Oracle DBA常用语句-丞旭猿

查看表空间的名称及大小

实现代码如下：

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; 

查看表空间物理文件的名称及大小:

实现代码如下：

SQL>select tablespace_name, file_id, file_name,round(bytes/(1024*1024),0) total_space from dba_data_files order by tablespace_name; 

查看回滚段名称及大小:

实现代码如下：

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; 

如何查看某个回滚段里面，跑的什么事物或者正在执行什么sql语句:

实现代码如下：

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; 

(备注：你要看哪个，就把usn=?写成几就行了)
查看控制文件:
SQL>select * from v$controlfile;
查看日志文件:
SQL> col member format a50
SQL>select * from v$logfile;
如何查看当前SQL*PLUS用户的sid和serial#:
SQL>select sid, serial#, status from v$session where audsid=userenv(‘sessionid’);
如何查看当前数据库的字符集:
SQL>select userenv(‘language’) from dual;
SQL>select userenv(‘lang’) from dual;
怎么判断当前正在使用何种SQL优化方式:
用explain plan产生EXPLAIN PLAN，检查PLAN_TABLE中ID=0的POSITION列的值。
SQL>select decode(nvl(position,-1),-1,’RBO’,1,’CBO’) from plan_table where id=0;
如何查看系统当前最新的SCN号：
SQL>select max(ktuxescnw * power(2,32) + ktuxescnb) from x$ktuxe;
在ORACLE中查找TRACE文件的脚本:
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;
如何查看客户端登陆的IP地址:
SQL>select sys_context(‘userenv’,’ip_address’) from dual;
如何在生产数据库中创建一个追踪客户端IP地址的触发器：

实现代码如下：

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; 
REM 记录登陆信息的触发器 
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; 

查询当前日期:
SQL> select to_char(sysdate,’yyyy-mm-dd,hh24:mi:ss’) from dual;
查看所有表空间对应的数据文件名：
SQL>select distinct file_name,tablespace_name,AUTOEXTENSIBLE from dba_data_files;
查看表空间的使用情况:

实现代码如下：

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; 

查看数据文件的hwm（可以resize的最小空间）和文件头大小:

实现代码如下：

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(+); 

数据文件大小及头大小:

实现代码如下：

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(+); 

(运行以上查询，我们可以如下信息：

实现代码如下：

Totle_pace:该数据文件的总大小，字节为单位 
Free_space:该数据文件的剩于大小，字节为单位 
Used_space:该数据文件的已用空间，字节为单位 
Data_space:该数据文件中段数据占用空间，也就是数据空间，字节为单位 
File_Head:该数据文件头部占用空间，字节为单位) 

数据库各个表空间增长情况的检查：

实现代码如下：

SQL>select A.tablespace_name,(1-(A.total)/B.total)*100 used_percent 
From (select tablespace_name,sum(bytes) total from dba_free_space group by tablespace_name) A,(select tablespace_name,sum(bytes) total from dba_data_files group by tablespace_name) B where A.tablespace_name=B.tablespace_name; 
SQL>SELECT UPPER(F.TABLESPACE_NAME) “表空间名”, 
D.TOT_GROOTTE_MB “表空间大小(M)”, 
D.TOT_GROOTTE_MB – F.TOTAL_BYTES “已使用空间(M)”, TO_CHAR(ROUND((D.TOT_GROOTTE_MB – F.TOTAL_BYTES) / D.TOT_GROOTTE_MB * 100, 2), ‘990.99’) “使用比”, F.TOTAL_BYTES “空闲空间(M)”, 
F.MAX_BYTES “最大块(M)” FROM (SELECT TABLESPACE_NAME, 
ROUND(SUM(BYTES) / (1024 * 1024), 2) TOTAL_BYTES, 
ROUND(MAX(BYTES) / (1024 * 1024), 2) MAX_BYTES 
FROM SYS.DBA_FREE_SPACE GROUP BY TABLESPACE_NAME) F, 
(SELECT DD.TABLESPACE_NAME,ROUND(SUM(DD.BYTES) / (1024 * 1024), 2) TOT_GROOTTE_MB FROM SYS.DBA_DATA_FILES DD 
GROUP BY DD.TABLESPACE_NAME) D WHERE D.TABLESPACE_NAME = F.TABLESPACE_NAME 
ORDER BY 4 DESC; 

查看各个表空间占用磁盘情况:

实现代码如下：

SQL>col tablespace_name format a20; 
SQL>select b.file_id file_ID, 
b.tablespace_name tablespace_name, 
b.bytes Bytes, 
(b.bytes-sum(nvl(a.bytes,0))) used, 
sum(nvl(a.bytes,0)) free, 
sum(nvl(a.bytes,0))/(b.bytes)*100 Percent 
from dba_free_space a,dba_data_files b 
where a.file_id=b.file_id 
group by b.tablespace_name,b.file_id,b.bytes 
order by b.file_id; 

数据库对象下一扩展与表空间的free扩展值的检查：

实现代码如下：

SQL>select a.table_name, a.next_extent, a.tablespace_name 
from all_tables a,(select tablespace_name, max(bytes) as big_chunk 
from dba_free_space group by tablespace_name ) f where f.tablespace_name = a.tablespace_name and a.next_extent > f.big_chunk 
union select a.index_name, a.next_extent, a.tablespace_name 
from all_indexes a,(select tablespace_name, max(bytes) as big_chunk 
from dba_free_space group by tablespace_name ) f where f.tablespace_name = a.tablespace_name and a.next_extent > f.big_chunk; 

Disk Read最高的SQL语句的获取：

实现代码如下：

SQL>select sql_text from (select * from v$sqlarea order by disk_reads) 
where rownum<=5; 

查找前十条性能差的sql

实现代码如下：

SELECT * FROM (SELECT PARSING_USER_ID 
EXECUTIONS,SORTS,COMMAND_TYPE,DISK_READS, 
sql_text FROM v$sqlarea ORDER BY disk_reads DESC) 
WHERE ROWNUM<10 ; 

等待时间最多的5个系统等待事件的获取：

实现代码如下：

SQL>select * from (select * from v$system_event where event not like ‘SQL%’ order by total_waits desc) where rownum<=5; 

查看当前等待事件的会话:

实现代码如下：

col username format a10 
set line 120 
col EVENT format a30 
select SE.Sid,s.Username,SE.Event,se.Total_Waits,SE.Time_Waited,SE.Average_Wait 
from v$session S,v$session_event SE where S.Username is not null and SE.Sid=S.Sid 
and S.Status=’ACTIVE’ and SE.Event not like ‘%SQL*Net%’; 
select sid, event, p1, p2, p3, wait_time, seconds_in_wait, state from v$session_wait where event not like ‘%message%’ and event not like ‘SQL*Net%’ and event not like ‘%timer%’ and event != ‘wakeup time manager’; 

找到与所连接的会话有关的当前等待事件：

实现代码如下：

select SW.Sid,S.Username,SW.Event,SW.Wait_Time,SW.State,SW.Seconds_In_Wait SEC_IN_WAIT 
from v$session S,v$session_wait SW where S.Username is not null and SW.Sid=S.Sid 
and SW.event not like ‘%SQL*Net%’ order by SW.Wait_Time Desc; 

Oracle所有回滚段状态的检查：

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