On Reactive Spring side we have decided to just support NoSql async drivers for now because we don't want to build a Reactive API on top of a thread pool. That's why Spring Data Reactive supports "only" MongoDB, Cassandra and Redis for now. JDBC is blocking by design and async JDBC won't be there until Java 10, but maybe native driver will evolve to something we could leverage. Fyi Reactor Core 3.1 will introduce support for Reactive Context which could be used to support transactions at driver or application level.