How do you nest a UDT inside another UDT in Cassandra? - cassandra

Question

I have created the following user defined types (UDT) in cassandra :
CREATE TYPE keyspace.location (
latitude text,
longitude text,
accuracy text,
address text
);
CREATE TYPE keyspace.person (
name text,
contact_no text,
alternate_contact text
);
and I want to use these to create another UDT
CREATE TYPE keyspace.pinpoint(
user <person>,
location <location>
);

Answer 1

You can nest UDTs by simply specifying your UDT as the type within another UDT in this manner:
CREATE TYPE keyspace.pinpoint (
user person,
location location
);
You don't enclose them in <> brackets because those are used for collections.
As a side note, I personally wouldn't nest UDTs unless you have no other option. UDTs are not as flexible as native columns. Inserting or updating data in a nested UDT can get very complicated and hard to maintain.
Whenever possible, try to use generic table definitions. For example instead of defining the type pinpoint, try to use a table with native column types and clustered rows. Cheers!

Answer 2

You need to declare these nested UDTs as frozen<UDTName>, like:
CREATE TYPE keyspace.pinpoint(
user frozen<person>,
location frozen<location>
);
But this means that you won't be able to update their individual fields - you'll able only update the whole field, with complete UDT instance, for example, complete user or location.