--识别'低效执行'的SQL语句：

SELECT ?EXECUTIONS , DISK_READS, BUFFER_GETS,?

ROUND((BUFFER_GETS-DISK_READS)/BUFFER_GETS,2) Hit_radio,?

ROUND(DISK_READS/EXECUTIONS,2) Reads_per_run,?

SQL_TEXT?

FROM ?V$SQLAREA?

WHERE ?EXECUTIONS>0?

AND ?BUFFER_GETS > 0?

AND ?(BUFFER_GETS-DISK_READS)/BUFFER_GETS < 0.8?

ORDER BY ?4 DESC;

?

?

----查看连接数

select count(*) from v$session; ?

?

----查看并发连接数

Select count(*) from v$session where status='ACTIVE';?

?

----查看最大连接

show parameter processes; ?

?

?

?

--查看表空间情况

?select sum(bytes)/(1024*1024) as free_space,tablespace_name?

? from dba_free_space?

?group by tablespace_name;?

?

--查看回滚段名称及大小?

?select segment_name, tablespace_name, r.status,?

? ? ? ? (initial_extent/1024) InitialExtent,(next_extent/1024) NextExtent,?

? ? ? ? max_extents, v.curext CurExtent?

? ?From dba_rollback_segs r, v$rollstat v?

?Where r.segment_id = v.usn(+)?

?order by segment_name ;?