参考文档https://www.postgresql.org/download/linux/redhat/
先安装ca认证包
yum install -y ca-certificates.noarch
然后安装postgresql 的yum包
yum install https://download.postgresql.org/pub/repos/yum/11/redhat/rhel-6-x86_64/pgdg-centos11-11-2.noarch.rpm
然后安装
yum install postgresql11.x86_64