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 ~]$
本文转自健哥的数据花园博客园博客，原文链接：http://www.cnblogs.com/gaojian/p/3240338.html，如需转载请自行联系原作者
