create or replace function gibberish(int) returns text language SQL as $_$ select left(string_agg(md5(random()::text),$$$$),$1) from generate_series(0,$1/32) $_$;
create table j1 as select x, md5(random()::text) as t11, gibberish(1500) as t12 from generate_series(1,20e6) f(x);
I should have added, found it on HEAD, verified it also in 12.5.