599166320 commented on code in PR #13031: URL: https://github.com/apache/druid/pull/13031#discussion_r966246719
########## processing/src/main/java/org/apache/druid/query/scan/ScanQueryOrderByLimitRowIterator.java: ########## @@ -0,0 +1,110 @@ +/* + * 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.druid.query.scan; + +import com.google.common.collect.Iterators; +import org.apache.druid.collections.MultiColumnSorter; +import org.apache.druid.java.util.common.UOE; +import org.apache.druid.query.QueryPlus; +import org.apache.druid.query.QueryRunner; +import org.apache.druid.query.context.ResponseContext; + + +import java.util.ArrayList; +import java.util.Comparator; +import java.util.LinkedHashMap; +import java.util.List; +import java.util.stream.Collectors; + +public class ScanQueryOrderByLimitRowIterator extends ScanQueryLimitRowIterator Review Comment: > I would suggest not combing the order by operation with the limit operation. The typical way this is done is to sort in the leaf nodes (or, if we like, in the root node), then start pulling from the result set. The limit (and offset) sit on top, and control what we pull. I think for unordered column sorting, it needs to traverse all the data. If it puts orderby and limit together, it can control the use of memory and avoid excessive memory use. -- 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. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
