| /* |
| * 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; |
| |
| import com.google.common.base.Function; |
| import com.google.common.collect.Iterables; |
| import com.google.common.collect.Lists; |
| import org.apache.commons.lang.StringUtils; |
| import org.apache.druid.java.util.common.ISE; |
| import org.apache.druid.java.util.common.Pair; |
| import org.apache.druid.java.util.common.guava.MergeSequence; |
| import org.apache.druid.java.util.common.guava.Sequence; |
| import org.apache.druid.java.util.common.guava.Sequences; |
| import org.apache.druid.query.context.ResponseContext; |
| import org.apache.druid.query.planning.DataSourceAnalysis; |
| |
| import java.util.stream.Collectors; |
| import java.util.stream.IntStream; |
| |
| public class UnionQueryRunner<T> implements QueryRunner<T> |
| { |
| private final QueryRunner<T> baseRunner; |
| |
| public UnionQueryRunner( |
| QueryRunner<T> baseRunner |
| ) |
| { |
| this.baseRunner = baseRunner; |
| } |
| |
| @Override |
| public Sequence<T> run(final QueryPlus<T> queryPlus, final ResponseContext responseContext) |
| { |
| Query<T> query = queryPlus.getQuery(); |
| |
| final DataSourceAnalysis analysis = DataSourceAnalysis.forDataSource(query.getDataSource()); |
| |
| if (analysis.isConcreteTableBased() && analysis.getBaseUnionDataSource().isPresent()) { |
| // Union of tables. |
| |
| final UnionDataSource unionDataSource = analysis.getBaseUnionDataSource().get(); |
| |
| if (unionDataSource.getDataSources().isEmpty()) { |
| // Shouldn't happen, because UnionDataSource doesn't allow empty unions. |
| throw new ISE("Unexpectedly received empty union"); |
| } else if (unionDataSource.getDataSources().size() == 1) { |
| // Single table. Run as a normal query. |
| return baseRunner.run( |
| queryPlus.withQuery( |
| Queries.withBaseDataSource( |
| query, |
| Iterables.getOnlyElement(unionDataSource.getDataSources()) |
| ) |
| ), |
| responseContext |
| ); |
| } else { |
| // Split up the tables and merge their results. |
| return new MergeSequence<>( |
| query.getResultOrdering(), |
| Sequences.simple( |
| Lists.transform( |
| IntStream.range(0, unionDataSource.getDataSources().size()) |
| .mapToObj(i -> new Pair<>(unionDataSource.getDataSources().get(i), i + 1)) |
| .collect(Collectors.toList()), |
| (Function<Pair<TableDataSource, Integer>, Sequence<T>>) singleSourceWithIndex -> |
| baseRunner.run( |
| queryPlus.withQuery( |
| Queries.withBaseDataSource(query, singleSourceWithIndex.lhs) |
| // assign the subqueryId. this will be used to validate that every query servers |
| // have responded per subquery in RetryQueryRunner |
| .withSubQueryId(generateSubqueryId( |
| query.getSubQueryId(), |
| singleSourceWithIndex.lhs.getName(), |
| singleSourceWithIndex.rhs |
| )) |
| ), |
| responseContext |
| ) |
| ) |
| ) |
| |
| ); |
| } |
| } else { |
| // Not a union of tables. Do nothing special. |
| return baseRunner.run(queryPlus, responseContext); |
| } |
| } |
| |
| /** |
| * Appends and returns the name and the position of the individual datasource in the union with the parent query id |
| * if preseent |
| * |
| * @param parentSubqueryId The subquery Id of the parent query which is generating this subquery |
| * @param dataSourceName Name of the datasource for which the UnionRunner is running |
| * @param dataSourceIndex Position of the datasource for which the UnionRunner is running |
| * @return Subquery Id which needs to be populated |
| */ |
| private String generateSubqueryId(String parentSubqueryId, String dataSourceName, int dataSourceIndex) |
| { |
| String dataSourceNameIndex = dataSourceName + "." + dataSourceIndex; |
| if (StringUtils.isEmpty(parentSubqueryId)) { |
| return dataSourceNameIndex; |
| } |
| return parentSubqueryId + "." + dataSourceNameIndex; |
| } |
| } |