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 gaming company stores player scores in Azure Cosmos DB using the NoSQL API. Each document contains: PlayerID (unique to player), GameID, Score, Timestamp. The most common query is: 'Retrieve all scores for a specific GameID, ordered by Score descending.' Which property should be chosen as the partition key to minimize Request Unit (RU) consumption?
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.
Why wrong: Incorrect. PlayerID has high cardinality and queries filter by GameID, not PlayerID. Using PlayerID would scatter documents across partitions, requiring a fan-out query and higher RU cost.
B
GameID
Correct. GameID groups all scores for a game together, so the query targets a single partition, minimizing RU.
C
Score
Why wrong: Incorrect. Score changes frequently and is not a filtering key in the query. Using Score as partition key would cause hot partitions and inefficient queries.
D
Timestamp
Why wrong: Incorrect. Timestamp is monotonically increasing and would create hot partitions on the latest time. Queries filter by GameID, not timestamp.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
GameID
GameID is the correct partition key because the most common query filters on GameID, and Cosmos DB routes each query to the physical partition(s) containing that GameID's data. Using GameID ensures the query touches only the relevant partition(s), minimizing RU consumption by avoiding cross-partition fan-out. A partition key that matches the filter predicate is essential for efficient, single-partition 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.
✗
PlayerID
Why it's wrong here
Incorrect. PlayerID has high cardinality and queries filter by GameID, not PlayerID. Using PlayerID would scatter documents across partitions, requiring a fan-out query and higher RU cost.
✓
GameID
Why this is correct
Correct. GameID groups all scores for a game together, so the query targets a single partition, minimizing RU.
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.
✗
Score
Why it's wrong here
Incorrect. Score changes frequently and is not a filtering key in the query. Using Score as partition key would cause hot partitions and inefficient queries.
✗
Timestamp
Why it's wrong here
Incorrect. Timestamp is monotonically increasing and would create hot partitions on the latest time. Queries filter by GameID, not timestamp.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often pick PlayerID because it's unique and seems like a natural key, but they fail to realize that a partition key must align with the most common query filter to avoid costly cross-partition queries, not just be unique.
Detailed technical explanation
How to think about this question
Cosmos DB uses the partition key to hash documents into logical partitions, each stored on a physical partition. When a query includes the partition key in the filter (e.g., WHERE GameID = 'xyz'), the query engine routes the request directly to the partition(s) holding that key, enabling single-partition queries with minimal RU. Without the partition key in the filter, the query must fan out to all physical partitions, incurring at minimum the RU cost of a cross-partition query (often 2-10x more RUs). In real-world scenarios, choosing a partition key with high cardinality (many unique values) and even request distribution prevents throttling and ensures predictable performance.
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: GameID — GameID is the correct partition key because the most common query filters on GameID, and Cosmos DB routes each query to the physical partition(s) containing that GameID's data. Using GameID ensures the query touches only the relevant partition(s), minimizing RU consumption by avoiding cross-partition fan-out. A partition key that matches the filter predicate is essential for efficient, single-partition 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.
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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