实例状态：SELECT status FROM v$instance;（返回 OPEN 表示运行正常）
活跃会话与长事务/等待
查看活跃 SQL 与等待（示例）：
col inst_sid heading “INST_ID|:SID” format a7
col username format a10
col machine format a12
col sql_exec_start heading “SQL|START|D HH:MM:SS” format a11
col sql_id format a13
col sql_text format a40
col event format a33
col wait_sec heading “WAIT|(SEC)” format 99999
set linesize 200
select ses.inst_id||chr(58)||ses.sid as inst_sid,username,
(sysdate - sql_exec_start) day(1) to second(0) as sql_exec_start,
ses.sql_id,substr(sql.sql_text,1,40) sql_text,
substr(case time_since_last_wait_micro when 0 then (case wait_class when ‘Idle’ then 'IDLE: '||event else event end) else ‘ON CPU’ end,1,33) event,
(case time_since_last_wait_micro when 0 then wait_time_micro else time_since_last_wait_micro end)/1000000 wait_sec
from gv$session ses,gv$sqlstats sql
where ses.inst_id||chr(58)||ses.sid <> sys_context(‘USERENV’,‘INSTANCE’)||chr(58)||sys_context(‘USERENV’,‘SID’)
and username is not null and status=‘ACTIVE’
and ses.sql_id=sql.sql_id (+)
order by sql_exec_start,username,ses.sid,ses.sql_id;