My web host is sending me emails recommending I upgrade mySQL from 5.5 to at least 5.7.
I see the "Pre-Installation Checklist" says "5.5+" so it seems like a good thing to do.
Yes, UBB.threads works just fine with MySQL 5.5 and newer database. https://www.ubbcentral.com/doc_install.php
UBB.threads Supported MySQL Databases
MySQL Recomended 5.6 +
MySQL Minimum 5.5
I need to check whether Joomla would run with mySQL 5.7.
Joomla! 1.6, 1.7, & 2.5 system requirements are over here:https://downloads.joomla.org/us/technical-requirements-us
Joomla! 1.6, 1.7, & 2.5 Supported MySQL Databases
MySQL Recomended 5.5.3 +
MySQL Minimum 5.1
If you are on a managed server (not VPS), Its basically up to your webhost as to which database back-end you will be running.
According to the following linked summary comparison, there are no major benefits you'd gain from demanding to switch backends vs just upgrading to the current version of your current database engine.Which Database Is Right For Your Business?
MySQL: MySQL is a proven database that has a strong following around the globe. The Oracle Corporation continues to maintain, enhance, and support the product.
MariaDB: The MariaDB provides a drop-in replacement for organizations running MySQL. It is managed by the MariaDB Foundation, allowing people to contribute to the open source product and documentation.
Both products may continue to diverge in the future. For many organizations, the fundamental question comes down to: Which one do you feel more comfortable with?
Would you prefer a larger corporation like Oracle Corp that manages MySQL, or would you feel more comfortable with an open solution like MariaDB?