The answer is to configure the Azure Stream Analytics output to Azure Synapse Analytics with the 'Exactly once' output mode. This is correct because this mode leverages checkpointing and transactional writes to guarantee that each event is delivered idempotently, meaning even if a write operation is retried due to a transient failure, the destination will not receive duplicate records. On the DP-203 exam, this scenario tests your understanding of Stream Analytics output modes and their guarantees, often appearing as a distractor against the default 'At least once' mode, which can produce duplicates. A common trap is assuming that idempotent sinks alone solve the problem without enabling the specific output mode. For a quick memory tip, think of the phrase "Checkpoint and Commit" — the 'Exactly once' mode commits checkpoints only after the transaction to Synapse succeeds, ensuring no event is written twice.
DP-203 Develop data processing Practice Question
This DP-203 practice question tests your understanding of develop data processing. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
You are developing a streaming solution with Azure Stream Analytics that outputs results to Azure Synapse Analytics. The output requires exactly-once semantics to avoid duplicates. Which configuration should you use?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Configure the output to Azure Synapse Analytics with 'Exactly once' output mode.
Azure Stream Analytics supports an 'Exactly once' output mode for Azure Synapse Analytics, which ensures that each event is written exactly once to the destination, preventing duplicates. This mode uses a combination of checkpointing and transactional writes to guarantee idempotent delivery without requiring custom logic.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Use an Azure Function output to write data idempotently to Synapse.
Why it's wrong here
Azure Functions can be idempotent but Synapse does not support idempotent writes directly.
✓
Configure the output to Azure Synapse Analytics with 'Exactly once' output mode.
Why this is correct
Stream Analytics supports exactly-once output to Synapse dedicated SQL pool.
Related concept
Read the scenario before looking for a memorised answer.
✗
Set the event serialization format to Avro and enable 'Exactly once' event delivery.
Why it's wrong here
Event delivery is for input, not output.
✗
Output to Azure Blob Storage and then use a COPY statement in Synapse.
Why it's wrong here
This approach does not guarantee exactly-once semantics end-to-end.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse 'exactly-once' with 'at-least-once' and assume that idempotent writes via Azure Functions or staging in Blob Storage can achieve the same guarantee, but Stream Analytics' built-in output mode is the only supported way to guarantee exactly-once delivery to Synapse without custom complexity.
Trap categories for this question
Command / output trap
Event delivery is for input, not output.
Detailed technical explanation
How to think about this question
Under the hood, the 'Exactly once' output mode in Stream Analytics for Synapse uses a two-phase commit protocol with the Synapse target, leveraging the output's internal checkpointing to track which events have been committed. This ensures that even if a job restarts, it will not re-process already committed data, effectively eliminating duplicates. In real-world scenarios, this is critical for financial or IoT pipelines where duplicate records could cause incorrect aggregations or billing errors.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this DP-203 question in full detail.
Develop data processing — This question tests Develop data processing — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Configure the output to Azure Synapse Analytics with 'Exactly once' output mode. — Azure Stream Analytics supports an 'Exactly once' output mode for Azure Synapse Analytics, which ensures that each event is written exactly once to the destination, preventing duplicates. This mode uses a combination of checkpointing and transactional writes to guarantee idempotent delivery without requiring custom logic.
What should I do if I get this DP-203 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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