g == gryzman@gmail.com writes:
g> you should use it, whenever you need db to keep its own key internally.
g> Advantage of sequence is also the fact, that you can have the sequence
g> value used on different columns/tables .
g> My rule of thumb is , in that case: as long as it is a short type (not
g> of toastable, or/and variable length), and as long as it won't change,
g> and is unique - I can use it. Otherwise, I use sequence to connect
g> rows internally for database.
g> First rule, is because of index access, and the way btree works.
g> Second is, because update of value will update other rows too - and
g> HOT won't help you here, so that's not efficient. And also, forcing it
g> to be unique is harder than.
g> Hth.
That does help. So, in my example of a table consisting of rows for
each periodic table element, the atomic number would suffice as a
unique key since, well, it's unique and not going to change. Right?
--
Brandon