Re: [HACKERS] Raising funds for PostgreSQL

wieck@debis.com (Jan Wieck) writes:
> Tom Lane wrote:
>>>> - Could a subquery be included in the target list of a query
>>>>   select a,(select b from c) from d where e = f;
>> [ is done ]

> Uh,
>     who did the latter one?

Me.

>     Just  running  some  qry  through  psql  I  see that it works
>     partially.  Especially I see a
>         ExecSetParamPlan: more than one tuple returned by expression subselect

Yes.  I allowed the existing kinds of subselect expressions in
targetlists (not only in qual clauses), and fixed things so that
a subselect yielding a single result can appear anywhere in an
expression, not only as the righthand-side argument of an operator.
Subselects yielding multiple rows are still valid only as the
righthand argument of an IN, quantified boolean operator
(such as = ANY or = ALL), or EXISTS.  It's a perfectly straightforward
generalization (and simplification!) of what we already had.

>     So I assume it's not implemented in the form I outlined - the
>     subselecting  range  table  entry. I'll take a look at it the
>     next  days  and  maybe  complain  about  that  change  if  it
>     interferes  with  the  needs  of  the  rule  system  to  make
>     aggregate, distinct, group by, sort  by  and  all  the  other
>     (long wanted) view stuff possible.

I don't believe this has anything to do with subselects as range
table entries.  That facility will be quite separate from subselects
in expressions, no?
        regards, tom lane