aggregating EmbeddedRocksDB using Null engine and MV

q.sql

-- https://fiddle.clickhouse.com/43192eb8-cf28-4654-ad07-b7a78bdcb872
CREATE TABLE users (uid Int16, names Array(Tuple(name String, age Int16))) 
  ENGINE=EmbeddedRocksDB
    primary key uid;

INSERT INTO users VALUES (1231, [('John', 33)]);
INSERT INTO users VALUES (6666, [('Ksenia', 48)]);
INSERT INTO users VALUES (8888, [('Alice', 50)]);

SELECT * FROM users;

create table users_insert (uid Int64, name Tuple(name String, age Int16)) engine = Null;

create materialized view users_agg
  to users
  AS
  with grouped_inserted as (
    select uid, groupUniqArray(name) as names from users_insert group by uid
  )
  select uid, arrayDistinct(arrayConcat(u.names, grouped_inserted.names)) as names from grouped_inserted
    left any join users u on u.uid = grouped_inserted.uid;

insert into users_insert (uid, name) values
  (1231, ('Jen', 33)), (31, ('hi', 31)), (31, ('hey', 32));

SELECT * FROM users;