Create a database

You can use the CREATE DATABASE syntax to create a database in a Lindorm instance and configure attributes such as TTL for the database to manage data in a unified manner.

Applicable engines and versions

The CREATE DATABASE syntax is applicable to LindormTable and LindormTSDB.
The CREATE DATABASE syntax is supported by LindormTable 2.2.16 and later versions.
The CREATE DATABASE syntax is supported by all versions of LindormTSDB.

Syntax

create_database_statement ::=  CREATE DATABASE [ IF NOT EXISTS ] database_identifier [ WITH attribute_statement ]
attribute_statement       ::= '(' attribute_definition (',' attribute_definition)* ')'
attribute_definition      ::= attr_identifier '=' attr_val

Note

LindormTable whose version is earlier than 2.2.16 supports only the CREATE SCHEMA [ IF NOT EXISTS ] schema_identifier syntax. LindormTable 2.2.16 and later versions support its equivalent syntax CREATE SCHEMA [ IF NOT EXISTS ] schema_identifier. SCHEMA is equivalent to DATABASE. After you create a database, the database is represented by the DATABASE keyword.

Supported parameters

The following table describes the parameters of the CREATE DATABASE syntax supported by LindormTable and LindormTSDB.

Parameter	LindormTable	LindormTSDB
Database name (database_identifier)	〇	〇
Databae attributes (attribute_definition)	✖️	〇

Parameters

Database name (database_identifier)

The database name must comply with the following rules:

The name can be 4 to 16 characters in length.
The name can contain digits, letters, hyphens (-), and underscores (_).
The following reserved words cannot be used as database names: lindorm, default, and global.

Database attributes (attribute_definition)

This parameter is supported only by LindormTSDB.

You can use the WITH keyword to configure one or more attributes for the database. Example: WITH (cold_boundary=30, ttl=60). The following table describes the attributes that you can configured for a database.

Attribute	Type	Description
cold_boundary	BIGINT	The hot and cold data boundary. Unit: days. The default value of this attribute is 0, which indicates that cold storage is not enabled for the database. Note To configure this attribute, you must enable the cold storage feature in the Lindorm console. For more information, see Enable cold storage.
partition_interval	BIGINT	The interval based on which data is partitioned. Data and indexes within the same interval are stored in the same partition. Unit: days. The default value of this attribute varies with the version of LindormTable. If the version of LindormTable is 3.4.19 and later, the default value of this attribute is 30. If the version of LindormTable is earlier than 3.4.19, the default value of this attribute is 0.
ttl	BIGINT	The TTL of data in the database. Unit: days. Data that exceeds the TTL is automatically cleared. Default value: 0. If you leave this attribute unspecified or keep the default value of this attribute, data in the database is permanently stored. Note If you configure the ttl attribute and the cold_boundary attribute, make sure that the value of the ttl attribute is greater than the value of the cold_boundary attribute.

Examples

CREATE DATABASE DB1;

Verify the result

You can execute the SHOW DATABASES; statement to check whether the database is created.

Configure attributes for a database

Create a database named DB1 and specify that data in DB1 is transferred to cold storage after 30 days and is cleared after 60 days.

CREATE DATABASE DB1 WITH(cold_boundary=30,ttl=60);

Verify the result

You can execute the SHOW DATABASES; statement to check whether the database is created.
You can execute the DESCRIBE DATABASE DB1; statement to view the attributes configured for the database DB1.