Nagios Support Forum

I know that new version NagiosXI is using MariaDB while old version using Postgresql?!
If true, from what version it began to use MariaDB?

Switching from postgres to mysql/mariadb was done a long time ago (2015) in Nagios XI 5R1.0. It was/is done only on a new installs. The upgraded instances of Nagios XI will keep storing the nagiosxi database in postgres.