CREATE SCHEMA

Function

CREATE SCHEMA creates a schema.

Named objects are accessed either by "qualifying" their names with the schema name as a prefix, or by setting a search path that includes the desired schema(s). When creating named objects, you can also use the schema name as a prefix.

Optionally, CREATE SCHEMA can include sub-commands to create objects within the new schema. The sub-commands are treated essentially the same as separate commands issued after creating the schema, If the AUTHORIZATION clause is used, all the created objects are owned by this user.

Precautions

• A database can have one or more schemas, and a schema can contain tables and other data objects, such as data types, functions, and operators. One object name can be used in different schemas. For example, both Schema1 and Schema2 can contain a table named mytable.
• Different from databases, schemas are not isolated. You can access the objects in a schema of the connected database based on your schema permissions. To manage schema permissions, you need to have a good understanding of the database permissions.
• A schema named with the PG_ prefix cannot be created because this type of schema is reserved for the database system.
• If a user is created, a schema named after the user will also be created in the current database.
• As long as the current user has the CREATE permission, the user can create a schema.
• The owner of an object created by a system administrator in a schema with the same name as a common user is the common user, not the system administrator.
• To reference a table that is not modified with a schema name, the system uses search_path to find the schema that the table belongs to. pg_temp and pg_catalog are always the first two schemas to be searched no matter whether or how they are specified in search_path. search_path is a schema name list, and the first table detected in it is the target table. If no target table is found, an error will be reported. (If a table exists but the schema it belongs to is not listed in search_path, the search fails as well.) The first schema in search_path is called current schema. This schema is the first one to be searched. If no schema name is declared, newly created database objects are saved in this schema by default.

Syntax

• Create a schema based on a specified name:

  1 2	CREATE SCHEMA schema_name [ AUTHORIZATION user_name ] [ WITH PERM SPACE 'space_limit'] [ schema_element [ ... ] ];

• Create a schema based on a user name:

  1	CREATE SCHEMA AUTHORIZATION user_name [ WITH PERM SPACE 'space_limit'] [ schema_element [ ... ] ];

Parameter Description

• schema_name

  Indicates the name of the schema to be created.

  

  • The name must be unique,
  • and cannot start with pg_.

  Value range: a string. It must comply with the naming convention rule.

• AUTHORIZATION user_name

  Indicates the name of the user who will own this schema. If schema_name is not specified, user_name will be used as the schema name. In this case, user_name can only be a role name.

  Value range: An existing user name/role.

• WITH PERM SPACE 'space_limit'

  Indicates the storage upper limit of the permanent table in the specified schema. If space_limit is not specified, the space is not limited.

  Value range: A string consists of an integer and unit. The unit can be K/M/G/T/P currently. The unit of parsed value is K and cannot exceed the range that can be expressed in 64 bits, which is 1 KB to 9007199254740991 KB.

• schema_element

  Indicates an SQL statement defining an object to be created within the schema. Currently, only CREATE TABLE, CREATE VIEW, CREATE INDEX, CREATE PARTITION, and GRANT are accepted as clauses within CREATE SCHEMA.

  Objects created by sub-commands are owned by the user specified by AUTHORIZATION.

If objects in the schema on the current search path are with the same name, specify the schemas different objects are in. You can run the SHOW SEARCH_PATH command to check the schemas on the current search path.

Examples

-- Create the role1 role.

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CREATE ROLE role1 IDENTIFIED BY '{Password}';

Create a schema named role1 for the role1 role. The owner of the films and winners tables created by the clause is role1.

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CREATE SCHEMA AUTHORIZATION role1
     CREATE TABLE films (title text, release date, awards text[])      
     CREATE VIEW winners AS         
     SELECT title, release FROM films WHERE awards IS NOT NULL;

Helpful Links

ALTER SCHEMA, DROP SCHEMA