Hive学习笔记02.txt

1:表的重命名
alter table log_message rename to logmsgs;


2:新增加表分区
alter table log_message add if not exists
PARTITION (year='2013',month='10',day='11') LOCATION '/user/hadoop/warehouse/table_name';


ALTER TABLE table_name ADD PARTITION (partCol = 'value1') location 'loc1'; //示例


ALTER TABLE table_name ADD IF NOT EXISTS 
PARTITION (dt='20130101') LOCATION '/user/hadoop/warehouse/table_name'; //一次添加一个分区


ALTER TABLE page_view ADD 
PARTITION (dt='2008-08-07', country='us') location '/path/to/us/part080807'
PARTITION (dt='2008-08-08', country='us') location '/path/to/us/part080808'
PARTITION (dt='2008-08-09', country='us') location '/path/to/us/part080809';  //一次添加多个分区


3:高效的移动位置来修改某个分区的路径
alter table log_message  PARTITION (year='2013',month='10',day='11') 
set LOCATION 's3n://ourbucket/2013/10/11';




4删除分区
alter table log_message  drop if exists PARTITION (year='2013',month='10',day='11') 
ALTER TABLE login DROP IF EXISTS PARTITION (dt='2008-08-08');
ALTER TABLE page_view DROP IF EXISTS PARTITION (dt='2008-08-08', country='us');
 


5：修改分区


ALTER TABLE table_name PARTITION (dt='2008-08-08') SET LOCATION "new location";
ALTER TABLE table_name PARTITION (dt='2008-08-08') RENAME TO PARTITION (dt='20080808');


6： 动态分区
insert overwrite  table employees
partition(country,state)
select ...,se.cnty,se.st  from staged_employees  se;


7:动态分区  和静态分区相结合：但是静态分区必须放在动态分区键的之前


insert overwrite  table employees
partition(country='US',state)
select ...,se.cnty,se.st  from staged_employees  se  where se.cnty='US';


8：单个查询语句中，创建表并加载数据
create table ca_employees  as 
select name,salary,address from employess  se where  se.state='CA';


9: 导出数据
9.1: 不指定分隔符
insert overwrite local directory '/home/admin/xxg/qz/acc/'
select * from employee;


9.2:指定分隔符
insert overwrite local directory '/home/admin/xxg/qz/acc/'
row format delimited
fields terminated by '\t'
select * from  paper_count ;




select  count(distinct userid) from qz_count  where doQuesCount>=500 order by   doQuesCount  desc ;


select   distinct userid  from qz_count  where doQuesCount>=500 
group by  userid  limit 100;