# 獲取安裝包，網速較慢，建議Ke Xue Shang Wang
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 postgresql12-server

# 資料目錄建立與賦權
sudo mkdir /mnt/data/pgdata
sudo chown -R postgres.postgres /mnt/data/pgdata

# 環境變數
sudo vim /usr/lib/systemd/system/postgresql-12.service
Environment
 
=PGDATA=/mnt/data/pgdata
sudo systemctl daemon-reload

# 初始化（以下操作在postgres角色下進行）
/usr/pgsql-12/bin/postgresql-12-setup initdb
systemctl start postgresql-12

# 建立主從備份使用者及改密
psql
create role pgpool with login password 'postgres';
create role repl login replication encrypted password 'postgres';
alter user postgres with password 'postgres';


主節點進行以下配置
cat 
 
>> /mnt/data/pgdata/pg_hba.conf << EOF
host    all            all     0.0.0.0/0          md5 
host    replication    repl    本機ip/32    trust
host    replication    repl    節點1 ip/32    trust #從節點1
host    replication    repl    節點n ip/32    trust #從節點n
host    all                all      本機ip 最後一位替換為0/24      md5 
EOF

cat 
 
>> /mnt/data/pgdata/postgresql.conf << EOF
listen_addresses = '*' #開啟後子節點才能訪問
archive_mode = on
max_connections = 21000
archive_command = 'cp "%p" "/var/lib/pgsql/archivedir/%f"'
max_wal_senders = 10
max_replication_slots = 10
wal_level = replica
hot_standby = on
wal_log_hints = on
EOF


從節點進行以下配置：
cat >> /mnt/data/pgdata/postgresql.conf << EOF
primary_conninfo = 'host=主節點ip port=5432 user=repl(主節點對應賬號) password=密碼'
recovery_target_timeline = latest  
hot_standby = on
max_standby_streaming_delay = 30s
wal_receiver_status_interval = 10s
hot_standby_feedback = on
EOF

echo "standby_mode = on" >> /mnt/data/pgdata/standby.signal


# 重啟服務
使用啟停方式，不要restart

# 從庫進行以下驗證：
rm ‐rf /mnt/data/pgdata/*
pg_basebackup -h 主節點ip -U repl -D /data/pgdata -X stream -P 
iptables -I INPUT -p tcp --dport 5432 -j ACCEPT

# 查詢同步狀態
select client_addr,usename,backend_start,application_name,sync_state,sync_priority FROM pg_stat_replication;