更新时间:2024-08-30 GMT+08:00
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CREATE TABLE

本章节主要介绍Doris创建表的SQL基本语法和使用说明。

基本语法

CREATE TABLE [IF NOT EXISTS] [database.]table

(

column_definition_list,

[index_definition_list]

)

[engine_type]

[keys_type]

[table_comment]

[partition_info]

distribution_desc

[rollup_list]

[properties]

[extra_properties]

使用示例

  • 创建一个名为table1的普通表:

    CREATE TABLE example_db.table1

    (

    k1 TINYINT,

    k2 DECIMAL(10, 2) DEFAULT "10.5",

    k3 CHAR(10) COMMENT "string column",

    k4 INT NOT NULL DEFAULT "1" COMMENT "int column"

    )

    COMMENT "table comment"

    DISTRIBUTED BY HASH(k1) BUCKETS 32;

  • 创建一个名为table2的分区表。

    使用event_day列作为分区列,建立3个分区:p201706、p201707、p201708,取值为:

    • p201706:范围为[最小值, 2017-07-01)
    • p201707:范围为[2017-07-01, 2017-08-01)
    • p201708:范围为[2017-08-01, 2017-09-01)

    每个分区使用siteid进行哈希分桶,桶数为10。

    创建表命令如下:

    CREATE TABLE table2

    (

    event_day DATE,

    siteid INT DEFAULT '10',

    citycode SMALLINT,

    username VARCHAR(32) DEFAULT '',

    pv BIGINT SUM DEFAULT '0'

    )

    AGGREGATE KEY(event_day, siteid, citycode, username)

    PARTITION BY RANGE(event_day)

    (

    PARTITION p201706 VALUES LESS THAN ('2017-07-01'),

    PARTITION p201707 VALUES LESS THAN ('2017-08-01'),

    PARTITION p201708 VALUES LESS THAN ('2017-09-01')

    )

    DISTRIBUTED BY HASH(siteid) BUCKETS 10

    PROPERTIES("replication_num" = "2");

    • Doris创建表时限制至少指定2副本,以保证高可用。
    • 可以对Table增加上卷表(Rollup)以提高查询性能。
    • 表的列的Null属性默认为true,会对查询性能有一定的影响。
    • Doris表必须指定分桶列。
  • 查看表内容:
    • SHOW TABLES;
      +----------------------+
      | Tables_in_example_db |
      +----------------------+
      | table1               |
      | table2               |
      +----------------------+
      2 rows in set (0.01 sec)
    • DESC table1;
      +----------+-------------+------+-------+---------+-------+
      | Field    | Type        | Null | Key   | Default | Extra |
      +----------+-------------+------+-------+---------+-------+
      | siteid   | int(11)     | Yes  | true  | 10      |       |
      | citycode | smallint(6) | Yes  | true  | N/A     |       |
      | username | varchar(32) | Yes  | true  |         |       |
      | pv       | bigint(20)  | Yes  | false | 0       | SUM   |
      +----------+-------------+------+-------+---------+-------+
      4 rows in set (0.00 sec)
    • DESC table2;
      +-----------+-------------+------+-------+---------+-------+
      | Field     | Type        | Null | Key   | Default | Extra |
      +-----------+-------------+------+-------+---------+-------+
      | event_day | date        | Yes  | true  | N/A     |       |
      | siteid    | int(11)     | Yes  | true  | 10      |       |
      | citycode  | smallint(6) | Yes  | true  | N/A     |       |
      | username  | varchar(32) | Yes  | true  |         |       |
      | pv        | bigint(20)  | Yes  | false | 0       | SUM   |
      +-----------+-------------+------+-------+---------+-------+
      5 rows in set (0.00 sec)

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