ORACLE应用经验(2)[转载]

ORACLE应用经验(2)

------谁正在访问数据库?

Select c.sid, c.serial#,c.username,a.object_id,b.object_name,

c.program,c.status,d.name,c.osuser 

from v$Locked_object a,

 All_objects b,

 v$session c,

 audit_actions d

where a.object_id=b.object_id

 and a.session_id =c.sid(+)

 and c.command=d.action;

alter system kill session '&1,&2';

Select a.sid,a.serial#,a.username,a.status,a.program,b.name,a.osuser

from v$session a,audit_actions b 

where a.command=b.action

Andusername='&1';

------谁被锁住?

Select a.sid,a.serial#,a.username,A.LOCKWAIT,a.status,a.program,b.name

from v$session a,audit_actions b 

where a.command=b.action

AND LOCKWAIT IS NOT NULL;

------谁在锁表?

Select a.sid,a.serial#,a.username,A.LOCKWAIT,a.status,a.program,b.name

from v$session a,audit_actions b 

where a.command=b.action

AND STATUS='ACTIVE';

Select sid, serial#, object_name, row_wait_block#,

 row_wait_row#, row_wait_file#

from all_objects, v$session

 where row_wait_obj#=object_id and type='USER'

 and lockwait is not null ;

Select sl.username, sl.sid, sl.serial#

from v_$lock l1, v$session s1

 where exists (select * from v_$lock l2, v$session s2

 where l2.sid=s2.sid and l2.id1=l1

 and s2.lockwait=l2.kaddr

 and request=0

and l1.sid=s1.sid) ;

select count(*) from v$session;

select count(*) from sys.v_$process;

select count(*) from sys.v_$transaction;

 ZYP_35.98

------查看哪些包要固定

COLUMN OWNER FORMAT A10

Select owner, name, type,

 source_size+code_size+parsed_size+error_size BYPES

from dba_object_size

 where type='PACKAGE BODY' ORDER BY 4 DESC ;

------查看一个用户拥有哪些表空间的实体信息:

Select tablespace_name, owner, segment_name,segment_type

from dba_segments

 where owner-'SyS'

 and segment_type_-'ROLLBACK'

 order by tablespace_name, owner, segment_name ;

break on owner on segment_name

COLUMN segment_name FORMAT A15

cOLUMN tablespace_name FORMAT A15

COLUMN file_name FORMAT A20

SELECT A.owner, a.segment_name, b.tablespace_name, b.file_name,

 sum(a.bytes) bytes

from dba_extents a, dba_data_files b

 where a.file_id-b.file_id group by a.owner, a.segment_name,

 b.tablespace_name, b.file_name ;

------看内存缓冲区使用效率的指数是命中率HITS:

 Hits=Logical_reads/(logical_reads+physical_reads)

其中：logical_reads=db_block_gets+consistent_reads

select cur.value db, con.value con, phy.value phy,

 (cur.value+con.value)/cur.value+con.value+phy.value)*100 HITS

from v$sysstat cur, v$sysstat con, v$sysstat phy

 where CUR.NAME='db block gets' AND

 CON.NAME='consistent gets' AND

 PHY.NAME='physical reads' ;

------如何检测ROLLBACK SEGMENT竞争?

select class, count from v$waitstat

 where class in

 ('system undo header', 'system undo block',

 'undo header', 'undo block') ;

select sum(value) from v$sysstat where name in

 ('db block gets', 'consistents gets') ;

 若count/sum(value)大于1%，则应考虑增加ROLLBACK SEGMENT

------查看有事务在哪几个回退段中：

COLUMN u FORMAT A15

COLUMN s FORMAT A15

COLUMN s FORMAT A80

select osuser o, username u, segment_name s, sa.sql_text

from v$session s, v$transaction t, dba_rollback_segs r, v$sqlarea sa

 where s.taddr=t.addr and t.sidusn=r.segmant_id(+)

 and s.sql_address=sa.address(+) ;