"woger151" <woger151@jqpx37.cotse.net> writes:
> Reading around, I've seen the following methods discussed:
> (1) Within a transation, do the INSERT, and then do a SELECT CURVAL
> (2) Not necessarily within a transaction, get a candidate for the pk using
> SELECT NEXTVAL, then INSERT the row.
> (3) Use LASTVAL
You don't need a transaction for any of these; at least not unless
you're using connection-pooling code that might swap you to a different
physical session at transaction boundaries.
Since all of them are going to cost you two round trips to the server,
it's probably about a wash performance-wise. I'd tend to go with (2)
just because it requires no assumptions about anything. Even without
the session-change risk, (1) and especially (3) can bite you in a
sufficiently complex application: some other part of your own code
could touch this or another sequence between the two steps.
regards, tom lane