question

Hello, hope you're having a good day. I have a user defined type:

CREATE TYPE hashtag (
    id text,
    creator_id text,
    text text,
    updated timestamp
);

Used in:

CREATE TABLE post (
    id bigint,
    user text,
    thread_id text,
    hashtags set<frozen <hashtag>>,
    post_body text,
    created timestamp,
    updated timestamp,
    PRIMARY KEY ((thread_id, user), id)
) WITH CLUSTERING ORDER BY (id DESC);

Is it possible to ensure that on executing the query below 2 times - it won't add 2 values to the set, but verify uniqueness by id? If not, obviously I should use a map. Just curious if it's possible to configure in which way Cassandra defines uniqueness of a set.

UPDATE post
  SET hashtags = hashtags + {
    {
      id: 'some_hashtag_id',
      creator_id: '78ead5b6-187b-4f6e-9945-a72ab95483f3',
      text: '#nice',
      updated: toTimestamp(now())
    }
  }
  WHERE thread_id='24283c41-b829-4a7d-91c7-cd1277e0a5f7'
  AND user='78ead5b6-187b-4f6e-9945-a72ab95483f3'
  AND id=512988294041042944;