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