with t as (
  select 1 as num, '10.02.2020' as "date" union all
  select 1, '11.02.2020' union all
  select 2, '11.02.2020' union all
  select 3, '11.02.2020' union all
  select 3, '12.02.2020' union all
  select 3, '13.02.2020' union all
  select 3, '22.02.2020'),
tt as (
  select 
      *
      ,cast("date" as timestamp) -  row_number()over(partition by num order by "date") * interval '1 day' as inv
  from t)
select
	num
    ,min("date") as start_date
    ,max("date") as end_date
from tt  
group by 
	num
    ,inv
order by 1,2

with t as (
  select 1 as id, '10.02.2020' as "dat" union all
  select 1, '11.02.2020' union all
  select 2, '11.02.2020' union all
  select 3, '11.02.2020' union all
  select 3, '12.02.2020' union all
  select 3, '13.02.2020' union all
  select 3, '22.02.2020') 
select id, min(start_date), max(end_date) from t group by id order by id;

with t as (
    select 1 as num, cast('10.02.2020' as timestamp) as "date" union all
    select 1, cast('11.02.2020' as timestamp) 
    union all
    select 1, cast('12.02.2020' as timestamp) 
    union all
    select 2, cast('13.02.2020' as timestamp) 
    union all
    select 3, cast('13.02.2020' as timestamp) 
    union all
    select 3, cast('14.02.2020' as timestamp) 
    union all
    select 3, cast('15.02.2020' as timestamp) 
    union all
    select 3, cast('22.02.2020' as timestamp) 
    union all
    select 3, cast('26.02.2020' as timestamp) 
    )
select v_begin.b_date, min(v_end.e_date) as e_date,
       v_begin.num
  from 
       ( -- Находим все начала диапазонов:
          select num, "date" as b_date
            from t s1
           where not exists (
                               select null
                                 from t s2
                                where s2."date" < s1."date"
                                  and s2."date" + interval '1 days' >= s1."date"
                                  and s1.num = s2.num
                            )
       ) v_begin
  join 
       ( -- Находим все кончала диапазонов:
          select num, "date" as e_date
            from t s1
           where not exists (
                               select null
                                 from t s2
                                where s2."date" + interval '1 days' > s1."date" + interval '1 days' 
                                  and s2."date" <= s1."date" + interval '1 days' 
                                  and s1.num = s2.num
                            )
       ) v_end
--
-- Сливаем начала с кончалами:
    on v_begin.b_date <= v_end.e_date
   and v_begin.num = v_end.num
 group by v_begin.b_date, v_begin.num
 order by v_begin.num, min(v_end.e_date)