Install PostgreSQL

Learn how to install a PostgreSQL external database for use with NiFi Registry.

If you have already installed a MySQL database, you may skip these steps. Both databases are not required.

For a list of supported PostgreSQL databases, see Supported NiFi Registry databases.

Install Red Hat Package Manager (RPM) according to the requirements of your operating system:
```
yum install https://yum.postgresql.org/9.6/redhat/rhel-7-x86_64/pgdg-redhat96-9.6-3.noarch.rpm
```

Install Postgres version 9.x or 10.x:

yum install postgresql96-server postgresql96-contrib postgresql96

Initialize the database.
For CentOS 7, use the following syntax:
```
/usr/pgsql-9.6/bin/postgresql96-setup initdb
```
Start Postgres.
For example, if you are using CentOS 7, use the following syntax:
```
systemctl enable postgresql-9.6.service
systemctl start postgresql-9.6.service
```
Verify that you can log in:
```
sudo su postgres
psql
```

Once you have installed PostgreSQL, configure the database for use with NiFi Registry.