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From Julian Hyde <jul...@hydromatic.net>
Subject Re: Adding Exchange operator and Distribution trait
Date Thu, 12 Feb 2015 19:44:21 GMT
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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