DP-900 Describe core data concepts Practice Question
Your organization has a large dataset of customer transactions stored in Azure Blob Storage as CSV files. You need to run ad-hoc SQL queries on this data without loading it into a database. Which Azure service should you use?
⚠ Common exam trap
Test-takers frequently confuse Azure Data Factory (a data movement/orchestration tool) with a query engine, or assume Azure SQL Database can query external files via PolyBase (which requires loading into external tables, not direct ad-hoc querying).
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 Synapse Serverless SQL pool
Azure Synapse Serverless SQL pool allows you to query data directly from files in Azure Blob Storage using standard T-SQL syntax, without needing to load or move the data into a database. It uses a pay-per-query model and supports CSV, Parquet, and JSON formats, making it ideal for ad-hoc analytical queries over large datasets stored in data lakes.
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 Data Factory
Why it's wrong here
Azure Data Factory is an integration and orchestration service for building ETL/ELT pipelines, not an interactive query engine. It moves and transforms data between stores or triggers compute, but it cannot run ad-hoc T-SQL statements that directly read CSV, Parquet, or JSON files in Blob Storage for on-demand analysis. You would need to pair it with a query technology like Synapse Serverless SQL to actually explore the data.
- ✗
Azure SQL Database
Why it's wrong here
Azure SQL Database is a fully managed relational database that expects data to be populated into its tables before querying. It does not support PolyBase or external table queries against Azure Blob Storage, unlike Synapse SQL or SQL Server 2019. To analyze customer transactions stored in blobs, you would first have to import or load them into Azure SQL Database, which adds latency and undermines direct file access scenarios.
- ✓
Azure Synapse Serverless SQL pool
Why this is correct
Azure Synapse Serverless SQL pool is the correct choice because it is a compute-on-demand query endpoint that runs T-SQL directly over files in Azure Blob Storage or Data Lake Storage Gen2. It uses a distributed query engine to read semi-structured and structured formats like Parquet, Delta, and CSV without any data movement or provisioning of dedicated resources. You can issue standard SELECT statements and let the service scale compute automatically, making it ideal for ad-hoc exploration of large datasets.
- ✗
Azure Analysis Services
Why it's wrong here
Azure Analysis Services is an enterprise-grade OLAP engine that hosts tabular models in memory, which requires loading data from sources into the model's workspace. It does not directly query files on Blob Storage at runtime; you must first design a model, import data, and process the model to make it queryable. That setup is meant for interactive BI reporting and KPIs, not for ad-hoc T-SQL queries over raw transaction files.
Quick reference
Azure Blob Storage Tier Comparison
| Tier | Storage Cost | Retrieval Cost | Latency | Use Case |
|---|---|---|---|---|
| Hot | Highest | Lowest | Immediate | Active data, frequent reads |
| Cool | Lower | Higher | Immediate | Data accessed < once / month |
| Cold | Lower still | Higher | Immediate | Data accessed < once / quarter |
| Archive | Lowest | Highest + rehydration delay | Hours | Long-term compliance retention |
Go deeper
Related to this question
Learn chapter
Data Roles and Core Concepts
Key term
Dataset
A dataset is a collection of related data, usually in a structured format, that can be used for analysis, training models, or reporting in Azure data services.
Key term
Service
A service is a software component or system that performs a specific function and is available to be used by other programs or users over a network.
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Senior Network & Security Engineer · founder of Courseiva
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