DP-300 Practice Question: Monitor, configure, and optimize database resources
You manage an Azure SQL Database that runs an online transaction processing (OLTP) workload. Users report that transactions are slow during business hours. You query sys.dm_os_wait_stats and notice a high number of PAGEIOLATCH_SH waits. You need to reduce these waits without changing the application. What should you do?
⚠ Common exam trap
The trap here is assuming that enabling a diagnostic feature like Query Store or ADR will automatically improve performance, when in fact these features do not address physical I/O bottlenecks.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Increase the database's service tier to add more memory and IOPS.
PAGEIOLATCH_SH waits occur when SQL Server waits for a data page to be read from disk into the buffer pool. The most direct way to reduce these waits without changing the application is to increase the service tier, which provides more memory for the buffer pool and higher storage IOPS. This reduces the need to read pages from disk and speeds up the reads that do occur.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Configure Query Store to capture wait statistics for the database.
Why it's wrong here
Query Store captures query plans and runtime statistics, and it can be configured to include wait stats, but enabling it does not reduce PAGEIOLATCH_SH waits. It is a diagnostic tool, not a performance optimization. While it can help identify problematic queries, it does not address the underlying I/O bottleneck that is causing the waits in the first place.
- ✗
Enable Accelerated Database Recovery (ADR) on the database.
Why it's wrong here
ADR speeds up crash recovery and rollback by using a persistent version store, but it does not reduce PAGEIOLATCH_SH waits, which occur when a thread waits for a data page to be read from disk into the buffer pool. ADR addresses transaction log and recovery latency, not physical I/O for user data pages, so it would not resolve the reported slowness for this OLTP workload.
- ✗
Enable Read Scale-Out and redirect read-only queries to the secondary replica.
Why it's wrong here
Read Scale-Out offloads read-only workloads to a read-only secondary replica, but the scenario describes an OLTP workload where transactions are slow. If the primary is experiencing I/O waits, redirecting only read-only queries may not help transactional writes, and the application is not designed to use the secondary. Additionally, Read Scale-Out requires the Business Critical tier, and the scenario does not specify that tier.
- ✓
Increase the database's service tier to add more memory and IOPS.
Why this is correct
PAGEIOLATCH_SH waits indicate that queries are waiting for data pages to be fetched from storage into the buffer pool. Increasing the service tier provides more memory (larger buffer pool) and higher IOPS, reducing the frequency and duration of these waits. This directly addresses the I/O bottleneck without modifying the application, making it the appropriate action for this scenario.
Go deeper
Related to this question
Learn chapter
Deploying and Configuring SQL Server on Azure Virtual Machines
Key term
Azure SQL Performance Tuning
Azure SQL Performance Tuning is the process of optimizing the speed and efficiency of queries and database operations in Microsoft Azure SQL Database or SQL Managed Instance to reduce latency and improve throughput.
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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Microsoft exam blueprint
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