4、pgpool-II 流复制模式

一、架构图

  1. PostgreSQL 流复制是基于 wal 日志复制。主库产生 wal 日志并发送给备库;备库接收 wal 日志记录;并重放这些 wal 日志。从而达到主备库数据同步。备库只读。
  2. 复制级别是实例级
  3. 在这个模式下:Pgpool 充当连接池作用;
  4. 读写查询智能分发;可以实现负载均衡;这是其他的HA软件不具有的

二、配置示例

本文是为后续文章做铺垫

Pgpool-II 流复制示例环境

|角色|ip|端口|数据目录|
|:----😐:----|:----😐:----|:----😐:----|:----😐:----|
|pgpool|192.168.1.221|9999| |
|primary|192.168.1.221|6000|/data/postgres/data|
|standby|192.168.1.221|6001|/data/postgres/data1|

1、搭建流复制

#1、搭建备库
[postgres@node3 data1]$ pg_basebackup -F p -R --progress -D /data1/postgres/data1 -h 192.168.1.221 -p 6000 -U replica
Password: 
66660/66660 kB (100%), 2/2 tablespaces
#2、启动备库
# 由于在同一台服务器上搭建;需要修改端口pgport:6001
[postgres@node3 data1]$ pg_ctl start -D /data1/postgres/data1
#3、查看是否搭建成功
[postgres@node3 ~]$ psql
psql (12.2)
Type "help" for help.
postgres=# \x
Expanded display is on.
postgres=# select * from pg_stat_replication ;
-[ RECORD 1 ]----+------------------------------
pid              | 4072
usesysid         | 73745
usename          | replica
application_name | walreceiver
client_addr      | 192.168.1.221
client_hostname  | 
client_port      | 52720
backend_start    | 2020-11-17 11:28:20.906093+08
backend_xmin     | 
state            | streaming
sent_lsn         | 0/1A000148
write_lsn        | 0/1A000148
flush_lsn        | 0/1A000148
replay_lsn       | 0/1A000148
write_lag        | 
flush_lag        | 
replay_lag       | 
sync_priority    | 0
sync_state       | async
reply_time       | 2020-11-17 11:29:11.113346+08

2、配置 pgpool.conf 文件

#1、 复制配置文件
$ cp pgpool.conf.sample-stream pgpool.conf
#2、修改pgpool.conf文件内容
listen_addresses = '*'
#配置后端信息
backend_hostname0 = '192.168.1.221'
backend_port0 = 6000
backend_weight0 = 1
backend_data_directory0 = '/data1/postgres/data'
backend_flag0 = 'ALLOW_TO_FAILOVER'
backend_application_name0 = 'server0'
backend_hostname1 = '192.168.1.221'
backend_port1 = 6001
backend_weight1 = 1
backend_data_directory1 = '/data1/postgres/data1'
backend_flag1 = 'ALLOW_TO_FAILOVER'
backend_application_name1 = 'server1'
#管理密码文件
pool_passwd = 'pool_passwd'
#pid文件存放炉具
pid_file_name = '/opt/pgpool/pgpool.pid'
# 管理日志存放路径
logdir = '/opt/pgpool'
#目前模式是流复制;非内置复制;所以该参数关闭
replication_mode = off
load_balance_mode = on
# MASTER/SLAVE MODE
master_slave_mode = on
master_slave_sub_mode = 'stream'
sr_check_user = 'pgpool'
sr_check_password = '123456'

3、启动 pgpool

[pgpool@node3 etc]$ pgpool -n > /tmp/pgpool.log  &
[1] 1386
[pgpool@node3 etc]$ 2020-11-25 10:32:26: pid 1386: LOG:  Backend status file /opt/pgpool/pgpool_status does not exist
2020-11-25 10:32:26: pid 1386: LOG:  memory cache initialized
2020-11-25 10:32:26: pid 1386: DETAIL:  memcache blocks :64
2020-11-25 10:32:26: pid 1386: LOG:  pool_discard_oid_maps: discarded memqcache oid maps
2020-11-25 10:32:26: pid 1386: LOG:  Setting up socket for 0.0.0.0:9999
2020-11-25 10:32:26: pid 1386: LOG:  Setting up socket for :::9999
2020-11-25 10:32:26: pid 1386: LOG:  find_primary_node_repeatedly: waiting for finding a primary node
2020-11-25 10:32:26: pid 1386: LOG:  find_primary_node: primary node is 0
2020-11-25 10:32:26: pid 1386: LOG:  find_primary_node: standby node is 1
2020-11-25 10:32:26: pid 1386: LOG:  pgpool-II successfully started. version 4.1.4 (karasukiboshi)
2020-11-25 10:32:26: pid 1386: LOG:  node status[0]: 1
2020-11-25 10:32:26: pid 1386: LOG:  node status[1]: 2
2020-11-25 10:32:26: pid 1422: LOG:  PCP process: 1422 started

三、参数配置

#1、打开主备模式,设置流复制必须打开
master_slave_mode = on
#2、模式是stream模式;还可以设置slony;
master_slave_sub_mode = 'stream'
#下面参数为了探测后端哪个是主库
# - Streaming -
#3、探测频率10s;0为不探测
sr_check_period = 10
sr_check_user = 'pgpool' 
sr_check_password = '123456'
sr_check_database = 'postgres'
# 该参数表明备库延迟多少个字节;读的请求不在发往备库;
delay_threshold = 10000000 

四、查看节点信息

pgpool=# show pool_nodes;
 node_id | hostname  | port | status | lb_weight |  role   | select_cnt | load_balance_node | replication_delay | replication_state | replication_sync_state | last_status_change
  
---------+-----------+------+--------+-----------+---------+------------+-------------------+-------------------+-------------------+------------------------+-------------------
--
 0       | localhost | 6000 | up     | 0.500000  | primary | 0          | false             | 0                 |                   |                        | 2020-11-25 10:50:0
9
 1       | localhost | 6001 | up     | 0.500000  | standby | 0          | true              | 0                 |                   |                        | 2020-11-25 10:50:0
9
posted @ 2020-12-01 17:11  lottu  阅读(1383)  评论(0编辑  收藏  举报