A practical guide to data freshness

Define freshness before you measure it

Freshness means nothing without a service-level objective attached. “Updated daily” is a vibe; “95% of rows land within 30 minutes of the source event” is a commitment you can monitor and be held to.

Once the objective is explicit, alerting becomes simple. You are no longer guessing whether late data matters — you already decided, and the system tells you the moment that promise is at risk.