Creating a user-defined type (UDT)

User-defined types (UDTs) can be used to attach multiple data fields to a column.

User-defined types (UDTs) can attach multiple data fields, each named and typed, to a single column. The fields used to create a UDT may be any valid data type, including collections and other existing UDTs. Once created, UDTs may be used to define a column in a table.

Procedure

  • Use the cycling keyspace.
    USE cycling;
  • Create a user-defined type named basic_info.
    CREATE TYPE cycling.basic_info (
      birthday timestamp,
      nationality text,
      weight text,
      height text
    );
  • Create a table for storing cyclist data in columns of type basic_info. Use the frozen keyword in the definition of the user-defined type column. In DataStax Distribution of Apache Cassandra™, the frozen keyword is not required for UDTs that contain only non-collection fields.
    When using the frozen keyword, you cannot update parts of a user-defined type value. The entire value must be overwritten. The database treats the value of a frozen, user-defined type like a blob.
    CREATE TABLE cycling.cyclist_stats (
      id uuid PRIMARY KEY,
      lastname text,
      basics FROZEN<basic_info>
    );  
  • A user-defined type can be nested in another column type. This example nests a UDT in a list.
    CREATE TYPE cycling.race (
      race_title text,
      race_date timestamp,
      race_time text
    );
    
    CREATE TABLE cycling.cyclist_races (
      id UUID PRIMARY KEY,
      lastname text,
      firstname text,
      races list<FROZEN <race>>
    );