How to assess · For hiring teams
How to Assess Database Administration Skills When Hiring
The test formats that actually work for Database Administration, what a strong answer looks like, sample questions and a scoring rubric you can use as-is.
The short answer
Assess Database Administration with a task, not a conversation: diagnose a slow query, plan a risky migration, ai-scored assessment (e.g. cohesyve) or recovery walkthrough. Score it against written criteria you fix before you see any submissions, and weight the criteria that the role actually depends on.
- Reads a query plan and can say why a query is slow and what to change
- Designs indexes from access patterns, and knows what each index costs on writes
- Runs migrations safely: online, in small steps, with a rollback, off-peak where needed
- Tests backups by restoring them, on a schedule, and knows the recovery time and point
Paste a job description; Cohesyve generates a role-specific assessment and rubric. Ten candidates free, no card.
Databases fail slowly and then suddenly: a query that was fine at ten thousand rows takes minutes at ten million, a backup nobody tested turns out to be unrestorable, a migration locks a table during peak. The administrator's job is to see these coming, and the skill is a mix of performance diagnosis, operational discipline and the judgement to change a live system safely. This page covers how to assess database administration for DBA, data platform and backend roles: query performance, indexing, backup and recovery, safe migrations and monitoring.
Why Database Administration is worth testing
The database is usually the hardest part of a system to fix under pressure and the one with the most at stake. A weak administrator adds indexes at random, runs migrations that lock production, and discovers during an incident that the backup does not restore. Testing shows whether a candidate can read a query plan, plan a safe change and prove a backup works, and each of those is a skill you want verified before the incident.
What strong Database Administration looks like
- Reads a query plan and can say why a query is slow and what to change
- Designs indexes from access patterns, and knows what each index costs on writes
- Runs migrations safely: online, in small steps, with a rollback, off-peak where needed
- Tests backups by restoring them, on a schedule, and knows the recovery time and point
- Monitors what matters: slow queries, locks, replication lag, disk, connections
- Understands transactions and isolation well enough to explain a deadlock
- Plans capacity and growth rather than reacting to full disks
Ways to assess Database Administration
Diagnose a slow query
Provide a query, its execution plan and table statistics for a query that has become slow. Ask the candidate to explain why and propose the fix, including its cost.
Pros
Cons
Best for Any level; scale via plan complexity.
Plan a risky migration
Describe a change — adding a non-null column with a default to a large, busy table, or changing a column type — and ask for a plan that keeps the service up.
Pros
Cons
Best for Mid and senior roles touching production.
AI-scored assessment (e.g. Cohesyve)
Generate a database scenario from the job description — a query diagnosis, a migration plan, a recovery exercise — with a rubric. Each candidate receives a different variant; reasoning is scored in writing.
Pros
Cons
Best for Screening a pool before interviews.
Recovery walkthrough
Describe a data-loss event and ask how they would recover, what would be lost, and what they would change afterwards.
Pros
Cons
Best for Senior DBAs and data platform engineers.
Cohesyve
Run a Database Administration assessment on your next opening
Cohesyve generates a unique Database Administration task per candidate from your job description, with the scoring rubric attached. Questions are different for every applicant, so they cannot be shared or looked up.
What to test
Query performance
Whether they can find and fix slowness.
Indexing
Whether indexes are designed, not guessed.
Safe change
Whether migrations keep the service up.
Backup, recovery and monitoring
Whether the data is safe and the system is watched.
Sample Database Administration questions
A query that was fast is now slow. What do you look at first?
EntryLook for The plan; statistics; whether an index is used; data growth; locks.
What does adding an index cost?
EntryLook for Write overhead, storage, maintenance; the planner may not use it; too many indexes hurt.
Add a non-null column with a default to a table with a hundred million rows without downtime.
MidLook for Add nullable, backfill in batches, add constraint, engine-specific awareness of what locks.
Two transactions deadlock nightly. How do you find and fix it?
MidLook for Deadlock logs, lock order, consistent ordering of updates, shorter transactions.
How do you know your backups work?
SeniorLook for Scheduled restores to a separate environment, measured recovery time, verified data, documented and rehearsed.
Red flags
- Adds indexes without reading a plan
- Runs migrations on production during peak without a plan
- Has never restored a backup
- Cannot explain a deadlock
- Does not monitor slow queries
Scoring rubric
| Criterion | Weight | What strong looks like |
|---|---|---|
| Performance diagnosis | 30% | Reads plans and finds the cause. |
| Indexing judgement | 20% | Designed from access patterns with costs understood. |
| Safe change | 25% | Migrations are online, batched and reversible. |
| Recovery and monitoring | 25% | Backups are tested; the right things are watched. |
Mistakes hiring teams make
- Testing SQL syntax rather than plans and operations
- Not including a migration scenario — it is where outages come from
- Accepting "we have backups" without asking about restores
- Ignoring monitoring
- Assuming ORM users understand the database
Roles that need Database Administration
Common questions
Which database engine should the assessment use?
The one you run. Plans, locking and migration behaviour differ between engines, and the details matter in production.
What is the best single database question?
Ask how they know their backups work. The answer separates people who have restored from people who assume.
How much database skill should a backend developer have?
Reading a plan, designing an index for their queries, and knowing which migrations are dangerous. Full administration is a specialist role.
How long should a database assessment take?
Forty-five minutes for a plan-and-migration exercise is enough to see judgement. Hands-on can be confirmed with finalists.
Cohesyve · Skill assessments for hiring
Test Database Administration before the first interview
Generate a role-specific Database Administration assessment from your job description and see who can do the work before you spend interview time on them.
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