搭建双节点pg_pool+主从postgresql架构

复制方式           优点                                                                 缺点
————————————————————————————————————————————————————————————————————————————————————
同步 数据一致性高                                            1.写入性能低
                                                                          2.只支持一个从节点、多余的从节点为备份
                                                                          3.若只有一个从节点时、从节点正好宕机、则阻塞主节点事物

异步方式（从节点都连接主节点） 写入性能高 1.数据一致性相对弱点（具体看网络部署）
                                                                          2.从节点多时，主节点存在压力较高

异步级联复制 主节点压力小 可靠性差、若前面从节点宕机，则后面从节点数据复制失效

异步+同步复制 数据一致性+高可用都会有保障 1. 需要对同步的从节点设置备份节点
                                                                           2. 故障切换复杂

搭建1主两从同步流复制环境

创建自定义网络类型，并且指定网段

 10.1.20.114:docker network create --subnet=172.172.0.0/ docker-br0
 10.1.20.124:docker network create --subnet=172.172.1.0/ docker-br0

创建docker系统

 docker run -d --privileged --name pg01 --hostname pg01 --net docker-br0 --ip 172.172.0.100 -v /data/pgdata:/pgdata -p  : -p  : centos:latest /usr/sbin/init
 docker run -d --privileged --name pg02 --hostname pg02 --net docker-br0 --ip 172.172.1.100 -v /data/pgdata:/pgdata -p  : -p  : centos:latest /usr/sbin/init

创建路由

  10.1.20.114:ip route add 172.172.1.0/ via 10.1.20.124 dev eth0
  10.1.20.124:ip route add 172.172.0.0/ via 10.1.20.114 dev eth0

安装postgresql(10.1.20.114)

###安装依赖包
yum install zlib-devel gcc make

###创建用户和组
groupadd postgres
useradd -g postgres postgres
passwd postgres

###创建postgresql安装目录
mkdir -p /usr/local/postgresql
chown -R postgres:postgres /usr/local/postgresql

###下载安装文件
cd /usr/local/src
wget https://ftp.postgresql.org/pub/source/v10.5/postgresql-10.5.tar.gz

###解压
tar -xzvf postgresql-10.5.tar.gz

###安装软件
cd postgresql-10.5
./configure --prefix=/usr/local/postgresql --without-readline
make && make install

###安装contrib目录下的一些工具，是第三方组织的一些工具代码，建议安装
cd contrib
make && make install

###创建postgresql的数据目录
mkdir -p /pgdata/postgresql/data
mkdir -p /pgdata/postgresql/logfile
mkdir -p /pgdata/postgresql/archive
chown -R postgres:postgres /pgdata

su - postgres
###配置环境变量

vi .bash_profile
export PGHOME=/usr/local/postgresql/
export PGDATA=/pgdata/postgresql/data
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$PGHOME/lib/
PATH=$PATH:/usr/local/postgresql/bin
source .bash_profile

###初始化数据库
initdb -D /pgdata/postgresql/data

###创建配置文件postgresql.conf

cat > /pgdata/postgresql/data/postgresql.conf << EOF
listen_addresses = '*'
port =
max_connections =
superuser_reserved_connections =
wal_level = logical ##pg10版本中，待选的值为minimal、replica、logical。 minimal --不能通过基础备份和wal日志恢复数据库。 replica = 9.6版本以前的archive和hot_standby --该级别支持wal归档和复制。logical --在replica级别的基础上添加了支持逻辑解码所需的信息。
full_page_writes = on
wal_log_hints = off
archive_mode = on
archive_command = 'cp %p /pgdata/postgresql/archive/%f < /dev/null'
max_wal_senders =
hot_standby = on
log_destination = 'csvlog'
logging_collector = on
log_directory = '/pgdata/postgresql/logfile'
log_filename = 'postgresql-%Y-%m-%d_%H%M%S'
log_rotation_age = 1d
log_rotation_size = 10MB
log_statement = 'mod'

log_timezone = 'PRC'
timezone = 'PRC'
EOF

###启动服务
pg_ctl -D /pgdata/postgresql/data -l logfile start

###设置为开机自启动

su - root
# 添加启动服务（确认文件postgresql内的目录正确）
cp /usr/local/src/postgresql-10.5/contrib/start-scripts/linux /etc/init.d/postgresql
chown -R postgres:postgres /etc/init.d/postgresql
chmod a+x /etc/init.d/postgresql
# 添加开启自启动
chkconfig --add postgresql

#修改开机启动文件/etc/init.d/postgresql的配置信息
vi /etc/init.d/postgresql
prefix=/usr/local/postgresql
PGDATA="/pgdata/postgresql/data"
PGLOG="/pgdata/postgresql/logfile/serverlog"
#重新加载并启动
systemctl daemon-reload
systemctl stop postgresql
systemctl start postgresql

###启动后进程情况如下

 postgres            : ?        :: /usr/local/postgresql/bin/postgres -D /pgdata/postgresql/data
 postgres         : ?        :: postgres: checkpointer process
 postgres         : ?        :: postgres: writer process
 postgres         : ?        :: postgres: wal writer process
 postgres         : ?        :: postgres: autovacuum launcher process
 postgres         : ?        :: postgres: stats collector process
 postgres         : ?        :: postgres: bgworker: logical replication launcher 

###测试

[root@pg01 data]# source ~/.bash_profile
[root@pg01 data]# psql -U postgres
Password for user postgres:
psql (10.5)
Type "help" for help.

postgres=# \l
                             List of databases
   Name    |  Owner   | Encoding  | Collate | Ctype |   Access privileges
-----------+----------+-----------+---------+-------+-----------------------
 postgres  | postgres | SQL_ASCII | C       | C     |
 template0 | postgres | SQL_ASCII | C       | C     | =c/postgres          +
           |          |           |         |       | postgres=CTc/postgres
 template1 | postgres | SQL_ASCII | C       | C     | =c/postgres          +
           |          |           |         |       | postgres=CTc/postgres
 test      | postgres | SQL_ASCII | C       | C     |
( rows)
postgres=# CREATE DATABASE pgpool ;
CREATE DATABASE
postgres=# \c pgpool
You are now connected to database "pgpool" as user "postgres".
pgpool=#
pgpool=# CREATE TABLE pgpool (id serial,age bigint,insertTime timestamp default now());
CREATE TABLE
pgpool=# insert into pgpool (age) values ();
INSERT
pgpool=# select * from pgpool;
 id | age |         inserttime
----+-----+----------------------------
   |    | -- ::03.329849
( row)

安装postgresql(10.1.20.124)

安装步骤和主库10.1.20.114一致

###登录主库并创建同步账号

ALTER USER postgres WITH PASSWORD 'postgres-vcredit';
CREATE USER  replica WITH PASSWORD 'replica-vcredit' REPLICATION;

###修改配置信息（10.1.20.114上执行）

vi pg_hba.conf
local   all             all                                  md5
host    all             all             0.0.0.0/0            md5
host    replication     replica         0.0.0.0/0            md5

local   all             all            ident map=map_root

注：trust为无密码信任登录，只需输入ip和port即可登录；mds需要用户验证登录；ident为映射系统账户到pgsql访问账户。

###同步主库数据（在10.1.20.124上执行）

pg_basebackup -F p --progress -D /pgdata/postgresql/data -h 10.1.20.114 -p  -U replica --password
#pg_basebackup -h 10.10.56.16 -p  -U repl -w -Fp -Xs -Pv -R -D /pgdata/postgresql/data

参数说明

-h  启动的主库数据库地址               -p  主库数据库端口
-U  流复制用户                        -w  不使用密码验证
-Fp 备份输出正常的数据库目录           -Xs 使用流复制的方式进行复制
-Pv 输出复制过程的详细信息             -R  为备库创建recovery.conf文件
-D  指定创建的备库的数据库目录

###创建recovery.cnf 文件（10.1.20.124）

cat >> recovery.conf << EOF
standby_mode = on
primary_conninfo = 'application_name=slave1 host=10.1020.114 port=5432 user=replica password=replica-vcredit'
recovery_target_timeline = 'latest'
#trigger_file = '/pgdata/postgresql/data/trigger_activesdb'
EOF

#################################  小技巧 ##########################################

我们默认情况下使用root，但是必须切换到postgres管理员用户才能执行initdb或psql等命令，而如果我们将root映射成postgres管理员，即可不需要切换用户。

#在pg_hba.conf添加本地账户为ident
vim pg_hba.conf
local all all ident map=map_root
#在pg_ident.conf中添加映射，将本地root账户映射为pgsql管理员账户postgres
vim pg_ident.conf
# MAPNAME SYSTEM-USERNAME PG-USERNAME
map_root root postgres
#测试在系统账户root下，直接以postgres账户登录数据库；而默认下是不允许这样登录的

###################################################################################

###重启服务

su - root
systemctl stop postgresql
systemctl start postgresql

至此主从搭建完毕

安装pgpool(10.1.20.114)

###安装依赖包

yum install gcc-c++ flex readline* readline-devel zlib* openssl openssl-devel -y
yum -y install openssh openssh-clients openssh-server openssh-askpass
yum -y install initscripts 

###创建安装目录

mkdir -p /usr/local/pgpool
chown -R postgres:postgres /usr/local/pgpool

###下载安装包

cd /usr/local/src
wget http://www.pgpool.net/mediawiki/images/pgpool-II-3.7.5.tar.gz

###解压

tar -xzvf pgpool-II-3.7..tar.gz

###编译安装

cd pgpool-II-3.7.
./configure --prefix=/usr/local/pgpool -with-pgsql=path -with-pgsql=/usr/local/postgresql --with-openssl
make && make install

###安装扩展包

cd src/sql/
$ cd pgpool-II-x.x.x/src/sql/pgpool-regclass
$ make
$ make install

psql -f pgpool-regclass.sql -h 172.172.1.100 -p  -U postgres template1

psql -f insert_lock.sql -h 172.172.1.100 -p  -U postgres template1

psql -f pgpool-recovery.sql -h 172.172.1.100 -p  -U postgres template1

chown -R postgres:postgres /usr/local/pgpool

连接主库，创建扩展函数(该步骤非必须，上述安装成功内部已经安装了扩展，下述只为方便查看)

postgres=# create extension pgpool_regclass;
CREATE EXTENSION
postgres=#  CREATE EXTENSION pgpool_recovery;
CREATE EXTENSION
postgres=# select * from pg_extension;
     extname     | extowner | extnamespace | extrelocatable | extversion | extconfig | extcondition
-----------------+----------+--------------+----------------+------------+-----------+--------------
 plpgsql         |        |            | f              | 1.0        |           |
 pgpool_regclass |        |          | t              | 1.0        |           |
 pgpool_recovery |        |          | t              | 1.1        |           |
( rows)

postgres=#

###服务器配置pgpool-Ⅱ

cd /usr/local/pgpool/etc
cp pcp.conf.sample pcp.conf
cp pgpool.conf.sample pgpool.conf
cp pool_hba.conf.sample pool_hba.conf

mkdir -p /pgdata/pgpool/data /pgdata/pgpool/logfile /pgdata/pgpool/script
chown -R postgres:postgres /pgdata

#执行完自动生成pool_passwd文件

pg_md5 -p -m -u postgres pool_passwd 
pg_md5 -p -m -u pg_check pool_passwd 
chown -R postgres:postgres /usr/local/pgpool/

###修改配置文件pgpool.conf

listen_addresses = '*'
port =
pcp_listen_addresses = '*'
pcp_port = 

backend_hostname0 = '172.172.1.100'                      #主库IP
backend_port0 =
backend_weight0 =
backend_data_directory0 = '/pgdata/postgresql/data'
backend_flag0 = 'ALLOW_TO_FAILOVER'

backend_hostname1 = '172.172.0.100'                     #从库IP
backend_port1 =
backend_weight1 =
backend_data_directory1 = '/pgdata/postgresql/data'
backend_flag1 = 'ALLOW_TO_FAILOVER'

enable_pool_hba = on
pool_passwd = 'pool_passwd'

pid_file_name = '/pgdata/pgpool/data/pgpool.pid'
logdir = '/pgdata/pgpool/logfile'

connection_cache = on
replication_mode = off
load_balance_mode = on

master_slave_mode = on
master_slave_sub_mode = 'stream'

sr_check_period =
sr_check_user = 'postgres'
sr_check_password = 'postgres-vcredit'
sr_check_database = 'postgres'
delay_threshold =
follow_master_command = ''

health_check_period =
health_check_timeout =
health_check_user = 'postgres'
health_check_password = 'postgres-vcredit'
health_check_database = 'postgres'
health_check_max_retries =
health_check_retry_delay =
connect_timeout = 

failover_command = '/pgdata/pgpool/script/failover.sh %d %P %H %R'
failback_command = ''
fail_over_on_backend_error = on
search_primary_node_timeout = 

use_watchdog = on
wd_hostname = '172.172.1.100'
wd_port =
wd_priority =
wd_authkey = ''
wd_ipc_socket_dir = '/tmp'

#delegate_IP = '172.172.0.220'                                     #VIP IP
#if_cmd_path = '/usr/sbin'

#if_up_cmd = 'ip addr add $_IP_$/24 dev eth0 label eth0:0'
#if_down_cmd = 'ip addr del $_IP_$/24 dev eth0' 

#arping_path = '/usr/sbin'
#arping_cmd = 'arping -U $_IP_$ -w 1 -I eth0'

wd_monitoring_interfaces_list = ''
wd_lifecheck_method = 'heartbeat'
wd_interval = 

wd_heartbeat_port =
wd_heartbeat_keepalive =
wd_heartbeat_deadtime =
heartbeat_destination0 = '172.172.0.100'                            #从库IP
heartbeat_destination_port0 =
heartbeat_device0 = 'eth0'

other_pgpool_hostname0 = '172.172.0.100'                            #从库IP
other_pgpool_port0 =
other_wd_port0 = 

###创建failover.sh文件

cat >> /pgdata/pgpool/script/failover.sh << EOF
#!/bin/bash  -x

falling_node=$
old_primary=$
new_primary=$
pgdata=/pgdata/pgpool/data

pghome=/usr/local/postgresql
log=/pgdata/pgpool/logfile/failover.log

date >> $log
echo "failed_node_id=$falling_node new_primary=$new_primary" >> $log

if [ $falling_node = $old_primary ]; then
    if [ $UID -eq  ]
    then
        su postgres -c "ssh -T postgres@$new_primary $pghome/bin/pg_ctl promote -D $pgdata"
    else
        ssh -T postgres@$new_primary $pghome/bin/pg_ctl promote -D $pgdata
    fi
    exit ;
fi;
exit ;
EOF

chmod  /pgdata/pgpool/script/failover.sh
chown -R postgres:postgres /pgdata/pgpool/script/failover.sh

###启动

pgpool -n -d -D -a /usr/local/pgpool/etc/pool_hba.conf -f /usr/local/pgpool/etc/pgpool.conf -F /usr/local/pgpool/etc/pcp.conf > /pgdata/pgpool/logfile/pgpool.log >& &

###停止

pgpool -m fast stop

###pgpool 状态查看

psql -h 10.200.22.114 -p  -U postgres pgpool
show pool_nodes;
show pool_processes; -- 查看 pgpool进程 信息
show pool_status;    -- 查看pgpool 配置信息
show pool_pools;     -- 查看 pgpool 连接池

###pcp 配置管理 pgpool

pcp_watchdog_info -h 10.1.20.114 -p  -U postgres -v  --查看 pgpool集群状态
pcp_node_count  -h 10.1.20.114 -p  -U postgres -v -- 查看节点数量
pcp_pool_status -h 10.1.20.114 -p  -U postgres -v  -- 查看pgpool集群配置
pcp_proc_count -h 10.1.20.114 -p  -U postgres -v     -- 查看pgpool processor进程信息

参考资料：

https://blog.csdn.net/yaoqiancuo3276/article/details/80983201
https://blog.csdn.net/kk185800961/article/details/78458999
https://blog.csdn.net/yanggd1987/article/details/51150190
https://my.oschina.net/Suregogo/blog/551626
https://my.oschina.net/Suregogo/blog/552765
https://www.jianshu.com/p/2d07339774c0
https://blog.csdn.net/hkyw000/article/details/51693683
https://www.cnblogs.com/yjf512/p/4499547.html