According to https://en.wikipedia.org/wiki/PostgreSQL#History:
- 8.4 is the latest of the series 8.x. It reached end of life in July 2014.
- 9.3 is the lowest version of series 9.x which is still "alive"
As a consequence PostgreSQL 9.2 and lower should not be longer supported by SonarQube. Server should fail at startup.