DP-900 Practice Question: Describe considerations for working with non-relational data on Azure
This DP-900 practice question tests your understanding of describe considerations for working with non-relational data 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.
A social media application stores user profiles in Azure Cosmos DB using the NoSQL API. Each profile includes UserID, Name, Email, and an array of Posts. The most common query retrieves a user's profile by UserID. The application requires strong consistency for writes so that once a profile is updated, all subsequent reads see the latest data. To minimize Request Unit (RU) consumption, which partition key should be chosen?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "minimum / minimize"
Why it matters: Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
UserID is unique and high cardinality, distributing data evenly. Retrieving by UserID becomes a point read, consuming the fewest RUs.
B
Email
Why wrong: Email may not be unique and could lead to uneven distribution; queries by UserID would become cross-partition queries if Email is the partition key.
C
Name
Why wrong: Name is not unique and has low cardinality, causing hot partitions. Queries by UserID would be cross-partition.
D
A synthetic partition key combining UserID and Region
Why wrong: Adding Region to the partition key may improve distribution but would cause queries by UserID alone to be cross-partition, increasing RU consumption.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
UserID
UserID is the correct partition key because it is the primary filter in the most common query (retrieving a profile by UserID), ensuring each query targets a single logical partition. This minimizes cross-partition queries and RU consumption. Additionally, UserID provides high cardinality and even distribution, which prevents hot partitions and supports the required strong consistency for writes.
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.
✓
UserID
Why this is correct
UserID is unique and high cardinality, distributing data evenly. Retrieving by UserID becomes a point read, consuming the fewest RUs.
Clue confirmation
The clue word "minimum / minimize" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Email
Why it's wrong here
Email may not be unique and could lead to uneven distribution; queries by UserID would become cross-partition queries if Email is the partition key.
✗
Name
Why it's wrong here
Name is not unique and has low cardinality, causing hot partitions. Queries by UserID would be cross-partition.
✗
A synthetic partition key combining UserID and Region
Why it's wrong here
Adding Region to the partition key may improve distribution but would cause queries by UserID alone to be cross-partition, increasing RU consumption.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often choose a synthetic key or a secondary attribute like Email, thinking they need to avoid hot partitions, but they overlook that the most common query pattern and the need for minimal RU consumption dictate using the primary query filter as the partition key.
Detailed technical explanation
How to think about this question
In Azure Cosmos DB NoSQL API, the partition key determines the physical partition where data is stored. When a query includes the partition key in the filter (e.g., WHERE UserID = '123'), the request is routed directly to the single partition containing that data, consuming only the RU for that operation. Without the partition key in the filter, the query must fan out to all partitions, multiplying RU consumption. Strong consistency requires that writes are replicated to a quorum of replicas within the same partition, so a well-chosen partition key like UserID ensures fast, consistent reads without cross-partition overhead.
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 considerations for working with non-relational data on Azure — This question tests Describe considerations for working with non-relational data on Azure — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: UserID — UserID is the correct partition key because it is the primary filter in the most common query (retrieving a profile by UserID), ensuring each query targets a single logical partition. This minimizes cross-partition queries and RU consumption. Additionally, UserID provides high cardinality and even distribution, which prevents hot partitions and supports the required strong consistency for writes.
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.
Are there clue words in this question I should notice?
Yes — watch for: "minimum / minimize". Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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