Analysis of Terasort algorithm in Hadoop
1. Overview
1TB sequencing is typically used to measure the data processing capabilities of a distributed data processing framework. Terasort is a sort job in Hadoop, and in 2008, Hadoop won the first place in the 1TB sort benchmark evaluation, taking 209 seconds. So how is te
Why did we put page rank in the hadoop study notes? This is because the first week of the hadoop course focused on Google's three major papers (GFS, map-Reduce and Big Table) and the source of hadoop ideas, PR in the solutions of Page Rank and map-ReduceAlgorithmThe idea of how to use distributed computing to process the Page Rank of trillions of webpages has not
There are different types of nodes in a Hadoop cluster, and their requirements for disk are different. The primary (master) node focuses on storage reliability, and data nodes require better read and write performance and larger capacity.
In a virtual cluster, storage (datastore) can be divided into two types: local and shared. Local storage can only be accessed by virtual machines on the host on which it resides, while shared storage is accessible t
("Kmeansbeijing") val sc = New Sparkcontext (CONF)//load DataSet val data = Sc.textfile ("File:///home/hadoop/yang/USA/AUG_tag.csv", 1) Val Parsedd ATA = Data.filter (!iscolumnnameline (_)). Map (line + vectors.dense (line.split (', '). Map (_.todouble)). Cache ()/// Data aggregation classes, 7 classes, 20 iterations, model training to form a data model Val Numclusters = 4 val numiterations = + val model = Kmeans.train (Parseddata, n Umclusters, num
Error message:Exception in thread "main" Java.lang.NumberFormatException:For input string: "6.50685140537736"At sun.misc.FloatingDecimal.readJavaFormatString (Unknown Source)At Java.lang.Double.parseDouble (Unknown Source)At Yun.testStringToDouble.main (teststringtodouble.java:36)C # Upload data file to, distributed file system, must be uploaded with Ascill code.Finally solved the problem of the above error.Error in algorithm for
Requires first column in ascending order, when the first column is the same, the second column is arranged in ascending order; not much. directly on the code1, the realization of mapper class/** * Mapper class implementation * @author Liuyazhuang * */static class Mymapper extends Mapper2, the realization of reducer class/** * Reducer class implementation * @author Liuyazhuang * */static class Myreducer extends Reducer3.Hadoop--Custom sorting
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