Re: extra function calls from query returning composite type

Ronald Peterson <ron@hub.yellowbank.com> writes:
> I added a 'raise notice' to a plpgsql function I was working on
> recently, and noticed that my notification was being raised more often
> than I expected.  The notification is raised in a function ('getone'
> in my example below) that returns a single composite value.  This
> function is then called by another function ('getset') that returns a
> setof that composite value.  It appears that 'getone' is called once
> for each column of my composite type.  I whittled this down to the
> following example.

> I get the expected result from my query, but I don't understand (what
> appear to be) the extra function calls.

This:

>     SELECT (getone(id)).*

is implemented as SELECT (getone(id)).foo, (getone(id)).bar

If you're using 9.3 or later you could avoid that by recasting the
call as LATERAL, ie

  SELECT go.*
    FROM dat, LATERAL getone(id) AS go
    WHERE set = setid;

            regards, tom lane