Finding Total Session Count: SELECT 'Currently, ' || (SELECT COUNT(*) FROM V$SESSION) || ' out of ' || VP.VALUE || ' connections are used.' AS USAGE_MESSAGE FROM V$PARAMETER VP WHERE VP.NAME = 'sessions'; To find sessions that are blocked or blocking other sessions, the one of the following queries: select t.process, t.sid, t.SERIAL#, t.blocking_session, t.USER#, t.USERNAME from v$session t where blocking_session is not null; select l1.sid, ' IS BLOCKING ', l2.sid from v$lock l1, v$lock l2 where l1.block =1 and l2.request > 0 and l1.id1=l2.id1 and l1.id2=l2.id2;