Unfortunately, the diagram you linked to is misleading; we don't have all of those plugins built yet. We've got a (quite rich) Python client (https://github.com/mozilla-services/heka-py) and a (rudimentary) Go client (https://github.com/mozilla-services/heka/tree/master/client) but Memcached and PostgreSQL connectors aren't yet in place. Fleshing out our plugin set (especially the inputs) is one of our highest priorities, so those should be coming Real Soon Now(tm). Contributions welcome!