Re: Idea on how to simplify comparing two sets

>
> FWIW I've found myself needing the precursor to this this (give me the
> full diff) at least a couple times, and it's quite a PITA on anything but a
> trivial relation.
>
> It's also not possible to make this easier via an SRF because you don't
> know in advance what the result set looks like. So the best I've ever come
> up with is a file that can be included in psql that depends on having set
> two psql variables to the names of relations that can be queried (and if
> you need more than a relation you need to create a temp view).
>
> I've wondered about the possibility of allowing PLs the ability to
> dynamically define their return type based on their arguments. That would
> allow for an SRF to handle this case, and would be significantly more
> flexible than trying to do that using pseudotypes.

My experiences are similar. At the moment, I'm resigned to using relying on
pgtap:

-- set environment/path to point to "control"
create temporary table test_1_wants as <query of table or function as it
was>;

-- set environment/path to point to "experiment"
create temporary table test_1_has as <query of thing we're trying to test
now>;

select results_eq( 'table test_1_has', 'table test_1_wants', 'test 1');

I've had to do it with temp tables any time the environment is different
between control/experiment, which is the case when you're developing a
drop-in replacement for an SRF or view or whatever.