The answer is to change the distribution key to a column with more unique values, such as TransactionID. This directly fixes data skew in Azure Synapse dedicated SQL pool because hash-distributing on a column with low cardinality, like AccountID, causes a few distributions to hold millions of rows while others sit idle, creating a bottleneck that slows parallel query execution. By switching to a highly unique key, data spreads evenly across all 60 distributions, allowing aggregation queries to run in balanced parallel. On the DP-900 exam, this scenario tests your understanding of distribution strategies and how skewed data degrades performance—a common trap is assuming you must redesign the schema or add indexes, but the simplest fix is choosing a better distribution column. Remember the memory tip: “Skew is cured by uniqueness”—if your distribution key has few distinct values, you get skew; pick a column with many unique values to keep distributions balanced.
DP-900 Describe an analytics workload on Azure Practice Question
This DP-900 practice question tests your understanding of describe an analytics workload on azure. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 a data engineer for a financial services company. The company uses Azure Synapse Analytics dedicated SQL pool for its data warehouse. They have a fact table named Transactions that contains 2 billion rows. The table is hash-distributed on the AccountID column. Users run reports that aggregate transaction amounts by date and account type. The reports are slow. Upon investigation, you find that the distribution is highly skewed because a few accounts have millions of transactions. You need to improve query performance without redesigning the entire schema. Which action should you take?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Change the distribution key to a column with more unique values, such as TransactionID
The correct answer is A because changing the distribution key to TransactionID, which has far more unique values than AccountID, will eliminate the data skew that is causing performance degradation. In a hash-distributed table, a skewed distribution key leads to some distributions holding a disproportionate amount of data, causing parallel query execution to be bottlenecked by the largest distribution. By using a highly unique column like TransactionID, the data will be evenly distributed across all 60 distributions, enabling balanced parallelism and faster aggregation queries.
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.
✓
Change the distribution key to a column with more unique values, such as TransactionID
Why this is correct
A column with high cardinality reduces skew and improves parallel processing.
Related concept
Read the scenario before looking for a memorised answer.
✗
Change the distribution to round-robin
Why it's wrong here
Round-robin distributes evenly but causes massive data movement during joins.
✗
Create a clustered columnstore index on the table
Why it's wrong here
The table likely already has a columnstore index; skew is not addressed by indexing.
✗
Replicate the Transactions table to all distributions
Why it's wrong here
Replication is for smaller tables; replicating 2 billion rows would be costly and slow.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume that a clustered columnstore index (Option C) is the universal fix for slow queries, but they fail to recognize that data skew in a hash-distributed table is a distribution-level problem that columnstore indexes cannot solve.
Detailed technical explanation
How to think about this question
Hash distribution in Azure Synapse Analytics uses a hash function on the distribution column to assign each row to one of 60 distributions. When the distribution column has low cardinality or skewed values (e.g., a few AccountIDs with millions of rows), the hash function maps many rows to the same distribution, creating a 'hot spot' that serializes query execution. Changing the distribution key to a column with high cardinality, such as TransactionID (which is unique per row), ensures that each distribution receives approximately the same number of rows, maximizing parallelism and minimizing data movement during aggregations.
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 cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this DP-900 question in full detail.
Describe an analytics workload on Azure — This question tests Describe an analytics workload on Azure — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Change the distribution key to a column with more unique values, such as TransactionID — The correct answer is A because changing the distribution key to TransactionID, which has far more unique values than AccountID, will eliminate the data skew that is causing performance degradation. In a hash-distributed table, a skewed distribution key leads to some distributions holding a disproportionate amount of data, causing parallel query execution to be bottlenecked by the largest distribution. By using a highly unique column like TransactionID, the data will be evenly distributed across all 60 distributions, enabling balanced parallelism and faster aggregation queries.
What should I do if I get this DP-900 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.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
This DP-900 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-900 exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.