insert into towns (
code, article, name, department
)
select
left(md5(i::text), 10),
md5(random()::text),
md5(random()::text),
left(md5(random()::text), 4)
from generate_series(1, 1000000) s(i)
create table t_random as select s, md5(random()::text) from generate_Series(1,5) s;
select your_columns from your_table ORDER BY random()