drop table if exists t;

create table t (a Int) engine = MergeTree order by a;

-- some magic to satisfy conditions to run optimizations in MergeTreeRangeReader
insert into t select number < 20 ? 0 : 1 from numbers(50);
alter table t add column s String default 'foo';

select s from t prewhere a != 1 where rand() % 2 = 0 limit 1;

drop table t;