Ali Ok Ok, understand. If we want to know what version each client is using (instead of just an aggregation showing the distribution) then Updates (in Elasticsearch or Postgres) allow that easily. But we could still store that information in Prometheus:

sdk_version{version="1", clientId="xxx"}

We simply add a label for 'clientId' to the metric. Then we could even see at what exact point in time the client switched versions. Or did i miss something important that we can't cover this way? Now i don't know much about the storage model of Prometheus. It's possible that ElasticSearch/Postgres are more efficient for this kind of requirement.