1、Install the repository RPM：

yum install https://download.postgresql.org/pub/repos/yum/9.5/redhat/rhel-7-x86_64/pgdg-centos95-9.5-2.noarch.rpm

2、Install the client packages：

yum install postgresql95

3、Optionally install the server packages：

yum install postgresql95-server

4、Optionally initialize the database and enable automatic start：

/usr/pgsql-9.5/bin/postgresql95-setup initdb
systemctl enable postgresql-9.5
systemctl start postgresql-9.5

5、Test：

su - postgres

$ psql

$\l

CREATE DATABASE myDb;

CREATE USER mytest CREATEDB LOGIN PASSWORD 'mytest';

GRANT ALL ON DATABASE myDb TO mytest;