Frequently asked in architect interviews.
Q1: Query is taking 10 minutes. What will you check?
- Execution plan
- Indexes
- Joins
- Statistics
Q2: Why avoid SELECT *?
Reads unnecessary columns.
Q3: Clustered vs Non-Clustered Index?
Clustered = physical ordering.
Non-clustered = separate lookup structure.
Q4: Why is index not being used?
- Function in WHERE clause
- Small table
- Outdated statistics
Q5: How do you identify bottlenecks?
Execution plan analysis.
