The above was based on just discovered https://extendsclass.com/postgresql-online.html
With this sql:
====
create table T1(id integer primary key, val text);
insert into T1(id, val) values(1, '1one'), (2, '1two'), (3, '1three');
create table T2(id integer primary key, val text);
insert into T2(id, val) values(1, '2one'), (2, '2two'), (3, '2three'), (4, '2four');
select id, t2_cnt.cnt, max_t1.cnt
from T2,
(select count(*) as cnt from T2) t2_cnt,
(select count(*) as cnt from T1) max_t1
order by id
limit case when t2_cnt.cnt > max_t1.cnt
then t2_cnt.cnt - max_t1.cnt
else 0 end;
====