> On Mon, Jul 21, 2008 at 08:19:35AM +0900, Tatsuo Ishii wrote:
> > > > Thus I think we should avoid this kind of ORDER BY. Probably we should
> > > > avoid LIMIT/OFFSET and FOR UPDATE as well.
> > >
> > > What of index-optimized SELECT max(...) ?
> >
> > Aggregate functions in a recursive term is prohibited by the
> > standard. For example,
> >
> > WITH RECURSIVE x(n) AS (SELECT 1 UNION ALL SELECT max(n) FROM x)
> > SELECT * FROM x;
> >
> > produces an error.
>
> On the other side of UNION ALL, it's OK, right? For example,
>
> WITH RECURSIVE x(n) AS (
> SELECT max(i) FROM t
> UNION ALL
> SELECT n+1 FROM x WHERE n < 20
> )
Yes, aggregate functions in the non-recursive term is allowed by the
standard.
--
Tatsuo Ishii
SRA OSS, Inc. Japan