In this scenario, we’re going to keep the data for X days after it’s created. Then we delete it. That’s it. X could be 3 days or 3 years–it doesn’t matter, we’ll follow the same design pattern.
In today’s world, we generate loads of log data, sensor data, telemetry data, etc. All that data is super duper valuable. But only for a while. Eventually, all that granular data becomes less useful, and isn’t worth keeping around. Maybe it gets aggregated, summarized, or maybe it just gets thrown out.
You’ll have a lot of data with more complex requirements, but I think you’ll also be surprised at how much data has simple date-based retention based on it’s creation.
Also read the comments, as they include additional techniques.