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Hive的动态分区

程序员文章站 2022-07-06 10:39:57
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一、简介

当使用静态分区时,在向分区表中插入数据时,我们需要指定具体分区列的值。此外,hive还支持动态提供分区值(即在插入数据时,不指定具体的分区列值,而是仅仅指定分区字段)。动态分区在默认情况下是禁用的(在hive2.3.4版本中默认是开启的,在hive-default.xml.template文件中进行配置),所以需要将hive.exec.dynamic.partition设为true。默认情况下,用户必须至少指定一个静态分区列,这是为了避免意外覆盖分区。要禁用此限制,可以设置分区模式为非严格模式(即将hive.exec.dynamic.partition.mode设为nonstrict,默认值为strict)。可以选择在命令行终端方式设置:

>SET hive.exec.dynamic.partition=true;

>SET hive.exec.dynamic.partition.mode=nonstrict;

或者在hive-site.xml中设置:

<property>
    <name>hive.exec.dynamic.partition</name>
    <value>true</value>
    <description>Whether or not to allow dynamic partitions in DML/DDL.</description>
</property>
<property>
    <name>hive.exec.dynamic.partition.mode</name>
    <value>nonstrict</value>
    <description>
      In strict mode, the user must specify at least one static partition
      in case the user accidentally overwrites all partitions.
      In nonstrict mode all partitions are allowed to be dynamic.
    </description>
</property>

二、例子

2.1准备数据

          001,tom,23,2019-03-16
          002,jack,12,2019-03-13
          003,robin,14,2018-08-13
          004,justin,34,2018-10-12
          005,jarry,24,2017-11-11
          006,jasper,24,2017-12-12

2.2创建表

(1)创建普通表,用于load数据

create table dynamic_tbl_temp(id int,name string,age int,start_date date)
row format delimited
fields terminated by ','

(2)创建分区表

create table dynamic_tbl(id int,name string,age int,start_date date)
partitioned by (year string,month string)
row format delimited
fields terminated by ','

2.3加载数据

(1)向普通表加载数据

load data local inpath '/opt/modules/data/dynamic.txt' into table dynamic_tbl_temp;

(2)向分区表中插入数据

insert into dynamic_tbl
partition(year,month)
select 
   id,
   name,
   age,
   start_date,
   year(start_date),
   month(start_date)
from
  dynamic_tbl_temp;

2.4查询数据

(1)查询year=2018的数据

select * from dynamic_tbl where year = 2018;

--结果
4       justin  34      2018-10-12      2018    10
3       robin   14      2018-08-13      2018    8

(2)查询year=2017,month=11的数据

select * from dynamic_tbl where year = 2017 and month = 11;

--结果:

5       jarry   24      2017-11-11      2017    11

 

相关标签: hive