DP-900 Describe core data concepts Practice Question
A data engineer needs to process streaming data from IoT devices in near real-time and store the results in Azure Cosmos DB. Which Azure service should they use for the stream processing?
⚠ Common exam trap
It's easy for candidates to confuse Azure Stream Analytics with Azure Data Factory or Azure Databricks, mistakenly thinking that any 'data processing' tool can handle real-time streaming, but only Stream Analytics is purpose-built for near-real-time, serverless stream processing with direct Cosmos DB integration.
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 Stream Analytics
Azure Stream Analytics is the correct choice because it is a fully managed, real-time stream processing engine designed specifically for low-latency, near-real-time analytics on streaming data. It can ingest data from IoT devices via Event Hubs or IoT Hub, apply SQL-based transformations, and directly output the results to Azure Cosmos DB with millisecond latency, making it ideal for this scenario.
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 Synapse Analytics
Why it's wrong here
Azure Synapse Analytics is an enterprise-grade distributed analytics service designed for large-scale data warehousing and big data workloads, but it is not a lightweight streaming engine. While Synapse can ingest streaming data via Event Hubs into its SQL or Spark pools, that ingestion pattern is effectively micro-batch landing, not continuous event-at-a-time processing. Achieving near real-time IoT processing in Synapse would require building custom orchestration around Event Hubs and incur additional latency that a dedicated streaming service avoids. Thus, it is overkill for simple IoT telemetry processing and lacks the native temporal-window SQL constructs that make stream processing straightforward.
- ✗
Azure Databricks
Why it's wrong here
Azure Databricks, while supporting stream processing through Apache Spark Structured Streaming, is not ideal for near real-time processing of IoT device streams due to its micro-batch architecture, which typically introduces higher latency than dedicated real-time stream processing services. It is tempting because Databricks is a powerful analytics platform, excellent for complex data transformations, machine learning, and advanced analytics on large datasets, including scenarios where micro-batch processing of streaming data is acceptable for less stringent latency requirements.
- ✓
Azure Stream Analytics
Why this is correct
Azure Stream Analytics is a fully managed, purpose-built stream-processing service that handles near real-time IoT telemetry with low latency. It provides a SQL-like query language that natively supports temporal windows, sliding windows, and event-time processing, allowing filters, aggregations, and even anomaly detection directly on the stream. Crucially, it has a native Cosmos DB sink and built-in connectors to Event Hubs, IoT Hub, and other Azure services, eliminating the need for custom glue code. Because it processes each event as it arrives rather than in micro-batches, it is the ideal choice for real-time IoT scenarios that require prompt alerts or continuous output.
- ✗
Azure Data Factory
Why it's wrong here
Azure Data Factory is a cloud data integration service focused on batch ETL/ELT, pipeline orchestration, and scheduled data movement. It does not provide continuous, event-at-a-time stream processing; rather, pipelines are triggered on schedules or discrete events such as a blob being created, and each run processes a finite set of data. While ADF can move batches of data from Event Hubs to a store, it lacks stream-processing primitives like watermarking, windowed aggregates, and sliding time windows that are essential for per-event IoT analysis. Attempting to force near real-time streaming through ADF would require frequent pipeline runs, adding latency and operational complexity without true streaming semantics.
Go deeper
Related to this question
Learn chapter
Data Roles and Core Concepts
Key term
IoT Hub
IoT Hub is a managed cloud service in Azure that acts as a central message hub for secure, bidirectional communication between IoT devices and the cloud.
Key term
Data
Data is raw, unprocessed information, like numbers, words, or measurements, that can be stored, processed, and analyzed by computers.
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