1.查看錶空間的名稱及大小:
sql> select t.tablespace_name, round(sum(bytes/(1024 * 1024)), 0) ts_size
from dba_tablespaces t, dba_data_files d
where t.tablespace_name = d.tablespace_name
group by t.tablespace_name;
2.查看錶空間物理文件的名稱及大小:
sql> select tablespace_name,file_id,file_name,round(bytes / (1024 * 1024), 0) total_space
from dba_data_files
order by tablespace_name;
3.查看回滾段名稱及大小:
sql> 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$rollstat v
where r.segment_id = v.usn(+)
order by segment_name;
4.如何查看某個回滾段裏面，跑的什麼事物或者正在執行什麼sql語句:
sql> select d.sql_text, a.name
from v$rollname a, v$transaction b, v$session c, v$sqltext d
where a.usn = b.xidusn
and b.addr = c.taddr
and c.sql_address = d.address
and c.sql_hash_value = d.hash_value
and a.usn = 1;
(備註：你要看哪個，就把usn=?寫成幾就行了)
5.查看控制文件:
sql> select * from v$controlfile;
6.查看日誌文件:
sql> col member format a50
sql>select * from v$logfile;
7.如何查看當前SQL*PLUS用戶的sid和serial#:
sql>select sid, serial#, status from v$session where audsid=userenv('sessionid');
8.如何查看當前數據庫的字符集:
sql>select userenv('language') from dual;
sql>select userenv('lang') from dual;
9.怎麼判斷當前正在使用何種SQL優化方式:
用EXPLAIN PLAN產生EXPLAIN PLAN?檢查PLAN_TABLE中ID=0的POSITION列的值
sql>select decode(nvl(position,-1),-1,'rbo',1,'cbo') from plan_table where id=0;
10.如何查看系統當前最新的SCN號：
sql>select max(ktuxescnw * power(2,32) + ktuxescnb) from x$ktuxe;
11.在ORACLE中查找TRACE文件的腳本:
sql>select u_dump.value || '/' || instance.value || '_ora_' ||
v$process.spid || nvl2(v$process.traceid, '_' || v$process.traceid, null ) || '.trc'"trace file" from v$parameter u_dump cross join v$parameter instance cross join v$process join v$session on v$process.addr = v$session.paddr where u_dump.name = 'user_dump_dest' and
instance.name = 'instance_name' and v$session.audsid=sys_context('userenv','sessionid');
sql>select d.value || '/ora_' || p.spid || '.trc' trace_file_name
from (select p.spid from sys.v_$mystat m,sys.v_$session s,
sys.v_$process p where m.statistic# = 1 and
s.sid = m.sid and p.addr = s.paddr) p,(select value from sys.v_$parameter where name ='user_dump_dest') d;
12.如何查看客戶端登陸的IP地址:
sql>select sys_context('userenv','ip_address') from dual;
13.如何在生產數據庫中創建一個追蹤客戶端IP地址的觸發器：
sql>create or replace trigger on_logon_trigger after logon on database
begin
dbms_application_info.set_client_info(sys_context('userenv', 'ip_address'));
end;
14.REM 記錄登陸信息的觸發器
create or replace trigger logon_history
after logon on database --when (user='wacos') --only for user 'wacos'
begin
insert into session_history select username,sid,serial#,audsid,osuser,action,sysdate,null,sys_context('userenv','ip_address'),terminal,machine,program from v$session where audsid = userenv('sessionid');
end;
15.查詢當前日期:
sql> select to_char(sysdate,'yyyy-mm-dd,hh24:mi:ss') from dual;
16.查看所有表空間對應的數據文件名：
sql>select distinct file_name,tablespace_name,autoextensible from dba_data_files;
17.查看錶空間的使用情況:
sql>select sum(bytes)/(1024*1024) as free_space,tablespace_name
from dba_free_space group by tablespace_name;
sql>select a.tablespace_name,a.bytes total,b.bytes used, c.bytes free,
(b.bytes*100)/a.bytes "% used",(c.bytes*100)/a.bytes "% free"
from sys.sm$ts_avail a,sys.sm$ts_used b,sys.sm$ts_free c
where a.tablespace_name=b.tablespace_name and a.tablespace_name=c.tablespace_name;
column tablespace_name format a18;
column sum_m format a12;
column used_m format a12;
column free_m format a12;
column pto_m format 9.99;
select s.tablespace_name,ceil(sum(s.bytes/1024/1024))||'m' sum_m,ceil(sum(s.usedspace/1024/1024))||'m' used_m,ceil(sum(s.freespace/1024/1024))||'m' free_m, sum(s.usedspace)/sum(s.bytes) ptused from (select b.file_id,b.tablespace_name,b.bytes, (b.bytes-sum(nvl(a.bytes,0))) usedspace, sum(nvl(a.bytes,0)) freespace,(sum(nvl(a.bytes,0))/(b.bytes)) * 100 freepercentratio from sys.dba_free_space a,sys.dba_data_files b where a.file_id(+)=b.file_id group by b.file_id,b.tablespace_name,b.bytes order by b.tablespace_name) s group by s.tablespace_name order by sum(s.freespace)/sum(s.bytes) desc;
18.查看數據文件的hwm（可以resize的最小空間）和文件頭大小:
select v1.file_name,v1.file_id,num1 totle_space,num3 free_space,
num1-num3 "used_space(hwm)",nvl(num2,0) data_space,num1-num3-nvl(num2,0) file_head
from
(select file_name,file_id,sum(bytes) num1 from dba_data_files group by file_name,file_id) v1,
(select file_id,sum(bytes) num2 from dba_extents group by file_id) v2,
(select file_id,sum(bytes) num3 from dba_free_space group by file_id) v3
where v1.file_id=v2.file_id(+) and v1.file_id=v3.file_id(+);
19.數據文件大小及頭大小:
select v1.file_name,v1.file_id,
num1 totle_space,
num3 free_space,
num1-num3 used_space,
nvl(num2,0) data_space,
num1-num3-nvl(num2,0) file_head
from
(select file_name,file_id,sum(bytes) num1 from dba_data_files group by file_name,file_id) v1,
(select file_id,sum(bytes) num2 from dba_extents group by file_id) v2,
(select file_id,sum(bytes) num3 from dba_free_space group by file_id) v3
where v1.file_id=v2.file_id(+)
and v1.file_id=v3.file_id(+);
(運行以上查詢，我們可以如下信息：
Totle_pace:該數據文件的總大小，字節爲單位
Free_space:該數據文件的剩於大小，字節爲單位
Used_space:該數據文件的已用空間，字節爲單位
Data_space:該數據文件中段數據佔用空間，也就是數據空間，字節爲單位
File_Head:該數據文件頭部佔用空間，字節爲單位)