I have a climate control automation tool running with Home Assistant. Hass supports many types of long-term db storage of it's entity states (sensor data etc), like datadog, influbdb, graphite etc. So far I've tried influxdb and graphite.
I've been using grafana to visualize the data. I want to store threshold values in the database, such as min/max temperature. These temperatures can be set using an input slider on the hass UI. Once set, these controls can be left for days, even weeks. So there may be only one data point in the db for very long periods of time.
If I want to display these on grafana, they disappear from the time range being looked at pretty quickly, and grafana simply removes the entity from the graph. Influx has a "use previous value", and graphite has a "keepLastValue" function that I thought I could use to pull the last value of the threshold from the db, but in both cases, the values must exist in the time range selected. If the previous value for the control was days before the time range, too bad, so sad.
I thought this would be a very common requirement, but perhaps not.
Does anyone know a combination of database and dashboard that can display the last value for an entity even if said last value was recorded far out of the time range selected?
