HeatWave now supports MySQL database 9.0.1, 8.4.2, and 8.0.39 versions. These versions provide security and bug fixes. New DB systems are now based on the 8.4.2 version, and you can optionally select the 9.0.1 or 8.0.39 version when creating a new DB system. For existing DB systems, you must manually upgrade them to newer version, such as from version 8.4.1 to 8.4.2 or from version 8.0.38 to 8.0.39.

All three versions, 9.0.1 (Innovation), 8.4.2 (LTS), and 8.0.39 (Bugfix), are of production-grade quality. If you are keen to leverage the most recent advancements and enhancements, and stay abreast of cutting-edge technologies, then the Innovation release might be the best fit for you. On the other hand, if your application requires established behavior, the LTS or Bugfix releases are more suitable.

For more information, see  MySQL 9.0.1 Release Notes, MySQL 8.4.2 Release Notes, and MySQL 8.0.39 Release Notes.