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https://issues.apache.org/jira/browse/SPARK-11072?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Wenchen Fan updated SPARK-11072:
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Description:
self-join is a diamond problem that confuse our analyzer. Our current solution
is creating new instances of leaf nodes in the right tree of join node, and
update all attribute reference there. Thus there is no diamond anymore and
problem fixed.
However, our execution engine can handle diamond plan and we only need to
distinguish the output between left and right. So we can simplify the self-join
handling by introducing a new Plan `NewOutput` to give different output
attributes.
was:
self-join is a diamond problem that confuse our analyzer. Our current solution
is creating new instances of leaf nodes in the right tree of join node, and
update all attribute reference there. Thus there is no diamond anymore and
problem fixed.
However, our execution engine can handle diamond plan and we only need to
distinguish the output between left and right. So we can simplify the self-join
handling by introducing a new
> simplify self join handling
> ---------------------------
>
> Key: SPARK-11072
> URL: https://issues.apache.org/jira/browse/SPARK-11072
> Project: Spark
> Issue Type: Improvement
> Components: SQL
> Reporter: Wenchen Fan
>
> self-join is a diamond problem that confuse our analyzer. Our current
> solution is creating new instances of leaf nodes in the right tree of join
> node, and update all attribute reference there. Thus there is no diamond
> anymore and problem fixed.
> However, our execution engine can handle diamond plan and we only need to
> distinguish the output between left and right. So we can simplify the
> self-join handling by introducing a new Plan `NewOutput` to give different
> output attributes.
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