ulysses-you commented on a change in pull request #30368: URL: https://github.com/apache/spark/pull/30368#discussion_r522960572
########## File path: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala ########## @@ -1452,11 +1452,23 @@ object PushPredicateThroughJoin extends Rule[LogicalPlan] with PredicateHelper { } /** - * Combines two adjacent [[Limit]] operators into one, merging the - * expressions into one single expression. + * 1. Eliminate [[Limit]] operators if it's child max row <= limit. + * 2. Combines two adjacent [[Limit]] operators into one, merging the + * expressions into one single expression. */ -object CombineLimits extends Rule[LogicalPlan] { - def apply(plan: LogicalPlan): LogicalPlan = plan transform { +object EliminateLimits extends Rule[LogicalPlan] { + private def canEliminate(limitExpr: Expression, childMaxRow: Option[Long]): Boolean = { + limitExpr.foldable && + childMaxRow.isDefined && + childMaxRow.get <= limitExpr.eval().toString.toInt + } + + def apply(plan: LogicalPlan): LogicalPlan = plan transformDown { Review comment: We need `transformDown` here, so better to use `transformDown` explicitly ? ---------------------------------------------------------------- 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