[Hadoop]Hive r0.9.0中文文档（三）之Hive相关命令

一、Hive命令选项  
Usage:

Usage: hive [-hiveconf x=y]* [<-i filename>]* [<-f filename>|<-e query-string>] [-S]

  -i <filename>             Initialization Sql from file (executed automatically and silently before any other commands)
  -e 'quoted query string'  Sql from command line
  -f <filename>             Sql from file
  -S                        Silent mode in interactive shell where only data is emitted
  -hiveconf x=y             Use this to set hive/hadoop configuration variables. 
  
   -e and -f cannot be specified together. In the absence of these options, interactive shell is started.  However, -i can be used with any other options.

   To see this usage help, run hive -h

下面的例子是做一个命令行的查询： 

$HIVE_HOME/bin/hive -e 'select a.col from tab1 a'

下面的例子是指定Hive配置查询：

$HIVE_HOME/bin/hive -e 'select a.col from tab1 a' -hiveconf hive.exec.scratchdir=/home/my/hive_scratch  -hiveconf mapred.reduce.tasks=32

   
下面的例子是将查询结果导入到文本文件： 

$HIVE_HOME/bin/hive -S -e 'select a.col from tab1 a' > a.txt

下面的例子是使用SQL文件进行操作：

$HIVE_HOME/bin/hive -f /home/my/hive-script.sql

下面的例子是在进入交互式界面之前跑一个初始化的脚本： 

$HIVE_HOME/bin/hive -i /home/my/hive-init.sql

二、hiverc file  

如果没有-i参数，那么hive会直接进入命令行界面，同时会加载HIVE_HOME/bin/.hiverc and $HOME/.hiverc作为初始化所需要的文件

三、hive交互的Shell命令

Command	Description
quit	 Use quit or exit to leave the interactive shell.
set key=value	 Use this to set value of particular configuration variable. One thing to note here is that if you misspell the variable name, cli will not show an error.
set	 This will print a list of configuration variables that are overridden by user or hive.
set -v	 This will print all hadoop and hive configuration variables.
add FILE [file] [file]*	 Adds a file to the list of resources
list FILE	 list all the files added to the distributed cache
list FILE [file]*	 Check if given resources are already added to distributed cache
! [cmd]	 Executes a shell command from the hive shell
dfs [dfs cmd]	 Executes a dfs command from the hive shell
[query]	 Executes a hive query and prints results to standard out
source FILE	 Used to execute a script file inside the CLI.

例子：

  hive> set  mapred.reduce.tasks=32;
  hive> set;
  hive> select a.* from tab1;
  hive> !ls;
  hive> dfs -ls;

四、Hive日志  

Hive使用Log4j写日志，这些日志将不会以标准输出方式进行输出，默认情况Hive将使用hive-log4j，配置文件在conf目录下，日志输出在 /tmp/$USER/hive.log 下，日志级别为WARN。 

为了Debug，你可以修改日志的输出格式以及改变日志的输出级别，你可以在命令行下使用以下命令：

$HIVE_HOME/bin/hive -hiveconf hive.root.logger=INFO,console 

hive.root.logger 指定了日志的级别以及日志输出位置，输出在控制台。这样日志不会输出到文件中。 

五、Hive 资源  
hive可以管理查询有效的附加资源到Session中。任何本地的acessible文件会加入到这个session，hive加载这个文件到session中后可以进行相关的map/reduce任务，hive使用haddop cache来处理被加载的文件。

   ADD { FILE[S] | JAR[S] | ARCHIVE[S] } <filepath1> [<filepath2>]*
   LIST { FILE[S] | JAR[S] | ARCHIVE[S] } [<filepath1> <filepath2> ..]
   DELETE { FILE[S] | JAR[S] | ARCHIVE[S] } [<filepath1> <filepath2> ..] 

文件资源仅被添加到目标cache中。Jar资源将被添加到Java classpath中。ARCHIVE资源将被自动添加来描述他们。 
例如： 

hive> add FILE /tmp/tt.py;
hive> list FILES;
/tmp/tt.py
hive> from networks a  MAP a.networkid USING 'python tt.py' as nn where a.ds = '2009-01-04' limit  10;

如果命令在所有节点上均有效就没有必要加入到Session中. For example:

... MAP a.networkid USING 'wc -l' ...: here wc is an executable available on all machines
... MAP a.networkid USING '/home/nfsserv1/hadoopscripts/tt.py' ...: here tt.py may be accessible via a nfs mount point that's configured identically on all the 

cluster nodes.