001 /* 002 * Copyright (c) 2007-2015 Concurrent, Inc. All Rights Reserved. 003 * 004 * Project and contact information: http://www.cascading.org/ 005 * 006 * This file is part of the Cascading project. 007 * 008 * Licensed under the Apache License, Version 2.0 (the "License"); 009 * you may not use this file except in compliance with the License. 010 * You may obtain a copy of the License at 011 * 012 * http://www.apache.org/licenses/LICENSE-2.0 013 * 014 * Unless required by applicable law or agreed to in writing, software 015 * distributed under the License is distributed on an "AS IS" BASIS, 016 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 017 * See the License for the specific language governing permissions and 018 * limitations under the License. 019 */ 020 021 package cascading.pipe; 022 023 import java.beans.ConstructorProperties; 024 025 /** 026 * The Merge Pipe allows for multiple branches, with the same fields to be spliced back into a single stream. 027 * <p/> 028 * The behavior is similar to the {@link GroupBy} merging features, but Merge does not perform any grouping or 029 * sorting on keys. Thus, when using a MapReduce platform, no Reducer is required. 030 * <p/> 031 * Merge is non-blocking and performs no processing. Any number of branches and merges may be performed in a 032 * {@link cascading.flow.Flow} without triggering any additional MapReduce jobs on the Hadoop platform. 033 * <p/> 034 * Unlike {@link HashJoin}, no preference need be made for left-hand or right-hand sided-ness of streams in relation 035 * to their sizes. 036 * 037 * @see GroupBy 038 */ 039 public class Merge extends Splice 040 { 041 /** 042 * Constructor Merge creates a new Merge instance. 043 * 044 * @param pipes 045 */ 046 @ConstructorProperties({"pipes"}) 047 public Merge( Pipe... pipes ) 048 { 049 super( null, pipes ); 050 } 051 052 /** 053 * Constructor Merge creates a new Merge instance. 054 * 055 * @param name 056 * @param pipes 057 */ 058 @ConstructorProperties({"name", "pipes"}) 059 public Merge( String name, Pipe... pipes ) 060 { 061 super( name, pipes ); 062 } 063 }