Re: plpgsql variable assignment with union is broken

easteregg@verfriemelt.org writes:
> i found, that the behaviour of variable assignment in combination with union is not working anymore:
>   DO $$
>   DECLARE t bool;
>   begin
>       t := a FROM ( SELECT true WHERE false ) t(a) UNION SELECT true AS a;
>   END $$;

> is this an intended change or is it a bug?

It's an intended change, or at least I considered the case and thought
that it was useless because assignment will reject any result with more
than one row.  Do you have any non-toy example that wouldn't be as
clear or clearer without using UNION?  The above sure seems like an
example of awful SQL code.

            regards, tom lane