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

　　And username='&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(+) ;

　　结束本文来自：http://doc.xiaoyaxiao.com/1726.html
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