Oracle体系结构及备份（十六）——bg-ckpt

妖狐艹你老母 2022-10-02 13:59 1阅读 0赞

### 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.

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### 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。

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