Quick Answer
Azure Cosmos DB is the correct choice because it natively stores semi-structured JSON data and supports SQL-like querying through its core (SQL) API, while guaranteeing high throughput with low latency at the 99th percentile. This makes it ideal for web applications that demand fast, scalable access to document data without sacrificing query flexibility. On the DP-900 exam, this scenario tests your ability to match workload requirements—specifically JSON format, SQL-like syntax, and performance guarantees—to the appropriate Azure data store. A common trap is choosing Azure SQL Database, which handles structured relational data well but lacks the native JSON document model and the single-digit millisecond latency guarantees of Cosmos DB. Another pitfall is Azure Table Storage, which stores key-value pairs but does not support rich SQL-like queries on nested JSON. Remember the memory tip: “Cosmos for JSON, SQL for schema.”
This DP-900 practice question tests your understanding of describe core data concepts. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
You need to store semi-structured JSON data from a web application and query it using SQL-like syntax. The solution must support high throughput with low latency. Which Azure data store should you use?
Azure Blob Storage
Why wrong: Blob Storage stores unstructured data, not queryable with SQL.
Azure Cosmos DB
Cosmos DB natively supports JSON documents and SQL-like queries.
Azure SQL Database
Why wrong: Azure SQL is relational and requires schema mapping for JSON.
Azure Table Storage
Why wrong: Table Storage is for key-value, not JSON documents.
Answer choices
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 offers SQL-like querying via its core (SQL) API. It is designed for high throughput and low latency with guaranteed single-digit millisecond response times at the 99th percentile, making it ideal for web applications with demanding performance requirements.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
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
Blob Storage stores unstructured data, not queryable with SQL.
Azure Cosmos DB
Why this is correct
Cosmos DB natively supports JSON documents and SQL-like queries.
Related concept
Read the scenario before looking for a memorised answer.
Azure SQL Database
Why it's wrong here
Azure SQL is relational and requires schema mapping for JSON.
Azure Table Storage
Why it's wrong here
Table Storage is for key-value, not JSON documents.
Common exam traps
The trap here is that candidates often confuse Azure Blob Storage's ability to store JSON files with the ability to query them using SQL syntax, overlooking that Blob Storage lacks a native query engine for semi-structured data.
Detailed technical explanation
Azure Cosmos DB achieves low latency through automatic indexing of all properties and global distribution with multi-region writes. Its SQL API translates SQL-like queries into native index scans, enabling efficient querying of nested JSON structures. In a real-world scenario, a real-time chat application storing user messages as JSON documents would benefit from Cosmos DB's ability to handle millions of writes per second with consistent sub-10ms reads.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
What to study next
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FAQ
Describe core data concepts — This question tests Describe core data concepts — Read the scenario before looking for a memorised answer..
The correct answer is: Azure Cosmos DB — Azure Cosmos DB is the correct choice because it natively supports semi-structured JSON documents and offers SQL-like querying via its core (SQL) API. It is designed for high throughput and low latency with guaranteed single-digit millisecond response times at the 99th percentile, making it ideal for web applications with demanding performance requirements.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Same concept, more angles
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Variation 1. 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?
easyWhy C: 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.
Last reviewed: Jun 24, 2026
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