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DP-900 Practice Question: Describe considerations for working with non-relational data on Azure

A healthcare application stores patient medical records as JSON documents. Each document contains a variable set of fields depending on the patient's conditions. The application needs to query records by any field and support high write throughput. Which Azure data store is most appropriate?

⚠ Common exam trap

Many exam-takers confuse Azure Table Storage's key-value capabilities with JSON document support, but Table Storage does not allow querying on arbitrary fields within a JSON document—it only supports queries on the partition key and row key, making it unsuitable for variable-schema medical records.

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 with SQL API

Azure Cosmos DB with SQL API is the most appropriate choice because it natively supports storing and querying JSON documents with variable schemas, enabling efficient queries on any field. Its multi-model architecture and configurable indexing policies allow high write throughput while maintaining low-latency queries, which is critical for healthcare applications with dynamic patient records.

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 an object store for unstructured binary data such as images, backups, or archived files, not for interactive queries over JSON documents. While you can upload JSON files as blobs, Blob Storage does not index their content or provide a query engine to filter on arbitrary fields; you would need to download and process each blob client-side, with no support for transactional updates or high-throughput point writes. This makes patient records inefficient and costly to search, update, or enforce schema validation at scale.

    When this WOULD be correct

    An application needs to store and serve large media files (e.g., patient X-ray images or PDF reports) with high durability and scalability, and does not require querying by document fields.

  • Azure Synapse Analytics

    Why it's wrong here

    Azure Synapse Analytics is a cloud-scale data warehousing service built on a Massively Parallel Processing (MPP) architecture that is optimized for analytics—large aggregations, complex joins, and columnar scans over vast datasets—not for online transaction processing (OLTP) with point reads and writes per second. Its columnar storage and query engine minimize I/O for analytical workloads but make single-document JSON operations inefficient due to overhead and stitched-together modeling. Synapse belongs in the data analytics tier (for example, aggregating population health trends) rather than serving as the operational store for individual patient records.

    When this WOULD be correct

    A question asks: 'A company needs to run complex analytical queries across petabytes of structured sales data, integrating with Power BI for reporting. Which Azure service should they use?'

  • Azure Cosmos DB with SQL API

    Why this is correct

    Azure Cosmos DB with the SQL API is the correct choice because it is a schema-agnostic document database that natively stores JSON, automatically indexes every property for efficient point reads and SQL-style queries, and scales horizontally with guaranteed single-digit-millisecond latency and throughput managed in request units. Unlike relational databases, it does not require a fixed schema and is designed for high write and read throughput on document workloads. The SQL API also supports rich queries over nested JSON fields, making it ideal for patient records with varying structures that require fast, interactive access.

  • Azure Table Storage

    Why it's wrong here

    Azure Table Storage is a key-value NoSQL store that requires a partition key and row key for every entity, and it stores entities as simple sets of typed properties rather than deeply nested JSON documents. Queries are limited to the primary key, plus a small set of indexed properties, so you cannot efficiently query on arbitrary nested fields inside patient records. It also lacks built-in document APIs, schema-agnostic indexing, and the sophisticated query capabilities (such as JSON path queries) that Cosmos DB provides for healthcare applications.

    When this WOULD be correct

    An application needs to store large volumes of structured, non-relational data (e.g., device telemetry) with simple key-based lookups and does not require complex queries or indexing on multiple fields. The data has a fixed schema and high throughput for point reads/writes is needed.

Option-by-option analysis

Why each answer is right or wrong

Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The DP-900 exam frequently reuses these exact scenarios with slightly different constraints.

Azure Cosmos DB with SQL APICorrect answer

Why this is correct

Azure Cosmos DB with the SQL API is the correct choice because it is a schema-agnostic document database that natively stores JSON, automatically indexes every property for efficient point reads and SQL-style queries, and scales horizontally with guaranteed single-digit-millisecond latency and throughput managed in request units. Unlike relational databases, it does not require a fixed schema and is designed for high write and read throughput on document workloads. The SQL API also supports rich queries over nested JSON fields, making it ideal for patient records with varying structures that require fast, interactive access.

Azure Blob StorageWrong answer — click to see why

Why this is wrong here

Azure Blob Storage is optimized for storing large unstructured binary data (like images or backups), not for querying individual fields within JSON documents with high write throughput and flexible schema.

★ When this WOULD be the correct answer

An application needs to store and serve large media files (e.g., patient X-ray images or PDF reports) with high durability and scalability, and does not require querying by document fields.

Why candidates choose this

Candidates may think Blob Storage can handle JSON because it supports storing JSON files, but they overlook the need for querying by any field and high write throughput, which Blob Storage does not natively support.

Azure Synapse AnalyticsWrong answer — click to see why

Why this is wrong here

Azure Synapse Analytics is a data warehouse and analytics service designed for large-scale, structured data processing and complex queries, not for high-throughput, low-latency operations on semi-structured JSON documents with variable fields.

★ When this WOULD be the correct answer

A question asks: 'A company needs to run complex analytical queries across petabytes of structured sales data, integrating with Power BI for reporting. Which Azure service should they use?'

Why candidates choose this

Candidates may confuse Synapse's analytics capabilities with the need for querying JSON data, or assume that any 'analytics' service can handle document queries efficiently.

Azure Table StorageWrong answer — click to see why

Why this is wrong here

Azure Table Storage is a NoSQL key-value store that does not support querying by arbitrary fields or indexing on multiple properties, making it unsuitable for querying JSON documents by any field. It also lacks native JSON support and flexible schema capabilities required for variable-field documents.

★ When this WOULD be the correct answer

An application needs to store large volumes of structured, non-relational data (e.g., device telemetry) with simple key-based lookups and does not require complex queries or indexing on multiple fields. The data has a fixed schema and high throughput for point reads/writes is needed.

Why candidates choose this

Candidates may confuse Azure Table Storage as a suitable NoSQL option for JSON documents because it is schema-less and supports high throughput, but they overlook its limited query capabilities and lack of native JSON support.

Analysis generated from the official DP-900blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”

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Written by Johnson Ajibi, MSc IT Security

Senior Network & Security Engineer · founder of Courseiva

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