使用yum命令的时候，报下面错误
Errors during downloading metadata for repository 'pgdg96'
解决方案：编辑/etc/yum.repos.d/pgdg-redhat-all.repo文件，把有关pgdg96的配置注释掉即可。
vim /etc/yum.repos.d/pgdg-redhat-all.repo
# 注释掉下面配置
#[pgdg96]
#name=PostgreSQL 9.6 for RHEL/CentOS $releasever - $basearch
#baseurl=https://download.postgresql.org/pub/repos/yum/9.6/redhat/rhel-$releasever-$basearch
#enabled=1
#gpgcheck=1
#gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-PGDG
#repo_gpgcheck = 1
...
#[pgdg96-source]
#name=PostgreSQL 9.6 for RHEL/CentOS $releasever - $basearch - Source
#failovermethod=priority
#baseurl=https://download.postgresql.org/pub/repos/yum/srpms/9.6/redhat/rhel-$releasever-$basearch
#enabled=0
#gpgcheck=1
#gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-PGDG
#repo_gpgcheck = 1
...
#[pgdg96-debuginfo]
#name=PostgreSQL 9.6 for RHEL/CentOS $releasever - $basearch - Debuginfo
#baseurl=https://download.postgresql.org/pub/repos/yum/debug/9.6/redhat/rhel-$releasever-$basearch
#enabled=0
#gpgcheck=1
#gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-PGDG
#repo_gpgcheck = 1
