DP-900 Identify considerations for relational data on Azure Practice Test 9 — 15 Questions

Question 1

A startup has an application with unpredictable usage patterns on Azure SQL Database. They want to minimize cost by paying only for the compute they use and the database should automatically pause during idle periods. Which Azure SQL Database option should they choose?

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

Accepted Answer

Serverless. Azure SQL Database Serverless is designed for applications with unpredictable usage patterns, as it automatically scales compute resources based on demand and pauses the database during idle periods to eliminate compute costs. This model charges per second for the compute used, making it the most cost-effective choice for workloads that have periods of inactivity.

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Provisioned (DTU or vCore)

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Hyperscale

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Business Critical

Question 2

A company uses Azure SQL Database for a sales application. They need to replicate the database to a secondary region for disaster recovery. The secondary should be readable for reporting purposes and data should be synchronized within seconds. Which feature should they use?

Accepted Answer

Active Geo-Replication. Active Geo-Replication is the correct choice because it creates a readable secondary replica in a different Azure region, with data synchronized within seconds via asynchronous replication. This meets the requirement for both disaster recovery and read-only reporting access, as the secondary can be queried directly without impacting the primary database.

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Auto-failover groups

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Point-in-time restore

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Long-term retention

Question 3

A company uses Azure SQL Database to store customer order data. They need to automatically track changes to the 'OrderStatus' column in the 'Orders' table. They want to be able to query the current status and also easily retrieve historical status changes for a given order without writing custom triggers or history tables. Which feature should they enable?

Accepted Answer

Temporal tables. Temporal tables (system-versioned) automatically track full row history, including changes to the 'OrderStatus' column, by maintaining a paired history table. This allows querying both current and historical states with simple T-SQL clauses like FOR SYSTEM_TIME, without custom triggers or manual history tables.

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Change Data Capture (CDC)

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Automatic tuning

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Geo-replication

Question 4

A company uses Azure SQL Database for an order processing system. The Orders table has columns: OrderID (PK), CustomerID, OrderDate, TotalAmount. The Customers table has CustomerID (PK), Name, Email. The database administrator wants to ensure that when a customer record is deleted, all orders for that customer are also automatically deleted. Which database constraint should be implemented?

Accepted Answer

ON DELETE CASCADE on Orders.CustomerID. ON DELETE CASCADE on the foreign key (Orders.CustomerID) automatically deletes all child rows in the Orders table when the parent row in the Customers table is deleted. This ensures referential integrity without requiring additional code or triggers, and is the standard SQL mechanism for cascading deletes in Azure SQL Database.

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ON DELETE SET NULL on Orders.CustomerID

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ON UPDATE CASCADE on Customers.CustomerID

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A trigger on Customers table

Question 5

A company runs an e-commerce application on Azure SQL Database. During seasonal promotions, traffic spikes significantly, but at other times traffic is low. They want to automatically adjust compute resources based on demand without manual intervention or provisioning. Which Azure SQL Database feature should they use?

Accepted Answer

Serverless compute. Serverless compute for Azure SQL Database automatically scales compute resources based on workload demand and pauses the database during inactive periods, charging only for storage and compute used per second. This matches the requirement for automatic adjustment without manual intervention or provisioning, especially for intermittent, unpredictable traffic spikes like seasonal promotions.

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Geo-replication

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Elastic pools

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Hyperscale

Question 6

A database administrator manages an Azure SQL Database with a table that has a clustered index on OrderID. Frequent queries filter on OrderDate and then sort the results by CustomerID. These queries perform poorly. Which indexing strategy will most improve performance for these specific queries?

Accepted Answer

Create a nonclustered index on (OrderDate, CustomerID). The query filters on OrderDate and then sorts by CustomerID. A nonclustered index on (OrderDate, CustomerID) supports both the WHERE clause (by OrderDate) and the ORDER BY clause (by CustomerID) as a covering index, allowing the database engine to perform a single index seek or scan without needing a separate sort operation. This directly addresses the performance bottleneck by eliminating the need to sort the results after filtering.

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Create a nonclustered index on (CustomerID, OrderDate)

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Change the clustered index to (OrderDate)

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Create a filtered index on OrderDate WHERE CustomerID IS NOT NULL

Question 7

A company runs a web application on Azure SQL Database that experiences unpredictable spikes in traffic. They want to automatically adjust compute resources based on demand without manual intervention and without over-provisioning. Which Azure SQL Database feature should they use?

Accepted Answer

Serverless compute tier. The Serverless compute tier for Azure SQL Database automatically scales compute resources based on workload demand, pausing databases during idle periods and resuming them when traffic spikes occur. This eliminates the need for manual intervention and prevents over-provisioning by charging only for the compute used per second, making it ideal for unpredictable traffic patterns.

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Active geo-replication

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Hyperscale service tier

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Read scale-out

Question 8

A company uses Azure SQL Database for an employee management system. The Employees table has 10 million rows and a clustered index on EmployeeID (the primary key). Queries that filter employees by Department and then sort by HireDate are very slow. Which indexing strategy will most improve performance for these queries?

Accepted Answer

Create a nonclustered index on (Department, HireDate) and include the other needed columns as included columns.. A nonclustered index on (Department, HireDate) with included columns is optimal because it supports both the WHERE clause filter on Department and the ORDER BY on HireDate as a covering index. The index key order matches the query's filter and sort requirements, allowing SQL Server to perform a single index seek and avoid key lookups by including all needed columns. This eliminates the need to scan the clustered index or sort rows after filtering.

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Create a nonclustered index on (HireDate, Department) with no included columns.

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Create a clustered index on Department.

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Drop the existing clustered index and recreate a clustered columnstore index.

Question 9

A company runs an e-commerce application on Azure SQL Database. The application experiences unpredictable traffic spikes during flash sales and promotional events. The company wants to automatically scale compute resources based on actual demand and pay only for the resources consumed. Which Azure SQL Database deployment option best meets these requirements?

Accepted Answer

Serverless. The Serverless deployment option for Azure SQL Database automatically scales compute resources (vCores) based on actual demand, pausing the database during idle periods and resuming on the first connection. This model charges per second for the compute used, making it ideal for unpredictable traffic spikes like flash sales, as it eliminates the need to over-provision and ensures you pay only for consumed resources.

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Provisioned DTU

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Provisioned vCore

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Hyperscale

Question 10

A financial application stores transactions in an Azure SQL Database table with columns: TransactionID (clustered index), AccountID, TransactionDate, Amount. Queries frequently filter on AccountID and TransactionDate together. The table contains millions of rows. Which index strategy will most improve query performance for these filters?

Accepted Answer

Nonclustered index on (AccountID, TransactionDate). Creates a nonclustered index on (AccountID, TransactionDate) that acts as a covering index for queries filtering on both columns. SQL Server can seek directly to the matching rows using the composite key order, avoiding a full table scan or key lookup. This is the most efficient strategy because the index is sorted by AccountID first, then TransactionDate, matching the query predicate exactly.

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Clustered index on (AccountID, TransactionDate)

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Nonclustered index on (TransactionDate)

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Nonclustered index on (AccountID) INCLUDE (TransactionDate)

Question 11

A company uses Azure SQL Database for an order management system. The 'Orders' table has millions of rows and is queried frequently with filters on OrderDate and CustomerID. The table currently has a clustered index on OrderID. Which action will most improve query performance for these frequent filters?

Accepted Answer

Create a non-clustered index on OrderDate and CustomerID. The frequent filters on OrderDate and CustomerID require a covering index that includes both columns. A non-clustered index on (OrderDate, CustomerID) allows SQL Server to perform an index seek for queries filtering on those columns, avoiding full clustered index scans on the existing clustered index on OrderID. This directly reduces I/O and improves query response times.

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Create a clustered index on OrderDate

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Create a non-clustered index on OrderID

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Partition the table by CustomerID

Question 12

A company has multiple independent databases for different business units, each with low to moderate usage and varying workload patterns. They want to consolidate these databases into a single Azure SQL Database deployment option to share resources and reduce costs, while ensuring that databases do not starve each other of resources. Which Azure SQL Database deployment option should they choose?

Accepted Answer

Elastic pool. Elastic pools are designed for exactly this scenario: multiple databases with low to moderate usage and varying workload patterns. They allow databases to share a fixed pool of resources (eDTUs or vCores) while using built-in resource governance to prevent any single database from starving others, thus optimizing cost and performance.

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Single database (DTU model)

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Managed Instance

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Database per server (hyperscale)

Question 13

A company uses Azure SQL Database for an e-commerce application. The Orders table has millions of rows. Queries that filter on CustomerID and order by OrderDate are slow. The table currently has a clustered index on OrderID (the primary key). Which index strategy will best improve these queries?

Accepted Answer

C. Create a nonclustered index on (CustomerID, OrderDate).. Creating a nonclustered index on (CustomerID, OrderDate) directly supports the query's filter (WHERE CustomerID = ?) and sort (ORDER BY OrderDate) operations. This composite index allows SQL Server to seek on CustomerID and then retrieve rows in OrderDate order without a separate sort, eliminating the need for a full clustered index scan on OrderID. It is a covering index for this query pattern, significantly reducing I/O and CPU overhead.

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A. Create a nonclustered index on OrderDate only.

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B. Create a filtered index on CustomerID where Status = 'Active'.

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D. Create a nonclustered index on OrderID and OrderDate.

Question 14

A company uses Azure SQL Database for an e-commerce system. The Orders table has millions of rows with a clustered index on OrderID (the primary key). Queries that filter on OrderDate and CustomerID to find recent orders for a specific customer are very slow. Which indexing strategy will most improve the performance of these queries?

Accepted Answer

Create a nonclustered composite index on (OrderDate, CustomerID). The query filters on both OrderDate and CustomerID, so a composite nonclustered index on (OrderDate, CustomerID) allows SQL Server to perform a single index seek to locate the matching rows without touching the clustered index until the final key lookup. This dramatically reduces I/O compared to scanning the entire clustered index or using multiple separate indexes.

Answer

Create a nonclustered index on OrderID only

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Create separate nonclustered indexes on OrderDate and CustomerID

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Create a clustered index on CustomerID instead of OrderID

Question 15

A company needs to store order data for an e-commerce platform. The system requires high concurrency, fast inserts, and the ability to enforce referential integrity between tables (e.g., Customers and Orders). Which Azure service should they use?

Accepted Answer

Azure SQL Database. Azure SQL Database is a fully managed relational database service that supports high concurrency, fast inserts, and enforces referential integrity through foreign key constraints. It provides ACID transactions and row-level locking to handle concurrent writes efficiently, making it ideal for e-commerce order processing where data consistency between Customers and Orders tables is critical.

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Azure Cosmos DB

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Azure Blob Storage

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Azure Data Lake Storage Gen2