postgresql搭建从库

postgresql搭建从库

master  10.40.196.27

slave   10.40.55.69

需求：master和slave作为主从流复制，当master宕机后，slave切换为新主继续服务；然而当master恢复故障后，作为从重新加入主从流复制。

 

master

1.创建复制用户

create user rep replication password 'rep';

2.设置pg_hba.conf

-bash-4.1$ cat pg_hba.conf|grep repli|grep -v '#'

host    replication     rep             10.40.55.69/32            md5

3.设置主库postgresql.conf

#add by b

wal_level='hot_standby'

archive_mode = on

archive_command = 'ssh 10.40.55.201 test ! -f /backup2/pgdata/digoal/19627/data04/pg93archdir/%f && scp %p

10.40.55.201:/backup2/pgdata/digoal/19627/data04/pg93archdir/%f'

#archive_command = 'archive.sh %p %f'

max_worker_processes = 16

max_wal_senders = 8

wal_keep_segments = 32

4.重启数据库

pg_ctl restart -D /data/pgsql/data

 

slave配置

1.创建数据目录

[postgres@db-hx-55-69 ~]$ echo $PGDATA

/opt/niu/postgresql/data

mkdir -p /opt/niu/postgresql/data;cd /opt/niu/postgresql

chown -R postgres.postgres data

chmod 700 data

cd $PGDATA   (/opt/niu/postgresql/data)

rm -rf *

master 196.27

-bash-4.1$ cd $PGDATA/pg_tblspc/

-bash-4.1$ ll

total 0

lrwxrwxrwx 1 postgres postgres 25 Jan 12 13:34 1031792 -> /opt/pgsql/bi_erp_itf_tbs

lrwxrwxrwx 1 postgres postgres 14 May 20  2016 16385 -> /opt/pgsql/tbs

[root@db-hx-55-69 pgsql]# pwd

/opt/pgsql

[root@db-hx-55-69 pgsql]# rm -rf *

2.使用pg_basebackup生成基础备份，放到slave上数据目录下

[postgres@db-hx-55-69 ~]$ pg_basebackup -D /opt/niu/postgresql/data -Fp -Xs -v -P -h 10.40.196.27 -p 5432 -U rep

Password: rep

3.配置recovery.conf

vi $PGDATA/recovery.conf

standby_mode = on

trigger_file = '/opt/niu/postgresql/pg.trigger'

primary_conninfo = 'host=10.40.196.27 port=5432 user=rep password=rep'

4.启动pgsql

$ pg_ctl start -D /opt/niu/postgresql/data

测试流复制

1.查看主库

主库$ ps -ef |grep postgres|grep sender |grep -v grep

postgres  89707  65237  0 00:15 ?        00:00:00 postgres: wal sender process rep 10.40.55.69(26717) streaming 9F1/51EE4FB0

确认主库中进程有“postgres: wal sender process”

2.查看从库

$ ps -ef |grep postgres |grep -v grep |grep receiver

postgres 14055 14013  1 00:15 ?        00:00:02 postgres: wal receiver process   streaming 9F1/5423E000  

确定备库进程中有”postgres: wal receiver process”

4.查看主备同步状态

postgres=# select * from pg_stat_replication;

  pid  |
usesysid | usename | application_name | client_addr | client_hostname |
client_port |         backend_start         | backend_xmin |   

state   | sent_location

| write_location | flush_location | replay_location | sync_priority | sync_state

-------+----------+---------+------------------+-------------+-----------------+-------------+-------------------------------+--------------

+-----------+---------------

+----------------+----------------+-----------------+---------------+------------

89707
|   988512 | rep     | walreceiver      | 10.40.55.69
|                 |       26717 | 2018-03-10 00:15:14.610005+08
|              |

streaming | 9F1/6073C458  

| 9F1/6073C458   | 9F1/6073C458   | 9F1/6073BFE0    |             0 | async

(1 row)

字段state显示的同步状态有：startup（连接中）、catchup（同步中）、streaming（同步）；

字段sync_state显示的模式有：async（异步）、sync（同步）、potential（虽然现在是异步模式，但是有可能升级到同步模式）

 

[postgres@db-hx-55-69 pgsql]$ psql

psql: FATAL:  the database system is starting up