DP-900 Describe core data concepts Practice Question
You need to choose a data storage solution for a global e-commerce platform that requires single-digit millisecond read and write latencies across multiple regions. The data is semi-structured and includes user profiles and product catalogs. Which Azure service should you use?
⚠ Common exam trap
Test-takers frequently confuse Azure Redis Cache's in-memory speed with the need for persistent, globally distributed storage, overlooking that Redis Cache is not designed for durable, multi-region data storage with consistency guarantees.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Azure Cosmos DB
Azure Cosmos DB is the correct choice because it is a globally distributed, multi-model database service that guarantees single-digit millisecond read and write latencies at the 99th percentile, regardless of the number of regions. It supports semi-structured data natively through its document (JSON) API, making it ideal for user profiles and product catalogs that require low-latency access across multiple geographic regions.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Azure Redis Cache
Why it's wrong here
Azure Redis Cache is an in-memory key-value store designed for caching and transient state, not a durable database. While it can offer extremely low latency, data is primarily held in memory and can be lost on restarts or failovers unless persistence is configured, and even then it lacks the transactional and query guarantees required for an e-commerce system of record. For a global e-commerce platform, it should only complement a durable data store, not serve as the primary storage solution.
- ✓
Azure Cosmos DB
Why this is correct
Azure Cosmos DB is the correct choice because it natively provides turnkey global distribution across Azure regions with multi-region write support, enabling low-latency reads and writes anywhere in the world. It offers single-digit millisecond latency at the 99th percentile, multiple well-defined consistency levels, and SLAs for availability, throughput, and consistency. Its schema-agnostic NoSQL model supports semi-structured data like product catalogs and user profiles, making it purpose-built for globally distributed e-commerce applications.
- ✗
Azure Table Storage
Why it's wrong here
Azure Table Storage is a NoSQL key-value store that can hold large amounts of semi-structured data, but it is not designed for single-digit millisecond latency across a truly global footprint. Its replication options are typically limited to a primary and secondary region with manual or automated failover, and it does not offer multi-region writes or the same granular consistency controls as Cosmos DB. For a global e-commerce platform that demands low latency in every region and high availability, Table Storage would introduce cross-region latency and operational complexity.
- ✗
Azure SQL Database
Why it's wrong here
Azure SQL Database is a fully managed relational database, but its global distribution model relies on geo-replication and failover groups, which can result in higher latency because reads might be served from a secondary region and writes always go to a primary. It does not natively support multi-region writes, so scaling globally often requires application-level sharding or other workarounds. While it can handle transactional data, it is not optimized for the flexible, schema-light, geographically distributed data workloads common in e-commerce product catalogs.
Go deeper
Related to this question
Learn chapter
Data Roles and Core Concepts
Key term
Service
A service is a software component or system that performs a specific function and is available to be used by other programs or users over a network.
Key term
Data
Data is raw, unprocessed information, like numbers, words, or measurements, that can be stored, processed, and analyzed by computers.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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