| /** |
| * 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.tajo.engine.planner.physical; |
| |
| import org.apache.tajo.worker.TaskAttemptContext; |
| import org.apache.tajo.catalog.Schema; |
| import org.apache.tajo.plan.logical.LimitNode; |
| import org.apache.tajo.storage.Tuple; |
| |
| import java.io.IOException; |
| |
| public class LimitExec extends UnaryPhysicalExec { |
| private final long fetchFirstNum; |
| private long fetchCount; |
| |
| public LimitExec(TaskAttemptContext context, Schema inSchema, |
| Schema outSchema, PhysicalExec child, LimitNode limit) { |
| super(context, inSchema, outSchema, child); |
| this.fetchFirstNum = limit.getFetchFirstNum(); |
| this.fetchCount = 0; |
| } |
| |
| @Override |
| public Tuple next() throws IOException { |
| Tuple tuple = child.next(); |
| fetchCount++; |
| |
| if (fetchCount > fetchFirstNum || tuple == null) { |
| return null; |
| } |
| |
| return tuple; |
| } |
| |
| public void rescan() throws IOException { |
| super.init(); |
| fetchCount = 0; |
| } |
| } |