Postgresql主从搭建

1. 安装PG数据库

安装过程略。注：slave端可以只装数据库，不初始化数据库

2. 创建流复制用户

master端执行

CREATE USER repuser replication LOGIN CONNECTION LIMIT 2 ENCRYPTED PASSWORD 'repuser';

3. 配置Master端的访问文件

vi  pg_hba.conf

增加一行：

host replication repuser 192.168.2.129/16 md5

4. 配置MASTER端配置文件

listen_addresses = '*'

max_wal_senders = 1

wal_level = hot_standby

archive_mode = on

archive_command = 'cd ./'

wal_keep_segments = 64

注：max_wal_senders是Slave库的节点数，有多少个slave库就设多少,

   wal_level是write ahead log参数值,设置流复制务必将此值更新成hot_standby

   wal_keep_segments默认值是16,是PG_XLOG下的日志文件大小

archive也可以选择关闭，归档是定时恢复用的，流复制不是必须的 

5. 主库备份(Master端)

5.1. 开启文件备份

前提是wal_level参数值必须是archive或者hot_standby

执行命令：select pg_start_backup('Replition work');

5.2. 拷贝数据文件

拷贝$PGDATA文件，并复制到Slave服务器上,排除pg_xlog内容。

tar czvf pgdata.tar.gz pgdata --exclude=pgdata/pg_xlog

远程拷贝至slave端并在备机端解压

scp pgdata.tar.gz root@192.168.2.129:/database/

tar xzvf pgdata.tar.gz

5.3. 结束master端的备份

上述步骤完成后,结束master端的备份

select pg_stop_backup(), current_timestamp;

6. 修改Slave端配置信息

6.1.  postgresql.conf文件

修改postgresql.conf文件

hot_standby = on

6.2.  recovery.conf文件

拷贝recovery.conf文件

$cp $PGHOME/share/recovery.conf.sample $PGDATA/recovery.conf

修改recovery.conf文件，新增以下三行

$ vi recovery.conf  

  standby_mode = 'on'

  trigger_file = '/database/pgdata/postgresql.trigger.1949'

  primary_conninfo = 'host=192.168.2.130 port=1949 user=repuser password=repuser keepalives_idle=60'

6.3.  配置.pgpass文件(slave端)

新增slave访问master的密码文件，可以不用输密码

192.168.2.130:1949:postgres:repuser:repuser

6.4. 删除pid文件

删除slave端(从master端拷过来的)的pid文件和pg_xlog

$ rm -rf  $PGDATA/pg_xlog

$ rm -f $PGDATA/postmaster.pid

$ mkdir  $PGDATA/pg_xlog

7. 启动Slave库

正常启动备库(pg_ctl -D $PGDATA -l pg.log start),有异常可以看log复制完成后，可以通过CSV日志去查看，本处未设，直接查看进程。

7.1.  查看master进程：

[postgres@localhost ~]$ ps -ef|grep postgres

root      2454  2438  0 20:25 pts/0    00:00:00 su - postgres

postgres  2461  2454  0 20:25 pts/0    00:00:00 -bash

postgres  2535  1 0 20:26 pts/1 00:00:00 /home/postgres/bin/postgres -D /database/pgdata

postgres  2537  2535  0 20:26 ?        00:00:00 postgres: writer process                       

postgres  2538  2535  0 20:26 ?        00:00:00 postgres: wal writer process                   

postgres  2539  2535  0 20:26 ?        00:00:00 postgres: autovacuum launcher process          

postgres  2540  2535  0 20:26 ?        00:00:00 postgres: archiver process                     

postgres  2541  2535  0 20:26 ?        00:00:00 postgres: stats collector process              

postgres  3079  2535  0 21:56 ?        00:00:00 postgres: wal sender process repuser 192.168.2.129(45446) streaming 0/C01EDB8

 

7.2.  查看slave进程：

[postgres@localhost ~]$ ps -ef|grep postgres

postgres  2856     1  0 21:54 pts/2    00:00:00 /home/postgres/bin/postgres -D /database/pgdata

postgres  2858  2856  0 21:54 ?        00:00:00 postgres: startup process   recovering 000000010000000000000003

postgres  2859  2856  0 21:54 ?        00:00:00 postgres: writer process                       

postgres  2860  2856  0 21:54 ?        00:00:00 postgres: stats collector process              

postgres  2899  2856  0 21:56 ?        00:00:00 postgres: wal receiver process   streaming 0/C01ED28

 

此时在slave端的pg_xlog下面也产生了日志文件,并且之前pg_start_backup生成的文件名也变成了old的了.

 

查看日志内容：

[postgres@localhost ~]$ more pgsql.log

LOG:  database system was shut down in recovery at 2012-04-23 18:33:25 PDT

LOG:  entering standby mode

LOG:  streaming replication successfully connected to primary

LOG:  redo starts at 0/8000020

LOG:  consistent recovery state reached at 0/C000000

LOG:  database system is ready to accept read only connections