90M datapoints per minute means 90M/60=1.5M datapoints per second. Such amounts of data may be easily handled by specialized time series databases even in a single-node setup [1].

> What if a developer wants to add a new dimension to their metrics, would that require us to perform an online table migration?

Specialized time series databases usually don't need defining any schema upfront - just ingest metrics with new dimensions (labels) whenever you wish. I'm unsure whether this works with TimescaleDB.

[1] https://victoriametrics.github.io/CaseStudies.html