With Prometheus, we can do simple aggregations.

With Postgres, we're unlimited.

For example, back then, I had trouble doing an aggregation like "how many unique clients we had between t0 and t1 per platform for a given appId". I need to revisit what's possible and what's not because I was doing these experiments more than a year ago.

Basically, we used Postgres to have a fully supported time series and document database and Prometheus won't support some features.

Let's hear from the WeaveWorks guys first and then based on their response, I can do some experiments on regular Prometheus push gateway or the aggregating gateway.