create function start_stop_record() returns vts_position as
$$
declare
sp record;
last_was_zero integer := -1;
records varchar(4000);
begin
for sp in select * from vts_position  order by rawid loop
if sp.speed =0 then
if last_was_zero = -1 then
last_was_zero = 1;
elsif last_was_zero = 1 then last_was_zero =1;
elsif last_was_zero = 0 then select ROW(sp.rawid)::vts_position; last_was_zero = 1; end if;
elsif sp.speed > 0 then
if last_was_zero =-1 then
select ROW(sp.rawid)::vts_position; last_was_zero = 0;
elsif last_was_zero = 0 then
last_was_zero=0;
elsif last_was_zero = 1 then
select ROW(sp.rawid)::vts_position; last_was_zero = 0;
end if;
else raise notice 'exception where rawid %',sp.rawid; end if;
end loop;
end;
$$
language plpgsql;