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How to maintain Oracle10g Recyclebin?

从Oracle10g开始,Oracle引入了flashback drop的新特性,这个新特性,允许你从当前数据库中恢复一个被drop了的对象。在执行drop操作时,现在Oracle不是真正删除它,而是将该对象自动将放入回收站。对于一个对象的删除,其实仅仅就是简单的重令名操作。


所谓的回收站,是一个虚拟的容器,用于存放所有被删除的对象。在回收站中,被删除的对象将占用创建时的同样的空间,你甚至还可以对已经删除的表查询,也可以利用flashback功能来恢复它, 这个就是flashback drop功能。

这个功能虽然可以极大的简化误drop导致的恢复操作,但是长时间的积累可能会导致大量的空间占用(虽然Oracle具有自己的清理机制),很多时候我们需要手工介入去清理回收站。本文主要介绍清理回收站的几种方法.

 1.大量累计的空间占用

Connected to Oracle Database 10g Enterprise Edition Release 10.1.0.3.0 
Connected as SYS

SQL> col owner for a12
SQL> select owner,object_name,CREATETIME,DROPTIME from dba_recyclebin
  2  order by droptime
  3  /
OWNER        OBJECT_NAME                    CREATETIME          DROPTIME
------------ ------------------------------ ------------------- -------------------
COMMON       BIN$AHsQ+pi+Kb/gRAADumkBdQ==$0 2005-08-29:16:42:19 2005-09-11:15:36:17
COMMON       BIN$AHsQ+pi9Kb/gRAADumkBdQ==$0 2005-08-29:16:42:19 2005-09-11:15:36:17
PDA          BIN$AdEb4zqqUcTgRAADumkBdQ==$0 2005-09-05:10:31:01 2005-09-28:15:40:39
......
BJLAIS_RUN   BIN$BtkGRT0dSwfgRAADumkBdQ==$0 2005-11-30:10:54:07 2005-12-01:16:13:17
BJLAIS_RUN   BIN$BtkGRT0cSwfgRAADumkBdQ==$0 2005-11-30:10:54:07 2005-12-01:16:13:17
750 rows selected
SQL> 

2.不同用户在回收站的对象

SQL> select owner,count(*) from dba_recyclebin group by owner;   
OWNER                  COUNT(*)
-------------------- ----------
BJLAIS_RUN                   44
COMMON                        8
MMSBLOG                     618
MMSHAWA_RUN                   2
PDA                           8
RING_RUN                     70
6 rows selected.

3.我们可以指定删除某些特定对象

SQL> purge table common.T_SERVICE_CODE_INFO;

Table purged.

4.指定清除某个表空间的所有回收站对象

SQL> purge tablespace common;
Tablespace purged.
SQL> select owner,count(*) from dba_recyclebin group by owner;   
OWNER                  COUNT(*)
-------------------- ----------
BJLAIS_RUN                   44
MMSBLOG                     618
MMSHAWA_RUN                   2
PDA                           8
RING_RUN                     70

5.以SYSDBA身份可以清除所有回收站对象

SQL> purge dba_recyclebin;

DBA Recyclebin purged.

SQL> select owner,count(*) from dba_recyclebin group by owner;  

no rows selected

6.禁用recyclebin

 

如果我们不希望使用Oracle的recyclebin,可以通过参数禁用这个特性。

在Oracle10gR1中,通过修改一个隐含参数:_recyclebin 为False可以禁用这个特性:

SQL> set linesize 132
SQL> column name format a30
SQL> column value format a25
SQL> select
  2    x.ksppinm  name,
  y.ksppstvl  value,
  3    y.ksppstdf  isdefault,
  4    5    decode(bitand(y.ksppstvf,7),1,'MODIFIED',4,'SYSTEM_MOD','FALSE')  ismod,
  6    decode(bitand(y.ksppstvf,2),2,'TRUE','FALSE')  isadj
  7  from
  8    sys.x$ksppi x,
  9    sys.x$ksppcv y
 10  where
 11    x.inst_id = userenv('Instance') and
 12    y.inst_id = userenv('Instance') and
 13    x.indx = y.indx and
 14    x.ksppinm like '%&par%'
 15  order by
 16    translate(x.ksppinm, ' _', ' ')
 17  /
Enter value for par: recyclebin
old  14:   x.ksppinm like '%&par%'
new  14:   x.ksppinm like '%recyclebin%'
NAME                           VALUE                     ISDEFAULT ISMOD      ISADJ
------------------------------ ------------------------- --------- ---------- -----
_recyclebin                    TRUE                      TRUE      FALSE      FALSE
1 row selected.

在Oracle10gR2中,recyclebin变成了一个常规参数,可以在session/system级动态修改:

[oracle@danaly ~]$ sqlplus "/ as sysdba"
SQL*Plus: Release 10.2.0.1.0 - Production on Mon Dec 12 15:34:56 2005
Copyright (c) 1982, 2005, Oracle.  All rights reserved.

Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production
With the Partitioning, Oracle Label Security, OLAP and Data Mining Scoring Engine options
SQL> show parameter recyclebin 
NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
recyclebin                           string      on
SQL> alter session set recyclebin=off;
Session altered.
SQL> alter session set recyclebin=on
  2  /
Session altered.
SQL> alter system set recyclebin=off;
System altered.
SQL> alter system set recyclebin=on;
System altered.

 


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By eygle on 2005-12-12 15:45 | Comments (3) | HowTo | Oracle12c/11g | 573 |

3 Comments

asefsdfsdfsdfd

show recyclebin没有任何返回提示,但是用select owner,object_name,CREATETIME,DROPTIME from dba_recyclebin返回有很多记录,确认删除的对象是表!不知为何?


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