oracle dba常用SQL语句

查看表空间的名称及大小:
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;
 
查看表空间物理文件的名称及大小:
SQL>select tablespace_name, file_id, file_name,round(bytes/(1024*1024),0) total_space from dba_data_files order by tablespace_name;
 
查看回滚段名称及大小:
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;
 
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:
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_hashvalue=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：
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;
 
 
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:
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;
 
SQL>column tablespace_name format a18;
SQL>column Sum_M format a12;
SQL>column Used_M format a12;
SQL>column Free_M format a12;
column pto_M format 9.99;
SQL>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:
SQL>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(+);
 
查看数据文件大小及头大小:
SQL>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：
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：
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: 
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：
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：
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:
SQL>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：
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:
SQL>col username format a10
SQL>set line 120
SQL>col EVENT format a30
SQL>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%';
SQL>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：
SQL>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：
SQL>select  segment_name,owner,tablespace_name,initial_extent,next_extent,dba_rollback_segs.status from dba_rollback_segs,v$datafile where file_id=file#;
 
 
Oracle回滚段扩展信息的检查:
SQL>col name format a10
SQL>set linesize 140        
SQL>select substr(name,1,40) name,extents,rssize,optsize,aveactive,extends,wraps,shrinks,hwmsize
from v$rollname rn,v$rollstat rs where (rn.usn=rs.usn);
 
extents:回滚段中的盘区数量。
Rssize:以字节为单位的回滚段的尺寸。
optsize：为optimal参数设定的值。
Aveactive:从回滚段中删除盘区时释放的以字节为单位的平均空间的大小。
Extends:系统为回滚段增加的盘区的次数。
Shrinks:系统从回滚段中清除盘区（即回滚段收缩）的次数。回滚段每次清除盘区时，系统可能会从这个回滚段中消除一个或多个盘区。
Hwmsize:回滚段尺寸的上限，即回滚段曾经达到的最大尺寸。
(如果回滚段平均尺寸接近OPTIMAL的值，那么说明OPTIMAL的值设置正确，如果回滚段动态增长次数或收缩次数很高，那么需要提高OPTIMAL的值)
 
 
查看回滚段的使用情况，哪个用户正在使用回滚段的资源:
SQL>select s.username, u.name from v$transaction t,v$rollstat r,
v$rollname u,v$session s where s.taddr=t.addr and
t.xidusn=r.usn and r.usn=u.usn order by s.username;
 
 
如何查看一下某个shared_server正在忙什么:
SQL>SELECT a.username,a.machine,a.program,a.sid,
a.serial#,a.status,c.piece,c.sql_text
FROM v$session a,v$process b,v$sqltext c
WHERE b.spid=13161 AND b.addr=a.paddr
AND a.sql_address=c.address(+) ORDER BY c.piece; 
 
 
数据库共享池性能检查:
SQL>Select namespace,gets,gethitratio,pins,pinhitratio,reloads,
Invalidations from v$librarycache where namespace in
('SQLAREA','TABLE/PROCEDURE','BODY','TRIGGER');
 
 
检查数据重载比率:
SQL>select sum(reloads)/sum(pins)*100 "reload ratio" from v$librarycache;
 
 
检查数据字典的命中率:
SQL>select 1-sum(getmisses)/sum(gets) "data dictionary hit ratio" from v$rowcache;
 
(对于library cache, gethitratio和pinhitratio应该大于90%,对于数据重载比率,reload ratio应该小于1%,对于数据字典的命中率,data dictionary hit ratio应该大于85%)
 
 
检查共享内存的剩余情况:
SQL>select request_misses, request_failures from v$shared_pool_reserved; 
(对于共享内存的剩余情况, request_misses 和request_failures应该接近0)
 
 
数据高速缓冲区性能检查:
SQL>select 1-p.value/(b.value+c.value) "db buffer cache hit
ratio" from v$sysstat p,v$sysstat b,v$sysstat c where
p.name='physical reads' and b.name='db block gets' and
c.name='consistent gets';
 
 
检查buffer pool HIT_RATIO执行
SQL>select name, (physical_reads/(db_block_gets+consistent_gets))
"MISS_HIT_RATIO" FROM v$buffer_pool_statistics WHERE (db_block_gets+ consistent_gets)> 0;
(正常时db buffer cache hit ratio 应该大于90%,正常时buffer pool MISS_HIT_RATIO 应该小于10%)
 
 
数据库回滚段性能检查:
检查Ratio执行
SQL>select sum(waits)* 100 /sum(gets) "Ratio", sum(waits)
   "Waits", sum(gets) "Gets" from v$rollstat;
 
检查count/value执行:
SQL>select class,count from v$waitstat where class like '%undo%';
SQL>select value from v$sysstat where name='consistent gets';
(两者的value值相除)
 
 
检查average_wait执行:
SQL>select event,total_waits,time_waited,average_wait from v$system_event
where event like '%undo%';
 
 
 
检查RBS header get ratio执行:
SQL>select n.name,s.usn,s.wraps, decode(s.waits,0,1,1- s.waits/s.gets)"RBS
 
 header get ratio" from v$rollstat s,v$rollname n where s.usn=n.usn;
 
(正常时Ratio应该小于1%, count/value应该小于0.01%,average_wait最好为0，该值越小越好,RBS header get ratio应该大于95%)
 
 
杀会话的脚本:
SQL>select A.SID,B.SPID,A.SERIAL#,a.lockwait,A.USERNAME,A.OSUSER,a.logon_time,a.last_call_et/3600 LAST_HOUR,A.STATUS,
'orakill '||sid||' '||spid HOST_COMMAND,
'alter system kill session '''||A.sid||','||A.SERIAL#||'''' SQL_COMMAND
from v$session A,V$PROCESS B where A.PADDR=B.ADDR AND SID>6;
 
 
查看排序段的性能:
SQL>SELECT name, value FROM v$sysstat WHERE name IN ('sorts (memory)', 'sorts (disk)'); 
 
 
查看数据库库对象:
SQL>select owner, object_type, status, count(*) count# from all_objects group by owner, object_type, status;
 
 
查看数据库的版本:　
SQL>Select * from v$version;
 
 
查看数据库的创建日期和归档方式:
SQL>Select Created, Log_Mode, Log_Mode From V$Database;
 
 
捕捉运行很久的SQL:
SQL>column username format a12
SQL>column opname format a16
SQL>column progress format a8
SQL>select username,sid,opname,round(sofar*100 / totalwork,0) || '%' as progress,time_remaining,sql_text from v$session_longops , v$sql where time_remaining <> 0 and sql_address=address and sql_hash_value = hash_value;
 
 
查看数据表的参数信息:
SQL>SELECT partition_name, high_value, high_value_length, tablespace_name,pct_free, pct_used, ini_trans, max_trans, initial_extent,next_extent, min_extent, max_extent, pct_increase, FREELISTS,freelist_groups, LOGGING, BUFFER_POOL, num_rows, blocks,empty_blocks, avg_space, chain_cnt, avg_row_len, sample_size,last_analyzed FROM dba_tab_partitions
--WHERE table_name = :tname AND table_owner = :towner
ORDER BY partition_position;
 
 
 
查看还没提交的事务:
SQL>select * from v$locked_object;
SQL>select * from v$transaction;
 
 
查找object为哪些进程所用:
SQL>select p.spid,s.sid,s.serial# serial_num,s.username user_name,
a.type  object_type,s.osuser os_user_name,a.owner,a.object object_name,decode(sign(48 - command),1,
to_char(command), 'Action Code #' || to_char(command) ) action,
p.program oracle_process,s.terminal terminal,s.program program,s.status session_status  from v$session s, v$access a, v$process p  where s.paddr = p.addr and s.type = 'USER' and a.sid = s.sid  and a.object='SUBSCRIBER_ATTR'order by s.username, s.osuser;
 
 
查看回滚段:
SQL>col name format a10
SQL>set linesize 100
SQL>select rownum, sys.dba_rollback_segs.segment_name Name, v$rollstat.extents Extents, v$rollstat.rssize Size_in_Bytes, v$rollstat.xacts XActs, v$rollstat.gets Gets, v$rollstat.waits Waits, v$rollstat.writes Writes, sys.dba_rollback_segs.status status from v$rollstat, sys.dba_rollback_segs, v$rollname where v$rollname.name(+) = sys.dba_rollback_segs.segment_name and v$rollstat.usn (+) = v$rollname.usn order by rownum;
 
 
查看耗资源的进程(top session):
SQL>select s.schemaname schema_name,decode(sign(48 - command), 1, to_char(command), 'Action Code #' || to_char(command) ) action,status session_status,s.osuser os_user_name,s.sid,p.spid,s.serial# serial_num,nvl(s.username,'[Oracle process]') user_name,s.terminal terminal,s.program program,st.value criteria_value from v$sesstat st,v$session s,v$process p where st.sid = s.sid and st.statistic# = to_number('38') and  ('ALL'='ALL' or s.status ='ALL') and p.addr=s.paddr order by st.value desc,p.spid asc,s.username asc,s.osuser asc;
 
 
根据PID查找相应的语句:
SQL>SELECT a.username,
       a.machine,a.program,a.sid,a.serial#,a.status,c.piece,c.sql_text
  FROM v$session a,v$process b,v$sqltext c WHERE b.spid=spid
   AND b.addr=a.paddr AND a.sql_address=c.address(+) ORDER BY c.piece;
 
 
根据SID找ORACLE的某个进程:
SQL> select pro.spid from v$session ses,v$process pro where ses.sid=21 and ses.paddr=pro.addr;
 
 
监控当前数据库谁在运行什么SQL语句:
SQL>SELECT osuser, username, sql_text from v$session a, v$sqltext b
where a.sql_address =b.address order by address, piece;
 
 
如何查看数据库中某用户，正在运行什么SQL语句
SQL>SELECT SQL_TEXT FROM V$SQLTEXT T, V$SESSION S WHERE T.ADDRESS=S.SQL_ADDRESS
AND T.HASH_VALUE=S.SQL_HASH_VALUE  AND S.MACHINE='XXXXX' OR USERNAME='WACOS';
 
 
如何查出前台正在发出的sql语句:
SQL> select user_name,sql_text from v$open_cursor where sid in(select sid from (select sid,serial# from v$session where status='ACTIVE'));
 
 
查询当前所执行的SQL语句：
SQL> select program ,sql_address from v$session where paddr in (select addr
from v$process where spid=3556);
 
 
 
PROGRAM                                          SQL_ADDRESS
 
------------------------------------------------ ----------------
 
sqlplus@ctc20 (TNS V1-V3)                        000000038FCB1A90
 
 
 
SQL> select sql_text from v$sqlarea where address='000000038FCB1A90';
 
 
 
找出消耗CPU最高的进程对应的SQL语句：
 
SQL>set line 240
 
SQL>set verify off
 
SQL>column sid format 999
 
SQL>column pid format 999
 
SQL>column S_# format 999
 
SQL>column username format A9 heading "ORA User"
 
SQL>column program  format a29
 
SQL>column SQL      format a60
 
SQL>COLUMN OSname format a9 Heading "OS User"
 
SQL>SELECT P.pid pid,S.sid sid,P.spid spid,S.username username,
 
S.osuser osname,P.serial# S_#,P.terminal,P.program  program,
 
P.background,S.status,RTRIM(SUBSTR(a.sql_text, 1, 80))  SQL
 
FROM v$process P, v$session S,v$sqlarea A WHERE P.addr = s.paddr
 
AND S.sql_address = a.address (+)  AND P.spid LIKE '%&1%';
 
 
 
Enter value for 1: PID（这里输入占用CPU最高的进程对应的PID）
 
 
 
 
 
SQL>set termout off
 
SQL>spool maxcpu.txt
 
SQL>SELECT '++'||S.username username,
 
RTRIM(REPLACE(a.sql_text,chr(10),''))||';'FROM v$process P, v$session S,
 
v$sqlarea A WHERE P.addr = s.paddr AND S.sql_address = a.address (+)
 
AND P.spid LIKE '%&&1%';
 
Enter value for 1: PID（这里输入占用CPU最高的进程对应的PID）
 
spool off(这句放在最后执行)
 
 
 
CPU用率最高的2条SQL语句的获取
 
执行：top，通过top获得CPU占用率最高的进程的pid。
 
SQL>select sql_text,spid,v$session.program,process from v$sqlarea,v$session,v$process where v$sqlarea.address=v$session.sql_address and v$sqlarea.hashvalue=v$session.sql_hash_value
 
and v$session.paddr=v$process.addr and v$process.spid in (pid);
 
 
 
SQL>col machine format a30
SQL>col program format a40
SQL>set line 200
SQL>select sid,serial# ,username,osuser,machine,program,process,to_char(logon_time,'yyyy/mm/dd hh24:mi:ss') from v$session where paddr in(select addr from v$process where spid in([$spid]));
 
 
 
SQL>select sql_text from v$sqltext_with_newlines
where hashvalue=(select SQL_HASH_VALUE from v$session where sid=&sid)
order by piece;
 
 
 
 
 
查看锁（lock）情况:
 
SQL>select /*+ RULE */ ls.osuser os_user_name, ls.username user_name, 
decode(ls.type,'RW','Row wait enqueue lock','TM','DML enqueue lock','TX','Transaction enqueue lock','UL','User supplied lock') lock_type,o.object_name object,decode(ls.lmode, 1, null, 2,'Row Share',3,'Row Exclusive',4,'Share',5,'Share Row Exclusive',6,'Exclusive',null)lock_mode,o.owner,ls.sid,ls.serial# serial_num,ls.id1,ls.id2 from sys.dba_objects o,(select s.osuser,s.username,l.type,l.lmode,s.sid,s.serial#,l.id1,l.id2 from v$session s,v$lock l where s.sid=l.sid)ls where o.object_id=ls.id1 and o.owner<>'SYS' order by o.owner, o.object_name;
 
 
 
SQL>select  sys.v_$session.osuser,sys.v_$session.machine,v$lock.sid,
sys.v_$session.serial#,decode(v$lock.type,'MR','Media Recovery',
'RT','Redo Thread','UN','User Name','TX', 'Transaction','TM','DML',
'UL','PL/SQL User Lock','DX','Distributed Xaction','CF','Control File',
'IS','Instance State','FS','File Set','IR','Instance Recovery',
'ST','Disk Space Transaction','TS','Temp Segment','IV','Library Cache Invalida-tion','LS','Log Start or Switch','RW','Row Wait','SQ','Sequence Number','TE','Extend Table','TT','Temp Table','Unknown') LockType,
rtrim(object_type) || ' ' || rtrim(owner) || '.' || object_name object_name,decode(lmode, 0, 'None',1, 'Null',2, 'Row-S',3, 'Row-X',4, 'Share',
5, 'S/Row-X',6, 'Exclusive','Unknown') LockMode,decode(request, 0, 'None',1, 'Null',2, 'Row-S',3, 'Row-X', 4, 'Share',5, 'S/Row-X',
6, 'Exclusive', 'Unknown') RequestMode,ctime, block b
from v$lock, all_objects, sys.v_$session
where v$Lock.sid > 6
and sys.v_$session.sid = v$lock.sid
and v$lock.id1 = all_objects.object_id;
 
 
 
以DBA角色, 查看当前数据库里锁的情况可以用如下SQL语句：
SQL>col owner for a12
SQL>col object_name for a16
SQL>select b.owner,b.object_name,l.session_id,l.locked_mode
from v$locked_object l, dba_objects b
where b.object_id=l.object_id;
 
SQL>select t2.username,t2.sid,t2.serial#,t2.logon_time
from v$locked_object t1,v$session t2
where t1.session_id=t2.sid order by t2.logon_time;
 
 
 
SQL>Select sql_address from v$session where sid=;
SQL>Select * from v$sqltext where address=;
 
 
 
SQL>select COMMAND_TYPE,PIECE,sql_text from v$sqltext where address=(select sql_address from v$session a where sid=18);   
 
 
 
SQL>select object_id from v$locked_object;
 
SQL>select object_name,object_type from dba_objects where object_id=’’;
 
如果有长期出现的一列，可能是没有释放的锁。我们可以用下面SQL语句杀掉长期没有释放非正常的锁：
SQL>alter system kill session 'sid,serial#';
 
查看等待（wait）情况:
 
SQL>SELECT v$waitstat.class,v$waitstat.count count, SUM(v$sysstat.value) sum_value FROM v$waitstat,v$sysstat WHERE v$sysstat.name IN('db block gets','consistent gets') group by v$waitstat.class,v$waitstat.count;
 
查看sga情况:
 
SQL>SELECT NAME, BYTES FROM SYS.V_$SGASTAT ORDER BY NAME ASC;
 
查看catched object:
 
SQL>SELECT owner,name,db_link,namespace,type,sharable_mem,loads,              executions,locks,pins,kept FROM v$db_object_cache;
          
查看V$SQLAREA:
 
SQL>SELECT SQL_TEXT,SHARABLE_MEM,PERSISTENT_MEM,RUNTIME_MEM,SORTS,
VERSION_COUNT,LOADED_VERSIONS,OPEN_VERSIONS,USERS_OPENING,EXECUTIONS,
USERS_EXECUTING,LOADS,FIRST_LOAD_TIME,INVALIDATIONS,PARSE_CALLS,
 
DISK_READS,BUFFER_GETS,ROWS_PROCESSED FROM V$SQLAREA;
 
查看object分类数量:
 
select decode(o.type#,1,'INDEX',2,'TABLE',3,'CLUSTER',4,'VIEW',5,'SYNONYM',6, 'SEQUENCE','OTHER') object_type , count(*) quantity from sys.obj$ o where o.type# > 1 group by decode(o.type#,1,'INDEX',2,'TABLE',3,'CLUSTER' ,4,'VIEW',5,'SYNONYM',6,'SEQUENCE','OTHER') union select 'COLUMN', count(*) from sys.col$ union select 'DB LINK' , count(*) from all_objects;
 
有关connection的相关信息:
 
1）查看有哪些用户连接
 
select s.osuser os_user_name,decode(sign(48 - command),1,to_char(command),
 'Action Code #' || to_char(command))action,p.program oracle_process,
status session_status,s.terminal terminal,s.program program,      
s.username user_name,s.fixed_table_sequence activity_meter,''query,  
0 memory,0 max_memory,0 cpu_usage,s.sid,s.serial# serial_num   
from v$session s,v$process p where s.paddr=p.addr and s.type = 'USER' 
 order by s.username, s.osuser;
 
 
2）根据v.sid查看对应连接的资源占用等情况
 
select n.name,v.value,n.class,n.statistic# 
from v$statname n,v$sesstat v where v.sid=18 and v.statistic# = n.statistic# order by n.class, n.statistic#;
 
 
3）根据sid查看对应连接正在运行的sql
 
select /*+ PUSH_SUBQ */ command_type,sql_text,sharable_mem, persistent_mem,runtime_mem,sorts,version_count,
 
loaded_versions,open_versions,users_opening,executions, users_executing,loads,first_load_time,invalidations, parse_calls,disk_reads,buffer_gets,rows_processed,sysdate start_time,sysdate finish_time,'>'|| address sql_address,
'N' status from v$sqlarea where address = (select sql_address from v$session where sid=8);
 
 
 
根据pid查看sql语句:
SQL>select sql_text from v$sql
where address in
(select sql_address from v$session
where sid in
(select sid from v$session where paddr in (select addr from v$process where spid=&pid)));
 
查询表空间的碎片程度:
SQL>select tablespace_name,count(tablespace_name) from dba_free_space group by tablespace_name having count(tablespace_name)>10;
 
SQL>alter tablespace name coalesce;
 
SQL>alter table table_name deallocate unused;
 
SQL>create or replace view ts_blocks_v as
select tablespace_name,block_id,bytes,blocks,'free space' segment_name from dba_free_space union all
select tablespace_name,block_id,bytes,blocks,segment_name from dba_extents;
 
SQL>select * from ts_blocks_v;
 
SQL>select tablespace_name,sum(bytes),max(bytes),count(block_id) from dba_free_space group by tablespace_name;
 
SQL>select 'alter tablespace '||TABLESPACE_NAME||' coalesce;'
from DBA_FREE_SPACE_COALESCED where PERCENT_EXTENTS_COALESCED<100
or PERCENT_BLOCKS_COALESCED<100;
 
由于自由空间碎片是由几部分组成，如范围数量、最大范围尺寸等，我们可
用fsfi--free space fragmentation index（自由空间碎片索引）值来直观体现:
 
fsfi=100*sqrt(max(extent)/sum(extents))*1/sqrt(sqrt(count(extents)))
 
rem fsfi value compute
rem fsfi.sql
column fsfi format 999,99
select tablespace_name,sqrt(max(blocks)/sum(blocks))*
(100/sqrt(sqrt(count(blocks)))) fsfi
from dba_free_space
group by tablespace_name order by 1;
spool fsfi.rep;
/
spool off;
 
 
 
可以看出，fsfi的最大可能值为100（一个理想的单文件表空间）。随着范
围的增加，fsfi值缓慢下降，而随着最大范围尺寸的减少，fsfi值会迅速下降。
 
比如，在某数据库运行脚本fsfi.sql,得到以下fsfi值：
tablespace_name fsfi
------------------------------ -------
rbs 74.06
system 100.00
temp 22.82
tools 75.79
users 100.00
user_tools 100.00
ydcx_data 47.34
ydcx_idx 57.19
ydjf_data 33.80
ydjf_idx 75.55
 
---- 统计出了数据库的fsfi值，就可以把它作为一个可比参数。在一个有着足够
有效自由空间，且fsfi值超过30的表空间中，很少会遇见有效自由空间的问题。
当一个空间将要接近可比参数时，就需要做碎片整理了。
 
 
 
查询有哪些数据库实例在运行:
SQL>select inst_name from v$active_instances;
 
以DBA角色, 查看当前数据库里锁的情况：
SQL>select object_id,session_id,locked_mode from v$locked_object;
SQL>select t2.username,t2.sid,t2.serial#,t2.logon_time  from  v$locked_object t1,v$session t2 where t1.session_id=t2.sid order by t2.logon_time;
 
查看表是否是分区表：
例子：
SQL>select TABLE_NAME,PARTITIONED from user_tables where TABLE_NAME='LOCALUSAGE';
 
TABLE_NAME                     PAR
------------------------------ ---           ---------
LOCALUSAGE                     YES
 
查看分区表的分区名和相应的表空间名：
SQL>select TABLE_NAME, PARTITION_NAME,TABLESPACE_NAME from user_tab_partitions where table_name like ‘%USAGE%’;
 
查看索引是否是分区索引：
SQL>SELECT INDEX_NAME, TABLE_NAME, STATUS, PARTITIONED FROM USER_INDEXES WHERE TABLE_NAME LIKE '%USAGE';
 
如果返回的PATITIONED为YES，请再执行如下语句来查询分区索引的类型：SELECT index_name,table_name,locality FROM user_part_indexes;
 
Dual是Oracle中的一个实际存在的表，任何用户均可读取，常用在没有目标表的Select中.
 
查看系统时间：
SQL>select to_char(sysdate,'yy-mm-dd hh24:mi:ss') shijian from dual;
 
查看索引段中extent的数量：
SQL>select segment_name,count(*) from dba_extents
where segment_type='INDEX' and owner='SCOTT' group by segment_name;
 
查看系统表中的用户索引（用来检查在system表空间内其他用户索引的存在）：
SQL>select count(*) from dba_indexes where tablespace_name=’SYSTEM’ and owner NOT IN(‘SYS’,’SYSTEM’);
 
 
 
查看wacos表空间内的索引的扩展情况：
SQL>SELECT SUBSTR(segment_name,1,20) "SEGMENT NAME",bytes, COUNT(bytes)
FROM dba_extents WHERE segment_name IN( SELECT index_name FROM dba_indexes
WHERE tablespace_name = 'WACOS') GROUP BY segment_name,bytes ORDER BY segment_name;
 
查看表空间数据文件的读写性能:
SQL>Select name,phyrds,phywrts,avgiotim,miniotim,maxiowtm,maxiortm from v$filestat,v$datafile where v$filestat.file#=v$datafile.file#;
 
SQL>Select fs.name name,f.phyrds,f.phyblkrd,f.phywrts,f.phyblkwrt ,f.readtim,f.writetim
from v$filestat f, v$datafile fs where f.file# = fs.file# order by fs.name;
(注意：如果phyblkrd与phyrds很接近的话，则表明这个表空间中存在全表扫描的表，这些表需要调整索引或优化SQL语句)
 
转换表空间为local方式管理:
SQL> exec sys.dbms_space_admin.tablespace_migrate_to_local('TBS_TEST') ;
 
查看一下哪个用户在用临时段:
SQL>SELECT username,sid,serial#,sql_address,machine,program,tablespace,segtype,
contents FROM v$session se,v$sort_usage su WHERE se.saddr=su.session_addr;
 
查看占io较大的正在运行的session:
SQL>SELECT se.sid,se.serial#,pr.SPID,se.username,se.status,se.terminal,se.program,  se.MODULE,se.sql_address,st.event,st.p1text,si.physical_reads,si.block_changes FROM v$session se,v$session_wait st,v$sess_io si,v$process pr WHERE st.sid=se.sid  AND st.sid=si.sid AND se.PADDR=pr.ADDR AND se.sid>6 AND st.wait_time=0 AND st.event NOT LIKE '%SQL%' ORDER BY physical_reads DESC; 
 
删除用户下所有表的语句:
SQL>select 'drop table '||table_name||' cascade constraints;' from user_tables;