ClickHouse/dbms/tests/queries/0_stateless/00800_low_cardinality_array_group_by_arg.sql

SET allow_experimental_low_cardinality_type = 1;

DROP TABLE IF EXISTS test.table1;
DROP TABLE IF EXISTS test.table2;

CREATE TABLE test.table1
(
dt Date,
id Int32,
arr Array(LowCardinality(String))
) ENGINE = MergeTree PARTITION BY toMonday(dt)
ORDER BY (dt, id) SETTINGS index_granularity = 8192;

CREATE TABLE test.table2
(
dt Date,
id Int32,
arr Array(LowCardinality(String))
) ENGINE = MergeTree PARTITION BY toMonday(dt)
ORDER BY (dt, id) SETTINGS index_granularity = 8192;

insert into test.table1 (dt, id, arr) values ('2019-01-14', 1, ['aaa']);
insert into test.table2 (dt, id, arr) values ('2019-01-14', 1, ['aaa','bbb','ccc']);

select dt, id, groupArrayArray(arr)
from (
	select dt, id, arr from test.table1
	where dt = '2019-01-14' and id = 1
	UNION ALL
	select dt, id, arr from test.table2
	where dt = '2019-01-14' and id = 1
)
group by dt, id;