14.2.2　Pig的下载、安装和配置

当前Pig最新版本为0.10.0，除此之外，Pig还有其他版本，如0.9.2、0.8.1两个版本，用户可以根据需要从Apache官方网站上下载相应的版本。本书使用最新版的Pig 0.10.0，安装包下载地址如下：

http：//www.apache.org/dyn/closer.cgi/pig

Pig的安装包下载完成后，需要使用tar-xvf pig-..*.tar.gz命令将其解压。我们可以将Pig放在系统中的任意位置上，并且只需要配置相应的环境变量就可以使用Pig了。不过我们建议将Pig放在Hadoop目录下，方便以后的操作。

解压完成后，需要设置Pig相应的环境变量。环境变量有多种设置方法，用户可以根据自己的需要进行选择。这里我们选择对profile文件进行修改，来设置Pig相应的环境变量。打开“/etc/profile”文件，插入下面的一条语句，保存关闭文件后需要重启系统以使环境变量设置生效：

export PIG_HOME=/＜path-to-pigDir＞

export PATH=$PIG_HOME/bin：$PIG_HOME/conf：$PATH

当环境变量设置生效后，我们可以通过“pig-help”命令来查看Pig是否安装成功。Pig安装成功后会出现如下所示的提示：

hadoop@master：～/hadoop-1.0.1/pig-0.10.0$pig-help

Apache Pig version 0.10.0（r1328203）

compiled Apr 19 2012，22：54：12

USAGE：Pig[options][-]：Run interactively in grunt shell.

Pig[options]-e[xecute]cmd[cmd……]：Run cmd（s）.

Pig[options][-f[ile]]file：Run cmds found in file.

options include：

-4，-log4jconf-Log4j configuration file, overrides log conf

-b，-brief-Brief logging（no timestamps）

-c，-check-Syntax check

-d，-debug-Debug level, INFO is default

-e，-execute-Commands to execute（within quotes）

-f，-file-Path to the script to execute

-g，-embedded-ScriptEngine classname or keyword for the ScriptEngine

-h，-help-Display this message.You can specify topic to get help for that topic.

properties is the only topic currently supported：-h properties.

-i，-version-Display version information

-l，-logfile-Path to client side log file；default is current working directory.

-m，-param_file-Path to the parameter file

-p，-param-Key value pair of the form param=val

-r，-dryrun-Produces script with substituted parameters.Script is not executed.

-t，-optimizer_off-Turn optimizations off.The following values are supported：

SplitFilter-Split filter conditions

PushUpFilter-Filter as early as possible

MergeFilter-Merge filter conditions

PushDownForeachFlatten-Join or explode as late as possible

LimitOptimizer-Limit as early as possible

ColumnMapKeyPrune-Remove unused data

AddForEach-Add ForEach to remove unneeded columns

MergeForEach-Merge adjacent ForEach

GroupByConstParallelSetter-Force parallel 1 for"group all"statement

All-Disable all optimizations

All optimizations listed here are enabled by default.Optimization values

are case insensitive.

-v，-verbose-Print all error messages to screen

-w，-warning-Turn warning logging on；also turns warning aggregation off

-x，-exectype-Set execution mode：local|mapreduce, default is mapreduce.

-F，-stop_on_failure-Aborts execution on the first failed job；default is off

-M，-no_multiquery-Turn multiquery optimization off；default is on

-P，-propertyFile-Path to property file