How to install wordpress with postgresql
It might be a little late, but the current answers are and were wrong. It is possible to use PostgreSQL, even though it is not officially supported and it is not recommend for various reasons: The official documentation says, that it would be expensive to realize since every new wordpress version would have to be tested against the other database back-ends and since many plugins also rely on mysql-specific calls it will probably never be possible to make 'everything' multi database compatible. Source: https://codex.wordpress.org/Using_Alternative_Databases
If you still want to use wordpress with PostgreSQL the better place to start would be the official PostgreSQL documentation. It says, that one needs a wordpress plugin called 'PG4WP' to make it work. Source: https://wiki.postgresql.org/wiki/Wordpress
Repo used in tutorial:https://github.com/kevinoid/postgresql-for-wordpress
=== PostgreSQL for WordPress (PG4WP) ===Contributors: Hawk__ (http://www.hawkix.net/)Requires at least: 2.9.2Tested up to: 4.5.3Stable tag: 1.3.1License: GPLv2 or laterPostgreSQL for WordPress is a special 'plugin' enabling WordPress to be used with a PostgreSQL database.