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 dwhere 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.osuserfrom v$session a,audit_actions b where a.command=b.actionAnd  username='&1';------谁被锁住?Select a.sid,a.serial#,a.username,A.LOCKWAIT,a.status,a.program,b.namefrom v$session a,audit_actions b where a.command=b.actionAND LOCKWAIT IS NOT NULL;------谁在锁表?Select a.sid,a.serial#,a.username,A.LOCKWAIT,a.status,a.program,b.namefrom v$session a,audit_actions b where a.command=b.actionAND STATUS='ACTIVE';Select sid, serial#, object_name, row_wait_block#,       row_wait_row#, row_wait_file#  from all_objects, v$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_$transaction; ZYP_35.98------查看哪些包要固定COLUMN OWNER FORMAT A10Select owner, name, type,       source_size+code_size+parsed_size+error_size BYPES  from dba_object_size where type='PACKAGE BODY' ORDER BY 4 DESC ;------查看一个用户拥有哪些表空间的实体信息:Select tablespace_name, owner, segment_name,segment_type  from dba_segments where owner-'SyS'       and segment_type_-'ROLLBACK' order by tablespace_name, owner, segment_name ;break on owner on segment_nameCOLUMN segment_name FORMAT A15cOLUMN tablespace_name FORMAT A15COLUMN file_name FORMAT A20SELECT A.owner, a.segment_name, b.tablespace_name, b.file_name,       sum(a.bytes) bytes  from dba_extents a, dba_data_files b where a.file_id-b.file_id group by a.owner, a.segment_name,       b.tablespace_name, b.file_name ;------看内存缓冲区使用效率的指数是命中率HITS:      Hits=Logical_reads/(logical_reads+physical_reads)其中：logical_reads=db_block_gets+consistent_readsselect cur.value db, con.value con, phy.value phy,       (cur.value+con.value)/cur.value+con.value+phy.value)*100 HITS  from v$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 A15COLUMN s FORMAT A15COLUMN s FORMAT A80select 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(+) ;