optical combiner

Brief IntroductionThe role of combiner is to combine the multiple of a map generation into a new one , and then the new one as the input of reduce;There is a combine function between the map function and the reduce function to reduce the intermediate result of the map output, which reduces the data of the map output and reduces the network transmission load ;It is not possible to use Combiner,

ArticleDirectory Declare combiner Function Many mapreduceProgramLimited by the available bandwidth on the cluster, it will try its best to minimize the intermediate data that needs to be transmitted between map and reduce tasks. Hadoop allows you to declare a combiner function to process map output, and use your own map processing result as the reduce input. Because

One: BackgroundIn the MapReduce model, the function of reduce is mostly statistical classification type of total, the maximum value of the minimum value, etc., for these operations can consider the map output after the combiner operation, so as to reduce network transport load, while reducing the burden of reduce tasks . The combiner operation is run on each node, only affects the output of the local map,

As we all know, the hadoop framework uses Mapper to process data into a In the above process, we can see at least two performance bottlenecks: If we have 1 billion million data records, mapper will generate 1 billion key-value pairs for transmission across the network, but if we only calculate the maximum value for the data, obviously, mapper only needs to output the maximum value it knows. This not only reduces the network pressure, but also greatly improves program efficiency. This defini

What is combiner Functions “Many MapReduce jobs are limited by the bandwidth available on the cluster, so it paysto minimize the data transferred between map and reduce tasks. Hadoop allows the user to specify a combiner function to be run on the map output—the combiner function’soutput forms the input to the reduce function. Since the

1.CombinerCombiner is an optimization method for MapReduce. Each map can generate a large amount of local output, and the Combiner function is to merge the output of the map end first to reduce the amount of data transferred between the map and reduce nodes to improve network IO performance. The combiner can be set only if the operation satisfies the binding law.The role of

Partitioner Programming data that has some common characteristics is written to the same file. Sorting and grouping when sorting in the map and reduce phases, the comparison is K2. V2 are not involved in sorting comparisons. If you want V2 to be sorted, you need to assemble K2 and V2 into new classes as K2,To participate in the comparison. If you want to customize the collation, the sorted object is implementedWritablecomparable interface, implementing collations in the CompareTo method

As we all know, the hadoop framework uses Mapper to process data into a In the above process, we can see at least two performance bottlenecks: If we have 1 billion million data records, mapper will generate 1 billion key-value pairs for transmission across the network, but if we only calculate the maximum value for the data, obviously, mapper only needs to output the maximum value it knows. This not only reduces the network pressure, but also greatly improves program efficiency. This defini

1. Concept2. ReferencesImprove the MapReduce job Efficiency Note II of Hadoop (use combiner as much as possible): Http://sishuo (k). com/forum/blogpost/list/5829.htmlHadoop Learning notes -8.combiner and custom Combiner:http://www.tuicool.com/articles/qazujavHadoop in-depth learning: combiner:http://blog.csdn.net/cnbird2008/article/details/23788233(mean Scene) 0Hadoop using

The bandwidth available on the cluster limits the number of mapreduce jobs, so the most important thing to do is to avoid the data transfer between the map task and the reduce task as much as possible. Hadoop allows users to specify a merge function for the output of the map task, and sometimes we also call it combiner, which is like mapper and reducer.The output of the merge function as input to the reduce function, because the merge function is an o

Li Guangcheng, vice president of Beacon Communications Technology Co., Ltd. The role of optical switching/optical routing in all optical networks With the progress of society, the social demand of the new data business, such as broadband video, multimedia service, ip-based real-time/quasi real time service, which can enrich and improve people's communication ef

Original Author: Li Guangcheng, vice president of beacon Communication Technology Co., Ltd. With the advancement of society, the social needs of emerging data services such as broadband video, multimedia services, real-time and quasi-real-time IP-based services that can greatly enrich and improve the communication performance and quality of people are growing. As emerging businesses consume a large amount of bandwidth resources, high-speed broadband integrated service networks have become the de

Use the disabled optical drive software to teach you how to disable the automatic operation of the optical drive and how to disable the settings of the optical drive in bios.Local networks of enterprises and institutions are in the security management of computer files. You must disable the Use of Computer Optical driv

Q A on knowledge of optical fiber coupler, optical fiber fuse box and optical fiber fuse box Integrated Wiring Read 93 comments 1 Font size: Medium Small The optical fiber coupler is used for two optical fiber or pigtails.Active connection,Flange.

Forty-five traditional knowledge of optical fiber and optical fiber cables 1. Briefly describe the composition of optical fiber. A: The optical fiber consists of two basic parts: the core, package layer and Coating Layer Made of transparent optical materials. 2. What are th

1. Preface A cylindrical media waveguide consists of three parts: Core, package layer, and coating layer. Generally, the diameter of the core of a single-mode or multi-mode optical fiber is 5 ~ 15 μm and 40 ~ 100 μm, with a diameter of about 125 ~ 600 μm. The processed optical fiber end face is ideally a smooth plane. However, in reality, the processing of the optical