Database Administrator
Interview Questions.
15 practice questions across 13 skills — each with what the interviewer is really listening for. Prepare with intent, not guesswork.
Free · No signup · Grouped by skill
How to use this page
Don't memorise answers. For each question, read what the interviewer is looking for, then practise answering out loud in your own words with a real example. The notes describe strong answers and common red flags — they are for your prep, not a script.
Database Performance Tuning
1 questionA query that was fast is now slow after data grew. How do you diagnose it?
AdvancedWhat the interviewer is looking for: Strong answers read the execution plan, check for missing or unused indexes, statistics, and full scans, and test changes. Randomly adding indexes without reading the plan is a red flag.
Indexing
1 questionHow do you decide what to index, and why can too many indexes hurt?
IntermediateWhat the interviewer is looking for: Look for indexing based on query patterns and selectivity, and awareness that indexes slow writes and consume storage. Indexing every column is a red flag.
Backup and Recovery
1 questionWalk me through your backup and recovery strategy for a critical production database.
AdvancedWhat the interviewer is looking for: Strong candidates cover full and incremental backups, offsite copies, RTO/RPO, and — crucially — regularly TESTING restores. A backup plan never tested with a real restore is a serious red flag.
SQL
1 questionWhat is the difference between the isolation levels, and when does it matter?
AdvancedWhat the interviewer is looking for: Look for understanding dirty reads, non-repeatable reads, and phantoms, and the concurrency-versus-consistency trade-off. Not knowing isolation levels exist is a red flag for a DBA.
Database Security
1 questionHow do you approach securing a database against both external and internal threats?
IntermediateWhat the interviewer is looking for: Strong answers use least-privilege access, encryption at rest and in transit, auditing, and patching. Shared admin accounts or unencrypted sensitive data are red flags.
PostgreSQL
1 questionHow do you perform a schema change on a large, busy PostgreSQL table without downtime?
AdvancedWhat the interviewer is looking for: Look for awareness of locking, doing changes in safe steps, and using techniques that avoid long locks. A blocking ALTER on a huge table during peak traffic is a red flag.
MySQL
1 questionHow do MySQL and PostgreSQL differ in ways that affect your decisions?
IntermediateWhat the interviewer is looking for: Strong candidates note practical differences in features, extensions, and behaviour, choosing based on needs. Claiming they are interchangeable or that one is universally better is a red flag.
Replication
1 questionHow do you set up replication for read scaling and failover, and what are the gotchas?
AdvancedWhat the interviewer is looking for: Look for understanding replication lag, read-after-write consistency, and failover promotion. Assuming replicas are always perfectly in sync is a red flag.
High Availability
1 questionHow do you design for high availability so a single node failure does not take you down?
AdvancedWhat the interviewer is looking for: Strong answers cover redundancy, automatic failover, and testing failover, tied to the business's tolerance for downtime. A single point of failure with no failover is a red flag.
Bash
1 questionHow comfortable are you scripting routine DBA tasks in Bash or Python?
BasicWhat the interviewer is looking for: Look for automating backups, health checks, and maintenance to reduce human error. Doing everything manually and repeatedly is a red flag for reliability.
Query Optimization
1 questionA developer's query is bringing the database to its knees. How do you handle it?
IntermediateWhat the interviewer is looking for: Strong candidates mitigate the immediate impact, then work with the developer to fix the query and prevent recurrence, not just kill it. Blaming developers without helping fix the root cause is a red flag.
Problem-Solving
1 questionHow do you approach a database migration or upgrade with minimal risk?
AdvancedWhat the interviewer is looking for: Look for testing in staging, a rollback plan, backups, and a maintenance window with clear comms. Upgrading production with no tested rollback is a red flag.
Technical Documentation
1 questionHow do you document database changes and standards so the team stays aligned?
BasicWhat the interviewer is looking for: Strong answers keep change logs, runbooks, and standards current and accessible. Undocumented ad-hoc changes to production are a red flag.
Behavioural & role-general
2 questionsTell me about a data-loss scare or incident you handled. What changed afterward?
BasicWhat the interviewer is looking for: Look for calm response, recovery from backups, and systemic prevention afterward. Claiming nothing ever goes wrong, or panic without process, are red flags.
How do you balance developers' desire for access and change speed with database stability?
IntermediateWhat the interviewer is looking for: Strong candidates enable teams with safe self-service and guardrails rather than being a pure bottleneck. Either blocking everything or allowing uncontrolled prod access are red flags.