Hi, I'm trying to understand RewriteCorrelatedScalarSubquery optimization and how extractCorrelatedScalarSubqueries [1] works. I don't understand how "The expression is rewritten and returned." is done. How is the expression rewritten?
Since it's private it's not even possible to write tests and that got me thinking how you go about code like this? How do you know whether it works fine or not? Any help? I'd appreciate. [1] https://github.com/apache/spark/blob/branch-2.3/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/subquery.scala?utf8=%E2%9C%93#L290-L299 Pozdrawiam, Jacek Laskowski ---- https://about.me/JacekLaskowski Mastering Spark SQL https://bit.ly/mastering-spark-sql Spark Structured Streaming https://bit.ly/spark-structured-streaming Mastering Kafka Streams https://bit.ly/mastering-kafka-streams Follow me at https://twitter.com/jaceklaskowski
