Database Administrator Interview Questions and Answers

Type of Questions to Expect in a Database Administrator (DBA) Interview

• Performance Tuning: "How would you identify and fix a slow-running query that is locking up a production table?"
• Backup and Recovery: "What is the difference between a full, differential, and transaction log backup? How do you ensure zero data loss during a crash?"
• Database Design: "Explain the process of Normalization. When would you purposefully 'denormalize' a database?"
• Security: "How do you manage user permissions to follow the 'Principle of Least Privilege'?"
• High Availability: "What are the pros and cons of Database Mirroring versus Replication or Clustering?"

What the Interviewer Will Expect

• Methodical Troubleshooting: When a database goes down, do you have a step-by-step plan to bring it back online safely?
• SQL Mastery: You should be an expert in the specific language of the role (e.g., T-SQL, PL/SQL, or PostgreSQL).
• Attention to Detail: One wrong command (like a DELETE without a WHERE clause) can be catastrophic. They need to see that you are cautious and disciplined.
• Proactive Monitoring: Do you wait for things to break, or do you set up alerts for disk space, CPU spikes, and long-running processes?
• Platform Specifics: Deep knowledge of the specific engine the company uses, whether it’s SQL Server, Oracle, MySQL, or MongoDB.

Tips on Getting Ready

1. Practice Complex Joins: Be ready to write SQL on a whiteboard or a shared screen. Practice Inner, Outer, and Cross Joins until they are second nature.
2. Prepare a "Recovery" Story: Use the STAR method to describe a time you saved a database from a major failure or successfully migrated data without downtime.
3. Review Indexing: Understand how Clustered and Non-Clustered indexes work. Being able to explain "how the database finds data" is a key part of the interview.
4. Know Your Tools: Be ready to discuss the tools you use for monitoring and administration (e.g., SSMS, pgAdmin, or Oracle Enterprise Manager).
5. Stay Updated on Cloud Trends: Many databases are moving to the cloud. Brush up on AWS RDS, Azure SQL, or Google Cloud SQL if the company uses cloud infrastructure.