DP-900 Describe core data concepts Practice Question
You need to store semi-structured JSON documents from a web application in Azure. The data will be accessed by a key/value lookup. Which Azure data store should you use?
⚠ Common exam trap
Many exam-takers confuse Azure Table Storage's key/value capabilities with JSON document support, but Table Storage stores flat entities, not nested JSON, and lacks native indexing for document fields.
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 natively supports semi-structured JSON documents and provides key/value lookup via its partition key mechanism. It offers single-digit millisecond latency for point reads, making it ideal for web application data that needs fast, scalable access by a unique key.
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 Blob Storage
Why it's wrong here
Azure Blob Storage is a highly scalable object storage service for unstructured data such as images, videos, and binary files. While you can store a JSON document as a blob, the service provides no native query engine or indexing for the JSON content; retrieving a piece of data requires downloading the entire blob and parsing it client-side. Because the question asks for storing JSON with key/value access, blob storage lacks the built-in query capabilities needed, making it incorrect.
- ✗
Azure Table Storage
Why it's wrong here
Azure Table Storage is a NoSQL key-value store that organizes data into entities with partition and row keys, and each entity's properties are typed columns rather than flexible JSON documents. Although you could serialize JSON into a property, Table Storage cannot run queries against nested JSON structures or index individual fields within the JSON, limiting its usefulness for semi-structured data. Its query model is optimized for simple key lookups and range scans, not for the rich document queries that the scenario requires.
- ✓
Azure Cosmos DB
Why this is correct
Azure Cosmos DB is a globally distributed, multi-model NoSQL database that natively stores JSON documents as its core data format, supporting both document queries through a SQL-like API and fast key-value lookups via point reads. It automatically indexes every property within a JSON document, enabling efficient queries on nested fields, and offers tunable consistency and throughput scaling, making it ideal for semi-structured web data. This native JSON support and flexible querying directly match the requirement to store and access semi-structured JSON documents by key/value.
- ✗
Azure SQL Database
Why it's wrong here
Azure SQL Database is a relational database engine that requires a predefined schema, whereas semi-structured JSON documents have variable fields that do not map cleanly to fixed columns. While SQL Database does provide JSON functions like JSON_VALUE and OPENJSON, it is optimized for relational data and joins, not for high-throughput key/value access on raw JSON documents; storing JSON often forces you to maintain schema changes or use less natural workarounds. For a web-based scenario focused on flexible JSON storage and direct key/value retrieval, the relational model makes it a poor fit.
Go deeper
Related to this question
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Data Roles and Core Concepts
Key term
Data
Data is raw, unprocessed information, like numbers, words, or measurements, that can be stored, processed, and analyzed by computers.
Key term
Azure Cosmos DB
Azure Cosmos DB is a fully managed, globally distributed NoSQL database service that offers fast reads and writes anywhere in the world with automatic scaling and multiple consistency models.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This DP-900 practice question is part of Courseiva's free Microsoft certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the DP-900 exam.