Question 1

You are designing an Azure Cosmos DB (NoSQL API) database for an IoT fleet management system.

The system receives telemetry from 100,000 vehicles. Each vehicle sends a JSON document every minute. The most common query run by the application is: `SELECT * FROM c WHERE c.VehicleId = 'V-12345' AND c.Timestamp > '2023-01-01'`.

You need to select a partition key that ensures even distribution of storage and throughput, and minimizes cross-partition queries.

Which property should you choose as the partition key?

Accepted Answer

A good partition key needs high cardinality (many unique values) for write distribution, and should be present in the WHERE clause of common queries for read efficiency.

Question 2

What mistakes do candidates make on this AZ-305 question?

Accepted Answer

Choosing `/id`. While it distributes writes perfectly, it ruins read performance because querying by `VehicleId` would require scanning every single partition (cross-partition query).

How to approach this question

Full Answer

Common mistakes

Practice the full Azure Solutions Architect Expert AZ-305 Practice Exam 5

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