PostgreSQL service start failed on CentOS 7

You have 3 steps before being abble to connect to a PostgreSQL Database:

• Install PostgreSQL
• Create the data cluster ($PGDATA)
• Start the server

You already installed PostgreSQL, you need now to create the cluster. The initdb tool is what you need.

You will find documentation here.

It might be confusing because when you're under a debian based distros, apt and perl wrappers do every steps for you.