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https://issues.apache.org/jira/browse/SPARK-11077?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Michael Armbrust updated SPARK-11077:
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    Target Version/s:   (was: 1.6.0)

> Join elimination in Catalyst
> ----------------------------
>
>                 Key: SPARK-11077
>                 URL: https://issues.apache.org/jira/browse/SPARK-11077
>             Project: Spark
>          Issue Type: New Feature
>          Components: SQL
>            Reporter: Ankur Dave
>            Assignee: Ankur Dave
>
> Join elimination is a query optimization where certain joins can be 
> eliminated when followed by projections that only keep columns from one side 
> of the join, and when certain columns are known to be unique or foreign keys. 
> This can be very useful for queries involving views and machine-generated 
> queries.
> Adding join elimination to Catalyst requires (1) support for unique and 
> foreign key hints in logical plans, (2) methods in the DataFrame API to let 
> users provide these hints, and (3) an optimizer rule that eliminates unique 
> key outer joins and referential integrity joins when followed by an 
> appropriate projection.
> This proposal is described in detail here: 
> https://docs.google.com/document/d/1-YgQSQywHfAo4PhAT-zOOkFZtVcju99h3dYQq-i9GWQ/edit?usp=sharing



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