Oracle体系结构及备份（十六）——bg-ckpt

一  什么是CKPT进程

 

        作用：

                发出信号给DBWn

                更新数据文件头

                更新控制文件

 

        At specific times, all modified databasebuffers in the system global area are written to the datafiles by DBWn. Thisevent is called a checkpoint. The checkpoint process is responsible forsignalling DBWn at checkpoints and updating all the datafiles and control filesof the database to indicate the most recent checkpoint.

 

二  操作示例

 

[oracle@localhost 桌面]$ ps -ef | grep ora_

oracle    6491     1  0 11:17 ?        00:00:00 ora_pmon_orcl

oracle    6493     1  0 11:17 ?        00:00:00 ora_psp0_orcl

oracle    6495     1  0 11:17 ?        00:00:00 ora_mman_orcl

oracle    6497     1  0 11:17 ?        00:00:00 ora_dbw0_orcl

oracle    6499     1  0 11:17 ?        00:00:00 ora_lgwr_orcl

oracle    6501     1  0 11:17 ?        00:00:00 ora_ckpt_orcl

oracle    6503     1  0 11:17 ?        00:00:00 ora_smon_orcl

oracle    6505     1  0 11:17 ?        00:00:00 ora_reco_orcl

oracle    6507     1  0 11:17 ?        00:00:00 ora_cjq0_orcl

oracle    6509     1  0 11:17 ?        00:00:00 ora_mmon_orcl

oracle    6511     1  0 11:17 ?        00:00:00 ora_mmnl_orcl

oracle    6513     1  0 11:17 ?        00:00:00 ora_d000_orcl

oracle    6515     1  0 11:17 ?        00:00:00 ora_s000_orcl

oracle    6519     1  0 11:17 ?        00:00:00 ora_qmnc_orcl

oracle    6527     1  0 11:18 ?        00:00:00 ora_q000_orcl

oracle    6529     1  0 11:18 ?        00:00:00 ora_q001_orcl

oracle    6538     1  0 11:19 ?        00:00:00 ora_j000_orcl

oracle    6541  2720  0 11:19 pts/0    00:00:00 grep ora_

[oracle@localhost 桌面]$ ps -ef | grep ora_ | grep ckpt

oracle    6501     1  0 11:17 ?        00:00:00 ora_ckpt_orcl

[oracle@localhost 桌面]$ kill -9 6501

[oracle@localhost 桌面]$ ps -ef | grep ora_ | grep ckpt

[oracle@localhost 桌面]$ ps -ef | grep ora_

oracle    6554  2720  0 11:20 pts/0    00:00:00 grep ora_

[oracle@localhost 桌面]$ sqlplus / as sysdba;



SQL*Plus: Release 10.2.0.1.0 - Production on Thu Jun 6 11:20:14 2013



Copyright (c) 1982, 2005, Oracle.  All rights reserved.



Connected to an idle instance.



SQL> startup

ORACLE instance started.



Total System Global Area  838860800 bytes

Fixed Size		    1222192 bytes

Variable Size		  788531664 bytes

Database Buffers	   46137344 bytes

Redo Buffers		    2969600 bytes

Database mounted.

Database opened.

SQL> exit;

Disconnected from Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production

With the Partitioning, OLAP and Data Mining options

[oracle@localhost 桌面]$ ps -ef | grep ora_ | grep ckpt

oracle    6568     1  0 11:20 ?        00:00:00 ora_ckpt_orcl

 

三  总结

 

        1.CKPT，非常非常重要的后台进程，同样不能kill。触发顺序：CKPT------>DBWR------->LGWR

        2.作用：发出信号给DBWn、更新数据文件头、更新控制文件

        3.Linux中使用ps命令查看CKPT进程。

我的邮箱：[email protected]  新浪微博：@Wentasy27

  微信公众平台：JustOracle（微信号：justoracle）

  数据库技术交流群：336882565（加群时验证 From CSDN XXX）

  Oracle交流讨论组：https://groups.google.com/d/forum/justoracle

  By Larry Wen

	@Wentasy 博文仅供参考，欢迎大家来访。如有错误之处，希望批评指正。原创博文如需转载请注明出处，谢谢 :) [CSDN博客]