patrick_big_data的博客

Hadoop Streaming Hadoop streaming is a utility that comes with the Hadoop distribution. The utility allows you to create and run Map/Reduce jobs with any executable or script as the mapper and/or the...

Prerequisites(前置条件) Hadoop集群必须安装好，配置好，可正常运行。 Overview(概览) MR(MapReduce简称，下同)任务会将input data-set切片(split)成独立的chunks然后交由map task并行处理，map task的输出经过sort(框架完成)后作为reduce task的输入。MR任务的输入和输出都存放在文件系统如HDFS。 一般来说...

文章目录Counters定义以源码的TaskCounter计数器为例自定义Counter例子 Counters定义 Counters represent global counters, defined either by the MapReduce framework or applications. Each Counter can be of any Enum type. Counters...

预备知识–Java比较器 java.util.Comparator和java.lang.Comparable都是接口，都是用来做对象比较用的。 内部比较器Comparable java.lang.Comparable被称为内部比较器，接口说明里是这样描述的。 This interface imposes a total ordering on the objects of each clas...