Sequences

I have a couple of questions about sequences:

1. Just how lightweight are sequences? From what I've read, they seem to provide a unique # for any number of requestors, without all the muss and fuss of creating a counter in a row, and going through the overhead of locking, etc; to maintain it. Right?
2. How many sequences can I have? We have an application which potentially require thousands of individual sequences, but's it's unclear how much overhead each one takes. From my reading, it looks like sequences are stored in the data dictionary, but does each one consist merely of a row?

Thanks in advance.. Received on Sat Aug 03 1996 - 00:00:00 CEST