a

 -- Check for long-running queries

SELECT sid, serial#, sql_id, status, event, wait_class, seconds_in_wait, sql_text

FROM v$session s

JOIN v$sql q ON s.sql_id = q.sql_id

WHERE s.status = 'ACTIVE';

-- Check for blocking sessions

SELECT blocking_session, sid, serial#, event, seconds_in_wait 

FROM v$session

WHERE blocking_session IS NOT NULL;