oracle 提示存在lob,案例:Oracle数据库临时文件特别大 commit后lob字段使用临时表空...
測試結果$ ./test1.sh
SQL*Plus: Release 10.2.0.5.0 - Production on Fri Oct 12 10:04:39 2012
Copyright (c) 1982, 2010, Oracle. All Rights Reserved.
SQL> Connected.
SQL> drop user xifenfei cascade
*
ERROR at line 1:
ORA-01918: user 'XIFENFEI' does not exist
Grant succeeded.
SQL>
Revoke succeeded.
SQL> SQL> SQL> Connected.
SQL>
TO_NCLOB('A')
--------------------------------------------------------------------------------
a
SQL> SQL>
SQL*Plus: Release 10.2.0.5.0 - Production on Fri Oct 12 10:04:39 2012
Copyright (c) 1982, 2010, Oracle. All Rights Reserved.
Connected.
USERNAME USER SESSION_ADDR
------------------------------ ------------------------------ ----------------
SESSION_NUM SQLADDR SQLHASH SQL_ID
----------- ---------------- ---------- -------------
TABLESPACE CONTENTS SEGTYPE SEGFILE# SEGBLK#
------------------------------- --------- --------- ---------- ----------
EXTENTS BLOCKS SEGRFNO#
---------- ---------- ----------
xifenfei xifenfei 07000002F96ECB30
10152 07000002AE1C36E0 1362191183 9z69tsx8m2sug
TEMP TEMPORARY LOB_DATA 201 3465
1 128 1
SQL> Disconnected from Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL> SQL>
Commit complete.
SQL> SQL>
SQL*Plus: Release 10.2.0.5.0 - Production on Fri Oct 12 10:04:39 2012
Copyright (c) 1982, 2010, Oracle. All Rights Reserved.
Connected.
USERNAME USER SESSION_ADDR
------------------------------ ------------------------------ ----------------
SESSION_NUM SQLADDR SQLHASH SQL_ID
----------- ---------------- ---------- -------------
TABLESPACE CONTENTS SEGTYPE SEGFILE# SEGBLK#
------------------------------- --------- --------- ---------- ----------
EXTENTS BLOCKS SEGRFNO#
---------- ---------- ----------
xifenfei xifenfei 07000002F96ECB30
10152 07000002AE1C36E0 1362191183 9z69tsx8m2sug
TEMP TEMPORARY LOB_DATA 201 3465
1 128 1
SQL> Disconnected from Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL> SQL> Disconnected from Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
--測試腳本2
$ ./test2.sh
SQL*Plus: Release 10.2.0.5.0 - Production on Fri Oct 12 10:03:56 2012
Copyright (c) 1982, 2010, Oracle. All Rights Reserved.
SQL> Connected.
SQL>
Session altered.
SQL>
TO_NCLOB('A')
--------------------------------------------------------------------------------
a
SQL> SQL>
SQL*Plus: Release 10.2.0.5.0 - Production on Fri Oct 12 10:03:56 2012
Copyright (c) 1982, 2010, Oracle. All Rights Reserved.
Connected.
no rows selected
SQL> Disconnected from Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL> SQL>
Commit complete.
SQL> SQL>
SQL*Plus: Release 10.2.0.5.0 - Production on Fri Oct 12 10:03:56 2012
Copyright (c) 1982, 2010, Oracle. All Rights Reserved.
Connected.
no rows selected
SQL> Disconnected from Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL> SQL> Disconnected from Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
1.Without event 60025 set (before and after commit):都出現v$tempseg_usage中存在對應記錄,而且提交后不能釋放Temp LOB space
2.With event 60025 set (before and after commit):都未現v$tempseg_usage中存在對應記錄,證明提交后釋放Temp LOB space
Oracle研究中心解決方案
通過上面的試驗證明我們可以通過設置event 60025來解決該版本的會話提交后Temp LOB space不能被回收的問題.
我們可以通過在session級別使用”alter session set events ’60025 trace name context forever’;”來實現。如果想實現全庫級別的，但是因為event 60025不能通過system設置生效,所以我們可以通過logon觸發器來實現該功能
create or replace trigger sys.login_db after logon on database
begin
execute immediate 'alter session set events ''60025 trace name context forever''';
end;
/
注意這個是ORCLE bug(Bug 5723140 – Temp LOB space not released after commit [ID 5723140.8]),從10.2.0.4開始雖然已經修復了該bug,但是默認情況下:為了更加高效的利用temp,在session未斷開前,不自動釋放temp 空間,可以通過設置event 60025來強制會話在commit之后就立即釋放temp space
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