drop table if exists t;
create table t (a int, b int, c int);
insert into t select mod(i,10),mod(i,10),i from generate_series(1,60000) s(i);
create index on t (a);
analyze t;

set min_parallel_table_scan_size = '1kB';
set min_parallel_index_scan_size = '1kB';
set parallel_setup_cost = 0;
set parallel_tuple_cost = 0;
set max_parallel_workers_per_gather = 2;

set enable_hashagg to off;

explain select * from t union select * from t;
explain select * from t union all select * from t;