gistfile1.txt

create materialized view mview 
as 
select a.userid, a.balance, d.date 
    from (select d as date from generate_series(timestamp '2023-05-01', '2023-06-2', interval '1 day') d) d 
    join lateral (select userid, balance, date from balance where date <= d.date order by date desc limit 1) a 
    on true union select userid, balance, date from balance order by date;
    
create materialized view mview2 
as 
select a.userid, a.balance, a.date as start, b.date as fin 
   from mview a 
   left join lateral 
      (select date 
           from mview 
           where date > a.date and 
           userid = a.userid 
           order by date asc limit 1) 
   b on true
   
create or replace function extract_time(p_timestamp timestamp) returns time
as
$$
declare p_time time := p_timestamp::time;
begin
return case p_time when '00:00:00'::time then '24:00:00'::time else p_time end;
end;

CREATE FUNCTION time_subtype_diff(x time, y time) RETURNS float8 AS
'SELECT EXTRACT(EPOCH FROM (x - y))' LANGUAGE sql STRICT IMMUTABLE;

CREATE TYPE timerange AS RANGE (
    subtype = time,
    subtype_diff = time_subtype_diff
);