DP-900 Describe considerations for working with non-relational data on Azure Practice Test 4 — 15 Questions

Question 1

A mobile game company stores player profiles and game state in Azure Cosmos DB. Each document contains playerId, level, score, inventory (an array of items), and lastLogin. The application requires fast point reads by playerId, queries to find all players within a specific score range, and global distribution with multi-region writes for low latency worldwide. They also want to use a familiar SQL-like query language. Which Azure Cosmos DB API should they choose?

Accepted Answer

Core (SQL) API. The Core (SQL) API is the correct choice because it provides native support for SQL-like queries, enabling the required point reads by playerId and range queries on score. It also offers multi-region writes for global distribution with low latency, which aligns with the application's need for worldwide player access. The document model with arrays (inventory) is directly supported, making it ideal for storing player profiles and game state.

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MongoDB API

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Cassandra API

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Gremlin API

Question 2

A manufacturing company stores IoT sensor data as blobs in Azure Blob Storage. Each blob is named with a device ID and a timestamp, and they need to quickly find all blobs for a specific device within a date range. Which Azure Blob Storage feature should they use to query blobs based on custom metadata?

Accepted Answer

Blob index tags. Blob index tags allow you to apply custom key-value metadata to blobs and then query them using a filtered query across containers or storage accounts. This enables efficient retrieval of blobs by device ID and timestamp without scanning all blob names or maintaining a separate index.

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Blob snapshots

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Blob soft delete

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Blob lifecycle management

Question 3

A retail company plans to store product catalog data that includes product ID, name, description, price, and a varying set of attributes (e.g., size, color, material). The application requires low-latency reads and writes, global distribution, and the ability to handle schema flexibility. Which Azure data store is best suited for this workload?

Accepted Answer

Azure Cosmos DB. Azure Cosmos DB is the best choice because it provides low-latency reads and writes (single-digit milliseconds at the 99th percentile), global distribution with multi-region writes, and automatic schema flexibility through its document model. It supports varying product attributes (e.g., size, color, material) without requiring schema changes, and its turnkey global distribution ensures data is replicated across regions for fast access.

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Azure SQL Database

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Azure Table Storage

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Azure Blob Storage

Question 4

A media company stores raw video footage as blobs in Azure Blob Storage. After processing, the raw footage is kept for compliance purposes and is accessed only a few times per year. The company wants to minimize storage costs while ensuring the data is durable and can be restored within 24 hours if needed. Which Azure Blob Storage access tier should they use?

Accepted Answer

Archive. The Archive tier is the correct choice because it offers the lowest storage cost for data that is rarely accessed (a few times per year) and can tolerate a retrieval latency of up to 15 hours, which is well within the 24-hour restoration requirement. Azure Blob Storage's Archive tier is designed for long-term retention, compliance, and backup scenarios where durability is maintained through geo-redundant replication options, and data can be rehydrated to an online tier (e.g., Hot or Cool) within the specified time frame.

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Hot

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Cool

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Cold

Question 5

A global gaming company uses Azure Cosmos DB to store player scores and profiles. The application reads and writes player data from multiple regions worldwide. The company wants to ensure that when a player updates their high score in one region, any subsequent read from another region will always see the latest value, even if there is network latency between regions. Which consistency level should they choose?

Accepted Answer

Strong. Strong consistency ensures that any read operation returns the most recent write across all regions. In Azure Cosmos DB, this is achieved by synchronously replicating writes to all replicas before acknowledging the write, guaranteeing that subsequent reads in any region always see the latest value, regardless of network latency.

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Bounded staleness

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Session

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Eventual

Question 6

A startup develops a mobile application that stores user preferences as simple key-value pairs. The app is only used in North America, and the team needs low-latency reads and writes with minimal cost. They do not require global distribution or complex querying. Which Azure data store should they choose?

Accepted Answer

Azure Table Storage. Azure Table Storage is the correct choice because it provides a cost-effective, low-latency key-value store for simple data like user preferences, with no need for global distribution or complex querying. It offers single-digit millisecond latency for reads and writes within a single region, and its pay-per-request pricing model minimizes cost for a startup. The Table API in Azure Cosmos DB would be overkill and more expensive for this North America-only, non-distributed scenario.

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Azure Cosmos DB (SQL API)

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Azure Cosmos DB (Table API)

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Azure SQL Database

Question 7

A mobile gaming company stores player data in Azure Cosmos DB using the Core (SQL) API. Each document contains fields: playerId, nickname, score, level, and an inventory array of item objects (each with name and type). The company wants to query all players whose score is above 5000 and who have a specific item (e.g., a sword) in their inventory. Which query clause should they use?

Accepted Answer

B) WHERE c.score > 5000 AND ARRAY_CONTAINS(c.inventory, {name: 'sword'}, true). Option B is correct because ARRAY_CONTAINS with the third parameter set to 'true' performs a partial match, checking if any element in the inventory array has a 'name' property equal to 'sword'. This is the standard way to query for an item within an array of objects in Azure Cosmos DB's SQL API, as it correctly handles the nested structure without requiring a JOIN or subquery.

Answer

A) WHERE c.score > 5000 AND c.inventory.some(item => item.name == 'sword')

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C) WHERE c.score > 5000 AND c.inventory.name == 'sword'

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D) WHERE c.score > 5000 AND 'sword' IN c.inventory

Question 8

A media publishing company stores high-resolution images and video files for their website. These files are large (hundreds of MBs each) and are accessed only a few times per month, but when accessed, they must be delivered within seconds. Additionally, they need to store a small amount of metadata (e.g., upload date, author) for each file. Which Azure service should they use for storing the binary files?

Accepted Answer

Azure Blob Storage. Azure Blob Storage is designed for storing massive amounts of unstructured binary data, such as high-resolution images and video files. It supports objects up to 4.75 TB in size, offers tiered storage (including cool and archive tiers) to optimize cost for infrequently accessed data, and provides low-latency access (typically under 10 seconds) for retrieval when needed. This makes it the ideal choice for the media publishing company's requirements.

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Azure Table Storage

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Azure File Storage

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Azure Queue Storage

Question 9

A global social media platform allows users to like posts. The platform is designed to prioritize availability and partition tolerance over strong consistency across its globally distributed Azure Cosmos DB instance. When a user likes a post, the like count may not be immediately visible to all users, but it will eventually become consistent across all regions. Which consistency model does this application follow?

Accepted Answer

Eventual consistency. Eventual consistency is the correct choice because the platform prioritizes availability and partition tolerance (AP from the CAP theorem) over strong consistency. In Azure Cosmos DB, eventual consistency guarantees that all replicas will converge to the same value over time without any ordering guarantees, which matches the scenario where like counts are not immediately visible but become consistent eventually.

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Strong consistency

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Bounded staleness consistency

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Session consistency

Question 10

A mobile gaming company is building a new feature that stores player profiles and game settings as key-value pairs. The development team is most familiar with SQL queries and wants to minimize the learning curve. They require low-latency reads and writes, and the data does not require complex joins. Which Azure Cosmos DB API should they choose?

Accepted Answer

A. Core (SQL) API. The Core (SQL) API is the correct choice because it provides native support for SQL queries, which aligns with the development team's familiarity with SQL and minimizes the learning curve. It stores data in JSON documents with key-value pairs, supports low-latency reads and writes, and does not require complex joins, making it ideal for player profiles and game settings.

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B. Azure Cosmos DB for Table API

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C. Azure Cosmos DB for MongoDB API

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D. Azure Cosmos DB for Cassandra API

Question 11

A logistics company tracks shipment locations using GPS devices that send JSON data with fields: shipmentId, latitude, longitude, timestamp, speed. The data is stored in Azure Cosmos DB using the Core (SQL) API. The application needs to query all shipments that are currently within a specific geographic bounding box and have a speed greater than 0. Which query approach should they use to efficiently retrieve the data?

Accepted Answer

Use ST_WITHIN to specify the bounding box polygon and add a WHERE clause for speed.. Option B is correct because Azure Cosmos DB's Core (SQL) API supports geospatial queries using the ST_WITHIN function, which efficiently checks if a point (latitude/longitude) lies inside a polygon (bounding box). Adding a WHERE clause for speed > 0 further filters the results, and Cosmos DB can leverage a composite index on the geospatial field and speed to optimize query performance.

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Use a BETWEEN clause on latitude and longitude and a WHERE clause for speed.

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Use ST_DISTANCE to measure distance from a center point and also filter on speed.

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Use the IN operator to list all acceptable coordinate pairs and a speed filter.

Question 12

A media company stores user profiles in Azure Cosmos DB using the Core (SQL) API. Each profile document contains a userId (unique), name, email, and a subscriptions array containing objects with a serviceName and startDate. The application needs to efficiently retrieve a single user by userId and also run a query to find all users who have a subscription to the service 'PremiumVideo'. Which partition key design is most appropriate for this workload?

Accepted Answer

Partition key on userId. Option B is correct because partitioning on userId ensures each document is evenly distributed across physical partitions, as userId is unique and used for point reads (the most efficient operation in Cosmos DB). The query for users with a 'PremiumVideo' subscription will be a cross-partition query regardless of partition key choice, but the primary workload—retrieving a single user by userId—is optimized with this design. Partitioning on userId also avoids hot partitions and adheres to the best practice of using a high-cardinality, frequently queried field as the partition key.

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Partition key on email

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Partition key on serviceName (extracted from subscriptions array)

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Partition key on a composite key combining userId and serviceName

Question 13

A media company needs to store millions of high-resolution photos for a public website. Each photo can be up to 50 MB. The storage solution must support secure access via URLs. Which Azure service should they use?

Accepted Answer

Azure Blob Storage. Azure Blob Storage is the correct choice because it is designed for storing massive amounts of unstructured data, such as high-resolution photos, and supports objects up to 4.7 TB per blob, easily accommodating 50 MB files. It provides secure access via URLs using shared access signatures (SAS) or public access levels, making it ideal for a public website serving media content.

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Azure Table Storage

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Azure Files

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Azure SQL Database

Question 14

A mobile gaming company stores player profiles in Azure Cosmos DB. Each profile document contains many optional fields, and queries frequently filter by the player's locale (a field present in about 30% of documents). Which approach will optimize query performance for these filters?

Accepted Answer

Create a composite index that includes the locale field. Option D is correct because creating a composite index that includes the locale field allows Azure Cosmos DB to efficiently filter queries by locale without scanning every document. Since locale is present in only 30% of documents, a composite index reduces the query RU cost by directly locating matching documents, leveraging the index's sorted structure for faster lookups.

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Embed all fields in a single document and rely on automatic indexing

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Normalize the data by storing locale in a separate container and use cross-container queries

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Define a fixed schema for all documents to ensure every document has the locale field

Question 15

A social media company stores user posts as JSON documents in Azure Cosmos DB. Each post may have a different number of fields and nested objects. Which type of data model does this represent?

Accepted Answer

Document. The scenario describes user posts stored as JSON documents with varying fields and nested objects. Azure Cosmos DB's Document data model (using the SQL API or MongoDB API) is designed for semi-structured, schema-agnostic data where each document can have a different structure, making it the correct choice.

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Key-value

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Column-family

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Graph