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https://issues.apache.org/jira/browse/CALCITE-5871?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17747228#comment-17747228
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LakeShen commented on CALCITE-5871:
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Hi [~grandfisher] ,can you explain the problem you described through an SQL
example? I think it will help people understand the problem better
> Data distributions need to be combined and represented.
> -------------------------------------------------------
>
> Key: CALCITE-5871
> URL: https://issues.apache.org/jira/browse/CALCITE-5871
> Project: Calcite
> Issue Type: Improvement
> Components: core
> Reporter: grandfisher
> Priority: Major
>
> For a distributed partition database, the data may be partitioned by time,
> and also hash partitioned by the `region` field.
> If there is agg that aggregate on "(Day,Region)", It's hard to show AGG rel
> distribution.（range(Day) hash(region))
> And for another hash shuffle join case `( L join R on L.a=R.c and L.b =R.d
> ) as T` , now T has satisfy two distributions, one is Hash(a,b) and another
> is Hash(c,d), it's not Hash(a,b,c,d). But we must lost one of them because
> the Reldistribution can only has one distribution.
> We think this is common in time-series distributed databases
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