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https://issues.apache.org/jira/browse/SPARK-16951?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15767904#comment-15767904
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Nattavut Sutyanyong commented on SPARK-16951:
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I was wrong on case 3 when the subquery produces empty row. The semantics of
the predicate
<expr> NOT IN ( <query-block> )
is
<expr> <> ALL ( <query-block> )
which is when the result of the <query-block> is empty, the predicate is True
and therefore all the rows from the parent side is returned.
> Alternative implementation of NOT IN to Anti-join
> -------------------------------------------------
>
> Key: SPARK-16951
> URL: https://issues.apache.org/jira/browse/SPARK-16951
> Project: Spark
> Issue Type: Sub-task
> Components: SQL
> Affects Versions: 2.0.0
> Reporter: Nattavut Sutyanyong
>
> A transformation currently used to process {{NOT IN}} subquery is to rewrite
> to a form of Anti-join with null-aware property in the Logical Plan and then
> translate to a form of {{OR}} predicate joining the parent side and the
> subquery side of the {{NOT IN}}. As a result, the presence of {{OR}}
> predicate is limited to the nested-loop join execution plan, which will have
> a major performance implication if both sides' results are large.
> This JIRA sketches an idea of changing the OR predicate to a form similar to
> the technique used in the implementation of the Existence join that addresses
> the problem of {{EXISTS (..) OR ..}} type of queries.
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