When you're supporting any ERP system, it is important to understand the underlying database architecture. Odoo 12.0 requires Postgres 9.3 or later as the backend database. Here is a list of resources that can help you maintain your Postgres server.
Finding Postgres resources
Official Postgres website
While Odoo handles many of the complex database management tasks you would have with other ERP systems, there will be times when the official Postgres website will be useful in maintaining your Odoo installation—find it at: http://www.postgresql.org/.
Note that Postgres is also commonly known as PostgreSQL; these terms are synonymous.