field with auto-enter serial, etc., but i need to avoid putting number in 1 by 1 by 1...

Sure, put the cursor into the new ID field and do Records->Replace Field Contents. In the dialog that follows, select the 'Replace with serial numbers' option, and have it update the serial number in the Entry Options.

The Replace Field Contents command, in the Records menu (and a script step) has an option to "serialize" the found set, with an Option to reset the auto-enter "next" number (or text). It can do 20,000 in just a few seconds.

But that's just a serial number for the current records. Are there really 20,000 unique contacts? Have you seriously checked?