Hiệu suất của các thủ tục được lưu trữ đệ quy trong MYSQL để nhận dữ liệu phân cấp

một giải pháp phía máy chủ db danh sách kề lặp đi lặp lại khá đơn giản: http://pastie.org/1056977

delimiter ;

drop procedure if exists employee_hier;

delimiter #

create procedure employee_hier
(
in p_emp_id smallint unsigned
)
begin

declare p_done tinyint unsigned default(0);
declare p_depth smallint unsigned default(0);

create temporary table hier(
 boss_id smallint unsigned, 
 emp_id smallint unsigned, 
 depth smallint unsigned
)engine = memory;

insert into hier values (null, p_emp_id, p_depth);

/* http://dev.mysql.com/doc/refman/5.0/en/temporary-table-problems.html */

create temporary table emps engine=memory select * from hier;

while p_done <> 1 do

    if exists( select 1 from employee e inner join hier on e.boss_id = hier.emp_id and hier.depth = p_depth) then

        insert into hier select e.boss_id, e.emp_id, p_depth + 1 
            from employee e inner join emps on e.boss_id = emps.emp_id and emps.depth = p_depth;

        set p_depth = p_depth + 1;          

        truncate table emps;
        insert into emps select * from hier where depth = p_depth;

    else
        set p_done = 1;
    end if;

end while;

select 
 e.emp_id,
 e.name as emp_name,
 b.emp_id as boss_emp_id,
 b.name as boss_name,
 hier.depth
from 
 hier
inner join employee e on hier.emp_id = e.emp_id
inner join employee b on hier.boss_id = b.emp_id;

drop temporary table if exists hier;
drop temporary table if exists emps;

end #

delimiter ;


call employee_hier(1);
call employee_hier(3);