--
-- timespan__exists_p/1
--
create or replace function timespan__exists_p(
  integer
) returns bool as $$

declare
       exists_p__timespan_id   alias for $1;
       v_result		integer;
begin
       -- Only need to check if any rows exist. 
       select count(*)
       into   v_result
       from dual
       where exists (select timespan_id
                     from   timespans
                     where  timespan_id = exists_p__timespan_id);

       if v_result = 0 then
           return false;
       else
           return true;
       end if;

end;$$ language plpgsql;