select '-- check that distinct with and w/o optimization produce the same result'; drop table if exists distinct_in_order sync; drop table if exists ordinary_distinct sync; select '-- DISTINCT columns are the same as in ORDER BY'; create table distinct_in_order (CounterID UInt32, EventDate Date) engine=MergeTree() order by (CounterID, EventDate); insert into distinct_in_order select distinct CounterID, EventDate from test.hits order by CounterID, EventDate settings optimize_distinct_in_order=1; create table ordinary_distinct (CounterID UInt32, EventDate Date) engine=MergeTree() order by (CounterID, EventDate); insert into ordinary_distinct select distinct CounterID, EventDate from test.hits order by CounterID, EventDate settings optimize_distinct_in_order=0; select distinct * from distinct_in_order except select * from ordinary_distinct; drop table if exists distinct_in_order sync; drop table if exists ordinary_distinct sync; select '-- DISTINCT columns has prefix in ORDER BY columns'; create table distinct_in_order (CounterID UInt32, EventDate Date) engine=MergeTree() order by (CounterID, EventDate); insert into distinct_in_order select distinct CounterID, EventDate from test.hits order by CounterID settings optimize_distinct_in_order=1; create table ordinary_distinct (CounterID UInt32, EventDate Date) engine=MergeTree() order by (CounterID, EventDate); insert into ordinary_distinct select distinct CounterID, EventDate from test.hits order by CounterID settings optimize_distinct_in_order=0; select distinct * from distinct_in_order except select * from ordinary_distinct; drop table if exists distinct_in_order sync; drop table if exists ordinary_distinct sync;