Mastery · Track: data engineering · lesson 5.1 open
The real format of the data interview
The typical stages, what each one measures, and how to distribute study time across them.
Promise: a map of the stages and a study plan proportional to what is actually tested.
Why it matters
Senior data engineers usually study what is comfortable. The interview tests what is verifiable in 45 minutes: SQL without looking things up, performance reasoning, pipeline design, and communication.
Common stages
| Stage | What it measures | Typical duration |
|---|---|---|
| Recruiter screening | chain, contract, rate, timezone | 20–30 min |
| Technical 1 — SQL | joins, window functions, aggregations, NULL pitfalls | 45–60 min |
| Technical 2 — Programming | Python/Scala for data transformation | 45–60 min |
| Pipeline design | decisions, trade-offs, failures, cost | 45–60 min |
| Platform specialist | Spark/Databricks/Snowflake, performance | 45–60 min |
| Behavioral | working with teams, conflict, ambiguity | 30–45 min |
| Manager / client | fit, expectations, availability | 30 min |
B2B contracts usually have fewer stages than full-time employment. Even so, expect SQL and pipeline design.
What a senior data interview tests and an algorithms interview does not
- Reasoning about scale (volume, skew, cost), not about tree complexity.
- Deciding between data modeling approaches and defending them.
- Handling failure: reprocessing, idempotency, late-arriving data.
- Communicating trade-offs in technical English.
Suggested study distribution (4 h per week)
| Topic | Hours | Module |
|---|---|---|
| Timed SQL | 1.0 | 5.2 |
| Spark and performance | 1.0 | 5.4 |
| Modeling + pipeline design | 1.0 | 5.3, 5.6 |
| Streaming/CDC | 0.5 | 5.5 |
| English and stories | 0.5 | 5.7 |
Set up an 8-week calendar with this distribution. Reserve fixed time slots. Note which topics you already feel you master, and which ones you avoid.
The exercises in this module are meant to be completed without AI and without looking things up first. Lesson 5.8 explains why and how.
Checklist
- Do I have 8 weeks planned with time slots?
- Do I know what each stage measures?
Lessons cited by number that are not in the library yet open later.
Checked on 05/10/2026. Educational content; tax and legal: confirm with a professional.