execute block
as
declare variable n integer;
begin
  select sum(1) from generate_serial(1, 1000000) into :n;
end
--Execute time = 967ms

execute block
as
declare procedure prc returns(n integer) as
                        begin
                          n = 1;
                          suspend;
                        end
declare variable n integer;
begin
  select sum((select n from prc)) from generate_serial(1, 1000000) into :n;
end
--Execute time = 952ms

execute block
as
declare function func returns integer as
                        begin
                          return 1;
                        end
declare variable n integer;
begin
  select sum(func()) from generate_serial(1, 1000000) into :n;
end
-- Execute time = 2s 340ms

-------------------------------------------
create or alter procedure GENERATE_SERIAL (
    from_value integer,
    to_value integer,
    step integer = 1)
returns (
    id integer)
as
begin
  id = from_value;
  while (id <= to_value) do
  begin
    suspend;
    id = id + step;
  end
end

execute block
as
declare procedure prc(par1 int) returns(n integer) as
                        begin
                          n = 1;
                          suspend;
                        end
declare variable n integer;
begin
  select sum((select n from prc(g.id))) from generate_serial(1, 1000000) g into :n;
end
-- Execute time = 3s 728ms

execute block
as
declare function func(par1 int) returns integer as
                        begin
                          return 1;
                        end
declare variable n integer;
begin
  select sum(func(g.id)) from generate_serial(1, 1000000) g into :n;
end
-- Execute time = 2s 652ms