Batch or Streaming

An electricity company has 200,000 smart meters. Each meter measures a home's use in 15-minute intervals and sends one reading when an interval ends. That is 96 readings per meter a day, and 200,000 x 96 = 19.2 million readings in all. Four teams use those readings, and each one states the oldest data it can accept:

• Monthly bills: 2,880 minutes (two days).
• The usage chart in the customer app: 90 minutes.
• An alert for overloaded neighborhood transformers: 20 minutes.
• The outage map: 5 minutes. It reads the power-loss alarm that a meter sends when its power fails.