Impala常用函数索引

1# 增加X自然天
2select days_add(now(),2)

字符串转Timestamp

select to_timestamp('2019-10-14 20:00:01', 'yyyy-MM-dd HH:mm:ss');

注意，Impala的timestamp的标准是 ISO 8601  参考：https://en.wikipedia.org/wiki/ISO_8601

两个时间戳比较，粒度是天。否则就自己用2个timestamp相减。

select datediff(to_timestamp('2019-10-14', 'yyyy-MM-dd'), to_timestamp('2019-10-10', 'yyyy-MM-dd'));

Timestamp转字符串函数

FROM_TIMESTAMP(TIMESTAMP datetime, STRING pattern), FROM_TIMESTAMP(STRING datetime, STRING pattern)

Purpose: Converts a TIMESTAMP value into a string representing the same value.

Return type: STRING

select FROM_TIMESTAMP(now(),'yyyy-MM-dd HH:mm:ss') ; 

regexp_replace, 使用正则匹配，剔除非中文字符

select regexp_replace('abcd1234中文你好','[^u4e00-u9fa5]+','') ;

Impala split_part函数

select split_part('a,b,c,d',',', 1) ; -- => a

Impala 授权模型使用记录：

1-- 创建角色，角色这个概念，是在Hive和Impala范围的
2create role impala;
3-- server1是一个默认的配置项
4grant all on server server1 to role impala with grant option;
5 
6grant select on database p2plog to role impala ;
7grant all on database p2plog to role impala;
8 
9-- 这个组对应到用户的LDAP所属组
10grant role impala to group impala;
11 
12-- 查看授权
13show roles;
14show current roles;
15show grant role bigdata_risk;
16;
17 
18-- 表级别授权,撤回
19grant select on table xxx_table_name to role role_name1;
20grant ALL | ALTER | CREATE | DROP | INSERT | REFRESH | SELECT | SELECT(column_name) on xxx_table_name to role role_name1;
21revoke update, select on table secured_table from role my_role;
22 
23show grant user user_name1 on table hive_table_name1;
24show grant user user_name1 on all;
25show grant on table hive_table_name1;