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Hadoop overview Hadoop composition HDFS Architecture Overview Hadoop Distributed File System (HDFS for short) is a distributed file system. NameNode (nn): stores the metadata of the file. Such as file name, file directory structure, file attributes (generation time, number of copies, file permissions), block list of each file, DataNo ...

1. Debug environment preparation 1.1 Debug code: MR classic introduction case WordCount 1.1.1 Mapper class public class WordCountMapper extends Mapper<LongWritable, Text,Text,LongWritable> { @Override protected void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException { String ...

Some experience on the use of HDFS Write before: I've been working on big data in the company for some time. Take time to sort out the problems encountered and some better optimization methods. 1.HDFS storage multi directory 1.1 production server disk 1.2 on HDFS site Configure multiple directories in the XML file, and pay attention t ...

1, Environment introduction Install the Ubuntu virtual machine using VirtualBox. Install Hadoop and Eclipse 3.0 in Ubuntu 8 compiler. Download and install JAVA environment, Download jdk and complete the pseudo distributed environment configuration of Hadoop. Import all the required JAR packages encountered by the compiler in Eclipse. Start Had ...

Preface - From Wan Junfeng Kevin The average delay of the service is basically about 30ms. One of the very big prerequisites is that we make extensive use of MapReduce technology, so that even if our service calls many services, it often depends only on the duration of the slowest request. For your existing services, you do not need to opti ...

To see which compression algorithms hadoop has [lqs@bdc112 hadoop-3.1.3]$ bin/hadoop checknative 2021-12-15 16:20:12,342 INFO bzip2.Bzip2Factory: Successfully loaded & initialized native-bzip2 library system-native 2021-12-15 16:20:12,345 INFO zlib.ZlibFactory: Successfully loaded & initialized native-zlib library 2021-12-15 16:20:12,3 ...

prerequisite: Install Hadoop 2 7.3 (under Linux system) Install MySQL (under Windows or Linux system) Install Hive (under Linux system) reference: Hive installation configuration Title: Download search data from Sogou lab for analysis The downloaded data contains 6 fields, and the data format is described as follows: Access time user ID ...

This paper is based on the realization of the function of counting the total salary of employees in each department. If it has not been realized, please refer to: Realize the function of counting the total salary of employees in each department Optimization project: 1. Use serialization 2. Implement partition partition 3.Map uses Combiner ...

Pre-environment You need to set up a hadoop pseudo-distributed cluster platform, which you can see in this tutorial Quick Start Tutorial for Hadoop Big Data Technology and Pseudo-Distributed Clustering Eclipse Environment Configuration Eclipse(Windows Local System) 1. Install plug-ins: hadoop-eclipse-plugin-2.7.3.jar Address: https:// ...

1, Previously on The last article introduced the Api calling method of MapReduce and the configuration of eclipse. This time, we will use MapReduce to count words in English article files! Welcome to my previous article: MapReduce related eclipse configuration and Api call 2, Preconditions Installation requiredDownload methodIDEAO ...