Re: [HACKERS] subselect

> BTW, note that for _expression_ subqueries (which are introduced without
> IN, EXISTS, ALL, ANY - this follows Sybase' naming) - as in your examples -
> we have to check that subquery returns single tuple...

It might be nice to have a tuple-counting operation or query node (is this the right
terminology?) which could be used to help implement EXISTS. It might help to
re-implement the count(*) function also.

                                                    - Tom