前言

前些天给个环境部署PostgreSQL 主从负载均衡,这里仅仅简单记录一下命令以备后续使用,至于数据库的更多配置请自行根据需求配置.

版本环境

• 服务器系统: CentOS 7.9
• PostgreSQL 版本: 14
• 主数据库内网 IP : 10.0.0.2
• 从数据库内网 IP : 10.0.0.3

主数据库 10.0.0.2

安装

sudo yum install -y https://download.postgresql.org/pub/repos/yum/reporpms/EL-7-x86_64/pgdg-redhat-repo-latest.noarch.rpm
sudo yum install -y postgresql14-server
## 主库初始化数据库
/usr/pgsql-14/bin/postgresql-14-setup initdb
## 启动
sudo systemctl enable postgresql-14
sudo systemctl start postgresql-14

初始化

su - postgres
psql
## 创建 postgres 密码
ALTER USER postgres WITH PASSWORD '123456';
# #创建 从库 replica 用户密码
CREATE ROLE replica login replication encrypted password 'replica';
## 检查账号
SELECT usename from pg_user;
# 结果如下

# usename
# ----------
# postgres
# replica
# (2 rows)

# 查看权限
SELECT rolname from pg_roles;
# 结果如下

# rolname
# ----------
# postgres
# replica
# (2 rows)

# 退出
\q
exit

配置

pg_hba.conf

vi /var/lib/pgsql/14/data/pg_hba.conf
## 添加从库网段
host    all             all             0.0.0.0/0               trust
# replication privilege.
local   replication     all                                     peer
host    replication     replica            10.0.0.3/24        md5

postgresql.conf

vi /var/lib/pgsql/14/data/postgresql.conf
listen_addresses = '*'
wal_level = hot_standby
synchronous_commit = remote_write
# synchronous_commit 参考文档可选其他 on
max_wal_senders = 32     #同步最大的进程数量
wal_sender_timeout = 60s #流复制主机发送数据的超时时间
max_connections = 100    #最大连接数，从库的max_connections必须要大于主库的

从数据库 10.0.0.3

安装

sudo yum install -y https://download.postgresql.org/pub/repos/yum/reporpms/EL-7-x86_64/pgdg-redhat-repo-latest.noarch.rpm
sudo yum install -y postgresql14-server
## 从主库同步数据
pg_basebackup -D /var/lib/pgsql/14/data -h 10.0.0.2 -p 5432 -U replica -X stream -P

配置

postgresql.conf

vi /var/lib/pgsql/14/data/postgresql.conf
## 移除或注释 wal_level
wal_level = xxx
## 修改或添加以下
primary_conninfo = 'host=10.0.0.2 port=5432 user=replica password=replica'
recovery_target_timeline = 'latest'

创建 standby.signal

vi /var/lib/pgsql/14/data/standby.signal
standby_mode = on
## 声明从库

权限

chown -R postgres.postgres /var/lib/pgsql/14/data

启动

sudo systemctl enable postgresql-14
sudo systemctl start postgresql-14

测试同步

主数据库 10.0.0.2

ps aux |grep sender
# 返回 postgres: walsender replica 10.0.0.2(56192) streaming 0/7000148

su - postgres
psql

select application_name, state, sync_priority, sync_state from pg_stat_replication;
# 返回 async
select pid,state,client_addr,sync_priority,sync_state from pg_stat_replication;
# 返回 async

从数据库 10.0.0.3

ps aux |grep receiver
# 返回 postgres: walreceiver streaming 0/7000148