DP-900 Describe considerations for working with non-relational data on Azure Practice Test 8 — 15 Questions

Question 1

A logistics company stores sensor data from delivery trucks in Azure Table Storage. Each sensor reading includes a TruckID, Timestamp, Location, and EngineTemperature. The most common query retrieves all readings for all trucks within a specific one-hour time window (e.g., between 10:00 and 11:00 on a given day). Currently, the table uses PartitionKey = TruckID and RowKey = Timestamp (ISO format). However, queries filtering by time range are slow and consume many transactions. Which design change will most improve the performance of these time-range queries?

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

Accepted Answer

Change PartitionKey to a date-based value (e.g., YYYY-MM-DD) and RowKey to a composite of TruckID and Timestamp.. Azure Table Storage queries are most efficient when they target a specific PartitionKey and a range of RowKey values. By setting PartitionKey to a date-based value (e.g., YYYY-MM-DD), all readings for a given day are co-located in the same partition. Then, using a composite RowKey of TruckID and Timestamp allows the query to filter by time range within that partition using a single partition scan, drastically reducing the number of transactions and improving performance.

Answer

Change RowKey to be a composite of TruckID and Timestamp while keeping PartitionKey as TruckID.

Answer

Use Azure Cosmos DB with a partition key on Timestamp instead of Azure Table Storage.

Answer

Enable indexing on the Timestamp column in Azure Table Storage.

Question 2

A social media startup stores user profile data, posts, and comments in Azure Cosmos DB. They notice that the logical partition size for a popular user's profile is growing beyond 20 GB, causing performance issues. The current partition key is 'userId'. Which action should they take to solve this?

Accepted Answer

Change the partition key to a synthetic key combining userId and postId. A is correct because the logical partition size limit in Azure Cosmos DB is 20 GB. By using a synthetic partition key that combines 'userId' and 'postId', you distribute the data for the popular user across multiple logical partitions, preventing any single partition from exceeding the 20 GB limit and resolving the performance bottleneck.

Answer

Increase the RU/s

Answer

Split the container into multiple containers by userId range

Answer

Use a different API like MongoDB

Question 3

A ride-sharing application uses Azure Cosmos DB for trip data. Each trip record contains TripID (unique), DriverID, RiderID, TripDate, and other details. The most common query retrieves all trips for a specific driver within a given date range. Which partition key should be chosen to minimize Request Unit (RU) consumption and ensure even data distribution?

Accepted Answer

DriverID. DriverID is the optimal partition key because the most common query filters on DriverID and a date range. Partitioning by DriverID ensures that all trips for a specific driver are stored in the same physical partition, making the query a single-partition operation that consumes minimal Request Units (RUs). It also provides even data distribution across partitions because each driver generates a roughly similar number of trips, avoiding hot spots.

Answer

TripID

Answer

TripDate

Answer

RiderID

Question 4

A global e-commerce platform uses Azure Cosmos DB to store product inventory data. Customers add items to their cart, which reduces the available inventory count. The application requires that after a customer adds an item, any subsequent read of that product's inventory from any region in the world must reflect the reduced count immediately. Which Cosmos DB consistency level should be used?

Accepted Answer

Strong consistency. Strong consistency ensures that any read operation returns the most recent write, regardless of the region. Since the application requires that after a customer adds an item, any subsequent read of that product's inventory from any region must reflect the reduced count immediately, Strong consistency is the only level that guarantees linearizability and zero staleness across all replicas.

Answer

Eventual consistency

Answer

Consistent prefix consistency

Answer

Session consistency

Question 5

A hospital stores patient vital signs data in Azure Cosmos DB. Each document contains PatientID, Timestamp, HeartRate, BloodPressure, and other measurements. The most common query retrieves all vital signs for a specific patient within a time range (e.g., last 24 hours). Which property should be chosen as the partition key to minimize Request Unit (RU) consumption and ensure even data distribution?

Accepted Answer

PatientID. PatientID is the ideal partition key because the most common query filters by PatientID and a time range. With PatientID as the partition key, Cosmos DB can route the query to a single physical partition containing all documents for that patient, minimizing cross-partition queries and reducing RU consumption. It also ensures even data distribution since each patient generates a similar volume of vital signs data, avoiding hot partitions.

Answer

Timestamp

Answer

HeartRate

Answer

BloodPressure

Question 6

A company stores terabytes of customer support chat transcripts in JSON format. The data is rarely modified and needs to be accessed by analysts using SQL queries. The analysts do not want to manage servers or provision throughput. Which Azure service should be used to store and query this data?

Accepted Answer

Azure Blob Storage (with Azure Data Lake Storage Gen2) and query using Azure Synapse Serverless SQL. Azure Blob Storage with Azure Data Lake Storage Gen2 provides a cost-effective, scalable solution for storing large volumes of JSON data in its native format. By using Azure Synapse Serverless SQL, analysts can query this data directly with standard T-SQL without provisioning any infrastructure or managing throughput, meeting the requirement for serverless, on-demand querying of rarely modified data.

Answer

Azure Cosmos DB

Answer

Azure Table Storage

Answer

Azure SQL Database

Question 7

A company stores backup files in Azure Blob Storage. The backup files are accessed frequently for the first 30 days, then only rarely for the next six months. After one year, the files must be retained for compliance but are never accessed. The company wants to minimize storage costs. Which solution should they use?

Accepted Answer

Use Azure Blob Storage lifecycle management policies. Azure Blob Storage lifecycle management policies allow you to automatically transition blobs to cooler tiers (e.g., from Hot to Cool after 30 days, then to Archive after one year) and delete blobs after a specified period, all without manual intervention. This directly matches the access pattern: frequent access for 30 days, rare access for six months, and never accessed after one year, minimizing storage costs by using the most cost-effective tier for each phase.

Answer

Manually move files between storage accounts

Answer

Use Azure File Sync

Answer

Use Azure NetApp Files

Question 8

A mobile app stores user preferences as JSON documents in Azure Cosmos DB. The document includes userId, theme, language, and notification settings. The most common query retrieves the document for a specific userId. To minimize cost and ensure even distribution, which property should be chosen as the partition key?

Accepted Answer

userId. The userId property is the ideal partition key because it provides high cardinality (each user has a unique ID) and ensures even request distribution across physical partitions. Since the most common query retrieves a document by userId, using it as the partition key makes those queries point reads (single-partition queries), which are the most cost-efficient and fastest in Azure Cosmos DB.

Answer

theme

Answer

language

Answer

a concatenation of userId and language

Question 9

A company is developing a web application that stores user profiles as JSON documents. The application needs to query these documents using SQL-like queries, and must support automatic indexing of all properties. They want a fully managed, globally distributed NoSQL database with low latency. Which Azure Cosmos DB API should they use?

Accepted Answer

SQL API. The SQL API (formerly DocumentDB API) is the correct choice because it natively supports querying JSON documents with SQL-like syntax (SELECT * FROM c WHERE c.property = value). It automatically indexes all properties by default, provides a fully managed, globally distributed NoSQL database with low-latency reads and writes, and is designed specifically for document-based workloads like user profiles.

Answer

Table API

Answer

Cassandra API

Answer

Gremlin API

Question 10

A company stores large video files in Azure Blob Storage. The files are accessed frequently for the first 30 days after upload, then rarely for the next 180 days, and after that they are only needed for compliance but never accessed. The company wants to minimize storage costs while ensuring the files remain durable and accessible. Which strategy should they implement?

Accepted Answer

Store files initially in the Hot tier, then use lifecycle management to move files to Cool after 30 days and to Archive after 210 days.. It aligns the access patterns with the appropriate Azure Blob Storage access tiers: Hot for frequent initial access, Cool for reduced-cost infrequent access after 30 days, and Archive for the lowest-cost long-term retention after 210 days. Azure lifecycle management policies automate these transitions, ensuring durability and accessibility while minimizing costs.

Answer

Store all files in the Cool access tier and apply lifecycle management to move files to the Archive tier after 30 days.

Answer

Store files in the Archive tier from the beginning to maximize cost savings.

Answer

Store files in the Premium tier for fast access, then manually delete files after 30 days.

Question 11

A social media application stores user posts in Azure Cosmos DB. Each post has fields: PostID (unique), UserID, Timestamp, Content, LikesCount. The application frequently queries for all posts by a specific UserID ordered by Timestamp descending. To minimize Request Unit (RU) consumption, which partition key and indexing strategy should be used?

Accepted Answer

Partition key: UserID, and create a composite index on (UserID, Timestamp DESC). UserID is the most frequently filtered attribute, making it an ideal partition key to distribute data evenly and avoid cross-partition queries. Adding a composite index on (UserID, Timestamp DESC) allows the query to be served from a single physical partition with an index seek, minimizing RU consumption by avoiding a full scan or sort operation.

Answer

Partition key: Timestamp, and sort by UserID in the query

Answer

Partition key: PostID, and use ORDER BY Timestamp

Answer

Partition key: UserID, and use ORDER BY PostID

Question 12

A gaming company stores player game scores in Azure Cosmos DB. Each document contains PlayerID, GameID, Score, Timestamp. The most common query is: 'Get all scores for a specific game ordered by score descending'. Which partition key should be chosen 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. This avoids cross-partition fan-out, minimizing RU consumption. A partition key that matches the query filter ensures efficient index lookup and data retrieval.

Answer

PlayerID

Answer

Score

Answer

Timestamp

Question 13

A company has an existing IoT application that uses Apache Cassandra for time-series sensor data. They want to migrate to Azure's fully managed NoSQL database service while continuing to use the Cassandra Query Language (CQL) and benefiting from global distribution and low latency. Which Azure Cosmos DB API should they use?

Accepted Answer

Cassandra API. The Cassandra API for Azure Cosmos DB is wire-protocol-compatible with Apache Cassandra, meaning you can use existing CQL (Cassandra Query Language) tools, drivers, and code with minimal changes. It provides a fully managed, globally distributed NoSQL database with low-latency reads and writes, which directly matches the company's requirement to migrate from self-managed Cassandra while preserving their CQL-based application logic.

Answer

Core (SQL) API

Answer

MongoDB API

Answer

Gremlin API

Question 14

A social media application stores user posts in Azure Cosmos DB. Each document contains fields: PostID (unique), UserID, Timestamp, Content, LikesCount. The most common query retrieves all posts by a specific UserID ordered by Timestamp descending. Which partition key and indexing strategy minimizes Request Unit (RU) consumption?

Accepted Answer

Partition key: UserID; Index: range on Timestamp. The query filters on UserID, so setting UserID as the partition key ensures all posts for a user are in the same physical partition, avoiding cross-partition queries. Adding a range index on Timestamp allows efficient sorting without additional RU overhead, as Cosmos DB can use the index to return results in descending order directly.

Answer

Partition key: PostID; Index: range on Timestamp

Answer

Partition key: Timestamp; Index: range on UserID

Answer

Partition key: UserID; Index: composite on (UserID, PostID)

Question 15

A mobile game company stores player scores in Azure Cosmos DB. Each document contains the fields PlayerID (unique to the player), GameID, Score, and 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 using it as the partition key ensures that all documents for a given GameID are stored in the same physical partition. This allows the query to target a single partition, minimizing cross-partition fan-out and reducing Request Unit (RU) consumption. A partition key that matches the query filter is essential for efficient, low-latency reads in Azure Cosmos DB.

Answer

PlayerID

Answer

Score

Answer

Timestamp