Mingcong Han created SPARK-27440:
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Summary: Optimize uncorrelated predicate subquery
Key: SPARK-27440
URL: https://issues.apache.org/jira/browse/SPARK-27440
Project: Spark
Issue Type: Improvement
Components: SQL
Affects Versions: 3.0.0
Reporter: Mingcong Han
Fix For: 3.0.0
Currently, we rewrite all the predicate subqueries(InSubquery, Exists) as
semi-join/anti-join. But uncorrelated predicate subquery can be evaluated using
a subplan instead of a join. We can firstly rewrite all the uncorrelated
predicate subqueries as `Exists`, then optimize it and compute it using a
subquery physical plan like ScalarSubquery.
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