Impala之DDL、DML

第5章DDL数据定义

5.1 创建数据库

CREATE DATABASE [IF NOT EXISTS] database_name[COMMENT database_comment][LOCATION hdfs_path];

注：Impala不支持WITH DBPROPERTIE…语法

[hadoop103:21000] > create database db_hive> WITH DBPROPERTIES('name' = 'ttt');
Query: create database db_hive
WITH DBPROPERTIES('name' = 'ttt')
ERROR: AnalysisException: Syntax error in line 2:
WITH DBPROPERTIES('name' = 'ttt')
^
Encountered: WITH
Expected: COMMENT, LOCATION

5.2查询数据库
5.2.1显示数据库

[hadoop103:21000] > show databases;
[hadoop103:21000] > show databases like 'hive*';
Query: show databases like 'hive*'
+---------+---------+
| name    | comment |
+---------+---------+
| hive_db |         |
+---------+---------+
[hadoop103:21000] > desc database hive_db;
Query: describe database hive_db
+---------+----------+---------+
| name    | location | comment |
+---------+----------+---------+
| hive_db |          |         |
+---------+----------+---------+

5.2.2删除数据库

[hadoop103:21000] > drop database hive_db;
[hadoop103:21000] > drop database hive_db cascade;

注：
Impala不支持alter database语法
当数据库被 USE 语句选中时，无法删除

5.3创建表

5.3.1 管理表

[hadoop103:21000] > create table if not exists student2(> id int, name string> )> row format delimited fields terminated by '\t'> stored as textfile> location '/user/hive/warehouse/student2';
[hadoop103:21000] > desc formatted student2;

5.3.2 外部表

[hadoop103:21000] > create external table stu_external(> id int, > name string) > row format delimited fields terminated by '\t' ;

5.4分区表

5.4.1 创建分区表

[hadoop103:21000] > create table stu_par(id int, name string)> partitioned by (month string)> row format delimited > fields terminated by '\t';

5.4.2 向表中导入数据

[hadoop103:21000] > alter table stu_par add partition (month='201810');
[hadoop103:21000] > load data inpath '/student.txt' into table stu_par partition(month='201810');
[hadoop103:21000] > insert into table stu_par partition (month = '201811')> select * from student;

注意：
如果分区没有，load data导入数据时，不能自动创建分区。
5.4.3 查询分区表中的数据

[hadoop103:21000] > select * from stu_par where month = '201811';

5.4.4 增加多个分区

[hadoop103:21000] > alter table stu_par add partition (month='201812') partition (month='201813');

5.4.5 删除分区

[hadoop103:21000] >  alter table stu_par drop partition (month='201812');

5.4.5查看分区

[hadoop103:21000] > show partitions stu_par;

第6章DML数据操作

6.1 数据导入（基本同hive类似）
注意：impala不支持load data local inpath…
6.2 数据的导出
1.impala不支持insert overwrite…语法导出数据
2.impala 数据导出一般使用 impala -o

[root@hadoop103 ~]# impala-shell -q 'select * from student' -B --output_delimiter="\t" -o output.txt
[root@hadoop103 ~]# cat output.txt
1001    tignitgn
1002    yuanyuan
1003    haohao
1004    yunyun

Impala 不支持export和import命令

第7章查询

1.基本的语法跟hive的查询语句大体一样
2.Impala不支持CLUSTER BY, DISTRIBUTE BY, SORT BY
3.Impala中不支持分桶表
4.Impala不支持COLLECT_SET(col)和explode（col）函数
5.Impala支持开窗函数

[hadoop103:21000] > select name,orderdate,cost,sum(cost) over(partition by month(orderdate)) from business;