NAME¶

ALTER_TYPE - change the definition of a type

SYNOPSIS¶

ALTER TYPE name action [, ... ]
ALTER TYPE name OWNER TO new_owner
ALTER TYPE name RENAME ATTRIBUTE attribute_name TO new_attribute_name [ CASCADE | RESTRICT ]
ALTER TYPE name RENAME TO new_name
ALTER TYPE name SET SCHEMA new_schema
ALTER TYPE name ADD VALUE new_enum_value [ { BEFORE | AFTER } existing_enum_value ]
where action is one of:


    ADD ATTRIBUTE attribute_name data_type [ COLLATE collation ] [ CASCADE | RESTRICT ]


    DROP ATTRIBUTE [ IF EXISTS ] attribute_name [ CASCADE | RESTRICT ]


    ALTER ATTRIBUTE attribute_name [ SET DATA ] TYPE data_type [ COLLATE collation ] [ CASCADE | RESTRICT ]

DESCRIPTION¶

ALTER TYPE changes the definition of an existing type. There are several subforms:

ADD ATTRIBUTE

DROP ATTRIBUTE [ IF EXISTS ]

SET DATA TYPE

OWNER

RENAME

SET SCHEMA

ADD VALUE [ BEFORE | AFTER ]

CASCADE

RESTRICT

The ADD ATTRIBUTE, DROP ATTRIBUTE, and ALTER ATTRIBUTE actions can be combined into a list of multiple alterations to apply in parallel. For example, it is possible to add several attributes and/or alter the type of several attributes in a single command.

You must own the type to use ALTER TYPE. To change the schema of a type, you must also have CREATE privilege on the new schema. To alter the owner, you must also be a direct or indirect member of the new owning role, and that role must have CREATE privilege on the type's schema. (These restrictions enforce that altering the owner doesn't do anything you couldn't do by dropping and recreating the type. However, a superuser can alter ownership of any type anyway.) To add an attribute or alter an attribute type, you must also have USAGE privilege on the data type.

PARAMETERS¶

name

new_name

new_owner

new_schema

attribute_name

new_attribute_name

data_type

new_enum_value

existing_enum_value

NOTES¶

ALTER TYPE ... ADD VALUE (the form that adds a new value to an enum type) cannot be executed inside a transaction block.

Comparisons involving an added enum value will sometimes be slower than comparisons involving only original members of the enum type. This will usually only occur if BEFORE or AFTER is used to set the new value's sort position somewhere other than at the end of the list. However, sometimes it will happen even though the new value is added at the end (this occurs if the OID counter “wrapped around” since the original creation of the enum type). The slowdown is usually insignificant; but if it matters, optimal performance can be regained by dropping and recreating the enum type, or by dumping and reloading the database.

EXAMPLES¶

To rename a data type:

ALTER TYPE electronic_mail RENAME TO email;

To change the owner of the type email to joe:

ALTER TYPE email OWNER TO joe;

To change the schema of the type email to customers:

ALTER TYPE email SET SCHEMA customers;

To add a new attribute to a type:

ALTER TYPE compfoo ADD ATTRIBUTE f3 int;

To add a new value to an enum type in a particular sort position:

ALTER TYPE colors ADD VALUE 'orange' AFTER 'red';

COMPATIBILITY¶

The variants to add and drop attributes are part of the SQL standard; the other variants are PostgreSQL extensions.

SEE ALSO¶

CREATE TYPE (CREATE_TYPE(7)), DROP TYPE (DROP_TYPE(7))