10일 20일 30일 1 1 3 2 dbms_pipe.receive_me 3 3 SLEEP20 4 OR 3 5 WAITFOR 2 6 dbms_pipe.receive_messagea20 7 PG_SLEEP20 5 1 1 2 dbms_pipe.receive_me 3 SLEEP20 3 4 OR 1 5 WAITFOR 1 6 PG_SLEEP20 1 7 dbms_pipe.receive_messagea20 1 1 2 dbms_pipe.receive_me 1 3 OR 1 4 SLEEP20 1 5 WAITFOR 3 6 PG_SLEEP20 7 dbms_pipe.receive_messagea20 11위 - 20위