Michael Nacos <m.nacos@gmail.com> writes:
> The interesting thing is SQL_exec(sql,1) resulted in a different
> execution plan while the stray FROM was still in place.
Well, the stray FROM resulted in a useless cross-join, which would
have generated a lot of extra no-op row updates. I think what the
limit was doing for you was stopping the UPDATE before it had performed
the extra updates.
regards, tom lane