DP-900 Describe considerations for working with non-relational data on Azure Practice Test 9 — 15 Questions

Question 1

A manufacturing company stores IoT sensor data as JSON documents in Azure Cosmos DB. Each document has fields: deviceId (high cardinality, many unique values), timestamp, temperature, and humidity. The most frequent query is: 'Retrieve all readings for a specific deviceId from the last hour.' To minimize Request Unit (RU) consumption, which combination of partition key and indexing policy should be chosen?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

Partition key: deviceId, Indexing: automatic on all properties. DeviceId is the most frequently filtered attribute (in the WHERE clause), making it an ideal partition key that ensures queries are scoped to a single physical partition, minimizing cross-partition fan-out. Automatic indexing on all properties allows efficient filtering on timestamp within the partition, while the index on deviceId is not strictly needed since the partition key itself routes the query, but it does not harm RU consumption significantly. This combination balances query performance and RU cost for the described workload.

Answer

Partition key: timestamp, Indexing: automatic on all properties

Answer

Partition key: deviceId, Indexing: none

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Partition key: temperature, Indexing: automatic on all properties

Question 2

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?

Accepted Answer

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.

Answer

PlayerID

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Score

Answer

Timestamp

Question 3

A data lake stores Parquet files in Azure Data Lake Storage Gen2, organized by date (e.g., /data/2023/01/15/). Analysts frequently run queries that filter on a specific date range. Which feature of Azure Data Lake Storage Gen2 directly enables efficient directory-level operations like renaming or moving entire date partitions without rewriting files?

Accepted Answer

Hierarchical namespace. The hierarchical namespace feature in Azure Data Lake Storage Gen2 enables true directory-level operations, such as renaming or moving entire partitions (e.g., /data/2023/01/15/), by treating directories as first-class objects. This allows atomic metadata operations without rewriting or copying the underlying Parquet files, which is essential for efficient partition management in data lake scenarios.

Answer

Blob soft delete

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Change feed

Answer

Immutable storage

Question 4

A media company stores large video files in Azure Blob Storage. The videos are accessed frequently for the first 30 days after upload, then rarely for the next 180 days. After that, they are only needed for compliance and are never accessed. Which access tier should be used for the first 30 days to minimize costs while maintaining low latency?

Accepted Answer

Hot tier. The Hot tier is the correct choice for the first 30 days because it provides the lowest latency access and highest throughput for frequently accessed data, which matches the requirement of frequent access during this period. While the Hot tier has the highest storage cost per GB, it has no retrieval costs, making it cost-effective for high-access patterns. The other tiers introduce either retrieval fees (Cool), high latency (Archive), or unnecessary cost (Premium) for this use case.

Answer

Cool tier

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Archive tier

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Premium tier

Question 5

A social media company stores user session data. Each session record must be quickly looked up by user ID and must have strong consistency so that once a session is written, subsequent reads always return the latest data. The company expects billions of session records globally and needs low-latency reads/writes. Which Azure data store best meets these requirements?

Accepted Answer

Azure Cosmos DB (SQL API). Azure Cosmos DB with SQL API is the correct choice because it offers single-digit millisecond read/write latencies at any scale, global distribution, and tunable consistency levels including strong consistency. Strong consistency ensures that once a write is acknowledged, all subsequent reads return the latest data, which is critical for session state where stale reads could cause authentication or authorization failures. Cosmos DB also supports automatic indexing and partitioning by user ID, enabling fast lookups across billions of records.

Answer

Azure Blob Storage

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Azure Table Storage

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Azure Cache for Redis

Question 6

A global gaming company stores player profiles in Azure Cosmos DB. Each profile document contains PlayerID (unique), PlayerName, Email, and a nested array of Achievements. The most common query is to look up a player by PlayerID and retrieve their achievements. The company needs strong consistency for reads and writes to ensure that when a player earns an achievement, it is immediately visible. Which partition key and consistency level should they choose?

Accepted Answer

B. Partition key: PlayerID; Consistency: Strong. PlayerID is the natural partition key for the most common query (lookup by PlayerID), ensuring efficient single-partition queries. Strong consistency is required to guarantee that when a player earns an achievement, the write is immediately visible to all subsequent reads, which is critical for the gaming scenario.

Answer

A. Partition key: PlayerID; Consistency: Eventual

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C. Partition key: Achievements; Consistency: Strong

Answer

D. Partition key: Email; Consistency: Bounded staleness

Question 7

A gaming company stores player scores in Azure Cosmos DB using the NoSQL API. Each document contains fields: PlayerID (unique to the 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?

Accepted Answer

GameID. GameID is the correct partition key because the most common query filters on GameID, and Cosmos DB routes queries to the exact physical partition(s) containing that GameID's data. This minimizes RU consumption by avoiding cross-partition fan-out, as the query engine can target a single partition. Using any other field would force scanning multiple partitions, increasing RU cost.

Answer

PlayerID

Answer

Score

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Timestamp

Question 8

A travel booking application stores user itineraries in Azure Cosmos DB using the NoSQL API. Each itinerary document contains: UserID (unique to user), ItineraryID, Destination, BookingDate, and a nested array of Activities. The most common query is: 'Retrieve all itineraries for a specific UserID sorted by BookingDate descending.' To minimize Request Unit (RU) consumption, which partition key should be chosen?

Accepted Answer

UserID. UserID is the correct partition key because the most common query filters on UserID, ensuring that all itineraries for a specific user are stored in the same physical partition. This allows the query to target a single partition, minimizing cross-partition queries and reducing Request Unit (RU) consumption. A partition key that aligns with the primary query filter is essential for optimal performance and cost efficiency in Azure Cosmos DB.

Answer

ItineraryID

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Destination

Answer

BookingDate

Question 9

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?

Accepted Answer

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.

Answer

Email

Answer

Name

Answer

A synthetic partition key combining UserID and Region

Question 10

A media company stores user profile images in Azure Blob Storage. Regulators require that the images cannot be deleted or overwritten for a period of 90 days after upload. Which Azure Blob Storage feature should the company enable to meet this requirement?

Accepted Answer

B: Immutable storage with a time-based retention policy. Immutable storage with a time-based retention policy (also known as WORM – Write Once, Read Many) prevents blobs from being deleted or overwritten for a specified retention interval. By setting a 90-day policy, the company ensures that user profile images remain unmodifiable and undeletable during that period, directly satisfying the regulatory requirement.

Answer

A: Soft delete

Answer

C: Access tiers (Hot, Cool, Archive)

Answer

D: Lifecycle management rules

Question 11

A travel booking application stores booking data in Azure Cosmos DB using the NoSQL API. Each booking document contains: BookingID (unique), UserID, Destination, TravelDate, Price. The most common query is: 'Retrieve all bookings for a specific UserID, sorted by TravelDate descending.' To minimize Request Unit (RU) consumption, which property should be chosen as the partition key?

Accepted Answer

UserID. UserID is the correct partition key because the most common query filters on UserID, and Cosmos DB routes queries to the exact physical partition(s) containing that UserID's data. This minimizes cross-partition fan-out, reducing RU consumption. A partition key should align with the primary query filter to enable efficient point-read or single-partition query execution.

Answer

BookingID

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Destination

Answer

TravelDate

Question 12

A media company stores high-definition video files for on-demand streaming. The files are accessed very frequently for the first 30 days after upload, then rarely (about once per month) for the next year, and after one year they are rarely accessed but must be retained for compliance (about once per year). Which set of access tier transitions minimizes cost while meeting access requirements?

Accepted Answer

Hot for 30 days, then Cool for 11 months, then Archive. It aligns the Azure Blob Storage access tier transitions with the access pattern: Hot tier for the first 30 days of frequent access, Cool tier for the next 11 months of monthly access, and Archive tier after one year for rare compliance access. This minimizes cost by moving data to progressively cheaper storage tiers as access frequency drops, while still meeting the access requirements (Cool supports monthly access, Archive supports yearly access with retrieval time).

Answer

Hot for 30 days, then Archive immediately

Answer

Cool for 30 days, then Cool for 11 months, then Archive

Answer

Hot for 365 days, then Archive

Question 13

A company stores JSON documents for a product catalog. Each document has a flexible schema because different product categories have different attributes. The catalog is read-heavy and requires low-latency lookups by product ID. The company expects to handle millions of products and needs to serve customers globally with low latency. Which Azure NoSQL data store should they choose?

Accepted Answer

Azure Cosmos DB. Azure Cosmos DB is the correct choice because it is a globally distributed, multi-model NoSQL database that natively supports JSON documents with flexible schemas, provides single-digit-millisecond latency for read-heavy workloads via automatic indexing, and offers turnkey global distribution across Azure regions to serve customers worldwide with low latency.

Answer

Azure Table Storage

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Azure Blob Storage

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Azure SQL Database

Question 14

A gaming application requires a high-performance leaderboard that stores player scores and retrieves the top 10 scores quickly. The data does not require complex queries or a fixed schema. The leaderboard must support updates as new scores are submitted. Which Azure data store is most appropriate for this scenario?

Accepted Answer

Azure Cache for Redis. Azure Cache for Redis is the most appropriate choice because it provides an in-memory data structure store with native support for sorted sets (via the ZADD and ZRANGE commands), which are ideal for maintaining a real-time leaderboard. It can handle high-throughput score updates and retrieve the top 10 scores in O(log(N)) time, meeting the low-latency and performance requirements without needing a fixed schema.

Answer

Azure Cosmos DB with SQL API

Answer

Azure Table storage

Answer

Azure Blob Storage

Question 15

A social media application stores user posts in Azure Cosmos DB using the NoSQL API. Each document includes: PostID (unique), UserID, Timestamp, Content. The most common query is: 'Get all posts for a specific UserID, sorted by Timestamp descending.' Which partition key should be chosen to distribute load evenly across physical partitions while also supporting this query efficiently?

Accepted Answer

UserID. UserID is the correct partition key because it evenly distributes write operations across physical partitions (each user has a unique ID) and directly supports the most common query: filtering by UserID. With UserID as the partition key, the query 'Get all posts for a specific UserID, sorted by Timestamp descending' becomes a single-partition query (using the partition key in the WHERE clause), which is efficient and avoids cross-partition fan-out. This design also allows Cosmos DB to use the Timestamp field as a sort key within each logical partition, enabling efficient sorting without additional indexing overhead.

Answer

PostID

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Timestamp

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Content