| // 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.impala.planner; |
| |
| import java.util.List; |
| |
| import org.apache.impala.analysis.Analyzer; |
| import org.apache.impala.analysis.TupleId; |
| import org.apache.impala.thrift.TExplainLevel; |
| import org.apache.impala.thrift.TPlanNode; |
| import org.apache.impala.thrift.TPlanNodeType; |
| import org.apache.impala.thrift.TQueryOptions; |
| |
| import com.google.common.base.Preconditions; |
| |
| /** |
| * Node that returns an empty result set. Used for planning query blocks with a constant |
| * predicate evaluating to false or a limit 0. The result set will have zero rows, but |
| * the row descriptor must still include a materialized tuple so that the backend can |
| * construct a valid row empty batch. |
| */ |
| public class EmptySetNode extends PlanNode { |
| public EmptySetNode(PlanNodeId id, List<TupleId> tupleIds) { |
| super(id, tupleIds, "EMPTYSET"); |
| Preconditions.checkArgument(tupleIds.size() > 0); |
| } |
| |
| @Override |
| public void computeStats(Analyzer analyzer) { |
| avgRowSize_ = 0; |
| cardinality_ = 0; |
| numNodes_ = 1; |
| } |
| |
| @Override |
| public void init(Analyzer analyzer) { |
| Preconditions.checkState(conjuncts_.isEmpty()); |
| // If the physical output tuple produced by an AnalyticEvalNode wasn't created |
| // the logical output tuple is returned by getMaterializedTupleIds(). It needs |
| // to be set as materialized (even though it isn't) to avoid failing precondition |
| // checks generating the thrift for slot refs that may reference this tuple. |
| for (TupleId id: tupleIds_) analyzer.getTupleDesc(id).setIsMaterialized(true); |
| computeMemLayout(analyzer); |
| computeStats(analyzer); |
| } |
| |
| @Override |
| public void computeNodeResourceProfile(TQueryOptions queryOptions) { |
| // TODO: add an estimate |
| nodeResourceProfile_ = ResourceProfile.noReservation(0); |
| } |
| |
| @Override |
| protected String getNodeExplainString(String prefix, String detailPrefix, |
| TExplainLevel detailLevel) { |
| return String.format("%s%s:%s\n", prefix, id_.toString(), displayName_); |
| } |
| |
| @Override |
| protected void toThrift(TPlanNode msg) { |
| msg.node_type = TPlanNodeType.EMPTY_SET_NODE; |
| } |
| |
| @Override |
| protected boolean displayCardinality(TExplainLevel detailLevel) { return false; } |
| } |