HQL operate daily use Command Summary

To build the table

create table mydb.userinfo(name string,addressi string)
ROW FORMAT DELIMITED
FIELDS TERMINATED BY '\t'
LINES TERMINATED BY '\n'
STORED AS TEXTFILE;

Create a partition table

CREATE TABLE mydb.userinfo    --创建表
(col1 string, col2 date, col3 double), 
partitioned by (datekey date),  --可以多个字段的组合分区 
ROW FORMAT DELIMITED 
FIELDS TERMINATED BY ',' 
Stored AS TEXTFILE;

Data into the table mydb.userinfo

load data local inpath "/home/dahaizi/data/userinfo.txt" 
overwrite into table mydb.userinfo;

Inserting data into the table

insert into table(col1,col2,col3) values('a','b','c')

The query data is inserted into an existing table

INSERT INTO TABLE table_Name
PARTITION (DateKey),
SELECT col1,col2,col3,DateKey FROM otherTable
WHERE DATEKEY IN ('2017-02-26','2013-06-12','2013-09-24'),
GROUP BY col1,col2,col3,DateKey
DISTRIBUTE BY DateKey

The hdfs catalog query data stored

insert overwrite directory '/jc_bdcqs/qsy'
row format delimited
fields terminated by ','
select * from zqs_gs_g60_0730_list;
!quit

HQL queries Common settings

1) Set the fault rate is calculated (to prevent an error calculation program aborted):
set mapred.max.map.failures.percent=100;
2) limit the number of query output file
set mapred.reduce.tasks=1;
3) reduce the maximum number of the control, does not affect the setting mapred.reduce.tasks
set hive.exec.reducers.max = 100;
4) a job will how many reducer to deal with, the default is 1G
set hive.exec.reducers.bytes.per.reducer = 1000000000;

Set dynamic partitioning

set hive.exec.dynamic.partition=true;(可通过这个语句查看：set hive.exec.dynamic.partition;), 
set hive.exec.dynamic.partition.mode=nonstrict; 
SET hive.exec.max.dynamic.partitions=100000;(如果自动分区数大于这个参数，将会报错),
SET hive.exec.max.dynamic.partitions.pernode=100000;

Delete table

drop table tb_name;
Or empty table
truncate table table_name;

Delete partition

ALTER TABLE table_Name DROP PARTITION (Datekey='20190606');

New zoning

alter table tb_name add partition (Datekey = ‘20190606’);