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

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✓

  A. Core (SQL) API

  Why this is correct

  The Core (SQL) API is the default Cosmos DB API, exposing a SQL query dialect that operates directly on JSON documents without any schema mapping. Because the team already knows SQL, they can immediately write SELECT, JOIN, and WHERE clauses with no additional learning curve. It also delivers single-digit-millisecond latency for key-value reads and writes, and its tunable consistency and built-in index management make it the most straightforward and cost-effective choice for the new feature.

• ✗

  B. Azure Cosmos DB for Table API

  Why it's wrong here

  Azure Cosmos DB for Table API is a schemaless key-value store that follows the Azure Table Storage data model, but it relies on OData-based REST queries rather than SQL. This query language focuses on primary-key lookups and limited range filters, lacking the full relational expressiveness of SQL, so the team would have to rewrite their query logic and become familiar with a different syntax and SDK idioms. While it can handle large key-value workloads, it does not align with the team's existing SQL expertise and would increase the learning curve.

  When this WOULD be correct

  If the question specified that the team is familiar with Azure Table storage or NoSQL key-value stores, and the data is simple key-value pairs with no need for SQL queries, then the Table API would be the correct choice.

• ✗

  C. Azure Cosmos DB for MongoDB API

  Why it's wrong here

  The Azure Cosmos DB for MongoDB API is wire-protocol compatible with MongoDB, meaning it expects BSON document formats and queries using MongoDB's query language (e.g., db.collection.find with comparison operators like $gt and $in). This approach is document-centric and heavily uses the aggregation pipeline, which is conceptually distinct from SQL's set-based operations and joins. Although it is excellent for migrating existing MongoDB applications, the team would need to learn MongoDB's data modeling, indexing, and query patterns, making it a poor fit when they want to minimize new learning while using their SQL background.

  When this WOULD be correct

  A question where the development team is already experienced with MongoDB and its query language, and the application requires document storage with flexible schema and low-latency operations, but SQL familiarity is not a requirement.

• ✗

  D. Azure Cosmos DB for Cassandra API

  Why it's wrong here

  Incorrect. The Cassandra API uses CQL (Cassandra Query Language), which, while similar to SQL in syntax, has significant differences in data modeling and query patterns. It is not the best fit for a team wanting to minimize learning.

  When this WOULD be correct

  A company needs to migrate an existing Cassandra workload to Azure Cosmos DB with minimal code changes, requiring high throughput and low latency for time-series data with no complex joins.

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.

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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