BTW, I've actually just done some work on hint error handling, which might be helpful to what you mentioned:
https://github.com/apache/spark/pull/24653 On Tue, Jun 11, 2019 at 8:04 PM Maryann Xue <maryann....@databricks.com> wrote: > I believe in the SQL standard, the original name cannot be accessed once > it’s aliased. > > On Tue, Jun 11, 2019 at 7:54 PM John Zhuge <jzh...@apache.org> wrote: > >> Yeah, it is a touch scenario. >> >> I actually have much simpler cases: >> >> 1) select /*+ broadcast(t1) */ * from db.t1 join db.t2 on t1.id = t2.id; >> 2) select /*+ broadcast(t1) */ * from db.t1 a1 join db.t2 a2 on a1.id = >> a2.id; >> >> 2) is the same as 1) but with aliases. Many users were surprised that 2) >> stopped working. >> >> Thanks, >> John >> >> >> On Tue, Jun 11, 2019 at 4:38 PM Maryann Xue <maryann...@apache.org> >> wrote: >> >>> Yes, and for a good reason: the hint relation has exactly the same scope >>> with other elements of queries/sub-queries. >>> >>> Suppose there's a query like: >>> >>> select /*+ broadcast(s) */ from (select a, b from s) t join (select a, b >>> from t) s on t1.a = t2.b >>> >>> If we allowed the hint resolving to "cross" the scopes, we'd end up with >>> a really confusing spec. >>> >>> >>> Thanks, >>> Maryann >>> >>> On Tue, Jun 11, 2019 at 5:26 PM John Zhuge <jzh...@apache.org> wrote: >>> >>>> Hi Reynold and Maryann, >>>> >>>> ResolveHints javadoc indicates the traversal does not go past subquery >>>> alias. Is there any specific reason? >>>> >>>> Thanks, >>>> John Zhuge >>>> >>> >> >> -- >> John Zhuge >> >
