francis0407 commented on a change in pull request #24344: [SPARK-27440][SQL] Optimize uncorrelated predicate subquery URL: https://github.com/apache/spark/pull/24344#discussion_r285879099
########## File path: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/subquery.scala ########## @@ -93,6 +93,21 @@ object SubqueryExpression { }.isDefined } + /** + * Returns true when an expression contains a correlated IN or correlated EXISTS and + * false otherwise. An IN is non-correlated only if the left values are foldable + * and the subquery has no outer references. + */ + def hasCorrelatedInOrExists(e: Expression): Boolean = { Review comment: Push down the LHS of IN into the subquery is the first step. We can also use a specific aggregation to reduce the result set to an acceptable size. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org With regards, Apache Git Services --------------------------------------------------------------------- To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org For additional commands, e-mail: reviews-h...@spark.apache.org