jcamachor commented on a change in pull request #557: HIVE-21338 Remove order by and limit for aggregates URL: https://github.com/apache/hive/pull/557#discussion_r262800893
########## File path: ql/src/java/org/apache/hadoop/hive/ql/optimizer/calcite/rules/HiveSortLimitRemoveRule.java ########## @@ -0,0 +1,60 @@ +/* + * 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.hadoop.hive.ql.optimizer.calcite.rules; + +import org.apache.calcite.plan.RelOptRule; +import org.apache.calcite.plan.RelOptRuleCall; +import org.apache.calcite.plan.RelOptRuleOperand; +import org.apache.hadoop.hive.ql.optimizer.calcite.HiveRelOptUtil; +import org.apache.hadoop.hive.ql.optimizer.calcite.reloperators.HiveSortLimit; + +/** + * Planner rule that removes + * a {@link org.apache.hadoop.hive.ql.optimizer.calcite.reloperators.HiveSortLimit}. + * Note that this is different from HiveSortRemoveRule because this is not based on statistics + */ +public class HiveSortLimitRemoveRule extends RelOptRule { + + //~ Constructors ----------------------------------------------------------- + + public HiveSortLimitRemoveRule() { + this(operand(HiveSortLimit.class, any())); + } + + private HiveSortLimitRemoveRule(RelOptRuleOperand operand) { + super(operand); + } + + //~ Methods ---------------------------------------------------------------- + + @Override + public boolean matches(RelOptRuleCall call) { + final HiveSortLimit sortLimit = call.rel(0); + + return HiveRelOptUtil.produceAtmostOneRow(sortLimit.getInput()); Review comment: The rules should be portable between planners, i.e., a rule should not be unwrapping a HepRelVertex. If you want to remain generic, a workaround is matching RelNode. However, I would try to make the rule matchers as restrictive as possible, since the more information we expose to the planner, the smarter decisions it can make, e.g., avoiding unnecessary triggering of rules. You do not need recursion. When the rule is executed, we should not have multiple consecutive Project operators in the plan. If there were, we would get rid of them using ProjectMerge and ProjectRemove rules. ---------------------------------------------------------------- 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
