Re: Set Returning Functions and array_agg() - Mailing list pgsql-general

Possibly due to my lack of thorough SQL understanding. Perhaps there's a better way of doing what I'm ultimately trying to accomplish, but still the question remains - why does this work:

pg_dev=# select unnest(array[1,2,3]);

 unnest 

--------

      1

      2

      3

(3 rows)

But not this:

pg_dev=# select array_agg(unnest(array[1,2,3]));

ERROR:  set-valued function called in context that cannot accept a set

The solution to the problem is actually of less interest right now then in understanding what's going on in the two statements above. It seems a bit inconsistent to me. If an aggregate function cannot handle rows generated in the columns-part of the statement, then why is a single-column row(s) result acceptable in the first statement?

On Wed, Apr 24, 2013 at 1:29 PM, hubert depesz lubaczewski <depesz@depesz.com> wrote:

On Wed, Apr 24, 2013 at 12:48:44PM -0700, Stephen Scheck wrote:
> I have a UDF (written in C) that returns SETOF RECORD of an anonymous
> record type
> (defined via OUT parameters). I'm trying to use array_agg() to transform
> its output to
> an array:
> pg_dev=# SELECT array_agg((my_setof_record_returning_func()).col1);
> ERROR:  set-valued function called in context that cannot accept a set

Is there any reason why you're not using normal syntax:
select array_agg(col1) from my_setof_record_returning_func();
?

Best regards,

depesz