User-defined types (UDTs)

UDT – A grouping of fields and data types that you can use to define a single column in Amazon Keyspaces. Valid data types for UDTs are all supported Cassandra data types, including collections and other UDTs that you've already created in the same keyspace. For more information about supported Cassandra data types, see Cassandra data type support.

user_defined_type::= udt_name
udt_name::= [ keyspace_name '.' ] identifier

CREATE TYPE

Use the CREATE TYPE statement to create a new type.

Syntax

create_type_statement ::=  CREATE TYPE [ IF NOT EXISTS ] udt_name
    '('field_definition ( ',' field_definition)* ')'
            field_definition::= identifier cql_type

Where:

• IF NOT EXISTS prevents CREATE TYPE from failing if the type already exists. (Optional)

• udt_name is the fully-qualified name of the UDT in type format, for example my_keyspace.my_type. If you define the current keyspace with the USE statement, you don't need to specify the keyspace name.

• field_definition consists of a name and a type.

The following table shows examples of allowed UDT names. The first columns shows how to enter the name when you create the type, the second column shows how Amazon Keyspaces formats the name internally. Amazon Keyspaces expects the formatted name for operations like GetType.

Entered name	Formatted name	Note
MY_UDT	my_udt	Without double-quotes, Amazon Keyspaces converts all upper-case characters to lower-case.
"MY_UDT"	MY_UDT	With double-quotes, Amazon Keyspaces respects the upper-case characters, and removes the double-quotes from the formatted name.
"1234"	1234	With double-quotes, the name can begin with a number, and Amazon Keyspaces removes the double-quotes from the formatted name.
"Special_Ch@r@cters<>!!"	Special_Ch@r@cters<>!!	With double-quotes, the name can contain special characters, and Amazon Keyspaces removes the double-quotes from the formatted name.
"nested""""""quotes"	nested"""quotes	Amazon Keyspaces removes the outer double-quotes and the escape double-quotes from the formatted name.

Examples

CREATE TYPE my_keyspace.phone (
    country_code int,
    number text
);

You can nest UDTs if the nested UDT is frozen. For more information about default values and quotas for types, see Amazon Keyspaces UDT quotas and default values.

CREATE TYPE my_keyspace.user (
    first_name text,
    last_name text,
    phones FROZEN<phone>
);

For more code examples that show how to create UDTs, see User-defined types (UDTs) in Amazon Keyspaces.

DROP TYPE

Use the DROP TYPE statement to delete a UDT. You can only delete a type that's not in use by another type or table.

Syntax

drop_type_statement ::=  DROP TYPE [ IF EXISTS ] udt_name

Where:

• IF EXISTS prevents DROP TYPE from failing if the type doesn't exist. (Optional)

• udt_name is the fully-qualified name of the UDT in type format, for example my_keyspace.my_type. If you define the current keyspace with the USE statement, you don't need to specify the keyspace name.

Example

DROP TYPE udt_name;