These answers are provided by our Community. If you find them useful, show some love by clicking the heart. If you run into issues leave a comment, or add your own answer to help others.
I do not believe that you can. Features that introduce parallelism in PostgreSQL are included in the (currently pre-release) 9.6 version and would not be present in 9.3.
The developer cloud
Scale up as you grow — whether you're running one virtual machine or ten thousand.
From GPU-powered inference and Kubernetes to managed databases and storage, get everything you need to build, scale, and deploy intelligent applications.