A parcel network is choosing between Azure SQL Database and Azure Cosmos DB for one service. The service must accept writes from depots on three continents with single-digit millisecond latency, and each parcel record carries different attributes depending on the country of origin. Which datastore should be chosen, and why?
- A.
Azure Cosmos DB, because relational tables cannot store more than a fixed number of columns per row
- B.
Azure Cosmos DB, because it distributes writes across regions and stores documents whose properties differ per record
- C.
Azure SQL Database, because a single logical server can be reached from any region over the public endpoint
- D.
Azure SQL Database, because parcel records with differing attributes can be held in one text column and parsed by the application
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Answer: B
Multi-region writes at single-digit millisecond latency over records with differing attributes is the Cosmos DB case.
- A. The obstacle is schema variation and write distribution, not any column-count limit.
- B. Globally distributed writes with low latency over per-record varying documents is Cosmos DB's core use case.
- C. Reachability is not latency; writers on other continents still pay the round trip to a single region.
- D. Hiding varying attributes in a text column removes field-level querying and pushes parsing into the application.