Creating a Table

Basic Syntax

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]

Usage Example

• Create a common table named table1.

  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;

• Create a partitioned table named table2. Use the event_day column to partition the table into p201706, p201707, and p201708. The values are as follows:
  • p201706: The value range is [Minimum value, 2017-07-01).
  • p201707: The value range is [2017-07-01, 2017-08-01).
  • p201708: The value range is [2017-08-01, 2017-09-01).

  Each partition is hashed into 10 buckets based on siteid. The command for creating a table is as follows:

  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" = "3");

  

  • You must specify at least three replicas when creating a table to ensure high availability.
  • For a non-node cluster, you do not need to specify replicas.
  • You can add a rollup to a table to improve query performance.
  • By default, the Null property of a column in a table is true, which affects the query performance.
  • The bucket column must be specified for a Doris table.

• View the table content.
  • View tables in the current database.

    SHOW TABLES;

    +----------------------+
    | Tables_in_example_db |
    +----------------------+
    | table1               |
    | table2               |
    +----------------------+
    2 rows in set (0.01 sec)

  • View the structure of table1.

    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)

  • View the structure of table2.

    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)