check constraints - how implemented and how fast????

Can anyone tell me how check constraintes are implemented on Oracle 7.3.x or 8.x?

I've been in the habit of creating indexes on all foreign keys. I assumed this would speed up the lookup when trying to delete a parent row that has child rows from another table using the key. I used to use triggers to implement the restriction, which needed the index for speed. I was talking to a friend and they said it's not needed with check constraints, but they couldn't tell me how Oracle does it.

Thanks,
Steve Received on Sun Dec 13 1998 - 13:21:56 CST