查詢鎖表

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select object_name, machine, s.sid, s.serial#
from v$locked_object l, dba_objects o, v$session s
where l.object_id = o.object_id
and l.session_id = s.sid;
解表
ALTER system kill session 'sid, serial#';
ALTER system kill session '256, 34034';
ques
1:oracl里是有很多鎖,但是很多它是自己用的。你無(wú)需操心。但要明白原理。
ques
2:
任何一條sql語(yǔ)句都會(huì)啟動(dòng)一種鎖。比如select就會(huì)啟動(dòng)共享鎖。如果用了select...for
update
就會(huì)在那一行加上排它鎖。不允許其他的會(huì)話改著條數(shù)據(jù),但是很多在完畢了就釋放了。因?yàn)檫\(yùn)行的很快。一般commit就會(huì)釋放鎖。
ques
3:事務(wù)T1對(duì)A加了一個(gè)排它鎖,在oracle中不可以加其它鎖了。
ques
4:事務(wù)T1對(duì)A加了一個(gè)共享鎖,還可以加共享鎖,和排他鎖。
一些ORACLE中的進(jìn)程被殺掉后,狀態(tài)被置為"killed",但是鎖定的資源很長(zhǎng)時(shí)間不釋放,有時(shí)實(shí)在沒(méi)辦法,只好重啟數(shù)據(jù)庫(kù)。現(xiàn)在提供一種方法解決這種問(wèn)題,那就是在ORACLE中殺不掉的,在OS一級(jí)再殺。
1.下面的語(yǔ)句用來(lái)查詢哪些對(duì)象被鎖:
select object_name,machine,s.sid,s.serial#
from v$locked_object l,dba_objects o ,v$session s
where l.object_id = o.object_id and l.session_id=s.sid;
2.下面的語(yǔ)句用來(lái)殺死一個(gè)進(jìn)程:
alter system kill session '24,111'; (其中24,111分別是上面查詢出的sid,serial#)
【注】以上兩步,可以通過(guò)Oracle的管理控制臺(tái)來(lái)執(zhí)行。
3.如果利用上面的命令殺死一個(gè)進(jìn)程后,進(jìn)程狀態(tài)被置為"killed",但是鎖定的資源很長(zhǎng)時(shí)間沒(méi)有被釋放,那么可以在os一級(jí)再殺死相應(yīng)的進(jìn)程(線程),首先執(zhí)行下面的語(yǔ)句獲得進(jìn)程(線程)號(hào):
select spid, osuser, s.program
from v$session s,v$process p
where s.paddr=p.addr and s.sid=24 (24是上面的sid)
4.在OS上殺死這個(gè)進(jìn)程(線程):
1)在unix上,用root身份執(zhí)行命令:
#kill -9 12345(即第3步查詢出的spid)
2)在windows(unix也適用)用orakill殺死線程,orakill是oracle提供的一個(gè)可執(zhí)行命令,語(yǔ)法為:
orakill sid thread
其中:
sid:表示要?dú)⑺赖倪M(jìn)程屬于的實(shí)例名
thread:是要?dú)⒌舻木€程號(hào),即第3步查詢出的spid。
例:c:orakill orcl 12345
查詢鎖表:SELECT l.session_id sid,
? s.serial#,
? l.locked_mode,
? l.oracle_username,
? l.os_user_name,
? s.machine,
? s.terminal,
? o.object_name,
? s.logon_time FROM? v$locked_object l,
? all_objects? ? ? o,
? v$session? ? ? ? s WHERE l.object_id = o.object_id ANd l.session_id = s.sid ORDER BY sid,
? s.serial#;
解鎖:ALTER system KILL session 'sid,serial#';
查詢鎖住原因:SELECT b.sid oracleID,b.username 登錄Oracle用戶名,b.serial#,spid 操作系統(tǒng)ID,paddr,?
sql_text 正在執(zhí)行的SQL,b.machine 計(jì)算機(jī)名 FROM v$process a, v$session b, v$sqlarea c?
WHERE a.addr = b.paddr AND b.sql_hash_value = c.hash_value? and b.USERNAME='FKPHIS24';
鎖表:LOCK TABLE tablename IN 鎖模式 MODE;
解鎖:commit或rollback;
鎖模式有以下幾種:
ROW SHARE
ROW SHARE permits concurrent access to the locked table but prohibits users from locking the entire table for exclusive access. ROW SHARE is synonymous with SHARE UPDATE, which is included for compatibility with earlier versions of Oracle Database.
ROW EXCLUSIVE
ROW EXCLUSIVE is the same as ROW SHARE, but it also prohibits locking in SHARE mode. ROW EXCLUSIVE locks are automatically obtained when updating, inserting, or deleting.
SHARE UPDATE
See ROW SHARE.
SHARE
SHARE permits concurrent queries but prohibits updates to the locked table.
SHARE ROW EXCLUSIVE
SHARE ROW EXCLUSIVE is used to look at a whole table and to allow others to look at rows in the table but to prohibit others from locking the table in SHARE mode or from updating rows.
EXCLUSIVE
EXCLUSIVE permits queries on the locked table but prohibits any other activity on it.
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