Github user julianhyde commented on a diff in the pull request: https://github.com/apache/drill/pull/193#discussion_r45012029 --- Diff: exec/java-exec/src/main/java/org/apache/drill/exec/planner/logical/DrillDirectScanRel.java --- @@ -0,0 +1,111 @@ +/** + * 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.drill.exec.planner.logical; + +import com.google.common.collect.Iterators; +import org.apache.calcite.plan.RelOptCluster; +import org.apache.calcite.plan.RelTraitSet; +import org.apache.calcite.rel.AbstractRelNode; +import org.apache.calcite.rel.RelWriter; +import org.apache.calcite.rel.type.RelDataType; +import org.apache.drill.common.logical.data.LogicalOperator; +import org.apache.drill.exec.physical.base.PhysicalOperator; +import org.apache.drill.exec.planner.physical.DrillScanPrel; +import org.apache.drill.exec.planner.physical.PhysicalPlanCreator; +import org.apache.drill.exec.planner.physical.PlannerSettings; +import org.apache.drill.exec.planner.physical.Prel; +import org.apache.drill.exec.planner.physical.PrelUtil; +import org.apache.drill.exec.planner.physical.visitor.PrelVisitor; +import org.apache.drill.exec.record.BatchSchema; +import org.apache.drill.exec.store.direct.DirectGroupScan; + +import java.io.IOException; +import java.util.Iterator; + +/** + * Logical and physical RelNode representing a {@link DirectGroupScan}. This is not backed by a {@link DrillTable}, + * unlike {@link DrillScanRel}. + */ +public class DrillDirectScanRel extends AbstractRelNode implements DrillScanPrel, DrillRel { --- End diff -- Yeah, I think DrillDirectScanRel is a wrong turn for this functionality, because you can't see that it is empty and reason about it. A DirectGroupScan is a runtime thing, so shouldn't be floating around at planning time. I notice that DrillValuesRel does not extend Values. If it did, it would get all of the rules in PruneEmptyRules for free - pruning away Filter, Project etc. on top of it.
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