Some notes:

• We don't do any aggregation in our App Metrics app. We simply push data to Postgres tables as JSON (BSON).
• In Grafana, we connect to Postgres DB and execute aggregation queries and show results.

Prometheus Push Gateway is not a simple replacement here. If we switch to that, that means we're going to store data in Prometheus and not in Postgres. Prometheus is not a full featured database, so the aggregations we do with our queries can't be supported fully.
In worst case, if we want to switch to this tool, we can revisit our dashboards and chop stuff.

Prometheus Aggregation Gateway: TBD