如何获得当前数据库的SCN值-Mysql Tutorial-php.cn

如何获得当前数据库的SCN值

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Release： 2016-06-07 14:59:51

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欢迎进入Oracle社区论坛，与200万技术人员互动交流 >>进入主要可以通过两种方式: 1.在Oracle9i及以上版本中可以使用dbms_flashback.get_system_change_number来获得 SQL select dbms_flashback.get_system_change_number from dual; GET_SYSTEM_CHANGE_NUM

欢迎进入Oracle社区论坛，与200万技术人员互动交流 >>进入

主要可以通过两种方式:

1.在Oracle9i及以上版本中

可以使用dbms_flashback.get_system_change_number来获得

SQL> select dbms_flashback.get_system_change_number from dual;

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GET_SYSTEM_CHANGE_NUMBER<br>------------------------<br>                 2982184

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2.在Oracle9i之前

可以通过查询x$ktuxe获得最接近当前系统scn值

X$KTUXE-------------[K]ernel [T]ransaction [U]ndo Transa[x]tion [E]ntry (table)

SQL> select max(ktuxescnw*power(2,32)+ktuxescnb) from x$ktuxe;

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MAX(KTUXESCNW*POWER(2,32)+KTUXESCNB)<br>------------------------------------<br>                             2980613

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3.通过oradebug获取

以前在l2g32003的站点上看到使用oradebug获取SCN的方法,转引在这里:

[oracle@neirong oracle]$ sqlplus "/ as sysdba"

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SQL*Plus: Release 9.2.0.4.0 - Production on Wed Dec 21 21:04:24 2005

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Copyright (c) 1982, 2002, Oracle Corporation.  All rights reserved.

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Connected to:<br>Oracle9i Enterprise Edition Release 9.2.0.4.0 - Production<br>With the Partitioning, OLAP and Oracle Data Mining options<br>JServer Release 9.2.0.4.0 - Production

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SQL> col a for 999999999999<br>SQL> oradebug setmypid<br>Statement processed.<br>SQL> oradebug DUMPvar SGA kcsgscn_<br>kcslf kcsgscn_ [1200BC68, 1200BC88) = 0000<strong>0003 BA84F392</strong> 00071266 00000000 00000000 00000000 00000000 1200B948<br>SQL> select to_number('3BA84F392','xxxxxxxxxxxx') a from dual;

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            A<br>-------------<br>  16014177170

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SQL> select dbms_flashback.get_system_change_number a from dual;

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            A<br>-------------<br>  16014177255

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SQL>

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方法有多种,但是涉及的知识各有巧妙不同,深入研究一下都是很有意思的.

如何获得当前数据库的SCN值