DP-300 Practice Question: Monitor, configure, and optimize database resources
You have an Azure SQL Database with a heavy workload. You notice that the `PAGEIOLATCH_SH` wait is the top wait. Which performance issue does this indicate?
⚠ Common exam trap
Watch out — candidates often confuse `PAGEIOLATCH_SH` with memory pressure or blocking, but the key distinction is that this wait type specifically measures I/O latency for reading pages from disk, not memory availability or lock contention.
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
✓
I/O subsystem bottleneck
The `PAGEIOLATCH_SH` wait type indicates that a query is waiting for a data page to be read from disk into the buffer pool. Since this is the top wait, it points to an I/O subsystem bottleneck where the storage cannot keep up with the demand for reading pages, causing performance degradation.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Blocking
Why it's wrong here
Blocking shows `LCK_M_*` waits.
- ✗
CPU bottleneck
Why it's wrong here
CPU bottlenecks show `SOS_SCHEDULER_YIELD` waits.
- ✓
I/O subsystem bottleneck
Why this is correct
`PAGEIOLATCH_SH` indicates slow I/O for reading pages.
- ✗
Memory pressure
Why it's wrong here
Memory pressure causes `PAGEIOLATCH` but the primary issue is I/O.
Go deeper
Related to this question
Learn chapter
Overview of Azure Data Platform Options
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 by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This DP-300 practice question is part of Courseiva's free Microsoft certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the DP-300 exam.