PostgreSQL 9.5 : Replication Settings2016/08/30

	Configure PostgreSQL Replication settings. This configuration is Master-Slave settings.
[1]	Install PostgreSQL 9.5 Server on all Nodes, refer to here.
[1]	Configure Master Host.

[root@dlp ~]#

postgresql-setup --initdb --unit rh-postgresql95-postgresql

Initializing database ... OK

[root@dlp ~]#

vi /var/opt/rh/rh-postgresql95/lib/pgsql/data/postgresql.conf

# line 59: uncomment and change

listen_addresses = '

# line 177: uncomment and change

wal_level =

hot_standby

# line 180: uncomment and change

# on ⇒ sync

# remote_write ⇒ memory sync

# local ⇒ slave is asynchronous

# off ⇒ asynchronous

synchronous_commit =

local

# line 210: uncomment and change (enable archive_mode)

archive_mode =

# line 212: uncomment and change (command to get archives)

archive_command = '

cp %p /var/opt/rh/rh-postgresql95/lib/pgsql/archive/%f

# line 228: uncomment and change (slave servers + 1)

max_wal_senders =

# line 230: uncomment and change

wal_keep_segments =

# line 242: uncomment and change (any name you like)

synchronous_standby_names = '

slave01

[root@dlp ~]#

vi /var/opt/rh/rh-postgresql95/lib/pgsql/data/pg_hba.conf

# add to the end

# host replication [replication user] [allowed IP addresses] password

host    replication     replica          127.0.0.1/32            md5
host    replication     replica          10.0.0.30/32            md5
host    replication     replica          10.0.0.51/32            md5

[root@dlp ~]#

systemctl start rh-postgresql95-postgresql

[root@dlp ~]#

systemctl enable rh-postgresql95-postgresql

# create a user for replication

[root@dlp ~]#

su - postgres

-bash-4.2$

createuser --replication -P replica

Enter password for new role:
Enter it again:

[2]	If Firewalld is running, allow PostgreSQL service.

[root@dlp ~]#

firewall-cmd --add-service=postgresql --permanent

success
[root@dlp ~]#

firewall-cmd --reload

success

[3]	Configure Slave Host.

[root@node01 ~]#

su - postgres

# get backup from Master Server

-bash-4.2$

pg_basebackup -h 10.0.0.30 -U replica -D /var/opt/rh/rh-postgresql95/lib/pgsql/data -P --xlog

Password:

# "replica" user's password

-bash-4.2$

vi /var/opt/rh/rh-postgresql95/lib/pgsql/data/postgresql.conf

# line 251: uncomment and change

hot_standby =

-bash-4.2$

cp /opt/rh/rh-postgresql95/root/usr/share/pgsql/recovery.conf.sample /var/opt/rh/rh-postgresql95/lib/pgsql/data/recovery.conf

-bash-4.2$

vi /var/opt/rh/rh-postgresql95/lib/pgsql/data/recovery.conf

# line 44: uncomment and change (command to get archives)

restore_command = '

scp 10.0.0.30:/var/opt/rh/rh-postgresql95/lib/pgsql/archive/%f %p

# line 116: uncomment and change

standby_mode =

# line 123: uncomment and change (connection info to Master Server)

primary_conninfo = '

host=10.0.0.30 port=5432 user=replica password=password application_name=slave01

-bash-4.2$

exit

logout
[root@node01 ~]#

systemctl start rh-postgresql95-postgresql

[root@node01 ~]#

systemctl enable rh-postgresql95-postgresql

[4]	It's OK all if result of the command below is like follows. Make sure the setting works normally to create databases on Master Server.

-bash-4.2$

psql -c "select application_name, state, sync_priority, sync_state from pg_stat_replication;"

 application_name |   state   | sync_priority | sync_state
------------------+-----------+---------------+------------
 slave01          | streaming |             1 | sync
(1 row)

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