You are designing a Cloud Bigtable schema for a time-series application that stores metrics from millions of devices. The row key is currently deviceID#timestamp. You want to avoid hotspotting on writes and optimize scan performance for reading all data from a specific device within a time range. Which two row key design strategies should you apply? (Choose 2)
Salting distributes writes across tablets to avoid hotspots.
Why this answer
Option A is correct because adding a salt prefix (e.g., a hash of the deviceID) distributes write load across multiple tablet servers, preventing hotspotting on a single node when many devices write concurrently. This ensures that sequential timestamps for the same device are not all written to the same tablet, which would otherwise cause a bottleneck.
Exam trap
Cisco often tests the misconception that reversing the timestamp alone solves hotspotting, but it only optimizes scan order; the salt is required to distribute write load, and candidates may overlook that both strategies are needed together.