Comment by isburmistrov

Columnar storage stores data very efficiently, too - because it compresses data of a similar nature (columns). Check e.g. ClickHouse on this matter: https://clickhouse.com/docs/en/about-us/distinctive-features, https://clickhouse.com/blog/working-with-time-series-data-an...

So I wouldn't say that events are "expensive" while metrics are "cheap" - both depend on the actual implementation, and events can be cheap too.

And so of course if you have to optimise things, you would need to drop some information you pass to the events, but you would need to do the same for metrics (reduce the number of metrics emitted, reduce the prometheus labels,...).