Yes it does. Only ORDER BY causes order. Julian
> On Apr 20, 2019, at 12:17, Gian Merlino <g...@apache.org> wrote: > > Hey Julian, > > I think it'd be fine to issue the queries in parallel with a few > adjustments. We'd want to avoid buffering, meaning we'd want to allow query > results to be mixed together (return rows in the order they become > available, rather than in query order sequence). I believe the SQL standard > allows "UNION ALL" to behave this way, but we should double check that too. > > On Fri, Apr 19, 2019 at 2:56 PM Julian Jaffe <jja...@pinterest.com.invalid> > wrote: > >> Hey all, >> >> Druid currently executes UNION ALL queries sequentially ( >> >> https://github.com/apache/incubator-druid/blob/master/sql/src/main/java/org/apache/druid/sql/calcite/rel/DruidUnionRel.java#L98 >> ). >> There's a comment in that method that restates this, but does not explain >> why. Is there a reason why each subquery of a union all query can't be >> executed in parallel? >> >> Thanks, >> Julian >> --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscr...@druid.apache.org For additional commands, e-mail: dev-h...@druid.apache.org
