obtaining primary key/rowid following insert, redux...

Peter:

Trying to solve my problem mentioned in the email of half an hour ago, I searched
through the archives of the interface list and found some of your replies suggesting
using "currval()" to get the last value assigned from a sequence... However,
here's what happens in a good database with multiple in-use sequences:

db=# select currval('foo_foo_id_seq');
ERROR: foo_foo_id_seq.currval is not yet defined in this session

As an alternative, I discovered that I can get the value this way:

db=# select last_value from foo_foo_id_seq;
last_value
---------
27

My questions are, (1) why does the currval() approach give the error message, and
(2) is it OK to use my alternative??

Finally, as far as I can tell, there is a real race condition problem here in a multiple-connection
scenario (e.g. another task can cause the sequence to be incremented between the insert
and the select) - but wrapping a transaction around the insert and select should
take care of it... Thoughts??

Thanks,
Mark Dzmura