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本章将介绍如何在系统中下载,安装和设置 Apache Pig

先决条件

在你运行Apache Pig之前,必须在系统上安装好Hadoop和Java。因此,在安装Apache Pig之前,请按照以下链接中提供的步骤安装Hadoop和Java:/hadoop/hadoop_enviornment_setup.htm

下载Apache Pig

首先,从以下网站下载最新版本的Apache Pig:https://pig.apache.org/

步骤1

打开Apache Pig网站的主页。News部分下,点击链接release page,如下面的快照所示。

Home Page

步骤2

点击指定的链接后,你将被重定向到 Apache Pig Releases 页面。在此页面的Download部分下,单击链接,然后你将被重定向到具有一组镜像的页面。

Apache Pig Releases

步骤3

选择并单击这些镜像中的任一个,如下所示。

click mirrors

步骤4

这些镜像将带您进入 Pig Releases 页面。 此页面包含Apache Pig的各种版本。 单击其中的最新版本。

Pig Release

步骤5

在这些文件夹中,有发行版中的Apache Pig的源文件和二进制文件。下载Apache Pig 0.16, pig0.16.0-src.tar.gz pig-0.16.0.tar.gz 的源和二进制文件的tar文件。

Pig Index

安装Apache Pig

下载Apache Pig软件后,按照以下步骤将其安装在Linux环境中。

步骤1

在安装了 Hadoop,Java和其他软件的安装目录的同一目录中创建一个名为Pig的目录。(在我们的教程中,我们在名为Hadoop的用户中创建了Pig目录)。

$ mkdir Pig

第2步

提取下载的tar文件,如下所示。

$ cd Downloads/ 
$ tar zxvf pig-0.15.0-src.tar.gz 
$ tar zxvf pig-0.15.0.tar.gz 

步骤3

pig-0.16.0-src.tar.gz 文件的内容移动到之前创建的 Pig 目录,如下所示。

$ mv pig-0.16.0-src.tar.gz/* /home/Hadoop/Pig/

配置Apache Pig

安装Apache Pig后,我们必须配置它。要配置,我们需要编辑两个文件 - bashrcpig.properties

.bashrc文件

.bashrc 文件中,设置以下变量

  • PIG_HOME 文件夹复制到Apache Pig的安装文件夹

  • PATH 环境变量复制到bin文件夹

  • PIG_CLASSPATH 环境变量复制到安装Hadoop的etc(配置)文件夹(包含core-site.xml,hdfs-site.xml和mapred-site.xml文件的目录)。

export PIG_HOME = /home/Hadoop/Pig
export PATH  = PATH:/home/Hadoop/pig/bin
export PIG_CLASSPATH = $HADOOP_HOME/conf

pig.properties文件

在Pig的 conf 文件夹中,我们有一个名为 pig.properties 的文件。在pig.properties文件中,可以设置如下所示的各种参数。

pig -h properties 

支持以下属性:

Logging: verbose = true|false; default is false. This property is the same as -v
       switch brief=true|false; default is false. This property is the same 
       as -b switch debug=OFF|ERROR|WARN|INFO|DEBUG; default is INFO.             
       This property is the same as -d switch aggregate.warning = true|false; default is true. 
       If true, prints count of warnings of each type rather than logging each warning.		 
		 
Performance tuning: pig.cachedbag.memusage=<mem fraction>; default is 0.2 (20% of all memory).
       Note that this memory is shared across all large bags used by the application.         
       pig.skewedjoin.reduce.memusagea=<mem fraction>; default is 0.3 (30% of all memory).
       Specifies the fraction of heap available for the reducer to perform the join.
       pig.exec.nocombiner = true|false; default is false.
           Only disable combiner as a temporary workaround for problems.         
       opt.multiquery = true|false; multiquery is on by default.
           Only disable multiquery as a temporary workaround for problems.
       opt.fetch=true|false; fetch is on by default.
           Scripts containing Filter, Foreach, Limit, Stream, and Union can be dumped without MR jobs.         
       pig.tmpfilecompression = true|false; compression is off by default.             
           Determines whether output of intermediate jobs is compressed.         
       pig.tmpfilecompression.codec = lzo|gzip; default is gzip.
           Used in conjunction with pig.tmpfilecompression. Defines compression type.         
       pig.noSplitCombination = true|false. Split combination is on by default.
           Determines if multiple small files are combined into a single map.         
			  
       pig.exec.mapPartAgg = true|false. Default is false.             
           Determines if partial aggregation is done within map phase, before records are sent to combiner.         
       pig.exec.mapPartAgg.minReduction=<min aggregation factor>. Default is 10.             
           If the in-map partial aggregation does not reduce the output num records by this factor, it gets disabled.
			  
Miscellaneous: exectype = mapreduce|tez|local; default is mapreduce. This property is the same as -x switch
       pig.additional.jars.uris=<comma seperated list of jars>. Used in place of register command.
       udf.import.list=<comma seperated list of imports>. Used to avoid package names in UDF.
       stop.on.failure = true|false; default is false. Set to true to terminate on the first error.         
       pig.datetime.default.tz=<UTC time offset>. e.g. +08:00. Default is the default timezone of the host.
           Determines the timezone used to handle datetime datatype and UDFs.
Additionally, any Hadoop property can be specified.

验证安装

通过键入version命令验证Apache Pig的安装。如果安装成功,你将获得Apache Pig的正式版本,如下所示。

$ pig –version 
 
Apache Pig version 0.16.0 (r1682971)  
compiled Jun 01 2015, 11:44:35