Database Server

As I see it, there are three main database engines for Linux: MySQL (and recent forks MariaDB and Drizzle), PostgreSQL, and Oracle. All of these database engines are used in production environments, although I have found Oracle to be the most difficult to get working in Gentoo.

You can find technical arguments why each one of these is the best. I don't know which is technically superior, so I will just accept that all three are trustworthy products. Given that, my decision on which one to use comes down to considering:

1. Is one is already in-use? If so, you have to consider whether the labour cost of migrating is worth it. Probably you should stick to the one that's in-use.
2. If there is no database engine in-use already the next question I would ask is, Do you plan to use the finished product commercially?
   • If you plan to sell subscriptions to the finished product, then look carefully at the licences before you leap.
   • If you will not use the finished product commercially, then the legal implications of all three are about equal.

The licence of each product are:

• Oracle: Commercial, not open-source. You obtain binary executables from Oracle and they generally are tailored to run in certain distributions, such as Red Hat. You can download and use Oracle as a developer for free, but you have to pay for a licence to then deploy your product commercially.
• MySQL (purchased by Sun, which was then purchased by Oracle): There is a commercial “Enterprise” version of MySQL as well as a “Community” version. The Community version of MySQL is released under the GNU GPL version 2, but there are add-ons which do not fall under this licence so you may need to consider that. Since Oracle already has an enterprise database, it's anybody's guess whether Oracle ownership will affect the MySQL Enterprise offering. The MariaDB branch of MySQL, started by the original creator of MySQL, aims to preserve and further develop the GPL 2 open source version of MySQL.
• PostgreSQL: Released under the BSD licence. There probably does not exist any simpler or more liberating licence for any software. You can read it here – it will take you perhaps five minutes to read it slowly and fully understand it. Essentially, you can do anything you want with it.

Here are pages describing the installation and configuration of MySQL and PostgreSQL, along with some tips that I (or possibly others) have that may be helpful.

MySQL (follow the same steps for the MariaDB fork of MySQL).

PostgreSQL