How to get PostgreSQL
PostgreSQL is 100% open source software and is freely available to use, alter, or redistribute in any way you choose. Its license is an approved open source license, very similar to the Berkeley Software Distribution (BSD) license, though only just different enough that it is now known as The PostgreSQL License (TPL). You can see the license here: https://opensource.org/licenses/PostgreSQL.
How to do it...
PostgreSQL is already being used by many different application packages, so you may find it already installed on your servers. Many Linux distributions include PostgreSQL as part of the basic installation or include it with the installation disk.
One thing to be wary of is that the included version of PostgreSQL may not be the latest release. It will typically be the latest major release that was available when that operating system release was published. There is usually no good reason to stick...