PostgreSQL的xlog实验一

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一,从initdb开始,initdb执行结束后,看xlog:

[pgsql@localhost pg_xlog]$ ls -lrt
total 16408
drwx------ 2 pgsql pgsql     4096 Aug  6 10:41 archive_status
-rw------- 1 pgsql pgsql 16777216 Aug  6 10:41 000000010000000000000001
[pgsql@localhost pg_xlog]$ 

然后,设置参数为这样:

archive_mode = on               # allows archiving to be done
                                # (change requires restart)
... archive_command
= 'copy %p "/home/pgsql/archive_log/%f"' # command to use to archive a logfile segment #archive_timeout = 0 # force a logfile segment switch after this # number of seconds; 0 disables wal_level = archive # minimal, archive, or hot_standby # (change requires restart)

二,启动PostgreSQL,然后一直等待...

看xlog是否有变化,等了一个小时以上,没有发现变化。

[pgsql@localhost pg_xlog]$ ls -lrt
total 16408
drwx------ 2 pgsql pgsql     4096 Aug  6 10:41 archive_status
-rw------- 1 pgsql pgsql 16777216 Aug  6 11:04 000000010000000000000001
[pgsql@localhost pg_xlog]$ 
[pgsql@localhost pg_xlog]$ 
[pgsql@localhost pg_xlog]$ ls ../../archive_log
[pgsql@localhost pg_xlog]$ 

三,关闭PostgreSQL: ./pg_ctl -D ../../DemoDir stop

可以发现,online redo log增加了一个。

[pgsql@localhost ~]$ ls -lrt ./DemoDir/pg_xlog
total 32812
-rw------- 1 pgsql pgsql 16777216 Aug 6 12:48 000000010000000000000001
drwx------ 2 pgsql pgsql 4096 Aug 6 12:48 archive_status
-rw------- 1 pgsql pgsql 16777216 Aug 6 12:48 000000010000000000000002
[pgsql@localhost ~]$ ls -lrt ./archive_log
total 16404
-rw------- 1 pgsql pgsql 16777216 Aug 6 12:48 000000010000000000000001
[pgsql@localhost ~]$

再次开启: ./pg_ctl -D ../../DemoDir start

因为没有什么操作,所以也无变化:

[pgsql@localhost ~]$ ls -lrt ./DemoDir/pg_xlog
total 32812
-rw------- 1 pgsql pgsql 16777216 Aug  6 12:48 000000010000000000000001
drwx------ 2 pgsql pgsql     4096 Aug  6 12:48 archive_status
-rw------- 1 pgsql pgsql 16777216 Aug  6 12:48 000000010000000000000002
[pgsql@localhost ~]$ ls -lrt ./archive_log
total 16404
-rw------- 1 pgsql pgsql 16777216 Aug  6 12:48 000000010000000000000001
[pgsql@localhost ~]$ 

再次关闭:./pg_ctl -D ../../DemoDir stop

[pgsql@localhost ~]$ ls -lrt ./DemoDir/pg_xlog
total 49216
-rw------- 1 pgsql pgsql 16777216 Aug  6 12:48 000000010000000000000004
-rw------- 1 pgsql pgsql 16777216 Aug  6 12:51 000000010000000000000002
drwx------ 2 pgsql pgsql     4096 Aug  6 12:51 archive_status
-rw------- 1 pgsql pgsql 16777216 Aug  6 12:51 000000010000000000000003
[pgsql@localhost ~]$ ls -lrt ./archive_log
total 32808
-rw------- 1 pgsql pgsql 16777216 Aug  6 12:48 000000010000000000000001
-rw------- 1 pgsql pgsql 16777216 Aug  6 12:51 000000010000000000000002
[pgsql@localhost ~]$ 

四,如果与性中,进行切换log:

postgres=# select pg_switch_xlog();
 pg_switch_xlog 
----------------
 0/3000098
(1 row)

postgres=# 
[pgsql@localhost ~]$ ls -lrt ./DemoDir/pg_xlog
total 49216
-rw------- 1 pgsql pgsql 16777216 Aug  6 12:48 000000010000000000000004
-rw------- 1 pgsql pgsql 16777216 Aug  6 12:51 000000010000000000000002
drwx------ 2 pgsql pgsql     4096 Aug  6 12:56 archive_status
-rw------- 1 pgsql pgsql 16777216 Aug  6 12:56 000000010000000000000003
[pgsql@localhost ~]$ ls -lrt ./archive_log
total 49212
-rw------- 1 pgsql pgsql 16777216 Aug  6 12:48 000000010000000000000001
-rw------- 1 pgsql pgsql 16777216 Aug  6 12:51 000000010000000000000002
-rw------- 1 pgsql pgsql 16777216 Aug  6 12:56 000000010000000000000003
[pgsql@localhost ~]$ 

  

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磨砺技术珠矶,践行数据之道,追求卓越价值

posted @ 2013-08-06 12:58  健哥的数据花园  阅读(1987)  评论(0编辑  收藏