Re: Allow SQL/plpgsql functions to accept record

On 4/25/15 4:50 PM, Tom Lane wrote:
> Well, we already support local variables of type RECORD in plpgsql, so
> it's not immediately clear to me that function arguments would be much
> worse. There are a lot of deficiencies with the RECORD-local-variable
> implementation: if you try to change the actual RECORD type from one call
> to the next you'll probably have problems. But it seems like we could
> avoid that for function arguments by treating RECORD as a polymorphic
> argument type, and thereby generating a separate set of plan trees for
> each actual record type passed to the function within a given session.
> So in principle it ought to work better than the local-variable case does
> today.
>
> In short I suspect that Jim is right and this has more to do with a
> shortage of round tuits than any fundamental problem.

I took a stab at plpgsql and it seems to work ok... but I'm not sure
it's terribly valuable because you end up with an anonymous record
instead of something that points back to what you handed it. The 'good'
news is it doesn't seem to blow up on successive calls with different
arguments...

> Not sure about the SQL-function case. That might be even easier because
> functions.c doesn't try to cache plans across queries; or maybe not.

This on the other hand was rather easy. It's not horribly useful due to
built-in restrictions on dealing with record, but that's certainly not
plsql's fault, and this satisfies my initial use case of

create function cn(record) returns bigint language sql as $$
SELECT count(*)
FROM json_each_text( row_to_json($1) ) a
WHERE value IS NULL $$;

Attached patches both pass make check. The plpgsql is WIP, but I think
the SQL one is OK.
--
Jim Nasby, Data Architect, Blue Treble Consulting
Data in Trouble? Get it in Treble! http://BlueTreble.com