DP-203 Design and implement data storage Practice Question
Which TWO Azure services can be used to implement a polyglot persistence architecture for an e-commerce application that requires both a relational database for orders and a document database for product catalogs?
⚠ Common exam trap
Candidates often confuse Azure Table Storage with a document database, but Table Storage is a key-value store without native JSON support or rich querying, whereas Cosmos DB provides a true document database with SQL API and indexing.
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 SQL Database
Azure SQL Database (B) is correct because it is a fully managed relational database engine based on SQL Server, providing ACID transactions, T-SQL, and relational schema enforcement needed for the orders workload. Azure Cosmos DB (C) is correct because it is a globally distributed, multi-model NoSQL service that natively supports the document (SQL/Core) API, making it suitable for storing product catalogs as JSON documents. Together they satisfy polyglot persistence by letting each workload use the data store best suited to it. Azure Cache for Redis (A) is an in-memory key-value cache, not a durable relational or document database. Azure Table Storage (D) is a key-attribute NoSQL store but is not a document database in the sense required here. Azure Data Lake Storage Gen2 (E) is object storage optimized for analytics, not transactional relational or document workloads.
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 Cache for Redis
Why it's wrong here
Azure Cache for Redis is an in-memory key-value cache, not a relational or document database, so it cannot store orders or product catalogues persistently. It is tempting as a fast data store, and would be correct for caching sessions or query results in front of a database.
- ✓
Azure SQL Database
Why this is correct
Azure SQL Database supplies the relational engine for order processing, enforcing ACID transactions and referential integrity across order and line-item tables. It satisfies the stem's relational requirement, pairing with Azure Cosmos DB's document model to deliver polyglot persistence.
- ✓
Azure Cosmos DB
Why this is correct
Azure Cosmos DB provides the document database capability for the product catalogue, storing semi-structured JSON items with flexible schemas and low-latency reads. Its API for NoSQL satisfies the non-relational half of the polyglot persistence requirement, complementing a relational service such as Azure SQL Database for orders.
- ✗
Azure Table Storage
Why it's wrong here
Azure Table Storage is a key-value NoSQL store, not a document database; it cannot hold the product catalogue's nested JSON documents or secondary-index queries. It tempts because it is cheap and schema-flexible for high-volume lookups, and would suit storing session state or simple entity records rather than catalogue documents.
- ✗
Azure Data Lake Storage Gen2
Why it's wrong here
Azure Data Lake Storage Gen2 is hierarchical blob storage for analytics files, not a document database serving per-item catalogue reads. It tempts because it stores semi-structured JSON cheaply at scale, and would be right for a data lake landing zone feeding Synapse or Databricks, not transactional catalogue queries.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This DP-203 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-203 exam.