SQL and Python Practice Problems for Data Engineers
Data Engineering Interview Practice Problems
1569+ data engineering interview practice problems with real code execution. Write SQL queries, Python solutions, and design schemas against live databases with instant feedback. Filter by domain, difficulty, seniority level, and target company.
Domains: SQL (930), Pipeline Architecture (144), Python (415), Data Modeling (67), AI Coding (13). Difficulty breakdown: medium (749), easy (550), hard (270).
SQL Practice Problems (930)
- 10 Lowest Uptime Services - medium - Ten services at the bottom of the reliability chart.
- 30-Day Page View Counts - easy - Thirty days of engagement. Quick snapshot.
- 7-Check Rolling Average - medium - Seven entries hold the trend.
- 7-Day Onboarding Conversion - hard - Signed up Monday. Still here by Sunday?
- 7-Day Token Retention - medium - Premium tokens, day by day.
- Above Average - easy - Products beating the catalog average.
- Above Average Interactions - easy - The average user is boring. Who is above?
- Above Average Product Prices - medium - Some products cost more than they should.
- Above Category Average - easy - The category average is one thing. These beat it.
- Above the Curve - medium - Spenders who break from the pack.
Pipeline Architecture Practice Problems (144)
- 4,500 Stores Before Sunrise - medium - The shelves open at 7. The data better be there.
- 45 Minutes Turned Into 3.5 Hours - medium - Spark jobs are running. Just not fast enough.
- 600 Million Events a Day - hard - 600 million events a day. Two years of retention.
- A Clean Number for Every Merchant - hard - Raw payment logs in. Clean merchant summaries out.
- All at Once - medium - Two databases. One direction. No data left behind.
- A Million Cars Phoning Home - hard - Every vehicle is a sensor. Deploy the pipeline to catch it all.
- A Million Moving Dots - medium
- Analysts Are Slowing the Store Down - medium - Orders placed. Data warehouse hungry.
- A New Column on a Billion Rows - hard - Add and backfill a new column to a billion-row production table with zero downtime.
- A Shared Drive Full of Contracts - medium - Buried in PDFs. The data is in there somewhere.
Python Practice Problems (415)
- Above the Title - medium - Some names carry a genre. Total the box office behind them.
- Absent Without Leave - medium - Between the first name and the last, the ones who never showed. Account for them.
- Against the Current - hard - Too big to load. Read what you can.
- Against the Grain - medium - Turn the grid on its side and let every column stand up as a row.
- All the Way Down - medium - However deep it nests, every leaf belongs on one line.
- All Told - easy - Every shift leaves a number behind. Total the fleet.
- Back to Back - medium - Windows stacked on windows. Find the real spans.
- Batch Records - medium - Too many at once. Break them into groups.
- Between the Clicks - medium - Clicks arrive scrambled. Find where one visit ends and the next begins.
- Between the Pings - medium - The fleet never stops talking. Find where each vehicle paused.
Data Modeling Practice Problems (67)
- A Number for the Seller - easy - They want a total. Give them the right schema first.
- Approval and After - medium - Approved, declined, or pending. Design the tables that say so.
- Between the Cameras - easy - Every plate that goes in should come out. Watch the ones that don't.
- Content Engagement Data Model - hard - Post published. Now measure everything that happens next.
- Crossing Over - medium
- Deal Flow - medium - Sellers want buyers. Buyers want deals.
- Every Line Remembered - medium - Customers move, products relaunch, and some stores have no address. Reshape the tables so nothing gets forgotten.
- Financial Trading Warehouse - hard - Every trade, every tick, every fraction of a share. The regulators want receipts.
- Food Truck Operations Data Model - medium - Mobile vendor, fixed menu, unpredictable locations.
- Ghosts in the Ledger - easy - Invoices go out, partial payments trickle in, and some customers are three months overdue.
AI Coding Practice Problems (13)
- Counted Twice - easy - Twice the revenue, half the truth.
- Drift - hard - Nothing changed. Everything moved.
- Four Million Echoes - medium - It happened. It happened again.
- Ghosts of Snapshots Past - easy - The past keeps rewriting itself.
- History Erased - medium - Yesterday never happened.
- One Bad Executor - medium - One node held the whole night hostage.
- One in Five - easy - Green, green, red, green.
- The Late Arrival - easy - The clock was lying.
- The Materialization Storm - hard - The graph started eating itself.
- The Quiet Partition - hard - One went quiet. All of them stopped.