I wouldn't think using a sequence would make much sense. You don't want
automatically generated unique values, you want to impose an order.
If you want easy insertion at the expense of larger indexes you are
probably better off using a text or numeric (using digits to the right
of the decimal point) key.
[JFO]
My use of the word sequence was ambiguous. What I ment was a "numeric" key.
Why do you want your rules in a database? I would think that a plain
text file would be a better approach unless you either want to be able
to ask questions about your firewall rules or have some automated
system for changing the firewall rules based on contidions (e.g. time of
day).
[JFO] Exactly, I need it very flexible. The tables are a small part of a
large administration database, which tell a lot of machines exactly what
firewall configuration they should have.