Yes, there are: http://www.postgresql.org/docs/9.4/static/extend-extensions.html http://www.postgresql.org/docs/9.4/static/extend-extensions.... https://wiki.

Yes, there are: http://www.postgresql.org/docs/9.4/static/extend-extensions.html http://www.postgresql.org/docs/9.4/static/extend-extensions.... https://wiki.postgresql.org/wiki/Foreign_data_wrappers https://wiki.postgresql.org/wiki/Foreign_data_wrappers