目录
- 架构图
- 部署详情
- postgresql的安装与配置
- pgpool的安装与配置
写在安装前
postgresql是一款很强大的数据库，具体有多强大呢，请谷歌。。。
网上的相关资料不是很多，参考了大神们的文档，结合自己趟了的坑，写了pg集群的安装文档。可能有一些参数没有配置好，希望大神们指出，谢谢。参照本文档，基本能实现pg的高可用，稍后会写出测试文档。
架构图
部署详情
| ip | host | 系统 | vip | 部署 |
|---|---|---|---|---|
| 192.168.123.180 | master | CentOS 6.8 | 192.168.123.183 | postgresql、pgpool |
| 192.168.123.181 | slave1 | CentOS 6.8 | 192.168.123.183 | postgresql、pgpool |
| 192.168.123.182 | slave2 | CentOS 6.8 | 192.168.123.183 | postgresql |
postgresql的安装
1、安装
1、Rpm包下载地址:
https://yum.postgresql.org/rpmchart.php
下载下面的包：
postgresql95-libs-9.5.8-1PGDG.rhel6.x86_64.rpm
postgresql95-contrib-9.5.8-1PGDG.rhel6.x86_64.rpm
postgresql95-9.5.8-1PGDG.rhel6.x86_64.rpm
postgresql95-server-9.5.8-1PGDG.rhel6.x86_64.rpm
2、安装：
yum install -y postgresql95-libs-9.5.8-1PGDG.rhel6.x86_64.rpm
yum install -y postgresql95-contrib-9.5.8-1PGDG.rhel6.x86_64.rpm
yum install -y postgresql95-9.5.8-1PGDG.rhel6.x86_64.rpm
yum install -y postgresql95-server-9.5.8-1PGDG.rhel6.x86_64.rpm
3、初始化db：
service postgresql-9.5 initdb
4、设置为开机启动：
chkconfig postgresql-9.5 on
5、安装的目录：
/var/lib/pgsql/9.5
配置白名单与流复制
1、 master的配置
PostgreSQL流复制默认是异步的。在主服务器上提交事务和从服务器上变化可见之间有一个小的延迟，这个延迟远小于基于文件日志传送，通常1秒能完成。如果主服务器突然崩溃，可能会有少量数据丢失。
同步复制必须等主服务器和从服务器都写完WAL后才能提交事务。这样在一定程度上会增加事务的响应时间。
配置同步复制仅需要一个额外的配置步骤： synchronous_standby_names必须设置为一个非空值。synchronous_commit也必须设置为on。
这里部署的是异步的流复制
1.2、配置白名单:
vim /var/lib/pgsql/9.5/data/pg_hba.conf
在配置文件最后加上：
host all all 192.168.123.180/32 trust
host all all 192.168.123.181/32 trust
host all all 192.168.123.182/32 trust
host replication replica 192.168.123.181/32 trust
host replication replica 192.168.123.182/32 trust
保存退出
我这里由于是内网，全部用的trust，如果要用密码，请修改为passwd
1.3、修改配置文件:
vim /var/lib/pgsql/9.5/data/postgresql.conf
data_directory = '/app/pgsql/data' #自定义data目录
listen_addresses = '*' #监听所有ip
archive_mode = on #允许归档
archive_command = 'cp %p /app/pgsql/pg_archive/%f' #使用命令归档
wal_level = hot_standby #选择热备
max_wal_senders = 16 #最多多少个流复制链接
wal_keep_segments = 256 #流复制保留最多的xlog数
wal_sender_timeout = 60s #流复制主机发送数据超时时间
max_connections = 99 #从库的max_connections必须大于主库的
1.4、创建data目录，赋权并修改启动文件
mkdir -p /app/pgsql/data && chown postgres:postgres /app/pgsql/data
mkdir -p /app/pgsql/pg_archive && chown postgres:postgres /app/pgsql/pg_archive
cd /app/pgsql && chmod 700 data
cd /app/pgsql && chmod 700 pg_archive
1.5、修改启动文件
vim /etc/init.d/postgresql-9.5
PGDATA=/app/pgsql/data
1.6、把原data目录下的文件copy到新的data的目录下,并改变属组：
cp -r /var/lib/pgsql/9.5/data/* /app/pgsql/data/
cd /app/pgsql && chown -R postgres:postgres data
1.7、启动
service postgresql-9.5 start
以后修改配置文件就在/app/pgsql/data下面修改
1.8、创建一个数据库用户进行主从同步。创建用户replica，并赋予登录和复制的权限
登陆到数据库里：
su postgres
psql
CREATE ROLE replica login replication encrypted password 'replica';
防火墙开放5432端口
在从库上：
psql -h 192.168.123.180 -U postgres
登陆主库成功
2、从库的配置
2.1、自定义data目录:
mkdir -p /app/pgsql/data/&&chmod 700 /app/pgsql/data/
chown -R postgres:postgres pgsql
mkdir /app/pgsql/pg_archive
cd /app/pgsql
chmod 700 pg_archive && chown postgres:postgres pg_archive/
2.2、切换用户:
su – postgres
2.3、备份数据：
pg_basebackup -h 192.168.123.180 -U replica -D /app/pgsql/data -X stream –P
2.4、修改启动文件:
vim /etc/init.d/postgresql-9.5
PGDATA=/app/pgsql/data
2.5、配置recovery.conf
su postgres
cp /usr/pgsql-9.5/share/recovery.conf.sample /app/pgsql/data/recovery.conf
vim /app/pgsql/data/recovery.conf
standby_mode = on \#该节点为从
primary_conninfo = 'host=192.168.123.180 port=5432 user=replica password=replica'
\#主服务器的ip、user
recovery_target_timeline = 'latest'
trigger_file = '/tmp/trigger_file0'
2.6、配置postgresql.conf
vim /app/pgsql/data/postgresql.conf
max_connections = 999 #大于主的连接数
max_standby_streaming_delay = 30s
wal_receiver_status_interval = 10s
hot_standby_feedback = on
2.7、重启服务：
service postgresql-9.5 restart
验证流复制
3.1、在master上登陆psql
查看状态:
select client_addr,sync_state from pg_stat_replication;
3.2、创建test库
Create database test;
3.3、slave上登陆psql
查看库
playboy => \l
发现已同步。
pgpool的安装
pgpool-II是PostgreSQL服务器之间一种有效的中间件和PostgreSQL数据库客户端。它提供了以下功能。
连接池
pgpool-II保存到PostgreSQL服务器的连接，当一个相同新连接(如用户名、数据库、协议版本)进来时，重用他们。它减少了连接开销，提高了系统的整体吞吐量。
复制
pgpool-II可以管理多个PostgreSQL服务器。使用复制功能可以使2个或更多的物理磁盘上创建一个实时备份，这样服务不会因服务器的磁盘故障而中断。
负载平衡
如果数据库是复制的，在任何服务器上执行一个SELECT查询会返回相同的结果。pgpool-II复制特性的优势在于减少每个PostgreSQL服务器上的负载，因为它可以使用分布在多个服务器之间进行SELECT查询，从而提高系统的整体吞吐量。最好是查询和PostgreSQL服务器数量成一定比例，多用户同时执行多查询达到负载均衡最好的效果。
限制连接数
PostgreSQL的最大并发连接数有一定限制的，当超过限制的连接数后，连接会被拒绝。然而，设置增加最大连接数又会增加资源消耗，影响系统性能。pgpool-II也有最大连接数限制，但超过的连接进来时是进行立即排队，而不是返回一个错误。
pgpool-II交互PostgreSQL的后端和前端协议时，起着继电器的作用。因此，数据库应用程序(前端)认为pgpool-II是真实的PostgreSQL服务器，服务器(后端)认为pgpool-II是它的客户端之一。因为pgpool-II在服务器和客户端是透明的，所以pgpool-II可以使用现有的数据库应用程序而做到几乎不修改它们。
版本：3.6
机器：192.168.123.180
192.168.123.181
4.1、免密码登陆
安装之前先配置密钥使master和slave1这两台虚拟机的postgres用户能免密连接
先修改postgres的密码，在root用户下
passwd postgres
新密码123456
Master到slave1的免密码登陆：
在master上切换至postgres用户，生成密钥
su postgres ssh-keygen -t rsa
然后全输入回车
切换到postgres用户：
su postgres ssh-copy-id -i /var/lib/pgsql/.ssh/id_rsa 192.168.123.181
然后ssh 192.168.123.181 成功，实现master到slave1的免密码登陆
Slave1到master的免密码登陆：
流程同上
4.2、安装
Rpm包下载地址:
http://www.pgpool.net/yum/rpms/3.6/redhat/rhel-6-x86_64/pgpool-II-pg95-3.6.0-1pgdg.rhel6.x86_64.rpm
安装:
yum install pgpool-II-pg95-3.6.0-1pgdg.rhel6.x86_64.rpm
4.3、配置
Master的配置:
配置白名单：
要和pg_hba.conf登陆权限一致，这里由于是私有云，都用trust
vim /etc/pgpool-II/pool_hba.conf
在最后改成:
配置pcp管理工具密码:
pg_md5 pwd
密码加密
vim /etc/pgpool-II/pcp.conf
把刚才加密的密码粘贴到文件里
配置系统命令权限:
Root用户下:
chmod u+s /sbin/ifconfig &&chmod u+s /usr/sbin
配置中间件配置文件:
vim /etc/pgpool-II/pgpool.conf
# CONNECTIONS
listen_addresses = '*'
port = 9999
pcp_listen_addresses = '*'
pcp_port = 9898
# - Backend Connection Settings -
backend_hostname0 = 'master'
backend_port0 = 5432
backend_weight0 = 1
backend_data_directory0 = ' /app/pgsql/data'
backend_flag0 = 'ALLOW_TO_FAILOVER'
backend_hostname1 = 'slave'
backend_port1 = 5432
backend_weight1 = 1
backend_data_directory1 = ' /app/pgsql/data''
backend_flag1 = 'ALLOW_TO_FAILOVER'
# - Authentication -
enable_pool_hba = off
pool_passwd = 'pool_passwd'
# FILE LOCATIONS
pid_file_name = '/opt/pgpool/pgpool.pid'
replication_mode = off
load_balance_mode = on
master_slave_mode = on
master_slave_sub_mode = 'stream'
sr_check_period = 5
sr_check_user = 'repuser'
sr_check_password = 'repuser'
sr_check_database = 'postgres'
#------------------------------------------------------------------------------
# HEALTH CHECK 健康检查
#------------------------------------------------------------------------------
health_check_period = 10 # Health check period
# Disabled (0) by default
health_check_timeout = 20
# Health check timeout
# 0 means no timeout
health_check_user = ' repuser '
# Health check user
health_check_password = ' repuser ' #数据库密码
# Password for health check user
health_check_database = 'postgres'
#必须设置，否则primary数据库down了，pgpool不知道，不能及时切换。从库流复制还在连接数据，报连接失败。
#只有下次使用pgpool登录时，发现连接不上，然后报错，这时候，才知道挂了，pgpool进行切换。
#主备切换的命令行配置
#------------------------------------------------------------------------------
# FAILOVER AND FAILBACK
#------------------------------------------------------------------------------
failover_command = ' /opt/pgpool/failover_stream.sh %d %H /tmp/trigger_file0 '
#------------------------------------------------------------------------------
# WATCHDOG
#------------------------------------------------------------------------------
# - Enabling -
use_watchdog = on
# - Watchdog communication Settings -
wd_hostname = 'master'
# Host name or IP address of this watchdog
# (change requires restart)
wd_port = 9000
# port number for watchdog service
# (change requires restart)
# - Virtual IP control Setting -
delegate_IP = ' 192.168.123.183 '
# delegate IP address
# If this is empty, virtual IP never bring up.
# (change requires restart)
if_cmd_path = '/sbin'
# path to the directory where if_up/down_cmd
# (change requires restart)
if_up_cmd = 'ifconfig eth0:0 inet $_IP_$ netmask 255.255.255.0'
# startup delegate IP command
# (change requires restart)
if_down_cmd = 'ifconfig eth0:0 down'
# shutdown delegate IP command
# (change requires restart)
# -- heartbeat mode --
wd_heartbeat_port = 9694
# Port number for receiving heartbeat signal
# (change requires restart)
wd_heartbeat_keepalive = 2
# Interval time of sending heartbeat signal (sec)
# (change requires restart)
wd_heartbeat_deadtime = 30
# Deadtime interval for heartbeat signal (sec)
# (change requires restart)
heartbeat_destination0 = 'slave1'
# Host name or IP address of destination 0
# for sending heartbeat signal.
# (change requires restart)
heartbeat_destination_port0 = 9694
# Port number of destination 0 for sending
# heartbeat signal. Usually this is the
# same as wd_heartbeat_port.
# (change requires restart)
heartbeat_device0 = 'eth0'
# Name of NIC device (such like 'eth0')
# used for sending/receiving heartbeat
# signal to/from destination 0.
# This works only when this is not empty
# and pgpool has root privilege.
# (change requires restart)
# - Other pgpool Connection Settings -
other_pgpool_hostname0 = 'slave' #对端
# Host name or IP address to connect to for
# (change requires restart)
other_pgpool_port0 = 9999
# Port number for othet pgpool 0
# (change requires restart)
other_wd_port0 = 9000
# Port number for othet watchdog 0
# (change requires restart)
4.4、Slave1的配置：
配置白名单：
要和pg_hba.conf登陆权限一致，这里由于是私有云，都用trust
vim /etc/pgpool-II/pool_hba.conf
在最后改成:
配置pcp管理工具密码:
pg_md5 pwd
密码加密
vim /etc/pgpool-II/pcp.conf
把刚才加密的密码粘贴到文件里
配置系统命令权限:
Root用户下:
chmod u+s /sbin/ifconfig &&chmod u+s /usr/sbin
配置中间件配置文件:
vim /etc/pgpool-II/pgpool.conf
# CONNECTIONS
listen_addresses = '*'
port = 9999
pcp_listen_addresses = '*'
pcp_port = 9898
# - Backend Connection Settings -
backend_hostname0 = 'master'
backend_port0 = 5432
backend_weight0 = 1
backend_data_directory0 = ' /app/pgsql/data'
backend_flag0 = 'ALLOW_TO_FAILOVER'
backend_hostname1 = 'slave1'
backend_port1 = 5432
backend_weight1 = 1
backend_data_directory1 = '/app/pgsql/data '
backend_flag1 = 'ALLOW_TO_FAILOVER'
# - Authentication -
enable_pool_hba = off
pool_passwd = 'pool_passwd'
# FILE LOCATIONS
pid_file_name = '/opt/pgpool/pgpool.pid'
replication_mode = off
load_balance_mode = on
master_slave_mode = on
master_slave_sub_mode = 'stream'
sr_check_period = 5
sr_check_user = 'repuser'
sr_check_password = 'repuser'
sr_check_database = 'postgres'
#------------------------------------------------------------------------------
# HEALTH CHECK 健康检查
#------------------------------------------------------------------------------
health_check_period = 10 # Health check period
# Disabled (0) by default
health_check_timeout = 20
# Health check timeout
# 0 means no timeout
health_check_user = ' repuser '
# Health check user
health_check_password = ' repuser ' #数据库密码
# Password for health check user
health_check_database = 'postgres'
#必须设置，否则primary数据库down了，pgpool不知道，不能及时切换。从库流复制还在连接数据，报连接失败。
#只有下次使用pgpool登录时，发现连接不上，然后报错，这时候，才知道挂了，pgpool进行切换。
#主备切换的命令行配置
#------------------------------------------------------------------------------
# FAILOVER AND FAILBACK
#------------------------------------------------------------------------------
failover_command = '/opt/pgpool/failover_stream.sh %d %H /tmp/trigger_file0 '
#------------------------------------------------------------------------------
# WATCHDOG
#------------------------------------------------------------------------------
# - Enabling -
use_watchdog = on
# - Watchdog communication Settings -
wd_hostname = 'slave1' #本端
# Host name or IP address of this watchdog
# (change requires restart)
wd_port = 9000
# port number for watchdog service
# (change requires restart)
# - Virtual IP control Setting -
delegate_IP = '192.168.123.183'
# delegate IP address
# If this is empty, virtual IP never bring up.
# (change requires restart)
if_cmd_path = '/sbin'
# path to the directory where if_up/down_cmd exists
# (change requires restart)
if_up_cmd = 'ifconfig eth0:0 inet $_IP_$ netmask 255.255.255.0'
# startup delegate IP command
# (change requires restart)
if_down_cmd = 'ifconfig eth0:0 down'
# shutdown delegate IP command
# (change requires restart)
# -- heartbeat mode --
wd_heartbeat_port = 9694
# Port number for receiving heartbeat signal
# (change requires restart)
wd_heartbeat_keepalive = 2
# Interval time of sending heartbeat signal (sec)
# (change requires restart)
wd_heartbeat_deadtime = 30
# Deadtime interval for heartbeat signal (sec)
# (change requires restart)
heartbeat_destination0 = 'master' #对端
# Host name or IP address of destination 0
# for sending heartbeat signal.
# (change requires restart)
heartbeat_destination_port0 = 9694
# Port number of destination 0 for sending
# heartbeat signal. Usually this is the
# same as wd_heartbeat_port.
# (change requires restart)
heartbeat_device0 = 'eth0'
# Name of NIC device (such like 'eth0')
# used for sending/receiving heartbeat
# signal to/from destination 0.
# This works only when this is not empty
# and pgpool has root privilege.
# (change requires restart)
# - Other pgpool Connection Settings -
other_pgpool_hostname0 = 'master' #对端
# Host name or IP address to connect to for
# (change requires restart)
other_pgpool_port0 = 9999
# Port number for othet pgpool 0
# (change requires restart)
other_wd_port0 = 9000
# Port number for othet watchdog 0
# (change requires restart)
下面在master和slave1这两台机器上
mkdir /opt/pgpool &&chown postgres:postgres /opt/pgpool
master上：
cd /opt/pgpool
vim failover_stream.sh
# Failover command for streaming replication.
# This script assumes that DB node 0 is primary, and 1 is standby.
#
# If standby goes down, do nothing. If primary goes down, create a
# trigger file so that standby takes over primary node.
#
# Arguments: $1: failed node id. $2: new master hostname. $3: path to
# trigger file.
failed_node=192.168.123.180
new_master=192.168.123.181
trigger_file=$3
# Do nothing if standby goes down.
if [ $failed_node = 1 ]; then
exit 0;
fi
# Create the trigger file.
/usr/bin/ssh -T $new_master /bin/touch $trigger_file
exit 0;
保存退出,并赋权
chown postgres:postgres failover_stream.sh &&chmod 777 failover_stream.sh
slave1上：
cd /opt/pgpool
vim failover_stream.sh
#! /bin/sh
# Failover command for streaming replication.
# This script assumes that DB node 0 is primary, and 1 is standby.
#
# If standby goes down, do nothing. If primary goes down, create a
# trigger file so that standby takes over primary node.
#
# Arguments: $1: failed node id. $2: new master hostname. $3: path to
# trigger file.
failed_node=192.168.123.181
new_master=192.168.123.180
trigger_file=$3
# Do nothing if standby goes down.
if [ $failed_node = 1 ]; then
exit 0;
fi
# Create the trigger file.
/usr/bin/ssh -T $new_master /bin/touch $trigger_file
exit 0;
保存退出并赋权:
chown postgres:postgres failover_stream.sh &&chmod 777 failover_stream.sh
在master和salve1上创建日志文件:
mkdir /var/log/pgpool
chown -R postgres.postgres /var/log/pgpool
mkdir /var/run/pgpool
chown -R postgres.postgres /var/run/pgpool
配置host：
在master、slave1、slave2的/etc/hosts配置ip映射
192.168.123.180 master
192.168.123.181 slave1
192.168.123.182 slave2
在master上创建repusr账号:
su postgres
psql
create user repuser with password 'repuser';
防火墙开放：5432 9999 9898 9000 9694
4.5、启动pgpool
先在master上启动pgpool：
pgpool -n -d -D > /var/log/pgpool/pgpool.log 2>&1 &
再在slave1上启动pgpool:
pgpool -n -d -D > /var/log/pgpool/pgpool.log 2>&1 &
Master上的ifconfig会多一个虚拟ip出来
快速停止pgpool的指令:
pgpool -m fast stop
连接虚拟ip进入数据库:
Su postgres
psql -h 192.168.123.183 -p 9999
查看集群节点状态：
show pool_nodes;
写在安装后
写文档才发现，边安装边趟坑边记录，还要注意格式是多么愉（xin）快（ku）的事，本着开源精神，贴出来给要用到pg集群的小伙伴们参考，本文侵删
