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 2013Copyright (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：wgbno27@163.com  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

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