[jrv]

I am not too familiar with the PG-TimescaleDB adapter, but the storage engine rewrite in Prometheus was definitely the most important improvement in Prometheus 2.0.

There are other changes than the storage though that are outlined in the migration guide: https://prometheus.io/docs/prometheus/latest/migration/

* Minor PromQL changes (mainly removals of deprecated features)

* Staleness handling (not sure if the TimescaleDB storage handles this correctly, as it relies on storing a special NaN value bit-wise correctly for marking series stale)

* New rule file format is now YAML and supports per-group evaluation intervals and serialization of rule executions within one group (in case of data dependencies)

* Other minor bits