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