Why we're ending support for MySQL in 12.1

This post details the decision to end support for MySQL in GitLab 12.1, citing limitations in supporting nested groups, column limits, partial indexes, and the inability to leverage specific database features like PostgreSQL's LATERAL JOIN. It also highlights the performance impact of maintaining MySQL-specific code and running dual test suites, as well as the cost savings from removing MySQL support. The post confirms that most customers are on PostgreSQL and provides migration guidance.