cloud-fan commented on a change in pull request #26011: [SPARK-29343][SQL] Eliminate sorts without limit in the subquery of Join/Aggregation URL: https://github.com/apache/spark/pull/26011#discussion_r334519992
########## File path: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/RemoveSortInSubquery.scala ########## @@ -0,0 +1,73 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You under the Apache License, Version 2.0 + * (the "License"); you may not use this file except in compliance with + * the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +package org.apache.spark.sql.catalyst.optimizer + +import org.apache.spark.sql.catalyst.expressions.{NamedExpression, PredicateHelper} +import org.apache.spark.sql.catalyst.expressions.aggregate.{AggregateExpression, OrderIrrelevantAggs} +import org.apache.spark.sql.catalyst.plans.logical._ +import org.apache.spark.sql.catalyst.rules.Rule + +/** + * [[Sort]] without [[Limit]] in subquery is useless. For example, + * + * {{{ + * SELECT * FROM + * (SELECT f1 FROM tbl1 ORDER BY f2) temp1 + * JOIN + * (SELECT f3 FROM tbl2) temp2 + * ON temp1.f1 = temp2.f3 + * }}} + * + * is equal to + * + * {{{ + * SELECT * FROM + * (SELECT f1 FROM tbl1) temp1 + * JOIN + * (SELECT f3 FROM tbl2) temp2 + * ON temp1.f1 = temp2.f3" + * }}} + * + * This rule try to remove this kind of [[Sort]] operator. + */ +object RemoveSortInSubquery extends Rule[LogicalPlan] with PredicateHelper { Review comment: + 1 for merging the 2 rules. We can call the merged rule `EliminateSorts`, as not only redundant sorts are removed. ---------------------------------------------------------------- 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: [email protected] With regards, Apache Git Services --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
