The answer is to increase the number of files to match the number of distributions. This is correct because Azure Synapse dedicated SQL pool distributes data across 60 distributions, and COPY INTO performance relies on parallel file reads. When you have only a few large files, like 1 GB each, many distributions remain idle waiting for work, creating a bottleneck. By splitting those files so you have at least 60 smaller files, each distribution can process a file simultaneously, maximizing throughput and reducing load time. On the DP-203 exam, this tests your understanding of distribution-level parallelism and how file granularity directly impacts ingestion speed. A common trap is assuming larger files are always faster, but the key is matching file count to distributions to avoid uneven workload. Remember the memory tip: "Sixty files for sixty piles" — each distribution needs its own file to stay busy.
DP-203 Design and implement data storage Practice Question
This DP-203 practice question tests your understanding of design and implement data storage. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 troubleshooting slow COPY INTO performance in Azure Synapse Analytics dedicated SQL pool when loading Parquet files from Azure Data Lake Storage Gen2. The files are 1 GB each. What should you do to improve performance?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Increase the number of files to match the number of distributions
Option C is correct because COPY INTO in Azure Synapse dedicated SQL pool distributes data across 60 distributions. To maximize parallelism, the number of input files should match or exceed the number of distributions. With 1 GB files, you have too few files to fully utilize all distributions, causing some distributions to remain idle. Increasing the number of files to at least 60 ensures each distribution gets work, improving throughput.
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.
✗
Reduce the file size to 100 MB to increase parallelism
Why it's wrong here
A is wrong because too many small files can cause overhead.
✗
Use PolyBase instead of COPY INTO
Why it's wrong here
B is wrong because COPY INTO is preferred and already optimized.
✓
Increase the number of files to match the number of distributions
Why this is correct
D is correct because each distribution can read a file in parallel, maximizing throughput.
Related concept
Read the scenario before looking for a memorised answer.
✗
Disable parallel processing in the COPY command
Why it's wrong here
C is wrong because parallel processing is beneficial.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates focus on file size reduction (Option A) as a general optimization, but the specific requirement in Synapse dedicated SQL pool is to match the number of files to the number of distributions (60) to avoid distribution skew and maximize parallelism.
Detailed technical explanation
How to think about this question
Under the hood, COPY INTO uses a distributed data movement service (DMS) that splits work across 60 distributions. Each distribution processes one or more files; if files are fewer than distributions, some distributions remain idle, causing skew. The optimal file count is a multiple of 60, and Parquet files benefit from columnar pruning and predicate pushdown, which are most effective when parallelism is maximized. In real-world scenarios, loading 60 files of ~100 MB each often yields better performance than 6 files of 1 GB each.
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.
Design and implement data storage — This question tests Design and implement data storage — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Increase the number of files to match the number of distributions — Option C is correct because COPY INTO in Azure Synapse dedicated SQL pool distributes data across 60 distributions. To maximize parallelism, the number of input files should match or exceed the number of distributions. With 1 GB files, you have too few files to fully utilize all distributions, causing some distributions to remain idle. Increasing the number of files to at least 60 ensures each distribution gets work, improving throughput.
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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