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From Jacques Nadeau <jacq...@apache.org>
Subject Re: Adding Exchange operator and Distribution trait
Date Thu, 12 Feb 2015 21:57:41 GMT
Got it.

On Thu, Feb 12, 2015 at 11:44 AM, Julian Hyde <julian@hydromatic.net> wrote:

> RelMdDistribution (the "Md" that distinguishes it from
> "RelDistribution" stands for "metadata") is just theory, but it will
> look a lot like RelMdCollation.
>
>
> https://github.com/apache/incubator-calcite/blob/master/core/src/main/java/org/apache/calcite/rel/metadata/RelMdCollation.java
>
> On Wed, Feb 11, 2015 at 6:47 PM, Ashutosh Chauhan <hashutosh@apache.org>
> wrote:
> > I think RelDistribution as a member of Exchange (as in Julian proposal)
> > makes more sense as compared to mine at field level.
> >
> > On Wed, Feb 11, 2015 at 6:42 PM, Jacques Nadeau <jacques@apache.org>
> wrote:
> >
> >> Does RelMdDistribution exist or as theory?
> >>
> >> Definitely inclined to "Exchange" over "Shuffle" as more
> generic/consistent
> >> with Volcano.
> >>
> >> Note, looking at Ashutosh I wonder a little about the need to have range
> >> versus hash at the field information level.  I'm sure we can come up
> with a
> >> use case but it seems to overcomplicate.  We already have space
> exploration
> >> problems when trying to do distribution subsumption for joins with trait
> >> propagation so I would be cautious about adding more dimensions to that
> >> attribute.
> >>
>

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