Bitfields always atomic? Other way to store attributes?

Dear List;

If I have two threads modifying the same "bit" field:
thread1=> update table set bf=bf | '01000'
thread2=> update table set bf=bf | '10000'
Will this operation always be safe (e.g. result in bf='11000')? Or must
I wrap things in
explicit transactions?

My application is to give attributes to an address table. But maybe
there is a better way?

I want to mark each addresses with attributes, e.g. the person may be a
"friend", "on my holiday card list", "owe me money", be an "employee", a
"volunteer on the xxx project", or none of the above.

I could assign each role a bit.

Or, create a string field: "Friend,Money, Emp,VolXXX".

Or, create related tables:
friend_pk, address_id
cardlist_pk, address_id
money_pk, address_id, amount_owed
volunteer_pk, address_id

Any thoughts?

-Bryce Nesbitt

--
----
Visit http://www.obviously.com/