NAME

       ALTER_DOMAIN - change the definition of a domain

SYNOPSIS

       ALTER DOMAIN name
           { SET DEFAULT expression | DROP DEFAULT }
       ALTER DOMAIN name
           { SET | DROP } NOT NULL
       ALTER DOMAIN name
           ADD domain_constraint [ NOT VALID ]
       ALTER DOMAIN name
           DROP CONSTRAINT [ IF EXISTS ] constraint_name [ RESTRICT | CASCADE ]
       ALTER DOMAIN name
            RENAME CONSTRAINT constraint_name TO new_constraint_name
       ALTER DOMAIN name
           VALIDATE CONSTRAINT constraint_name
       ALTER DOMAIN name
           OWNER TO new_owner
       ALTER DOMAIN name
           RENAME TO new_name
       ALTER DOMAIN name
           SET SCHEMA new_schema

DESCRIPTION

       ALTER DOMAIN changes the definition of an existing domain. There are several sub-forms:

       SET/DROP DEFAULT
           These forms set or remove the default value for a domain. Note that defaults only
           apply to subsequent INSERT commands; they do not affect rows already in a table using
           the domain.

       SET/DROP NOT NULL
           These forms change whether a domain is marked to allow NULL values or to reject NULL
           values. You can only SET NOT NULL when the columns using the domain contain no null
           values.

       ADD domain_constraint [ NOT VALID ]
           This form adds a new constraint to a domain using the same syntax as CREATE DOMAIN
           (CREATE_DOMAIN(7)). When a new constraint is added to a domain, all columns using that
           domain will be checked against the newly added constraint. These checks can be
           suppressed by adding the new constraint using the NOT VALID option; the constraint can
           later be made valid using ALTER DOMAIN ... VALIDATE CONSTRAINT. Newly inserted or
           updated rows are always checked against all constraints, even those marked NOT VALID.
           NOT VALID is only accepted for CHECK constraints.

       DROP CONSTRAINT [ IF EXISTS ]
           This form drops constraints on a domain. If IF EXISTS is specified and the constraint
           does not exist, no error is thrown. In this case a notice is issued instead.

       RENAME CONSTRAINT
           This form changes the name of a constraint on a domain.

       VALIDATE CONSTRAINT
           This form validates a constraint previously added as NOT VALID, that is, verify that
           all data in columns using the domain satisfy the specified constraint.

       OWNER
           This form changes the owner of the domain to the specified user.

       RENAME
           This form changes the name of the domain.

       SET SCHEMA
           This form changes the schema of the domain. Any constraints associated with the domain
           are moved into the new schema as well.

       You must own the domain to use ALTER DOMAIN. To change the schema of a domain, 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 domain's schema. (These restrictions enforce that altering the owner doesn't do
       anything you couldn't do by dropping and recreating the domain. However, a superuser can
       alter ownership of any domain anyway.)

PARAMETERS

       name
           The name (possibly schema-qualified) of an existing domain to alter.

       domain_constraint
           New domain constraint for the domain.

       constraint_name
           Name of an existing constraint to drop or rename.

       NOT VALID
           Do not verify existing column data for constraint validity.

       CASCADE
           Automatically drop objects that depend on the constraint.

       RESTRICT
           Refuse to drop the constraint if there are any dependent objects. This is the default
           behavior.

       new_name
           The new name for the domain.

       new_constraint_name
           The new name for the constraint.

       new_owner
           The user name of the new owner of the domain.

       new_schema
           The new schema for the domain.

NOTES

       Currently, ALTER DOMAIN ADD CONSTRAINT and ALTER DOMAIN SET NOT NULL will fail if the
       named domain or any derived domain is used within a composite-type column of any table in
       the database. They should eventually be improved to be able to verify the new constraint
       for such nested columns.

EXAMPLES

       To add a NOT NULL constraint to a domain:

           ALTER DOMAIN zipcode SET NOT NULL;

       To remove a NOT NULL constraint from a domain:

           ALTER DOMAIN zipcode DROP NOT NULL;

       To add a check constraint to a domain:

           ALTER DOMAIN zipcode ADD CONSTRAINT zipchk CHECK (char_length(VALUE) = 5);

       To remove a check constraint from a domain:

           ALTER DOMAIN zipcode DROP CONSTRAINT zipchk;

       To rename a check constraint on a domain:

           ALTER DOMAIN zipcode RENAME CONSTRAINT zipchk TO zip_check;

       To move the domain into a different schema:

           ALTER DOMAIN zipcode SET SCHEMA customers;

COMPATIBILITY

       ALTER DOMAIN conforms to the SQL standard, except for the OWNER, RENAME, SET SCHEMA, and
       VALIDATE CONSTRAINT variants, which are PostgreSQL extensions. The NOT VALID clause of the
       ADD CONSTRAINT variant is also a PostgreSQL extension.

SEE ALSO

       CREATE DOMAIN (CREATE_DOMAIN(7)), DROP DOMAIN (DROP_DOMAIN(7))