Role track
Data Engineer
SQL, pipelines, warehouses, streaming, and the platform sketch they ask at 3pm.
254 questions · SQL · Python · Orchestration · Streaming · System design · Behavioral
Suggested sequence
1. SQL you can defend
Windows, grain, anti-joins. Say evaluation order out loud.
DE coding →2. The flowchart
Foundations through on-call. Click nodes, check them off.
DE roadmap →3. Orchestrate the clock
Airflow or Dagster — not both this weekend.
Airflow questions →4. Design the platform
CDC, gold grain, and what you page.
System design →5. Behavioral loop
Incidents, cost, and saying no to a bad grain.
Behavioral →
Stacks in this loop
Sample questions
hard · SQL · Stripe
Deduplicate to the latest customer row. Why not filter the window in WHERE?
Practice →medium · SQL · Capital One
A join exploded revenue. How do you find the grain mismatch in five minutes?
Practice →medium · SQL · Meta
Running total of daily revenue. Why is SUM(SUM(amount)) OVER (...) valid?
Practice →hard · SQL · Google
NULL = NULL is unknown. How does that bite a MERGE or an anti-join?
Practice →hard · SQL · LinkedIn
When do you use a covering index / clustering key versus rewriting the query?
Practice →medium · SQL · Snowflake
QUALIFY vs a CTE for window filters — when do you use each?
Practice →