| /* |
| * 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; |
| |
| import java.util.Collections; |
| |
| import org.apache.calcite.plan.Context; |
| import org.apache.calcite.plan.Contexts; |
| import org.apache.calcite.plan.RelOptCluster; |
| import org.apache.calcite.plan.RelOptSchema; |
| import org.apache.calcite.rel.RelNode; |
| import org.apache.calcite.rel.core.RelFactories; |
| import org.apache.calcite.tools.RelBuilder; |
| import org.apache.calcite.tools.RelBuilderFactory; |
| import org.apache.calcite.util.Util; |
| |
| public class DrillRelBuilder extends RelBuilder { |
| public static final int DISABLE_MERGE_PROJECT = -1; |
| private final RelFactories.FilterFactory filterFactory; |
| |
| protected DrillRelBuilder(Context context, RelOptCluster cluster, RelOptSchema relOptSchema) { |
| super(context, cluster, relOptSchema); |
| this.filterFactory = |
| Util.first(context.unwrap(RelFactories.FilterFactory.class), |
| RelFactories.DEFAULT_FILTER_FACTORY); |
| } |
| |
| /** |
| * Original method {@link RelBuilder#empty} returns empty values rel. |
| * In the order to preserve data row types, filter with false predicate is created. |
| */ |
| @Override |
| public RelBuilder empty() { |
| // pops the frame from the stack and returns its relational expression |
| RelNode relNode = build(); |
| |
| // creates filter with false in the predicate |
| final RelNode filter = filterFactory.createFilter(relNode, |
| cluster.getRexBuilder().makeLiteral(false), Collections.emptySet()); |
| push(filter); |
| |
| return this; |
| } |
| |
| /** Creates a {@link RelBuilderFactory}, a partially-created DrillRelBuilder. |
| * Just add a {@link RelOptCluster} and a {@link RelOptSchema} */ |
| public static RelBuilderFactory proto(final Context context) { |
| Config conf = Util.first(context.unwrap(Config.class), Config.DEFAULT) |
| .withBloat(DISABLE_MERGE_PROJECT) |
| .withSimplify(false); |
| Context drillContext = Contexts.chain(Contexts.of(conf), context); |
| return (cluster, schema) -> new DrillRelBuilder(drillContext, cluster, schema); |
| } |
| |
| /** Creates a {@link RelBuilderFactory} that uses a given set of factories. */ |
| public static RelBuilderFactory proto(Object... factories) { |
| return proto(Contexts.of(factories)); |
| } |
| |
| } |