viirya commented on a change in pull request #32586: URL: https://github.com/apache/spark/pull/32586#discussion_r635480379
########## File path: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/EquivalentExpressions.scala ########## @@ -167,7 +167,25 @@ class EquivalentExpressions { * Returns all the equivalent sets of expressions. */ def getAllEquivalentExprs: Seq[Seq[Expression]] = { - equivalenceMap.values.map(_.toSeq).toSeq + equivalenceMap.values.map(_.toSeq).toSeq.sortBy(_.head)(new ExpressionOrdering) + } + + /** + * Orders [Expression] by parent/child relations. The child expression is smaller + * than parent expression. If there is child-parent relationships among the subexpressions, + * we want the child expressions come first than parent expressions, so we can replace + * child expressions in parent expressions with subexpression evaluation. + */ + class ExpressionOrdering extends Ordering[Expression] { + override def compare(x: Expression, y: Expression): Int = { + if (x.semanticEquals(y)) { + 0 + } else if (x.find(_.semanticEquals(y)).isDefined) { + 1 + } else { + -1 Review comment: Discussed offline. Thanks for the concern. I renamed the ordering class and added more comment. -- 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 --------------------------------------------------------------------- To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org For additional commands, e-mail: reviews-h...@spark.apache.org