Hive简单查询的Fetch Task功能与实战

一 简介

1、从Hive0.10.0版本开始支持。

2、配置方式有三种：

set hive.fetch.task.conversion=more;

hive --hiveconf hive.fetch.task.conversion=more

修改hive-site.xml文件

<property>

<name>hive.fetch.task.conversion</name>

<value>more</value>

</property>

二 实战

1 查询所有员工的所有信息

hive> select * from emp;

OK

1001.0 Tome null 5000.0 10.0

1002.0 Tome null 5000.0 10.0

7369.0 SMITH CLERK 4800.0 20.0

7499.0 ALLEN SALESMAN 5600.0 30.0

7521.0 WARD SALESMAN 5250.0 30.0

7566.0 JONES MANAGER 9075.0 20.0

7654.0 MARTIN SALESMAN 5250.0 30.0

7698.0 BLAKE MANAGER 8850.0 30.0

7782.0 CLARK MANAGER 8450.0 10.0

7788.0 SCOTT ANALYST 7000.0 20.0

7839.0 KING PRESIDENT 12111.0 10.0

7844.0 TURNER SALESMAN 5500.0 30.0

7876.0 ADAMS CLERK 5100.0 20.0

7900.0 JAMES CLERK 4950.0 30.0

7902.0 FORD ANALYST 7000.0 20.0

7934.0 MILLER CLERK 5300.0 10.0

Time taken: 3.664 seconds, Fetched: 16 row(s)

2、查询员工信息：员工号 姓名 月薪

hive> select empno,ename,sal from emp;

OK

1001.0 Tome 5000.0

1002.0 Tome 5000.0

7369.0 SMITH 4800.0

7499.0 ALLEN 5600.0

7521.0 WARD 5250.0

7566.0 JONES 9075.0

7654.0 MARTIN 5250.0

7698.0 BLAKE 8850.0

7782.0 CLARK 8450.0

7788.0 SCOTT 7000.0

7839.0 KING 12111.0

7844.0 TURNER 5500.0

7876.0 ADAMS 5100.0

7900.0 JAMES 4950.0

7902.0 FORD 7000.0

7934.0 MILLER 5300.0

Time taken: 0.166 seconds, Fetched: 16 row(s)

3、查询员工信息：员工号 姓名 月薪 年薪

hive> select empno,ename,sal,sal*12 from emp;

OK

1001.0 Tome 5000.0 60000.0

1002.0 Tome 5000.0 60000.0

7369.0 SMITH 4800.0 57600.0

7499.0 ALLEN 5600.0 67200.0

7521.0 WARD 5250.0 63000.0

7566.0 JONES 9075.0 108900.0

7654.0 MARTIN 5250.0 63000.0

7698.0 BLAKE 8850.0 106200.0

7782.0 CLARK 8450.0 101400.0

7788.0 SCOTT 7000.0 84000.0

7839.0 KING 12111.0 145332.0

7844.0 TURNER 5500.0 66000.0

7876.0 ADAMS 5100.0 61200.0

7900.0 JAMES 4950.0 59400.0

7902.0 FORD 7000.0 84000.0

7934.0 MILLER 5300.0 63600.0

Time taken: 0.184 seconds, Fetched: 16 row(s)