DP-900 Identify considerations for relational data on Azure Practice Test 5 — 15 Questions

Question 1

A company operates a high-volume order processing system on Azure SQL Database. During peak hours, many concurrent transactions try to insert and update rows in the same table, causing contention on page latches. Indexing and query optimization are already tuned. Which feature should the company implement to reduce write contention while preserving ACID properties?

Accepted Answer

In-Memory OLTP. In-Memory OLTP is correct because it uses memory-optimized tables and natively compiled stored procedures to reduce latch contention by eliminating the need for page latches entirely. Transactions operate directly on in-memory data structures, using optimistic multi-version concurrency control (MVCC) to detect conflicts without blocking, which preserves ACID properties while allowing high concurrency.

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Read Scale-out

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Elastic Database Query

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Transparent Data Encryption (TDE)

Question 2

A development team is designing a relational database for a hospital patient management system. They need to ensure that each patient's medical record number is unique and not null. Which database constraint should they use?

Accepted Answer

PRIMARY KEY. The PRIMARY KEY constraint enforces both uniqueness and non-nullability on the column(s) it is applied to. In a relational database, the medical record number is the natural candidate for the primary key of the Patient table because it uniquely identifies each patient and must always have a value. This directly meets the requirement that each patient's medical record number is unique and not null.

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FOREIGN KEY

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CHECK

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UNIQUE

Question 3

A database designer is creating a relational database for a library system. Each book can have multiple authors, and each author may have written many books. To avoid data redundancy, the designer creates a separate Authors table and a BookAuthors junction table. This process of organizing data to reduce redundancy and improve integrity is called:

Accepted Answer

Normalization. Normalization is the process of organizing data in a relational database to reduce redundancy and improve data integrity by dividing large tables into smaller, related tables and defining relationships between them. In this scenario, creating separate Authors and BookAuthors junction tables eliminates the redundancy of storing author information multiple times for each book, which is a classic example of normalization (specifically achieving third normal form). This directly supports the relational database goal of minimizing duplicate data and ensuring consistency.

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Denormalization

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Indexing

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Partitioning

Question 4

An e-commerce application uses Azure SQL Database. During flash sales, the database experiences high CPU usage and query timeouts. The team needs a solution that can handle sudden increases in demand without downtime. Which scaling option should they choose?

Accepted Answer

Hyperscale service tier. The Hyperscale service tier is designed for high-performance, rapidly growing workloads that require instant scalability. It separates compute from storage, allowing compute nodes to be added or scaled up in seconds without downtime, making it ideal for handling sudden spikes in demand like flash sales.

Answer

Read scale-out

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Elastic Pool

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Geo-replication

Question 5

A company uses Azure SQL Database for its order management system. The database has a table named Orders with columns OrderID (INT, PRIMARY KEY), CustomerID (INT), OrderDate (DATE), TotalAmount (DECIMAL). Queries that filter by OrderDate are slow. The database administrator observes that the nonclustered index on OrderDate has high fragmentation and many page splits. Which action will most likely improve query performance for these date-based queries?

Accepted Answer

Rebuild the nonclustered index on OrderDate with a FILLFACTOR of 80.. Rebuilding the nonclustered index on OrderDate with a FILLFACTOR of 80 reduces page splits by leaving free space in each leaf-level page. This accommodates future insertions and updates that modify the OrderDate values, lowering fragmentation and improving query performance for date-based filters.

Answer

Change the data type of TotalAmount from DECIMAL to FLOAT.

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Remove the clustered index on OrderID and create a clustered index on OrderDate.

Answer

Add a columnstore index on the OrderDate column.

Question 6

A multinational e-commerce company uses Azure SQL Database active geo-replication to replicate a critical inventory database to a secondary region. During a regional outage, the application automatically fails over to the secondary database. After the primary region recovers, the administrator wants to make the original primary the main database again without losing any data modifications made on the secondary during the outage. What should the administrator do?

Accepted Answer

Initiate a planned failover to switch back to the original primary.. Option C is correct because a planned failover (also known as graceful failover) in Azure SQL Database active geo-replication is designed to switch roles between the primary and secondary databases without data loss. After the original primary region recovers, initiating a planned failover synchronizes all data from the current primary (the former secondary) to the original primary, making it the new primary while preserving all modifications made during the outage. This operation ensures zero data loss because it forces a final synchronization before the role swap.

Answer

Drop the geo-replication relationship, then recreate the secondary from the current primary.

Answer

Perform a forced failover to switch back to the original primary.

Answer

Delete the secondary database and restore the original primary from a backup taken before the outage.

Question 7

A business analyst needs to query a large Azure SQL Database table that stores sales transactions. The table contains over 100 million rows. The analyst wants to retrieve aggregated sales per product category for the current month. The current query performs a full table scan and takes several minutes. Which indexing strategy will best improve the performance of this aggregation query?

Accepted Answer

Create a columnstore index on the table. A columnstore index stores data column-wise and uses batch processing, which dramatically accelerates aggregation queries (like SUM, COUNT, GROUP BY) over large tables. For a 100-million-row table, this reduces I/O and CPU by reading only the columns needed for the aggregation, making it the optimal choice for the analyst's current-month sales-per-category query.

Answer

Create a clustered index on the transaction date column

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Create a nonclustered index on the product category column

Answer

Create a filtered index on transactions from the current month

Question 8

An e-commerce company runs a product inventory database on Azure SQL Database. During a flash sale, write transactions are slow because many read queries are running simultaneously and consuming resources. The company wants to isolate read workloads without modifying application code or database schemas. Which Azure SQL Database feature should they implement?

Accepted Answer

Read scale-out. Read scale-out (B) is correct because it allows read-only queries to be offloaded to a read-only replica of the database, freeing up the primary replica for write transactions. This feature is built into Azure SQL Database at the Business Critical and Premium service tiers, and it requires no application code changes—just a connection string modification to use the `ApplicationIntent=ReadOnly` parameter. It directly addresses the performance bottleneck caused by concurrent read queries during the flash sale.

Answer

Active geo-replication

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Auto-failover groups

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Elastic pools

Question 9

A multinational e-commerce company uses Azure SQL Database for its order processing system. They need to ensure that if an entire Azure region becomes unavailable, the database remains available with minimal data loss and automatic failover. Which feature should they implement?

Accepted Answer

Active geo-replication. Active geo-replication (Option A) is correct because it creates readable secondary replicas of an Azure SQL Database in a paired Azure region, enabling automatic failover during a regional outage. This feature provides a recovery point objective (RPO) of as low as 5 seconds and a recovery time objective (RTO) of under 1 hour, ensuring minimal data loss and high availability.

Answer

Automatic tuning

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Elastic pools

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Serverless compute

Question 10

An e-commerce company uses Azure SQL Database for its product catalog. During promotional events, the database experiences unpredictable spikes in traffic. The company wants a solution that automatically adjusts compute resources based on demand without manual intervention. Which Azure SQL Database option should they use?

Accepted Answer

C) Serverless compute tier. The Serverless compute tier for Azure SQL Database automatically scales compute resources based on workload demand and pauses the database during idle periods, charging only for storage and used compute. This matches the requirement for handling unpredictable traffic spikes without manual intervention, as it provides instant scaling and cost efficiency for intermittent workloads.

Answer

A) Read replicas

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B) Active geo-replication

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D) Elastic pool

Question 11

A banking application processes fund transfers. When a transfer is executed, the system must either successfully debit one account and credit the other, or if any step fails, the entire operation must be rolled back so no partial changes remain. Which ACID property directly enforces this behavior?

Accepted Answer

A) Atomicity. Atomicity ensures that a transaction is treated as a single, indivisible unit of work. In this banking scenario, the debit and credit operations are part of one transaction; if either step fails, the entire transaction is rolled back, leaving no partial changes. This is the core property that enforces the 'all-or-nothing' behavior described.

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B) Consistency

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C) Isolation

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D) Durability

Question 12

A company uses Azure SQL Database for a financial application. Regulatory compliance requires that database backups be retained for 7 years. The current configuration uses the default point-in-time restore (PITR) retention of 7 days. Which Azure SQL Database feature should the company enable to meet the 7-year retention requirement?

Accepted Answer

Long-term retention (LTR) for backups. Azure SQL Database's default point-in-time restore (PITR) retains backups for only 7 days, which is insufficient for the 7-year regulatory requirement. Long-term retention (LTR) allows you to retain full database backups for up to 10 years by configuring backup policies in the Azure portal or via T-SQL, meeting the compliance need.

Answer

Active geo-replication

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Auto-failover groups

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Geo-redundant backup storage

Question 13

A hospital uses Azure SQL Database to store patient records. The database contains tables for patient information, insurance details, and treatment plans. The system must ensure that if a transaction updates a patient's insurance and their treatment plan in two separate rows, either both updates succeed or both fail. Which ACID property guarantees this behavior?

Accepted Answer

Atomicity. Atomicity ensures that a transaction is treated as a single, indivisible unit of work. In Azure SQL Database, if a transaction updates both the insurance and treatment plan rows, atomicity guarantees that either both updates are committed or both are rolled back, preventing partial updates that could leave data in an inconsistent state.

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Durability

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Consistency

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Isolation

Question 14

A company uses Azure SQL Database for an order management system. They have a table 'Orders' with columns: OrderID (PK), CustomerID, OrderDate, TotalAmount. Queries that filter on OrderDate are slow. They create a nonclustered index on OrderDate. However, after many inserts, the index becomes fragmented and page splits occur frequently. Which action should the DBA take to maintain query performance?

Accepted Answer

Rebuild the index online. Option A is correct because rebuilding the index online eliminates fragmentation and page splits without blocking concurrent queries, which is critical for a production order management system. The ALTER INDEX REBUILD operation reorganizes the index B-tree structure, consolidating pages and reducing logical fragmentation, thereby restoring query performance on OrderDate filters.

Answer

Drop and recreate the index

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Add a clustered index on OrderDate

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Change the index to a clustered columnstore index

Question 15

A SaaS provider hosts databases for hundreds of clients, each with light and sporadic usage. They notice that using separate single databases with provisioned DTUs is cost-inefficient. They need to consolidate the databases while optimizing cost and ensuring that a busy client does not monopolize resources. Which Azure SQL Database option should they use?

Accepted Answer

Elastic pool. An Azure SQL Database elastic pool is designed to optimize cost for multiple databases with light and sporadic usage by sharing a fixed set of resources (eDTUs) across all databases in the pool. This prevents a busy client from monopolizing resources through per-database resource limits (min and max DTU), ensuring performance isolation while consolidating costs.

Answer

Single database with provisioned DTU

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Managed Instance

Answer

SQL Server on Azure VM