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