Hive笔记--sql语法详解及JavaAPI

Hive SQL 语法详解:http://blog.csdn.net/hguisu/article/details/7256833
Hive SQL 学习笔记(常用):http://blog.sina.com.cn/s/blog_66474b16010182yu.html
Hive中的分区:http://blog.csdn.net/jiedushi/article/details/6660185

Hive基础知识:http://www.csdn.net/article/2014-01-07/2818052-about-hive

HiveJavaAPI:http://787141854-qq-com.iteye.com/blog/2068303
hive的group by速度慢,因为需要用到hadoop的map-reduce。这个可以在spark中实现

启动:hive --service hiveserver2

常用:

建表:CREATE TABLE pokes (foo INT, bar STRING);

建分区表:分区有data和pos, ip的描述:'IP Address of the User',用COMMENT来定义
字段之间用'\t'分割,行之间是断行
如果文件数据是纯文本,可以使用 STORED AS TEXTFILE。如果数据需要压缩,使用 STORED AS SEQUENCE

CREATE TABLE par_table(viewTime INT, userid BIGINT,
     page_url STRING, referrer_url STRING,
     ip STRING COMMENT 'IP Address of the User')
 COMMENT 'This is the page view table'
PARTITIONED BY(date STRING, pos STRING)
   ROW FORMAT DELIMITED
   FIELDS TERMINATED BY '\t'
   lines terminated by '\n'
STORED AS SEQUENCEFILE;
 
对分区的操作
(1). 如何定义分区,创建分区   
创建分区表:
hive> create table test(name string,sex int) partitioned by (birth string, age string);
添加3个分区:
hive> alter table test  add partition (birth='1980', age ='30');
hive> alter table test  add partition (birth='1981', age ='29');

hive> alter table test  add partition (birth='1982', age ='28');

hive> show partitions test;

birth=1980/age =30

birth=1981/age =29

birth=1982/age =28

(2)如何删除分区
hive> alter table test drop partition (birth='1980',age='30');

(3)加载数据到指定分区
load data local inpath '/home/hadoop/data.log' overwrite into table test partition(birth='1980-01-01',age='30');

创建分区原则: 最少粒度原则

(4)向partition_test的分区中插入数据:
hive> insert overwrite table partition_test
partition(stat_date='20110728',province='henan') select member_id,name
from partition_test_input where stat_date='20110728' and
province='henan';

 
(5)选择某一个分区的所有数据
select * from test where (birth = '1982')
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