Following the live layer effects, this allows to trigger actions or layer refresh in QGIS only when the database notifies QGIS it should do something. It will require less ressources than refreshing on interval, and you can even code a chat application in QGIS with that :)
See https://vimeo.com/236604742
http://oslandia.com/en/2017/10/07/refresh-your-maps-from-postgresql/
This feature was funded by QGIS.org Grant application
This feature was developed by OSLANDIA - Vincent Mora