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To run a JNI program on a Hadoop cluster, the first thing to do is to debug the program on a stand-alone computer until the JNI program is properly run, and then porting to the Hadoop cluster is a good deal. The way Hadoop runs t
Next "Ubuntu Kylin system Installation Hadoop2.6.0"In the previous article, Hadoop Pseudo-distributed is basically well-equipped.The next step is to run a mapreduce program, taking WordCount as an example:1. Build the Implementation class:Cd/usr/local/hadoopmkdir WorkspaceCD WorkspaceGedit Wordcount.javaCopy and paste the code.import java.io.ioexception;import ja
DemandCalculates the frequency of each word in the file. The output results are ordered in alphabetical order by word. Each word and its frequency occupy one line, and there is a gap between the word and the frequency.For example, enter a file with the following contents:Hello WorldHello HadoopHello MapReducecorresponding to the input sample given above, the output sample is:Hadoop 1Hello 3MapReduce 1World 1Programme developmentFor this case, the following m
I recently discovered in the process of writing code that some of the operations of the Hadoop MapReduce program are time-consuming and can make the program run 1 faster. I don't know if you've ever used that Partioner, this class can help us to export our data to the specified file in a custom way, such as: PRI vate s
The procedure is as follows: PackageCom.lcy.hadoop.examples;Importorg.apache.hadoop.conf.Configuration;Importorg.apache.hadoop.io.IOUtils;ImportOrg.apache.hadoop.io.compress.CompressionCodec;ImportOrg.apache.hadoop.io.compress.CompressionOutputStream;Importorg.apache.hadoop.util.ReflectionUtils; Public classStreamcompressor { Public Static voidMain (string[] args)throwsexception{//TODO auto-generated Method StubString codecclassname=args[0]; ClassClass.forName (codecclassname); Configuration con
Click to view original text Hadoop offers several ways to debug hadoopstreaming that you use to quickly locate problems. Let the Hadoopstreaming program run on the development machine. (Recommended for use at development time)Add mapred.job.tracker=local to the jobconf. The inputs and outputs of the data are from HDFsAt this point, Hadoopstreaming will run the program
link, the general meaning is that to save the table has the same name field, so it is not possible, then the solution is very obvious, let two then the field name is not the same, then give them their alias, then start to modify the code: 1, the initialization configuration is unchanged 2. Read the file unchanged 3, and do not get to two DF (JSON file loaded after loading is two DF), and set the alias Take out two table column names, val c_emp = Df_emp.columns val c_dept = df_dept.columns //Set
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