ALTER DOMAIN(7) PostgreSQL 16.7 Documentation ALTER DOMAIN(7)
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 | CURRENT_ROLE | CURRENT_USER | SESSION_USER }
ALTER DOMAIN name
RENAME TO new_name
ALTER DOMAIN name
SET SCHEMA new_schema
where domain_constraint is:
[ CONSTRAINT constraint_name ]
{ NOT NULL | CHECK (expression) }
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. 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, it verifies that all values in table columns of the domain
type 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 be able to SET ROLE to 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 stored data for constraint validity.
CASCADE
Automatically drop objects that depend on the constraint, and in
turn all objects that depend on those objects (see Section 5.14).
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
Although ALTER DOMAIN ADD CONSTRAINT attempts to verify that existing
stored data satisfies the new constraint, this check is not
bulletproof, because the command cannot "see" table rows that are newly
inserted or updated and not yet committed. If there is a hazard that
concurrent operations might insert bad data, the way to proceed is to
add the constraint using the NOT VALID option, commit that command,
wait until all transactions started before that commit have finished,
and then issue ALTER DOMAIN VALIDATE CONSTRAINT to search for data
violating the constraint. This method is reliable because once the
constraint is committed, all new transactions are guaranteed to enforce
it against new values of the domain type.
Currently, ALTER DOMAIN ADD CONSTRAINT, ALTER DOMAIN VALIDATE
CONSTRAINT, and ALTER DOMAIN SET NOT NULL will fail if the named domain
or any derived domain is used within a container-type column (a
composite, array, or range column) in any table in the database. They
should eventually be improved to be able to verify the new constraint
for such nested values.
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))
PostgreSQL 16.7 2025 ALTER DOMAIN(7)
postgresql 16.7 - Generated Sat Mar 22 10:05:53 CDT 2025