I think Aman and Vicki mentioned that this is a situation where most
databases diverge from the spec since people have a certain expectation.
On Fri, Jul 31, 2015 at 9:56 PM, Julian Hyde <jhyde@apache.org> wrote:
>
> > Jinfeng, the subquery's ORDER-BY can be dropped in some cases but not
> all..
> > for instance in the following query:
> > SELECT a1 FROM (SELECT a1 FROM t1 WHERE .... ORDER BY a1) LIMIT 10;
> > The OB should not be dropped. There are other cases, this is one
> example.
>
> FWIW, My understanding of the SQL standard is that that ORDER BY can be
> dropped. You can’t rely on the order of output from a sub-query. If you
> want the desired effect you have to combine ORDER BY and LIMIT into the
> same clause.
>
> Julian
>
>
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