amaliujia commented on a change in pull request #2329: URL: https://github.com/apache/calcite/pull/2329#discussion_r562121640
########## File path: core/src/main/java/org/apache/calcite/adapter/enumerable/EnumerableMergeUnionRule.java ########## @@ -0,0 +1,97 @@ +/* + * 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.calcite.adapter.enumerable; + +import org.apache.calcite.plan.RelOptRuleCall; +import org.apache.calcite.plan.RelRule; +import org.apache.calcite.rel.RelCollation; +import org.apache.calcite.rel.RelNode; +import org.apache.calcite.rel.core.Sort; +import org.apache.calcite.rel.core.Union; +import org.apache.calcite.rel.logical.LogicalSort; +import org.apache.calcite.rel.logical.LogicalUnion; +import org.apache.calcite.rex.RexLiteral; +import org.apache.calcite.rex.RexNode; + +import java.util.ArrayList; +import java.util.List; + +/** + * Rule to convert a {@link org.apache.calcite.rel.logical.LogicalSort} on top of a + * {@link org.apache.calcite.rel.logical.LogicalUnion} into a {@link EnumerableMergeUnion}. + * + * @see EnumerableRules#ENUMERABLE_MERGE_UNION_RULE + */ +public class EnumerableMergeUnionRule extends RelRule<EnumerableMergeUnionRule.Config> { + + /** Rule configuration. */ + public interface Config extends RelRule.Config { + Config DEFAULT_CONFIG = EMPTY.withDescription("EnumerableMergeUnionRule").withOperandSupplier( + b0 -> b0.operand(LogicalSort.class).oneInput( + b1 -> b1.operand(LogicalUnion.class).anyInputs())).as(Config.class); + + @Override default EnumerableMergeUnionRule toRule() { + return new EnumerableMergeUnionRule(this); + } + } + + public EnumerableMergeUnionRule(Config config) { + super(config); + } + + @Override public void onMatch(RelOptRuleCall call) { + final Sort sort = call.rel(0); + final RelCollation collation = sort.getCollation(); + if (collation == null || collation.getFieldCollations().isEmpty()) { + return; + } + + final Union union = call.rel(1); + final int unionInputsSize = union.getInputs().size(); + if (unionInputsSize < 2) { + return; + } + + // Push down sort limit, if possible. + RexNode inputFetch = null; + if (sort.fetch != null) { + if (sort.offset == null) { + inputFetch = sort.fetch; + } else if (sort.fetch instanceof RexLiteral && sort.offset instanceof RexLiteral) { + inputFetch = call.builder().literal( + RexLiteral.intValue(sort.fetch) + RexLiteral.intValue(sort.offset)); + } + } + + final List<RelNode> inputs = new ArrayList<>(unionInputsSize); + for (RelNode input : union.getInputs()) { + final RelNode newInput = sort.copy(sort.getTraitSet(), input, collation, null, inputFetch); Review comment: Yes that's the good point :) ---------------------------------------------------------------- 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]
