How many rounds does a data engineer interview loop have?

5 typical rounds: SQL (95 percent of loops), Python (70 percent), data modeling (55 percent), pipeline architecture or system design (52 percent of senior-and-above loops), and PySpark (30 percent at Spark-first companies). Phone screens are usually SQL plus a take-home or a 60-minute design walkthrough. Onsites add the remaining rounds plus a behavioral round.

What is the difference between a mid-level and senior data engineer loop?

Mid-level (L4) loops weight correctness and clean code: did you produce a working solution that handles the obvious edge cases. Senior (L5) loops weight trade-off articulation and failure-mode naming: did you name 2 alternatives, defend the choice, and call out what happens when the upstream dies on a holiday. Staff (L6) loops weight adapt-on-the-fly behavior: when the interviewer changes the SLA from 15-minute freshness to 1-minute mid-round, did you pivot cleanly.

Do all data engineer interviews include a Spark round?

No. Spark-first companies (Databricks, Netflix, Uber, Airbnb, DoorDash, Spotify) cover PySpark or Scala-Spark in a dedicated 45-to-60 minute round. Companies on Snowflake or BigQuery without Spark in production (Stripe, Block, Coinbase) generally skip the Spark round. Check the company-specific list for the round shape at your target.

How does an interviewer evaluate the data modeling round when there is no 'correct' answer?

By pressing on 4 things. Did you state 'one row per X' before you started drawing. Can you justify Type 1 versus Type 2 versus Type 3 per attribute in one sentence. Do your dimensions conform across the fact tables or does each fact carry its own customer schema. Can you argue star over snowflake or OBT for this specific domain. Several designs survive that questioning. What sinks a candidate is a design they cannot defend when the interviewer pushes.

What is the format of the pipeline architecture round?

A concrete scenario (e.g. 40 million clickstream events per day, 15-minute dashboard freshness SLA, downstream BI tool that cannot handle table swaps), 45 to 60 minutes, end-to-end design on a whiteboard or canvas. The rubric weights SLA match, cost reasoning, failure modes (what happens when Kafka brokers fail, when the source schema changes, when a partition is late), tool fit (why Kafka here and not S3 with notifications), and mid-round adapt-on-fly when the interviewer flips a requirement.

Should I prep for behavioral rounds too?

Yes. Behavioral rounds appear in every loop and account for the hire/no-hire decision when technical rounds split. Use STAR-D format (Situation, Task, Action, Result, Decision postmortem). Specific numbers required (latency, dollars, hours, downstream consumers). The decision postmortem (what you would do differently and why) is the senior-vs-mid signal.

How many problems should a data engineer solve before a FAANG onsite?

Roughly 150 problems for FAANG-level loops, distributed across rounds: 60 SQL, 40 Python, 20 modeling whiteboards, 20 pipeline designs, 10 PySpark if Spark-first. Plus 3 timed mocks in the final 2 weeks. The bottleneck most candidates hit is not volume; it is narration: thinking out loud under pressure without going silent for 2 minutes.

1,571 Data Engineer Interview Questions, 5 Rounds

Data Engineer Interview Questions

Practice problems that execute live, plus design problems answered with the objections a senior interviewer would raise, covering every round of the data engineer interview loop.

1,571 data engineer interview questions covering all 5 rounds of a typical loop: SQL (95% of loops), Python (70%), data modeling (55%), pipeline architecture (52% of senior-and-above), and PySpark (30% at Spark-first companies). Coding problems run against a real database and push back on the shortcut answer. Modeling and design problems come back with the objections an interviewer would raise about your grain, your SCD choice, and the failure mode you skipped.

A typical data engineer interview loop in 2026 has 5 rounds. SQL appears in 95 percent of loops as a 30-to-45 minute coding round on a Postgres-flavored editor, with patterns like top-N per group, dedup latest, sessionization, gap-and-island, SCD2 half-open joins, and idempotent MERGE. Python appears in 70 percent of loops as a 30-to-45 minute coding round on a sandbox, usually vanilla Python with pandas at most companies and polars at the leading edge. Data modeling appears in 55 percent of loops as a 45-minute whiteboard exercise on a marketplace, rideshare, payments ledger, or content platform domain. Pipeline architecture or system design appears in 52 percent of senior-and-above loops as a 45-to-60 minute end-to-end design with a concrete scenario (10 million events per day, 15-minute freshness SLA, downstream BI tool that cannot handle table swaps). PySpark appears in 30 percent of loops at Spark-first companies (Databricks, Netflix, Uber, Airbnb, DoorDash, Spotify) as a 45-to-60 minute coding round emphasizing DataFrame fluency, join strategy selection, skew diagnosis, and Spark UI reading.

What loses points across all 5 rounds is rarely syntax. In SQL it is a missed NULL case, a wrong grain, or a window definition that ties when the interviewer wanted a strict order. In Python it is catching bare Exception, not validating record-level errors, defaulting to O(n-squared) when a dict lookup is O(1). In modeling it is failing to state the grain in one sentence before drawing, or over-normalizing instead of picking a star with conformed dimensions. In design it is whiteboarding the right architecture without naming durability, replay, idempotency, and what happens when the upstream dies on a holiday. In Spark it is ignoring skew, broadcasting a table that will not fit in driver memory, or failing to read a Spark UI screenshot showing stage time imbalance.

Rubric weights are calibrated to data engineer interview write-ups from Meta, Amazon, Google, Netflix, Stripe, Databricks, Snowflake, Airbnb, Uber, DoorDash, and Pinterest. Mid-level (L4) rubrics weight correctness and clean code. Senior (L5) rubrics weight trade-off articulation and failure-mode naming (3 failure modes per component in design rounds). Staff (L6) rubrics weight adapt-on-the-fly behavior when the interviewer changes a requirement mid-round. The catalog is filterable down to seniority and to specific companies once you know your target.

SQL practice problems - Work the SQL problems with live validation and hidden tests.
Python practice problems - Work the Python problems with live validation and hidden tests.
Entry-level data engineer interview questions - The junior loop: SQL fundamentals, Python basics, and the first behavioral round.
SQL interview questions (95% of loops) - 930 problems, each run against 10 randomized fixtures on a real database, for the round that shows up in 95% of loops.
Python interview questions for data engineers - 415 pipeline-shaped problems with hidden test cases for the data engineer Python round.
Data modeling interview questions - Star schemas, SCD types, medallion, each answered with the follow-up an interviewer would press on.
Pipeline architecture interview questions - Clickstream, CDC, reconciliation, ML feature store designs with failure-mode rubrics.
PySpark interview problems - Join strategy, skew diagnosis, Spark UI reading at Spark-first companies.
Data engineer system design interview prep - End-to-end design rounds with SLA + cost + failure mode rubrics.
ETL design interview prep - Idempotent ETL, MERGE strategies, schema evolution, late-arriving data.
Senior data engineer interview problems - L5 and L6 rubrics emphasizing trade-off articulation and mid-round pivots.
FAANG data engineer interview problems - Questions reported from Meta, Amazon, Google, Netflix, and Apple loops, with per-company rubrics.
Data engineer interview questions with worked answers - Worked solutions for the 4 rounds with the why behind each answer.
the community challenge on real, dirty data - 1 data engineering challenge a week on dirty production-shaped data, scored blind on a hidden dataset. Submit before the freeze; results at the reveal.

How many rounds does a data engineer interview loop have?: 5 typical rounds: SQL (95 percent of loops), Python (70 percent), data modeling (55 percent), pipeline architecture or system design (52 percent of senior-and-above loops), and PySpark (30 percent at Spark-first companies). Phone screens are usually SQL plus a take-home or a 60-minute design walkthrough. Onsites add the remaining rounds plus a behavioral round.
What is the difference between a mid-level and senior data engineer loop?: Mid-level (L4) loops weight correctness and clean code: did you produce a working solution that handles the obvious edge cases. Senior (L5) loops weight trade-off articulation and failure-mode naming: did you name 2 alternatives, defend the choice, and call out what happens when the upstream dies on a holiday. Staff (L6) loops weight adapt-on-the-fly behavior: when the interviewer changes the SLA from 15-minute freshness to 1-minute mid-round, did you pivot cleanly.
Do all data engineer interviews include a Spark round?: No. Spark-first companies (Databricks, Netflix, Uber, Airbnb, DoorDash, Spotify) cover PySpark or Scala-Spark in a dedicated 45-to-60 minute round. Companies on Snowflake or BigQuery without Spark in production (Stripe, Block, Coinbase) generally skip the Spark round. Check the company-specific list for the round shape at your target.
How does an interviewer evaluate the data modeling round when there is no 'correct' answer?: By pressing on 4 things. Did you state 'one row per X' before you started drawing. Can you justify Type 1 versus Type 2 versus Type 3 per attribute in one sentence. Do your dimensions conform across the fact tables or does each fact carry its own customer schema. Can you argue star over snowflake or OBT for this specific domain. Several designs survive that questioning. What sinks a candidate is a design they cannot defend when the interviewer pushes.
What is the format of the pipeline architecture round?: A concrete scenario (e.g. 40 million clickstream events per day, 15-minute dashboard freshness SLA, downstream BI tool that cannot handle table swaps), 45 to 60 minutes, end-to-end design on a whiteboard or canvas. The rubric weights SLA match, cost reasoning, failure modes (what happens when Kafka brokers fail, when the source schema changes, when a partition is late), tool fit (why Kafka here and not S3 with notifications), and mid-round adapt-on-fly when the interviewer flips a requirement.
Should I prep for behavioral rounds too?: Yes. Behavioral rounds appear in every loop and account for the hire/no-hire decision when technical rounds split. Use STAR-D format (Situation, Task, Action, Result, Decision postmortem). Specific numbers required (latency, dollars, hours, downstream consumers). The decision postmortem (what you would do differently and why) is the senior-vs-mid signal.
How many problems should a data engineer solve before a FAANG onsite?: Roughly 150 problems for FAANG-level loops, distributed across rounds: 60 SQL, 40 Python, 20 modeling whiteboards, 20 pipeline designs, 10 PySpark if Spark-first. Plus 3 timed mocks in the final 2 weeks. The bottleneck most candidates hit is not volume; it is narration: thinking out loud under pressure without going silent for 2 minutes.

1556 practice problems matching this filter. Domains: SQL (930), Pipeline Architecture (144), Python (415), Data Modeling (67). Difficulty: medium (744), easy (546), hard (266).

SQL (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.
Above the Fold - hard - Every click is a vote on the ranking. Score each search.
Above Their Station - medium - Sometimes the report out-earns the boss. Find where the ladder bends.
Above the Line - hard - The budget line is here. How many crossed it?
Accounted For - medium - Every impression is a face in the crowd; some we can name, the rest are strangers. Measure the gap, campaign by campaign.
Across the Aisles - hard - The best customers never stay in one aisle.
Active API Tokens - easy - Tokens that have actually been used.
Active Campaigns - easy - Which campaigns are earning their keep?
Active Duo - medium - Shoppers who also browse. The overlap is the insight.
Active Token Owners in 2026 - easy - Active token owners this year.
Active User Penetration Rate - hard - How much of the user base is actually alive?
Active User Revenue for April - easy - Total revenue from active users in a single month
Active Users With April Transactions - easy - Active accounts that also opened their wallets. How many?
Activity Histogram - easy - How many users did X things? Build the distribution.
Actually Available - easy - The catalog is big. The shelf is smaller.
Ad Clickers - easy - Who clicked? What did they spend?
Ad Revenue by Age Bucket - medium - Ad dollars, sliced by country.
Ad Revenue 2026 - easy - Annual ad revenue. On the books.
After Hours API Calls - medium - The office is dark. The API is not.
After the Cutoff - easy - The calendar turned but prod kept moving. See which services never stopped shipping.
After the Handshake - medium - The first call is a promise. Judge the ones that follow.
Against the Clock - easy - Promised by noon. Delivered at midnight.
Age of Discovery - hard - Every generation searches differently. See who finds what they came for.
Alert Count by Severity Tier - medium - Alerts by severity. The breakdown matters.
Alert Hotspots by Service and Severity - easy - Some services and severities light up more than others.
Alert Response Breakdown - medium - An on-call postmortem asks which services are bleeding alerts nobody acknowledges.
Alert Severity - hard - When the alarms go off, who screams loudest?
All Infra Regions - easy - The infrastructure spans the globe. Map it.
All Known Endpoints - medium - Two tables. One truth. Every endpoint accounted for.
Allocations in Top Spending Region - hard - The biggest spenders live in one region.
Annual Cloud Spend - easy - One year of cloud bills. The total.
Annual Cloud Spend Summary - easy - A year of cloud bills. Add it all up.
Annual Pipeline Failures - easy - How many pipelines broke this year?
API Call Distribution Fraction - hard - Not all endpoints are created equal.
API Calls With and Without Errors - medium - Some calls succeed. Some do not. Break it down.
API Token Churn Rate - medium - Tokens come and go. What's the turnover?
App Stability by Region - medium - Some regions crash more than others.
April and May Active Users - easy - Spring cleaning for the user base. Who was actually around?
Auth Endpoint Callers - medium - Identify users who have called authentication API endpoints
Auth Endpoints - easy - Not all endpoints are visible to everyone.
Auth Service Health Checks - easy - One service. Full audit trail.
Average Accuracy by Framework - medium - Not all frameworks deliver the same accuracy.
Average API Latency by Year - medium - Latency year over year. Is it getting better?
Average Build Duration by Repo - easy - Some repos build fast. Others don't.
Average Compensation by Department and Status - medium - Average compensation. Department by department.
Average DQ Fail Rate - easy - Average failure rate, table by table.
Average Fulfillment Lag - medium - Ordered, then... waiting.
Average GPU Node CPU Usage - easy - GPU nodes burning CPU. How much?
Average Latency by Status - easy - Each status code has its own latency story.
Average Node CPU by Region - easy - Average infrastructure node CPU usage broken down by region
Average Node Utilization - easy - CPU and memory, region by region.
Average Rating by Category - easy - Category ratings. Some shine, some don't.
Average Response Time by Hour - easy - Hour by hour. When does latency spike?
Average Results for Python Searches - medium - Python searches. What's the click-through?
Average Review Comments by Author - medium - Some authors get more feedback than others.
Average Search Endpoint Latency - easy - One endpoint. Average speed.
Average Search Results Per User - easy - How many results per searcher?
Average Session Duration - medium - How long do users actually stay?
Average Session Duration by Device - easy - Session length, device by device.
Average Sessions Per User - hard - How often do users come back?
Average Spending by Account Status - medium - Average per-user lifetime spending segmented by account status
Average Watch Time by Format - medium - Which content format keeps viewers watching the longest
Back Again - medium - Acquisition is expensive. These customers didn't need convincing twice.
Back From the Brink - hard - Roll it back, then nail the next one.
Balance of Arms - hard - Every test has two sides. Count who actually landed on each.
Bargain Bin - easy - Floor prices. Right before the vendor call.
Bargains and Budget-Busters - hard - Every region has both. Find them.
Batch Job Performance Tiers - medium - Every batch job gets a grade.
Before the Rush - easy - The holidays are coming. See where each category's money moves, month by month.
Before They Walk - medium - A few names carry the whole ledger. Reach them first, before someone else does.
Behavioral Range - easy - Power users don't just visit more. They do more things.
Behind the Fleet - medium - Every machine keeps its own pace. Find the ones falling short of the average.
Below the Line - medium - Low severity. High volume.
Below the Peaks - hard - The biggest bills catch every eye. The overspend hiding just beneath them does not.
Best Accuracy to Training Time Ratio - medium - Fast to train. Accurate too. Which model?
Best Day for Ad Revenue - medium - Some days of the month convert far better than others.
Best in Class - medium - Every category crowns exactly one earner. Find who wears it.
Best in Show - medium - Every department has a peak. Name it, once each.
Between the Spaces - medium - Every pause between words is a vote for length. Count them.
Between Two Extremes - medium - Ignore the loudest and the quietest. The truth lives in the middle.
Between Worlds - easy - iOS today, Android tomorrow.
Beyond the Pacific - medium - Some services never crossed into Asia-Pacific. Those are the ones to price.
Beyond the Signup - medium - Anyone can create an account. Fewer actually return.
Biggest Deployment Decline - medium - One team's deploy count cratered. Which one?
Big Spenders - easy - The whale list.
Blast Radius - medium - When deploys fail, how bad is the blast radius?
Bookends - easy - The extremes of the user base.
Bookends of the Week - hard - Every week has two edges. Weigh what lands on each.
Both Arms of the Trial - easy - Some features were tried both ways.
Both Ends of the Pipe - medium - Dev and prod, both touched by the same hand. Who are they?
Bottom 2% Services by Spend - hard - The bottom 2% of spenders. Who are they?
Break Through - medium - A click is the only vote that counts.
Broken Promises Between Tables - medium - Every foreign key is a pinky-swear. Count the ones that got broken.
Bronze Medal - easy - Only the top few clear the bar.
Budget-Friendly Products - easy - Affordable does not mean invisible.
Build Health - medium - Score every repo by how often CI stays green.
Builds per Author per Branch - medium - Who triggered what, and where?
Build Success Rate by Trigger - medium - Which triggers produce green builds?
Build Success vs Failure by Repo - medium - Green versus red, repo by repo.
Buried Digits - medium - The version number is buried in the log.
Busiest Pipeline Month - medium - One month, more pipeline runs than any other.
Busy Authors - medium - Some developers spread their commits everywhere.
Buyers Who Never Browsed - easy - They bought without ever loading a page.
Cache Efficiency - hard - Some edges run hot. Others coast on the global average.
Campaign Bookend Engagement - hard - First impression versus last. The gap.
Campaign Click Rate - medium - Among engaged users, which campaigns landed.
Campaign Conversion Window - hard - A narrow window between impression and action.
Campaign Cost Effectiveness - medium - Money in, conversions out. What is the ratio?
Campaign Revenue Totals - easy - Every campaign has a price tag. Total them up.
Campaigns With Most Clicks - medium - The campaigns getting all the clicks.
Cart Sizes - easy - Power buyers. Big carts.
Category Buyers - medium - Which categories have the broadest reach?
Category Census - easy - Which aisles are worth restocking?
Category Revenue - medium - Which categories pull their weight?
Category Sales Summary - easy - Category by category. How did they do?
CDN Image Request Paths - easy - CDN image traffic. Every path.
CDN-Related DNS Lookups - easy - DNS lookups tied to the CDN.
CDN Traffic by Day and Hour - medium - CDN traffic, hour by hour.
Chain of Command - hard - The tree runs deep. Trace every branch back to the top.
Character Position in Endpoint - easy - URL patterns, character by character.
Cheapest CDN Route - easy - The cheapest path across regions.
Cheapest Cost Per Region - easy - Lowest spend per region.
Cheapest Line for Network-Heavy Teams - medium - Among the network spenders, the smallest single line.
Clean Averages - easy - Merchandising only cares about the categories customers actually rate.
Clean Cache CDN Edges - easy - Cached, clean, error-free edges.
Clean Exit - easy - Priority one. Only some of them made it to the end.
Clicked Ad Impressions - easy - They saw the ad. They clicked.
Click Revenue - easy - Which campaigns are earning their keep?
Click-Through by Campaign - medium - Which campaigns actually got the tap.
Closing the Books - easy - April is done. Finance wants the number, and it isn't the one printed on the invoice line.
Cloud Bill - easy - Which cost buckets are bleeding money?
Cloud Cost Breakdown by Provider - hard - Cloud costs, provider by provider.
Cloud Cost by Team - easy - Spend by team. Who's burning most?
Cloud Cost Stats by Provider - medium - Three providers. Three very different bills.
Cloud Cost Trend Analysis - medium - Cost trends across billing periods.
Commit Royalty - medium - In a sea of commits, only a few wear the crown.
Competing Standards - hard - Every framework has a star model.
Completion Rate - medium - Not every region closes orders cleanly. The percentages tell the story.
Compute Nodes in Key Regions - easy - Compute nodes across the key regions.
Consecutive Cost Growth Periods - hard - Five straight months of spending increases.
Consistent High-Quantity Revenue - medium - Big orders, consistent revenue. A rare combination.
Content by Specific Users - easy - Two creators. What did they publish?
Content Duration Snapshot - easy - A popularity snapshot by duration.
Content Mix - easy - One content format to bet the quarter on.
Content Page Spreads - hard - Content, laid out in two columns.
Content Published in 2026 - easy - Published back then. Still relevant?
Content Session Counts - medium - Session metrics, content item by item.
Content Sorted by Duration - easy - The catalog, sorted by length.
Content Type Distribution - easy - How many of each content type?
Content Types by Creator - easy - One creator. What did they make?
Content Viewer Penetration - easy - What share of the user base has viewed at least one piece of content
Cost Density Extremes - medium - Some regions pack more cost per node than others.
Cost Efficiency Ratio - easy - Dollars in, value out. What's the ratio?
Cost Efficiency Variance - hard - Cost efficiency varies. By how much?
Cost Share Within Category - medium - Each entry's slice of the category total.
CPU Utilization Summary - easy - The CPUs are working. How hard?
Creator Favorite Content Type - hard - Every creator has a go-to format.
Creatures of Habit - hard - Every big team has one service it can't quit.
Crossed Signals - hard - No shared key, only a shared clock.
Customer Full Name Concat - easy - First name, last name. Combine them.
Customers Without Orders - medium - Customers who have never ordered.
Custom Message Type Counts - medium - Not all messages are created equal.
Daily and Weekly Active Users - easy - One metric by day, one by week. Same users, different lenses.
Daily Cross-Platform Users - easy - Mobile and web. Same day, same users?
Daily Error Count Change - medium - Errors, trending up or down?
Daily Error Resolution Ratio - medium - Reported versus removed. The daily ratio.
Daily Net Revenue - hard - Net revenue, day by day. Refunds included.
Daily Session and User Counts - medium - Sessions and users, day by day.
Data Repo Fix Commits - medium - How many commits start with 'fix'?
Days with More Edited Than Unedited Messages - medium - Some days, more messages get edited than sent.
Deep Pockets - medium - One month, every customer, every dollar accounted for.
Department Running Totals - medium - Compute cumulative metric values within each department using window operations.
Department Snapshot - medium - Who is underperforming and who is excelling?
Department Spend Difference - easy - The compensation gap between departments.
Department Spend Gap - easy - Gap between Engineering's and Marketing's biggest single purchase
Deploy Author Performance Score - medium - Not all deployers are equally reliable.
Deploy Cadence - easy - Which environments ship the most?
Deploy Count by Service - easy - Some services deploy constantly. Others barely at all.
Deployed Models by Framework - easy - Which frameworks are actually in production?
Deployment Duration by Status - easy - Fast deploys versus slow ones. By outcome.
Deployments per Environment - medium - Dev, staging, prod. Where do most deploys land?
Deploy Outcomes by Service - hard - Success, failure, rollback - side by side.
Deploy Velocity - hard - Days between deploys. Some services ship fast, others crawl.
Deploy Velocity Swings - medium - Month to month, who sped up and who stalled.
Device Mix - easy - The device breakdown before the redesign.
Device Type Serving Most Users - medium - One device type serves more users than the rest.
Did Anyone Actually Read It? - easy - A push isn't a win until a thumb taps it.
Did We Actually Make Money? - medium - Cancelled deals don't count. The rest shows where the money really came from.
Diminishing Returns - medium - When search comes back thin, does the click still follow?
Disabled Feature Flags - easy - Disabled flags. Still worth auditing.
Disabled-Flag Share by Owner - medium - Which teams ship everything off by default.
Distinct Product Categories - easy - A quick category inventory.
Diverse Shoppers - medium - They shop the whole catalog.
Double or Nothing - hard - Same shelf, wildly different stickers. Spot the pricing gaps.
Double Take - medium - Passed QA twice. That's the problem.
Double Vision - easy - Before the records move, the ones wearing the same name twice have to surface.
DQ Fail Rate by Table - medium - Pass rates, table by table.
DQ Score Spread - medium - The spread in data quality scores.
Duplicated User Event Messages - medium - Duplicated messages from the alerts topic.
Early 2026 Data Pipelines - easy - Which pipelines ran before the year turned mid.
Ebb and Flow - hard - The rise and fall of revenue, one month against the last.
Echo Chamber - medium - Same status, same pattern. Coincidence?
Email Census - easy - The reachability split.
Endless Scroll - medium - Some visitors never close the tab. Find the five who go deepest.
Endpoint Latency Spread - medium - Latency spread across endpoints.
Endpoint Performance Report - medium - Every endpoint has a speed and a reliability story.
Endpoint Ranking - hard - The slowest endpoints. Called to the principal's office.
Engagement by Content Type - medium - Some content types get all the attention.
Engagement Gap - medium - Zero transactions is still a data point. Count everyone.
Error Category Breakdown - hard - Postmortem time. Categorize the errors.
Error Hall of Fame - medium - The year's worst error categories.
Error Severity Buckets - easy - Errors sorted by how much they hurt.
Errors With Service Health - easy - Error data, enriched with health context.
Even-ID February Signups - easy - A very specific slice of a very specific cohort.
Even-ID June Signups - easy - Odd IDs, even IDs. The filter is precise.
Event Count on Key Days - easy - Key days. Key event volumes.
Even the Silent Ones - medium - The quietest accounts still belong in the numbers.
Events by Month Across Years - easy - Month by month, year by year. The pattern emerges.
Event Types Spanning Multiple Months - easy - Some events span seasons.
Everybody Wants a Bigger Screen - easy - The search bar never lies about what people actually want.
Every Door They Opened - easy - Add up the hours, count the rooms they walked through.
Everyone Counts - easy - Every account lands in a segment, even the ones with nothing on file.
Every Touch Counts - medium - A bid, a click, a search: each one is a vote. Total them honestly.
Experiment Impact - hard - Which experiments moved the needle? Settle the standings inside every variant.
Extreme Category Totals - medium - The highest and the lowest. Both are interesting.
Extremely Late Resolutions - medium - Twenty minutes past the SLA. Still unresolved.
Fastest Page View to Click - hard - How fast from view to click?
Fastest Regions by Latency - medium - The fastest regions. Benchmarked.
Fault Lines - medium - Errors by day and region. Some areas are worse than they appear.
Feature Flag Adoption - medium - How widely adopted are the flags?
Feature Flag Engagement Impact - hard - Flags on versus flags off. The engagement gap.
Feature Name Intersection - hard - Training names versus serving names. The overlap.
Feature Quality by Source - medium - Quality varies by source.
Features With Missing Values - easy - Missing data in the features.
Feature Vote Winner - medium - Users voted with their clicks. Who won?
February 2024 Signups - easy - One signup window. One cohort. Who joined the club?
Filtered User Roster - easy - A clean roster for the all-hands.
Find Deploy Authors - easy - Same person. Many different spellings.
Find the Fifth Largest Cost - medium - Not the biggest. Not the smallest. The fifth.
First Among Equals - medium - When more than one product wears the crown, name every one of them.
First Among Many - medium - Each segment has a favorite category.
First Among Results - hard - When queries run long, does the top hit still win?
First and Last Peak Accuracy Dates - medium - Peak accuracy. When it first hit and when it last did.
First and Last Timeout Per Service - medium - First timeout. Last timeout. Each service.
First Arrivals - medium - Every customer has a first day. Find when the crowds showed up.
First Build per Repository - easy - Every repo had a first build.
First Contact - medium - Every user's first hello to an endpoint. Timed.
First Deploy Attribution - medium - The first deploy per service.
First Half of Page Views - medium - Half the data. The first half.
First Impressions - easy - Just the first three characters. That is all.
First Interaction Credit - hard - Attribute transactions to earliest touchpoint
First Light - medium - Every repo has a scrappy stretch before its first green build. See who was shipping then, and how big their changes were.
First Migration Record - easy - The very first migration. Where it all began.
First Time Learners Per Day - medium - Brand new users, day by day.
Flag Check - easy - Which flags are actually live?
Follow the Money - easy - Every dollar leaves a trail. Find the accounts moving the most of it.
Frequent Message Senders - medium - Someone is sending too many messages.
Fresh Ink - medium - Recent activity is the only activity that counts. Name the busiest hands.
Friday Spending Analysis - hard - Friday spending during Q1.
Full Funnel - hard - Search. Browse. Buy. Only a few do all three.
Gateway Connection Timeouts - easy - Timeouts at the gateway.
Ghost Products - medium - Listed but never sold. The shelves collect dust.
Ghosts in the Campaign - easy - The holiday sale campaign. How did it do?
Ghosts in the Scheduler - easy - It says running. It has been running.
Going Once - medium - The hammer falls. Who bid the most?
Gone to Ground - medium - The control group held steady. Some of them slipped away. Find the ones who stopped answering.
Green Lights on the Order Line - easy - How often did the orders API just... work?
Health Checks per Service - easy - Some services get checked constantly.
Healthiest Service Check History - hard - The healthiest service. Full history.
Heavy Ad Exposure - medium - Saturated with ads. Is it too much?
Heavy Hitters - medium - Some repos never sleep.
Heavy Namespaces - medium - Kubernetes has favorites. Some namespaces carry more weight.
High Engagement Pages - hard - Some pages hold attention longer than others.
Higher Performing Variant - easy - Control versus treatment. One wins.
Higher Than Supervisor - easy - When the student outscores the teacher.
Highest and Lowest Cloud Costs - medium - The extremes in cloud spending.
Highest Cost Per Team - easy - Peak cost, team by team.
Highest Daily Spend - medium - Somewhere in that window, someone broke the spending record.
Highest Latency Endpoints - easy - The slowest endpoints. Everyone notices.
Highest Throughput Pipelines - medium - The pipes that carry the most water.
High-Output Creators - easy - High engagement creators.
High Price Products - easy - Everything above 100.
High-Rated In-Stock Percentage - easy - Highly rated and in stock. A rare combo.
High-Spend 2025 Campaigns - easy - Big-budget campaigns from last year.
High-Traffic Endpoints in February - easy - When traffic spikes, some endpoints get buried. How many crossed the line?
High-Value Electronics - easy - The five priciest electronics.
High Volume Batch Jobs - easy - Batch jobs that processed millions.
Holiday Promo Campaign Click Year - easy - One year, the holiday campaign exploded.
Honeymoon Phase - medium - Every signup class starts hot. Which ones spend the year they arrive?
Hottest Regions by CPU - medium - Where the fleet runs warmest.
Idle Team Members - easy - Sprint started. Some people never got assigned.
Impressions by Search Keyword - hard - Campaign performance, keyword by keyword.
Inactive Users in Date Range - medium - Ghost accounts. Active signup, zero sessions.
Infant Mortality - hard - The youngest ones break first.
In the Shadow of the Peak - medium - Every provider has a top-line cost. Find the one right behind it.
iOS Sessions by Device Type - medium - iOS engagement, device by device.
Job Status Duration - medium - How long in each job state?
Keep Most Recent Record - medium - Carbon copies clutter the table. Only the latest matters.
Keys That Never Die - medium - Some API keys have no expiry date at all. That should worry someone.
Keyword-Based User Search - medium - The search terms reveal intent.
Kings for a Day - medium - Every day, one job moves more rows than all the rest.
Kings of the Aisle - medium - Every category crowns exactly one winner. Go find them.
Kings of the Calendar - hard - Every month has a winner.
Largest A/B Test by Participants - medium - The biggest experiment ever run.
Largest CDN Response - hard - One edge location served something massive.
Largest Group - easy - One group towers above the rest.
Largest Single Cloud Cost - medium - One line item. The biggest bill of all.
Last Five Batch Jobs - easy - The last five. A quick tail check.
Last Migration Record - easy - The most recent migration. Is it the last?
Last Seen - easy - Everyone has a most recent session.
Last Server Activity - easy - Each server's last heartbeat.
Latency Gap to 10th Fastest - medium - One server. Compared to the 10th fastest.
Latency Variance and Std Dev - hard - How much does latency actually vary?
Latest Commit Build Cost - medium - The latest commit came with a build cost.
Latest Metric Values - easy - Stale records hiding in the metrics.
Latest Migration Output per Author - medium - Each author's most recent migration output.
Latest Version Per Service - easy - The latest version deployed. Each service.
Least Viewed Content - medium - Nobody is watching. Should it still exist?
Left On - medium - Some switches never got flipped back.
Left on Read - medium - Every campaign fights for the tap. Find the ones the field is leaving behind.
Lines on the Map - medium - Every region keeps its own ledger. The totals set the order.
Live Wire - medium - The last switch each team flipped.
Loaded Dice - hard - Every flag's rollout is a bet. Map the odds from longest shot to favorite.
Log Entries by Level - easy - Info, warn, error, fatal. The breakdown matters.
Log Levels - easy - Severity breakdown with response times.
Log Priority - easy - Which servers are on fire before coffee?
Longest Deploy With Full Identifier - easy - The longest deployment. Full ID.
Longest Gap Between Token Events - medium - The longest gap between token events.
Longest Running Pipeline - medium - One pipeline outlasted them all.
Longest Uptime Streak - hard - Pass, pass, pass. How long until fail?
Long Messages - medium - Some commit messages tell a novel.
Long Searches Containing 'er' - easy - Long queries with 'er'. A pattern?
Losing Altitude - hard - Two months apart, the same campaigns. Find the ones that slipped.
Loudest in the Room - medium - Every day, a few endpoints carry the load. Surface them.
Love and Loathing - hard - Some teams champion the flag. Others would kill it.
Low-Byte CDN Responses - easy - Tiny responses from the edge.
Low-Engagement Sessions - medium - Users whose average session duration is below the engagement threshold
Lowest Average Price Category - easy - The cheapest category. Not necessarily the worst.
Lowest CPU Pods per Namespace - hard - The five lightest pods per namespace.
Lowest Latency per Service - medium - The fastest response each service ever gave.
Low Latency API Calls - easy - Fast endpoints. Confirmed fast.
Low Severity DQ Checks - easy - Low severity checks. All of them.
Low Throughput Pipelines - easy - Pipelines barely moving data.
Low Uptime Services - easy - Underperforming services.
Low-Volume Stream Topics - medium - Quiet topics in the stream.
Loyalty's Double Tap - medium - When a nudge and a banner team up.
Many Eyes - medium - Every codebase draws its own circle of watchers. Count who shows up.
March Revenue by Customer - medium - One month, every customer, every dollar accounted for.
Market Share - hard - Every category wants a bigger slice.
Max Value Per Location - easy - Every location has a peak.
Median Failure Rate by Table - hard - Half the tables fail more than this.
Median Model Accuracy - hard - The median accuracy. Not the mean.
Median Transaction by Category - hard - The middle transaction in each category.
Memory-Heavy Pods - easy - Memory-hungry workloads.
Mentorship User Pairs - medium - Pair them up. Mentor and mentee.
Messages Containing Keyword - easy - Flagged terms in the messages.
Messages From Specific Users - easy - Specific users. What did they say?
Metric Range by Department - medium - Where each team's numbers sit, low to high.
Metric Range Per Group - easy - The spread within each group.
Metric Trend by Department - easy - How each team's numbers moved, year over year.
Metric Value Pairs Over Threshold - medium - Two metrics, both above the line.
Metric Value Quarter Complement - easy - Two metrics that accidentally match.
Metric Volatility Gap - easy - Stable metrics are boring. Volatile ones need attention.
Mid-CPU Nodes - easy - Not the heaviest. Not the lightest. The middle.
Minimum Parallel Workers - hard - Too few workers and it stalls.
Missing Email for Non-Active Users - easy - No email on file. No recent activity. Something smells off.
Mobile Event Counts - easy - Mobile engagement, device by device.
Mobile vs Desktop Session Duration - medium - Mobile versus desktop. Who stays longer?
Models With Variable Accuracy - medium - Accuracy should be stable. These models are not.
Model Training Completion Rate - medium - How many models finished training?
Monthly Active Users per Endpoint - easy - One endpoint, many users. Which ones showed up?
Monthly Running Total - medium - Cumulative sales per product across months.
Monthly Signup Counts - easy - Signups, month by month.
Months in Motion - medium - Engagement, counted one month at a time.
Month With Fewest Deploys - medium - One month, nobody deployed.
Morning Warning Logs - easy - Warnings before noon.
Most Active Chat Users - medium - The loudest voices on the platform.
Most Common Monday Outcome - medium - Mondays have a pattern.
Most Efficient Region by Token Usage - hard - Some regions squeeze more out of every token.
Most Frequent Error Types - medium - The errors that keep coming back.
Most Popular Signup Day - medium - One day of the week wins on signups.
Most Recent Token Usage - easy - Each user's latest token activity.
Multi-Host Regions by Node Type - medium - Some regions are quietly building empires.
Mutual Channel Connections - medium - Two users. What channels do they share?
Name Recognition - medium - The name tells you what it is. Mostly.
Net Lines - medium - Some authors build. Others trim. The net tells the truth.
Never-Ordered Products - easy - In the catalog. Never purchased.
New User Purchases - medium - What's this year's signup cohort worth so far?
New vs Returning User Share - hard - Fresh faces versus familiar ones.
Nobody Was Watching - easy - Every release shipped clean. Not one had a tripwire set. Find the ones flying blind.
No Dead Months - hard - Every month it ran, it landed a click. Among those, find the ones whose worst month of spend stayed lowest.
Nodes by Region and Type - medium - Broken down by region. Broken down by type.
Nodes in Target Regions - easy - The target regions need attention.
Node Summary Per Region - easy - Every region has a node story.
Node Utilization - hard - Overloaded nodes hiding in busy regions. Spot the hot spots.
No Gaps - easy - Zero blanks. A clean contact list.
Noisiest Tables by DQ Failures - medium - The tables that fail the most checks.
Noisy Endpoints - medium - The routes generating the most noise.
Non-Bot Acknowledged Alerts - easy - Human-acknowledged alerts only.
Non-Draft Content - easy - Everything except drafts.
Non-Trivial Fatal Errors - medium - Short errors are noise. Long ones matter.
Normalization Tradeoffs in Practice - hard - Clean data or fast queries? You can't always have both.
Not All Fires Are Equal - medium - The alert volume varies. So does what it means.
Not From Around Here - easy - The data is mixed. Only some of it belongs.
Nth Highest Salary Per Department - medium - Third place in every department.
Off Target - medium - Most models are fine. The bottom 10% are not.
Once and Only Once - hard - Repeated readings are noise. The value seen a single time is the signal.
One-Track Mind - medium - Some users only ever read, never write. Find where the read-only crowd gathers.
One Year to the Next - hard - This year versus last year. Growing or shrinking?
Only Here - hard - Exclusive to one source. Missing from the other.
On Their Way Out - easy - They signed up. They never really showed up.
Open Wounds - hard - Every service has one alarm that was never silenced. Find the one that has been screaming the longest.
Overlapping User Sessions - medium - Two sessions, one user, same clock. Something overlaps.
Overloaded Infrastructure Nodes - medium - CPU above 90. Memory above 80. Red alert.
Pairwise Latency Maximum - medium - Every pair compared.
Parallel Traces - medium - Same experiment. Different variants. Who overlaps?
Past the Threshold - medium - Somewhere after the third visit, a habit quietly forms. Find the ones who crossed over.
Peak Company - hard - Every token lived among others. Find the moment the crowd was largest.
Peak Concurrent Batch Jobs - medium - Jobs pile up. Find the moment the scheduler sweats the most.
Peak Hour Power Callers - medium - One hour. The phone lines exploded.
Peak Metric Per Department - easy - Peak metrics for the quarterly deck.
Peak Non-Converting Month - easy - Everyone showed up. Nobody bought anything.
Peak Retargeting Revenue Month - medium - Retargeting revenue. The peak month.
Peak Satisfaction - easy - Which departments are winning on satisfaction?
Peak Season - medium - One region, one month. Peak profit.
Peak Spending Month - easy - One month, the bill was unforgettable.
Pipeline Completion Rate - medium - How far do users get through the flow?
Pipeline Overhead by Environment - medium - Production overhead versus staging.
Pipeline Run History - easy - The lineage trail.
Platform Check - easy - When a session drags on, the platform it ran on is the first suspect.
Platform Speed - medium - Which devices keep users longest?
Platform Team Feature Flags - easy - The platform team owns a lot of flags.
Platform Team Mobile Flags - easy - Mobile flags under platform ownership.
Pod CPU to Memory Ratio - medium - CPU versus memory. Resource efficiency.
Point of Entry - hard - Everyone starts by looking. Count who came back to buy.
Poles Apart - medium - Two extremes, one result: the busiest tokens and the quietest.
Popular Categories - easy - Merchandising only cares about categories big enough to negotiate shelf space.
Power Users - medium - Engagement separates tourists from regulars.
Power Users by Session Activity - medium - More sessions. More time. The power users.
Presence vs. Participation - medium - Being in the region and being active are two very different things.
Present and Accounted For - easy - Every product lands on the report, even the ones Electronics never touched.
Price Check - easy - Priced to sell or priced to sit?
Price Rank - medium - In every category, someone charges the most. Who's on top?
Priciest Item in Each Category - medium - The most expensive item per category.
Prime Real Estate - easy - Not every screen earns the build. Find the ones that do.
Product Name Letter Replace - easy - A quick text transform on product names.
Product Ratings vs Sales - medium - Do higher ratings actually mean more revenue?
Product Revenue Ranking - easy - Rank them by revenue. See who leads.
Products Without Sales - easy - Listed but never sold.
Product Transaction Counts - medium - Show how many transactions each product has, sorted by product ID.
Profitable Categories by Price - easy - The most profitable categories.
Profit Tiers - medium - High, moderate, or in the red. Every order gets a label.
Prolific Authors in Largest Service Teams - medium - Senior leads in the biggest teams.
Proof of Presence - medium - Two-factor sent. How many confirmed?
Provider Cost Change H1 - easy - Cost swings in the first half of the year.
Purchase Log - easy - Names on receipts, not just IDs.
Push Opens by Platform and Campaign - medium - Opens by platform and campaign.
Q2 Search Volume - easy - Q2 search volume. The numbers.
Q by Q - easy - Thirteen weeks. This is how the team spent them.
Quarterly Peak Cloud Costs - hard - Every quarter has a peak bill.
Quarters Apart - hard - Latency trending up or down? The quarters have the answer.
Quiet Failures - medium - Some services land every release; others only look like they do. Find the ones production can't count on.
Radio Silence - hard - Some codebases stop speaking for too long.
Rapid Retry Detection - medium - Detect retried API calls within 5 minutes of failure.
Rate Limit Rules Per Endpoint - medium - Threshold rules, endpoint by endpoint.
Rating Tiers - medium - No gaps, no skips. Ratings stacked tight within each category.
Read the Manual - easy - Some titles promise to walk you through it. Count the ones that say so out loud.
Recent Price Drops - medium - The price just dropped. Who noticed?
Recurring Error Types - easy - The same errors, recurring.
Regional Footprint - easy - Every node costs money. Know what you own.
Regional Profits - easy - P&L by region. Before the board meeting.
Regional Sales Growth QoQ - hard - Quarter-over-quarter growth. Region by region.
Regional Status - easy - The full regional breakdown.
Regions by Alert Volume - medium - Some regions are quiet. Others never stop screaming.
Repeat Buyers Across Halves - medium - First half buyer. Second half buyer. Same person.
Repeat Offenders of the Search Bar - easy - Once is a fluke. Twice is a habit.
Repeat Purchases Within a Week - medium - They bought again within seven days.
Repeat Purchase Window - medium - The retention squad is looking for repeat purchasers.
Repository Commit Ranking - medium - Lines added tell the story of a repo's ambition.
Repos with More Builds Than Commits - medium - More builds than commits. Something is off.
Resolved vs Unresolved Alerts - hard - Resolved versus open. By severity.
Response Buckets - medium - Fast, normal, or slow. Every API call gets a verdict.
Retargeting Campaign Impressions - easy - Retargeting impressions. All of them.
Retried Failed API Calls - medium - Spot users who retry API calls within 5 minutes of a failure.
Returning Buyers - medium - They came back and bought again.
Return on a Glance - easy - Every impression costs something. Find the campaigns earning it back.
Return on Patience - medium - The best answers cost the least time. Find the ones that pay off.
Reviewer Performance Metrics - medium - Some reviewers are thorough. Others are fast.
Reviews Per Reviewer - easy - The workload split across reviewers.
Revoked Tokens by Scope - medium - Banned tokens, sorted by what they had access to.
Rollback Roulette - easy - Some ships sink before they leave the harbor.
Roll Call - easy - Every name on the books, in order.
Rolling Revenue Average - hard - Smooth out the revenue bumps. The trend matters more.
Rooms in Common - hard - Two people, one channel, a connection you never counted.
Running Node Pairs - easy - Two servers, same region, both alive.
Running Tab - medium - Every purchase adds to the total. Watch the tab grow.
Rush Hour API Latency - medium - Rush hour hits the API differently.
Same-Day Session and Transaction Correlation - hard - Same day session and purchase. Connected?
Same First and Last Reply Target - medium - They started and ended the month messaging the same person.
Satisfaction by Platform - medium - Satisfaction scores, platform by platform.
Search Endpoint Status Distribution - easy - Status codes on the health endpoint.
Searches by Users With Email - easy - One user's search behavior.
Search Terms Starting With G - easy - Queries starting with 'g'.
Second Fiddle - hard - The spotlight finds number one. The story is in what comes right after.
Second Highest Cloud Cost - medium - The second biggest bill on record.
Second Highest Latency by Method - medium - Almost the slowest. By method.
Second Highest Salary - easy - Silver medal. Almost the top, but not quite.
Second Highest Value - easy - Almost the top. Not quite.
Second Purchase - hard - The first buy is curiosity. The second is commitment.
Second to One - medium - Across every team, the pay figure that sits just shy of the summit.
Seen and Unseen - medium - Every ping lands somewhere. Not every one gets read.
Seen or Ignored - medium - A send is only half the story. Find where the taps actually land.
Selling Where Nobody Lives - medium - Shipments land in regions our customer list has never heard of.
Servers Returning to Origin - medium - Servers that migrated back home.
Server With Most Errors - medium - One server stands out. Not in a good way.
Service Alert Frequency - easy - How often does each service trigger alerts?
Service Budget per Head - medium - Budget per head. Pipeline by pipeline.
Service Component Classification - medium - Classified by naming pattern.
Service Reliability Tiers - medium - Reliability tiers. Based on uptime.
Service Roll Call - easy - The mesh is sprawling. Find out exactly how many services are actually running.
Services at Median Uptime - medium - Exactly at the median. Not above, not below.
Service Scorecard - hard - Deploys vs. alerts. One row per service tells the whole story.
Services With Most Checks in 2025 - hard - Last year's most-checked services.
Services With Most Error Occurrences - easy - The noisiest services.
Services With Multi-Quarter Uptime - hard - Multi-quarter uptime streaks.
Service Uptime Minutes - medium - Status changed. How long was it actually up?
Service With Most Critical Alerts - hard - One service keeps setting off the alarms.
Session Count Distribution - hard - How are sessions distributed among the newest users?
Session Duration by Account Status - medium - Average session duration broken down by user account status
Session-Fit Content - easy - Content that fits the session length.
Session Logins Dec 13 to 19 - easy - Logins during one specific window.
Session Overview - medium - Full engagement picture, even for the ones who never showed up.
Session Page View Distance - hard - Page view distance per session.
Session Pulse - easy - Engagement is slipping. Who is phoning it in?
Session Rank - medium - Longest sessions rise to the top. Within each user, a pecking order.
Sessions by Content Type - medium - Engagement, broken down by content format.
Sessions Per Device Type - easy - Sessions, device by device.
Shadow Spend - medium - Region by region. Service by service. Where does the money go?
Shared Category Purchasers - medium - They bought different things from the same aisle.
Shared Endpoints - medium - Shared credentials across endpoints.
Ship It or Skip It - easy - The calendar doesn't lie. How aggressive is this team, really?
Shipped to Prod - easy - Every environment keeps its own tally. Read the funnel.
Signups by Age Bucket Since April - easy - Recent signups by age.
Silent Users - medium - Users who have never typed a query.
Single Service Owners - medium - One owner, one service. Nobody else.
Sirens and Smoke - easy - Stale alerts. Still ringing.
Six Degrees - hard - Every reply ties two names together. Find whose web reaches the furthest.
Slow Failures - easy - SRE is hunting for the endpoints that fail slowly enough to burn timeouts.
Slow Production Deploys - easy - Production deploys that took way too long.
Smooth Latency - medium - Noisy latency readings, smoothed into a trend you can trust.
Speed and Substance - hard - When a run takes longer, is it moving more rows or just stalling?
Spend and Rank - hard - Five thrones at the top of the spending leaderboard.
Spending by Account Status - medium - Segment user spending and activity by account status across the platform
Spending Range - hard - Between the smallest purchase and the biggest lies the story.
Spending Tiers - medium - High rollers, mid-spenders, and the frugal. Everyone gets a tier.
Spending Velocity - medium - Fraud hides in the pace, not the price. Watch each customer's last seven purchases roll forward.
Split Metric Sums - medium - One column, two totals.
Splitting the Load - medium - The heaviest bills each team carries.
Status Report - easy - Where are orders getting stuck?
Still Breathing - medium - One specific day. Which tokens were still alive?
Still Climbing - easy - Which services kept gaining month over month?
Still Standing - medium - The busiest keys are the ones that never had a deadline.
Stock Status - easy - Human-readable availability labels.
Storage Node Lookup - easy - The storage nodes hold the critical data.
Stumbling Out of the Gate - medium - Some model versions never recover from a bad opening run.
Successful Build Duration by Repository - medium - CI throughput, repo by repo.
Successful Call Volume per Endpoint - medium - Not every ping is honest.
Successful Pipeline Runs - easy - Which pipelines completed successfully?
Successful Production Deploys - easy - Successful production deploys with duration.
Super Reviewers - medium - The most prolific code reviewers.
Suspected Bot Sessions - easy - Five seconds or less. Probably a bot.
Symmetric Reply Network - medium - Every reply is an edge. Draw it both ways.
Tables With Many DQ Failures - medium - Some tables have never once passed QA.
Tables With Most DQ Failures - medium - The tables with the most failures.
Targeted Ad Campaigns - easy - High-value impressions. Targeted precisely.
Team Cost Allocation Comparison - hard - Individual spend versus team average.
Tenure Mentorship Match - medium - Pair by tenure. Longest with newest.
The Above Average - medium - What counts as good depends on the company you keep.
The A/B Verdict - medium - Variant A or Variant B. The conversion numbers pick the winner.
The Accumulator - hard - A total that builds row by row. Structure the query to match.
The Address That Changed - hard - Addresses change. History must not be erased.
The Ad Ledger - easy - Annual ad revenue. On the record.
The Apprentices Still in the Forge - easy - A model is not a model until it stops learning and starts earning.
The Biggest Fish - medium - In every aisle, one customer outspends the rest. Find them.
The Blast Radius - medium - A reliability scoreboard for deploy teams.
The Blind Spot - medium - Pages they haven't discovered yet.
The Budget Line - easy - Some rows are over. Some are under. Label every one.
The Campaign Trail - easy - Impressions are vanity. Conversions are sanity.
The Cannibalization Report - hard - The new product launched. The old one suffered.
The Clean Aisle Numbers - medium - Clear the noise. What did each category actually earn?
The Cloud Bill - medium - Every provider sent an invoice. Every month tells a different story.
The Comfortable Middle - hard - Above average but not extreme.
The Company You Keep - medium - Only experiments with a crowd count. Find the Friday sessions they drove.
The Compliance Order - easy - Token scopes need to be in the right sequence before the audit.
The Conversion Story - medium - Signups are one thing. Paid purchases are another. Find the gap by source.
The Costliest Trio - medium - Three products, one price tag. Surface the priciest bundles.
The Crowded Hour - easy - Every device type has a moment when the room is fullest. Find it.
The Days That Line Up - medium - No key ties these tables but the calendar. Read it right.
The Dormant Accounts - easy - They are still paying. They stopped showing up.
The Elite - easy - The top-scoring models. What's their average?
The Engagement Curve - medium - Longer sessions, more pages? Check.
The Engagement Gap - medium - Two kinds of gone. One still stirs more.
The Extremes - hard - Only the biggest and the smallest reach the executive review.
The Faithful Few - medium - Loyal to one platform only.
The Far Ends - easy - Ordinary hides in the middle. The story is at the extremes.
The Fast Lane - medium - Only the quick runs make the cut. Measure what they move.
The Fault Lines - medium - Some account groups hit far more errors than others. Surface the ones that break most.
The February Cohort - easy - One signup window. One cohort. Who joined the club?
The Final Sale - medium - Every product has a last sale. When was it?
The First Door - medium - The first interaction matters most. Or does it?
The First Half - easy - New arrivals during one specific window.
The First Year - medium - Activated early. A good sign.
The Floor Price - medium - Before the negotiation, find what each provider really charges at its cheapest.
The Footprint - medium - Some regions carry more of the fleet than others. Show how it is spread.
The Freshest Record - medium - Duplicates everywhere. Only the most recent version of the truth survives.
The Full Picture - easy - Two tables know different things about the same people. Combine them.
The Gap Between Neighbors - hard - Same region, and still they disagree.
The Green Light - easy - Success hides behind a dozen spellings. Find who actually shipped.
The Ground We Keep - hard - Every region is a claim once made. Measure how much of it endures.
The Heaviest Carts - medium - Inside every age group, a few customers carry the basket. Find them.
The Heaviest Hitters - easy - A handful of impressions earn more than the rest combined. Bring them to the top.
The Heavy Hitters - easy - Total sales tell the real story. Surface the products that carry the catalog.
The Heavy Lifters - medium - In some categories, a handful of big orders carry the rest.
The High and the Low - hard - The fastest and slowest in every region.
The Holdouts - medium - Subscribed. But never upgraded.
The Ides of March - medium - Every endpoint has one March it would rather forget.
The Last Checkout - medium - Their last visit. Everything in the bag.
The Legacy Hunt - easy - Old data. Still matters.
The Lion's Share - medium - Every category claims its slice. Find out who really owns the table.
The Long Climb - medium - Each purchase stacks on the last. Watch it climb.
The Longest Take - easy - The content that held the number-one spot.
The Long Tail - medium - Averages hide the pain. The tail is where SLOs live.
The Long Wait - easy - Every route runs at its own pace. Find the ones lagging.
The Long Watch - medium - Some formats hold you longer than others. Measure which ones.
The Long Way Back - hard - Some services fell apart and clawed their way back. Find them, and measure the climb.
The Loudest Caller - easy - One account carries the traffic. Trace it back to everything it can touch.
The Loudest Failures - medium - Twelve months of errors. Which types showed up most?
The Loudest in the Room - medium - Somewhere in the noise, two keep knocking. Find who.
The Loudest Machines - medium - Every server keeps a diary. Find the ones that never stop writing.
The Loudest Neighbor - hard - In every namespace, one pod does most of the eating.
The Loudest Rooms - medium - Every channel has an audience. Find where it is biggest.
The Loudest Signals - easy - Only the extremes make the list.
The Loudest Threads - medium - The code reviews that started a debate.
The Loudest Voices - medium - In every channel, a few names never stop scrolling.
The Merge Counter - easy - How many builds came from merges?
The Merit Circle - medium - Ten seats at the top, and the ratings decide who sits.
The Middle of the Missing - medium - Across the float features, how much of the data typically goes missing?
The Most Recent Word - hard - Every table keeps a record. Only the latest verdict still speaks.
The Named Transaction - easy - Transaction IDs are useless without context. Bring in the product names.
Then and Now - hard - Accuracy used to be higher.
The Ninety-Day Comeback - hard - Everyone shows up once. Who comes back before the quarter ends?
The Noise Floor - medium - Not every alert deserves a 3 a.m. page. Find the services where most of them claim they do.
The Notification Lifecycle - medium - Sent, opened, ignored. What happened after the alert went out?
The Notification That Paid Off - hard - The message went out to thousands. A smaller number actually bit.
The Ones Nobody Calls - medium - The POST paths the traffic forgot.
The Ones Still Listening - medium - A buzz only counts when someone who is still around answers it.
The Ones That Move - medium - Every aisle has its champions. Surface the three that carry each one.
The Ones That Woke Us - easy - The year's serious incidents, and nothing quieter.
The Ones We Watch - medium - Only the services still under watch count. Rank them by where the errors gather.
The Ones Who Carry Us - easy - Every quarter, a few names hold up the whole line. Name them.
The Ones Who Clicked - hard - Every signup cohort runs its searches. Find the years that turned queries into clicks.
The Ones Who Finish - medium - Plenty of members press play. Far fewer reach the final rep. Find the formats that hold them.
The Ones Who Hold Attention - medium - Time on screen is the real vote. Find the creators earning it.
The Ones Who Return - medium - One purchase is a trial. Two is a habit. Find how many members formed one.
The Ones Worth Paging - hard - Three levels wake someone up at night. Tally each one.
The One That Flew - medium - The fastest build ever. When did it happen?
The Opening Run - easy - Before the tuning, before the records. What the first pass carried home.
The Open Question - medium - Push sent. How many opened?
The Org Chart in Numbers - hard - Headcount by department, sliced by quarter. Every seat accounted for.
The Path Not Taken - hard - Some found the new path without ever walking the old one.
The Phantom Readers - medium - They read everything. They bought nothing.
The Podium Finish - medium - Top two products per category.
The Premium Shelf - medium - The catalog's high end, weighed one unit at a time.
The Price of a Tap - easy - The campaign fired thousands of pushes. Find what each open really cost.
The Provinces - easy - The home office isn't the whole story. Find the zones carrying the rest.
The Proving Ground - medium - One team, one framework. Let the accuracy numbers decide.
The Publishing Audit - easy - Published years ago. Still generating views?
The Quiet Alarms - medium - Low severity. High volume. Worth a look.
The Quiet Drain - easy - Some AWS services quietly drain the budget.
The Quiet Middle - easy - Not the biggest, not the smallest. The overlooked middle.
The Quiet Outlier - hard - Ignore what the traffic does all day. Find the spike that barely showed up.
The Regulars - hard - Some users drift off after one visit. Find the ones who kept coming back.
The Relentless Searchers - medium - Most users look once and leave. A few never stop looking.
The Revenue Cliff - medium - Revenue was climbing. Then it wasn't. Spot the drop.
The Roads In - easy - Every reader arrives from somewhere. Trace where the blog's traffic begins.
The Roster - easy - Every department, counted head by head.
The Row Count Surprise - easy - Same tables. Different handshakes. Wildly different results.
The Scorched Earth Reviews - easy - Someone left a trail of one-star wreckage. Round up every product they burned.
The Screens They Carry - medium - One age cohort, and every kind of screen it reaches for.
The Seventh Day - medium - Day one was promising. Day seven tells the truth.
The Severity Matrix - medium - When services cry wolf, the numbers reveal who's serious.
The Shape of a Day - medium - Traffic has a rhythm across the hours. Find where it runs busiest.
The Shape of a User - medium - Every user leaves a trail of events. The report needs them lined up side by side.
The Shape of the Year - medium - Revenue has a rhythm. Trace it, month by month.
The Shape of Waiting - hard - Every request waits its turn, and some wait far longer than the rest. Map where the patience runs out.
The Silent Probe - easy - One probe never recorded. The rest still need reporting.
The Slow Build - medium - Month over month, the number grows. Track how the average moves with it.
The Slow Creep - medium - Every year the builds got heavier. Find where the minutes went.
The Slow Fade - medium - They all arrive together. Watch the room empty, month by month.
The Slow Lane - medium - Peak API load. The slow endpoints.
The Space Between - hard - The time between events is the tell.
The Space Between Us - hard - Every viewer lives inside a world of campaigns. Measure how much two of those worlds are really one.
The Spender Leaderboard - easy - Spending speaks. The leaderboard does the listening.
The Spending Floor - easy - Everyone has a smallest purchase.
The Spending Rhythm - easy - Every month tells a spending story, user by user.
The Stable and the Restless - easy - Some pods never restart. That could mean anything.
The Standing Fleet - easy - Some hosts wear many hats. Count the machines, not the mentions.
The Standings - hard - Every category earns its place on the board. Find where each one lands.
The Steady Few - medium - Endurance is measured in the hours you hold the line. Rank the regions that keep it.
The Subscription Ghost - medium - Some charges come back to haunt the same card a month later.
The Sweet Spot - medium - Cheap and highly rated. A rare combination.
The Switchboard - medium - On or off. Every flag at a glance.
The Tag Order - hard - Tags arrived in chaos. The system needs them in line.
The Threshold - medium - Every visit begins with three doors. Find the ones most often opened.
The Tiebreaker - easy - One column wasn't enough. The second column settles it.
The Token Census - easy - How many tokens are out there?
The Transaction Breakdown - easy - Multiple time windows. One query. The business wants all of it at once.
The Turning Tide - medium - Two time windows. Did the cloud bill go up or down?
The Undone - hard - Some migrations don't stick. Find the databases where they keep coming undone.
The Upgrade Divide - medium - The install numbers don't match the hype.
The Upper Rungs - easy - The top rungs set the ceiling for everyone below.
The Usual Suspects - hard - Same services, same checks, same problems.
The Vanishing Rows - easy - Some records disappear when the tables meet. Figure out why.
The Vital Signs - easy - Each check records a verdict. See how they stack up.
The Vote Tally - hard - One product, every day it sold, and the money it brought in.
The Waiting Room - easy - Signed up. Never verified. Never came back.
The Warm Edges - medium - Some edges keep the cache warm. Measure what they carry.
The Weak Link - medium - Build failures happen. Which repos break the most?
The Weekly Pulse - medium - Notifications by platform and day. When does the audience actually show up?
The Weight of a Click - hard - Where users actually spend their attention.
The Weight of a Verdict - easy - Every run carries the full measure of all who ended the same way.
The Weight of Between - easy - Between the floor and the ceiling, the ledger keeps its quiet accounts. Sort what rests there.
The Weight of Everything Before - medium - Every purchase carries the ones that came before it. Trace the climb.
The Weight of Giants - medium - In every sky, only two hold the throne.
The Weight of the Cloud - medium - Not every dollar counts the same. Close the quarter.
The Weight of Things - medium - Every category claims part of the year. Find where it gathers.
The Weight of Words - easy - Verbose commits. Risky changes?
The Well-Defended Borders - easy - Some frontiers already stand ready. Find the ones that do.
The Widest Net - medium - Not the clicks. The crowd: how many people each campaign actually pulled in.
The Words That Page Us - hard - Certain words trigger an investigation.
Third Highest Spender - medium - Bronze medal in spending.
Third Largest Batch Job - easy - Bronze medal in the batch job rankings.
Thirty Days of Shipping - easy - A month in the life of an engineering team, counted one deploy at a time.
This Year's Class - easy - The cohort is in. Time to count who made it through the door.
Threads Excluding User - easy - Every thread they're not part of.
Three Clouds - easy - AWS, GCP, Azure. Side by side.
Three Lowest Distinct Cloud Cost Amounts - easy - The three cheapest bills on record.
Three Peaks - hard - Every team's steepest months, and nothing below them.
Three-Value Sum Combinations - medium - Pick three. See what they add up to.
Tiers of Want - hard - In each category, some carts weigh more than others. Sort the shoppers by what they spend.
Timeout Status Records - easy - Unknown status in the health records.
Timeout Warning Logs - easy - Timeout warnings. The postmortem trail.
Time Served - hard - The tokens still in service each carry a history; measure how far it stretches, scope by scope.
Tipping Points - hard - A service's health is a story told in how it turns. Find every turn.
Titles Ending With S - easy - Naming conventions. Specifically the plurals.
Tokens With Non-Read Scope Prefix - medium - Tokens that don't start with 'read'.
Top 100 Batch Jobs Total Output - easy - The hundred biggest jobs. Combined output.
Top 10 Batch Jobs - easy - The ten biggest batch jobs.
Top 10 CPU-Heavy Nodes - medium - The ten hungriest nodes.
Top 10 Model Accuracies - easy - Top ten model performance.
Top 10 Slowest Endpoints - easy - The ten endpoints nobody wants to call.
Top 2 Active Push Days - medium - Two days stood out from the rest. Which ones?
Top 2 Ad Campaigns by Spend - medium - Two campaigns. Most of the budget.
Top 2 Busiest API Slots - medium - Two time slots per week. The busiest.
Top 2 Callers per Endpoint - medium - Two top callers per endpoint.
Top 3 Revenue Months - medium - The three best months on record.
Top 5 Slowest DNS Lookups - easy - Five DNS lookups that took too long.
Top Accuracy Model - medium - The single best-performing model.
Top Active Senders per Channel - medium - Top three messages per channel by replies.
Top Ad Campaigns by Revenue - easy - Every campaign has a bottom line. Stack them up.
Top Alert Resolvers - medium - The engineers who resolve the most.
Top API Caller - medium - One user triggered more API calls than anyone.
Top Average By Region - easy - Region by region, who pulls the best average?
Top Batch Job Under Priority 1 - medium - Priority one. Top performer.
Top Buyers of Premium Products - medium - Which users bought the most top-rated products
Top Campaign by User Revenue - medium - Which campaign made each user spend the most?
Top Commit Authors by Repo - hard - Three authors per repo. The top committers.
Top Committers in 2025 - medium - In a sea of commits, only a few wear the crown.
Top Content by Lifetime Value - medium - Lifetime value. Measured in total watch time.
Top Content by Views - medium - Top five content items by views.
Top Content by Watch Time - medium - Some content holds attention. Others get skipped.
Top Cost Categories - medium - Three categories eating the budget.
Top CPU Pods per Namespace - hard - The two most CPU-hungry pods in each namespace.
Top Deployed Model - easy - The best-performing model in production.
Top Device by Sessions - easy - One device type generates the most sessions.
Top Earner Per Campaign - medium - The top-earning user per campaign.
Top Endpoint by Power Users - hard - Power users have a favorite endpoint.
Top Error-Service Pair - medium - Which error-service pair triggered the most resolved incidents
Top Framework by Deployments - hard - The framework most often deployed.
Top Frameworks by Accuracy - medium - Top three frameworks by accuracy.
Top Identified Event Types - medium - The top users by events, but only the identifiable ones.
Top Lessons Each Month - medium - Rank items within time periods and keep top 3
Top Metric Values - easy - The five highest numbers. No duplicates.
Top of the Bill - medium - Every cloud bill has a headliner or two. Find them.
Top of the Line - easy - The five priciest items for the luxury section.
Top Pattern Matches - medium - A needle in a haystack, but how many haystacks?
Top Per Category - hard - Every category has a champion. Crown them all.
Top Percentile API Tokens - hard - The most suspicious tokens.
Top Percentile Spenders - medium - Top 1% of users by total spend via percentile bucketing.
Top Performing Models - easy - The models that actually perform.
Top Product Categories - medium - Top three categories by page views.
Top Product Categories by Sales - easy - The highest-grossing categories.
Top Product Category by Transactions - medium - Organic purchases, no marketing nudge. Which category wins?
Top Products by Quantity Sold - medium - The bestsellers. By volume.
Top Products per Category - medium - Five winners per category.
Top-Ranked Wines by Variety - easy - The best bottles. Ranked by variety.
Top Recent Sellers - easy - Fresh data, top sellers. The recent leaderboard.
Top Region by Order Volume - medium - The single busiest region.
Top Regions by Critical Alerts - medium - Which regions have the highest volume of critical alerts
Top Regions by High CPU Nodes - hard - Five regions with the hottest CPUs.
Top Repos by Commit Volume - medium - The most active repos in the org. No ties left behind.
Top Repos by Successful Builds - medium - Green builds. Which repos lead?
Top Revenue Products H1 - medium - First half of the year. Which products led the revenue race?
Top Selling Items - easy - Revenue crowns the winners. Who sold the most?
Top Services by Uptime - medium - Uptime is a competition. Which services never blink?
Top Shelf - easy - Buyers need to know ceiling prices before negotiating with vendors.
Top Spender - medium - When your spending exceeds the priciest item on the shelf.
Top Users by Recent Spend - medium - Big spenders in the last 30 days.
Top Users by Session Time - medium - They spent the most time here.
Total Compute Cloud Cost - easy - Total compute spend. The number.
Total Cost by Category - easy - Total spend per category.
Total Engineering Cost Allocation - easy - Engineering's total allocated budget.
Total Hours Between Consecutive Events - hard - Hours between state changes.
Total User Spend - easy - Each customer's total. Summarized.
Transaction Overview - easy - The executive snapshot. Users, products, revenue.
Transaction Share of User Spend - medium - Each transaction's share of the whole.
Transaction Source Features - easy - One pipeline reviewed them. What did it see?
Transaction Timeline - medium - First purchase to last. The full spending arc.
Trend Spotter - medium - What did they spend last time? Context changes everything.
Trim Endpoints Right - easy - Trailing whitespace. Clean it up.
Trim Search Terms Left - easy - Leading whitespace. Clean it up.
Turned Away - medium - Every gate keeps a record of who it stopped.
Twice Over - medium - Same model, trained twice.
Two Names, One Campaign - easy - The ad team and the push team never agreed on naming. Find where they secretly meant the same thing.
Two Names on the Ledger - easy - Two accounts. One ledger. Watch the spend stack up.
Two Sides of the Ledger - hard - Two cost tables, one region. Which way does the balance tip?
Two-Way Street - medium - A conversation reads the same from either side.
Unclicked Searches by Campaign - medium - Searched but never clicked.
Under the Line - medium - Twice the average is the ceiling. Find the teams comfortably beneath it.
Under the Same Name - easy - The same state wears different casing. Read the latency behind each one.
Unique Hostnames per Region - medium - How many distinct machines live in each region?
Unique Reporters per Content - medium - How many people flagged each item?
Unique Searchers - easy - How many users actually searched?
Unique Stream Topics - easy - A clean inventory of streaming topics.
Unique Visitors - easy - Which months actually had an audience?
Unmatched Categories - easy - Categories with nothing on the shelf. Empty aisles.
Unmatched Deploy Services - medium - Two registries. They do not agree.
Unreviewed Models - easy - Models that have never been evaluated.
Unsold Product Categories - medium - Dead inventory inflating storage costs.
Until Relieved - medium - Every deploy stands its post until the next one arrives. Find the ones that stood longest.
Unused Read Tokens - easy - Active tokens that nobody uses.
US-East KV Store Entries - easy - KV store inventory. us-east-1.
User 360 - hard - One row per user. Everything they did, or didn't do.
User Age Ranking - easy - Age brackets, stacked from top to bottom.
User Devices - medium - Desktop, mobile, tablet. What does each user actually use?
User Engagement Summary - medium - Sessions plus searches. The full engagement picture.
User Roster - easy - Which account states are bleeding users?
User Session Roster - easy - Every user paired with their sessions, even users who never logged in
User Sessions on Specific Days - easy - One user. Specific days. What happened?
Users Outperforming Control - medium - Treatment beat control. For these users.
User Spend Audit - medium - One user. One category. Total spend.
Users Per Device Type - easy - Users per device. The split.
Users Who Churned in February - hard - Gone in February.
Users Who Clicked Ads - easy - Ad clickers and their account details.
Users With Admin Tokens - medium - Admin tokens. Who holds them?
Users With and Without Ad Clicks - hard - Clicked an ad versus never clicked. The split.
Users With API Errors - medium - Count unique users who have triggered an API error response
Users Without Purchases - medium - How many registered users have never made a single purchase
Users Without Sessions - medium - Account created. Never logged in.
Users With Purchase Events - easy - At least one purchase. That changes everything.
User With Most Transactions - medium - The most active buyer.
Verbose by Design - hard - Some paths say in six segments what others say in two.
Verify Commit ID Uniqueness - easy - Duplicate commit IDs. Are there any?
View Count Per Page - easy - Every page has visitors. Some just have more.
Views by Content Type - medium - Count content views broken down by content type
Views by Specific Users - easy - Retrieve all content views for a set of flagged user accounts
Weekend Warriors - easy - Weekdays vs. weekends. When does the action really happen?
Weekly Build Status Report - hard - Every CI run, bucketed by week.
Weekly Transaction Volume - easy - Weekly volume. The pulse.
Welcome Wagon - easy - How many signed up this year?
Whale Watch - easy - The accounts driving the top line.
What Fills the Feed - medium - Every slot in the catalog is a bet. See which format keeps winning it.
What Never Arrives - easy - Every run reads more than it delivers. Find the pipelines bleeding the most between the door and the destination.
What Set It Off - easy - Every build has a cause. Tally the work behind each one.
What's in a Name - easy - The first letter is a fingerprint. Read the crowd by it.
What the Shelf Never Sold - medium - Some products never moved a single unit. They still belong on the report.
When It Rains - medium - The worst failures never arrive alone.
When They Opened - medium - Push after push goes out. Some months, people actually read them.
Where in the World Are Our Customers? - medium - One country dominates the logo wall. Or does it?
Where the Bill Settles - hard - When a handful of giant charges skew the average, the middle tells the truth.
Where the Data Breaks - medium - Every dataset has a weak point. Surface the ones the checks already caught.
Where the Exports Land - easy - Every export run ends somewhere. Tally the endings, loudest first.
Where the Fleet Lives - medium - Six regions on the map. Where does the fleet cluster?
Where the Heat Pools - easy - Across the fleet, some regions run hotter than others.
Where The Lights Stay On - medium - Every region promises reliability. See which ones keep it.
Where the Minutes Go - hard - Attention piles up device by device. Find where it pools.
Where the Money Burns - medium - Some services quietly burn more than the rest.
Where the Money Goes - hard - Every provider has one service quietly eating the budget. Find it.
Where the Money Pools - medium - Top spenders in one region.
Where the Money Sits - medium - Every team carries a cost, and some of it is what keeps the servers running.
Where the Money Went - medium - Allocated on paper. Spent for real. Reconcile the two.
Where the Noise Lives - easy - Some days are noisier than others.
Where The Rows Go - easy - Every run loses a little on the way. Measure what makes it through.
Where the Signal Drops - medium - Every endpoint answers. Some just answer wrong. Find the ones dropping the most.
Where the Talking Stops - easy - Which channels are ghost towns?
Where the Year Leans - medium - Some teams file early, some file late. See which way each one tips.
Where Users Linger - easy - Attention is the scarcest resource. Find the platform that holds it longest.
Where We Left Off - medium - Every user has a last visit on file. Surface the state you last saw them in.
Where You Stand - easy - Each service versus its region's average.
Who Comes Early - easy - Every year opens with a wave of new names. See how the first seven months compare.
Who Moved the Needle - medium - In every experiment, a handful of users carry the result. Find them.
Who's Holding Up Traffic - medium - Some endpoints carry the product. Others are barely touched.
Who's Looking - easy - Every search is a question someone needed answered. Count the people asking.
Who Stayed - hard - Day after day after day. Who kept coming back?
Who We Reached - easy - Monthly reach, campaign by campaign.
Workers Earning Above Department Average - medium - Earning above the department average.
Yearly Output - easy - Publishing velocity for the board deck.
Year-over-Year Content Launches - medium - Launch velocity, year over year.
Yesterday's Crown - hard - Every dawn inherits the spending of the day before.
Yesterday's Weather - hard - The forecast was off. By how much?
Zero-Retry Job Ratio by Priority - hard - No retries needed. First try success rate.

Pipeline Architecture (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.
A Stream All Day and a File at Midnight - hard - Real-time and batch. Same pipeline. No compromises.
Badging Items That Already Sold Out - hard - Same-day delivery. The features have to be faster.
Basel, CCAR, and Monday Morning - medium - The regulator does not accept 'eventually consistent.'
Before the Batch Is Lost - hard
Bikes Before Rush Hour - hard - Bikes in, bikes out. The city needs to predict demand.
Counted Once, Remembered Forever - hard
Credit for Every Touch - medium - They saw the ad, clicked the email, then bought. Who gets credit?
Disappearing Ink - easy
Doubling Every Six Months - hard - Tuesdays are quiet. Black Friday is not.
Eight-Hour-Old Positions - hard - Positions shift by the second. The math cannot lag.
Eight Teams, Eight Latencies - medium - Millions of gamers. The architecture decision changes everything.
End of Day Is Too Late - medium - Every swipe tells a story.
Equities, ETFs, and the SEC - hard - Fractional shares, multi-currency, point-in-time. All of it.
Event System for Multiple Consumers - hard - One event, many hungry consumers.
Every Dataset Needs a Paper Trail - hard - The FDA has opinions about your data pipeline.
Every Deal Is a Financial Transaction - hard - Real money on the table. Reconstruct every hand.
Every Device, Every Impression - hard - Every ad seen. Every second watched. Real-time.
Every Device Has Its Own Dialect - medium - Three sources. Three formats. Same workout.
Every Firm Formats It Differently - medium - The regulator changed the format. Again. Handle it.
Every Format Imaginable - hard - PDFs, HL7, JSON. All of it lands in the same lake.
Everyone Wants the Same Data, Differently - hard - How you store it decides how fast you can read it.
Every Region Exports Its Own Way - medium - Sales data, BigQuery, Dataflow. Make it all sing.
Every Scan, Every Parcel, Every Pin Code - medium - Out for delivery. Delivered. Except the events arrived backwards.
Everything Lands, Then It Ships - medium
Every Version of You - medium
Fifty Thousand Retailers - medium - Retail data at CPG scale. Every SKU, every store.
Five Times the Traffic, Five Times the Bill - hard - Scale up when needed. Do not bankrupt the team.
Five Years of Cron Jobs - hard - Half the jobs run on cron. Half run on events. All of it has to move.
Flying Blind Until Midnight - hard - Intraday risk, full lineage. The regulator is watching.
Four Teams, One Topic, No Agreement - hard - Everybody is writing to it. Nobody documented it. Now production is fragile.
Fresh and Forever - medium
Greenfield Build for Six Sources - hard - Infrastructure as code. Meaning as a service.
Half a Million Rental Cars - medium - Every vehicle is reporting. Every rental matters.
Listens From Everywhere, Counted Once - hard - Phones, tablets, laptops. And some of them report late.
Live Viewers, Live Billing - hard - The stream is live. The data cannot wait.
Mark to Market - medium
Near-Real-Time Trending Dishes Dashboard - hard - The dish rankings update faster than the kitchen.
Nightly Exports Are Too Slow - medium - Healthcare claims change constantly. The warehouse cannot fall behind.
Not Every Team Can See Every Row - hard - Everyone can see the bucket. Not everyone should.
One Bill Across Three Clouds - medium - AWS, Azure, GCP. Three bills. One truth.
One Earthquake, Ten Thousand Tweets - hard - The firehose is on. Separate signal from noise.
Out of the Data Center - medium - The on-prem servers are not getting any younger.
Prove the Number Is Right - hard - Bad data in fintech is not just messy. It is expensive.
Real Data, Fake Patients - hard - Dev needs production data. HIPAA says absolutely not.
Recommendations Now, Royalties Later - medium - The catalog updated. Did anyone notice?
Replicate It Without Breaking It - hard - The source changed. The lake needs to know immediately.
Risk Models on Week-Old Data - medium - Loan approved. Loan denied. Every decision is an event.
SaaS API Connector with Incremental Sync - medium - The API has rate limits. You have deadlines.
Same-Day Sales, Every Store - medium - The cash register data needs to be queryable by morning.
Score It Before It Clears - hard - The fraudsters move fast. Your pipeline has to move faster.
Seconds and Months - medium
Seconds to Trend - medium
Ship Before Fraud Finishes Checking - hard - The claim looks clean. The fraud model disagrees.
Six Hours to Miss a Deadline - medium - The rebuild works. It just doesn't finish in time.
Six Hours to Refresh Every Number - medium - Ratings change. The incremental model has to keep pace.
Six Million Rows Before the Market Opens - medium - One massive CSV. Millions of timestamps.
Six Sources, One Platform - medium - ADF orchestrates. Unity Catalog governs. Nothing leaks.
Sixty Minutes, Every Hour - medium - Every hour, on the hour. No excuses.
Someone Else's Server - hard
Store, Site, and Distributor - medium - Sales data is piling up. Someone has to make sense of it.
The Acquisition Still Taking Bookings - hard - Two systems, two schemas. One truth.
The Agency That Changes the Columns - medium - The schema changed overnight. Again.
The Analysts Cannot Touch Production - medium - Production is the source. Analytics needs its own copy.
The Analyst Who Saw the Salary Data - hard - Two incidents. One shared lake. The access model was never designed, just assumed.
The API Drip Feed - medium - The API gives you 100 records at a time. You need millions.
The Bad Row That Broke the Dashboard - medium - Bad records cannot reach the warehouse.
The Binding and the Claim - medium - Policies are instant. Claims take their time.
The Booking That Came Three Ways - hard - PMS, OTA, and website all think they took the reservation first.
The Boutique That Sold in Six Currencies - hard - Every sale is real. The rate it was converted at depends on who is asking.
The Bucket Full of Resumes - medium - A thousand resumes. Structured data inside each one.
The Carrier Moving to Azure - medium - Claims arrive messy. The medallion cleans them up.
The Claim That Picks Its Own Lane - medium - Three entry points. Different workflows. All must route correctly.
The Clicks We Throw Away - hard - Every tap, swipe, and scroll. At scale.
The Clock That Runs Two Ways - hard - Nightly batch and live events. One dashboard.
The Consent Stitcher - medium - Consent was given. Or was it? Stitch the records together.
The Dashboard and the Attribution Model - hard - Streaming and batch. One pipeline to rule them.
The Decision Before the Door Closes - hard - The window to stop it is smaller than you think.
The Distributor Filing Problem - medium - Hundreds of suppliers. One warehouse. One deadline.
The Early Warning - medium
The Event Pile - hard - 600 million clicks a day. The budget is not infinite.
The Fare Aggregator - medium - Airfares shift every minute. Catch the best ones.
The Firehose and the Ledger - hard
The Fleet That Never Stops - hard - Every truck is talking. Not everyone can hear them yet.
The Identity Problem - hard - Old systems. New demands. The same customer appears under three different names.
The Leaderboard That Costs $25K a Month - hard - Product wants it live. Engineering has a price tag.
The Ledger and the Live Wire - hard
The Living Table - medium - Data lands continuously. History must survive every update.
The Meal Kit That Knows You - medium - What they ordered says a lot about what they want next.
The Metric That Moved - medium
The Migration That Cannot Break Morning - hard - It all works today. Moving it without losing a single report is the hard part.
The Models Going Stale - hard - The model is only as good as what you feed it.
The Morning File - medium
The Next Track - medium
The Panel and the Set-Top Boxes - hard - Set-top boxes tell you who watched. Projection tells you how many.
The Patients We Cannot Move - hard - Patient data stays local. Insights have to be global.
The Points Arrive Two Days Late - medium - The bank data shows up late. The rewards were already sent.
The Provider That Sometimes Sleeps - medium - The models run at dawn. The data has to be there first.
The Query That Used to Be Fast - medium - Queries used to be fast. Something changed.
The Queue That Wouldn't Stop Growing - medium - 500,000 messages behind and the number keeps climbing.
The Register Never Sleeps - medium - Every swipe lands in the warehouse. The table has to stay current without breaking.
The Revenue That Was Wrong for Two Weeks - medium - Nobody caught it until the CFO asked a question. Design the system that catches it first.
The Sale That Needs to Land Now - medium - Three channels feeding one view. Not all of them speak the same language.
The Same Stream Twice - hard
The Signals That Power Recommendations - medium - Fresh signals, many teams, one pipeline.
The Speed Layer - medium - Dashboards can't wait for raw logs. Something has to happen upstream.
The Thirty-Second Rule - medium
The User Who Asked to Be Forgotten - hard - Users want their data erased. Completely.
The Vendor Who Never Warns You - medium - Every month, something is different. The dashboards have no idea.
The What-If Machine - hard - A million slots. A thousand campaigns. Every combination matters.
The Whiteboard Exercise - medium - Marker in hand. Draw the whole thing.
Thirty Cities, One Forecast - hard - Five cities. Five data formats. One prediction.
Thirty Countries, One Solvency Number - hard - Premiums collected globally. Losses happen locally.
Thirty Million Unique Jobs a Year - hard - One press run, many orders. Group them right.
Thousands of Practices, One Dataset - hard - Patient records in, operational insights out.
Three Providers, One Workout - hard - The same ride, reported three times.
Three Regions, One Finance Team - hard - Payments from everywhere. One consistent report.
Three Regions, One Report - hard - Three regions, billions of payments, one merchant summary by 6 AM.
Towers and Phones, Same Story - hard - Tower signals meet app events. Somewhere in between is the truth.
Traders, Risk, and the Regulators - medium - Markets move in milliseconds. The pipeline has to keep up.
Two Hundred Million Redirects - medium - Billions of clicks. One tiny code. Two very different clocks.
Two Million Boxes by Monday Morning - hard - Shipped, maybe. Delivered, debatable.
Two Sources of Truth - medium
Two Systems, One Room Count - hard - Two booking systems. Rooms do not duplicate themselves.
Two Ways to Catch a Change - medium - Two ways to watch the database. Each has a cost.
Two Years of Clicks, Cheap - hard - Two years of clicks. Every query has to be affordable.
Two Years of Every Click - hard - Every click, every aisle, every day for two years.
Under One Roof - hard
What Everyone Is Watching - hard - Someone is watching. Capture everything.
What Should We Recommend Tonight - hard - They ordered pad thai twice. That means something.
Where Is Every Truck, Right Now - medium - Trucks are moving. Every ping counts.
Where the Crowd Goes - medium
Which Promotion Is Actually Working - hard - Was the promotion worth it? The data knows.
Who Is Churning and Why - medium - Subscribers churn. The pipeline cannot.
Who Saw the Ad Twice - hard - TV and digital. Same viewer, two measurement worlds.

Python (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.
Birds of a Feather - medium - Every record finds its kin; keep them in the order they arrived.
By What They Answer To - medium - Every name reports to its first letter. Sort the roll call as it comes in.
Caesar Shift Check - easy - The key turns. Does it open?
Carrying Forward - medium - The total grows with every row.
Carry the One - medium - In grade-school subtraction you scribble a mark each time you borrow. Recover those marks.
Char Profile - medium - Every character in the string tells a story.
Closing Bell - medium - Every share you own, priced at today's close. Tally the gains.
Closing Time - easy - Every bracket you open is a promise. Check that the parser keeps all of them.
Column Range - easy - From minimum to maximum. What is the spread?
Corner to Corner - medium - A grid pressed flat still remembers its corners.
Detect Outliers - medium - Most values are normal. Some are suspicious.
Dice Roll Scoring - medium - The pattern rewards the patient.
Dictionary Key Intersection - medium - Two dictionaries. What do they share?
Double Duty - medium - Split the money. Some wore two hats.
Downstream - hard - Nothing runs until what it needs has run.
Down the Line - medium - Load has to keep moving. Pass it down the line.
Even Filter - easy - Only the even ones survive.
Every Line on the Receipt - medium - Nested deep inside the receipt. Pull every item out.
Everything Beneath - medium - Every account carries the weight of all it contains.
Everything Said Twice - easy - Every word leaves a mark. Count who keeps coming back.
Everything That Repeats - easy - Say it once, then say how many times it stayed.
Every Trace - medium - It is in there somewhere. Where exactly?
Execution Timer Wrapper - medium - Function wrapped with a timer. Duration captured on exit.
Explode List - easy - One row holds many values. Unpack it.
Extract Domain - easy - The domain is buried in the string.
Extract Leaf Values - medium - The tree has leaves. Pluck them.
Faces in the Crowd - medium - New arrivals keep showing up. Count the ones you have not seen yet.
Familiar Faces - easy - The same signals keep coming back. Count how often they meet.
Familiar Ground - medium - Keep walking. Sooner or later you may recognize where you're standing.
Find Mode - medium - One value appears more than the rest.
Footprints in the Feed - medium - Every trade left a footprint.
Full Circle - medium - Follow the chain long enough and it might loop back.
Greeting Formatter Class - easy - First impressions are formatted carefully.
Group Average - hard - Same group, different values. What is typical?
Hands Apart - easy - Two hands. One gap. One number.
Hidden Depths - medium - Each dot marks a level. Rebuild the tree it stands for.
Higher Ground - medium - Somewhere the ground stops climbing.
High Water - easy - Every reading remembers the highest that came before.
High Water Mark - easy - Even below zero, one reading still stands above the rest.
Holding the Center - hard - The middle value keeps moving as new data arrives.
Into One Stream - easy - Some arrive alone, some in batches. Line them all up.
Letters in the Noise - easy - Case and punctuation are distractions. Find what each letter really weighs.
Max Length Token - medium - The longest token wins.
Members Only - easy - Every digit wants in. Only the odd ones make the cut.
Merge Counters - medium - Two tallies. Combine them.
Moving Day - hard - Old schema in, new schema out.
Never Walk Alone - easy - Every step is measured against the one before it.
Next in Line - medium - Every server gets its turn. Keep the line honest as the pool changes.
No Days Off - medium - Show up every day. Miss one and the count starts over.
No One Left Behind - medium - Every record stays; fill the gaps where a match exists.
Normalize Name - easy - Names are messy. Standardize them.
No Shortcuts - easy - The peak value. Built-ins off the table.
No Vacancy - hard - Every booking needs a room. Find the busiest moment.
Null Counter - easy - How many holes in the data?
One Step Behind - medium - What came before this row?
Open and Shut - easy - Every opener is a promise. The order you close them in decides whether it holds.
Ordered Character Check - easy - Check if all As appear before all Bs.
Out of Nowhere - hard - Every stream has a rhythm. Find the readings that break it.
Parse Log Line - medium - One line. A dozen fields hidden inside.
Points of Order - medium - Every page makes its case for the top. Settle it, and settle the ties.
Precision and Recall - medium - Precision and recall. Both matter.
Prefix Based Word Replacement - medium - Every word trimmed to its root.
Progress Milestones - easy - Progress at every 10% increment. Keep the receipts.
Quality Gate - easy - Not everything passes inspection.
Quantile Calculator - easy - Mark the boundary value at a given point.
Read Both Ways - easy - Placeholders hide in plain sight. The symmetric ones give themselves away.
Reads The Same Both Ways - medium - Somewhere in the noise, a stretch that mirrors itself. Find the longest one.
Record Filter - easy - Some records belong. Others do not.
Rename Keys - medium - Old names out. New names in.
Reverse Field - easy - Flip it. See what happens.
Right of Way - medium - Every packet asks the same question of the firewall. Answer it the way the table intends.
Roots and Branches - medium - Flat strings carry a hierarchy. Recover it.
Round and Round They Go - medium - Each face waits its turn as the wheel comes back around.
Row Aggregates - medium - Each row holds its own summary.
Sanitize Field - easy - Dirty input. Clean output.
Schema Checker - easy - The schema says one thing. The data says another.
Shortest Unique Metric Tag - medium - One token per metric. Make it unambiguous.
Single Element Among Pairs - easy - One element has no partner.
Single File - easy - However deep the nesting, every voice arrives in its own turn.
Skip a Beat - easy - Two in a row is never allowed. Collect the most from what remains.
Sort Descending - easy - Biggest first. No exceptions.
Steady State - medium - Turn a jittery stream into a calm read, one step at a time.
Stock Range Finder - medium - Prices move. One stretch had the widest gap.
Subarray Signal - medium - One stretch carries the strongest signal.
Sum of Their Parts - medium - A stream of raw actions, folded into one portrait per person.
The Account Manager - easy - Deposits, withdrawals, and a ledger you can walk back.
The Additive Chain - easy - Each value is the sum of the two before it - no calls to itself allowed.
The Address Surgeon - easy - One string hides a street, a city, a state, and a zip.
The Alphabet Score - easy - Every letter has a secret numeric value - what's your total?
The Alphabet Sorter - easy - Filing cabinet logic: everything goes in its proper drawer.
The Balanced Inspector - medium - Every branch should carry the same weight.
The Balanced Sum - easy - Some numbers have a rare quality that mathematicians revere.
The Bipartite Test - medium - Can this crowd be split into two perfectly separated groups?
The Bit Counter - easy - How many lights are on in the binary representation?
The Bit Reverser - medium - Sometimes the answer is literally backwards.
The Bitwise Judge - easy - No division, no modulo - just a single bit tells you everything.
The Blind Multiplier - medium - Compute the result of everything around you - without seeing yourself.
The Bonus Round - medium - Consecutive matching dice rolls trigger a special scoring rule.
The Bouncer - easy - Every door has a guest list.
The Bronze Medalist - easy - Not first, not last - somewhere in the middle of the podium.
The Bug Spotter - easy - It compiles. The answer is still wrong.
The Build Order - medium - Some tasks must wait for others to finish first.
The Calendar Sort - easy - Time has its own opinion about order.
The Carousel - easy - Keep moving, same ride.
The Chain Transform - medium - One small step at a time can cover a great distance.
The Change Tracker - medium - Before and after snapshots. The delta is in there.
The Character Clans - medium - Words sharing the same letters belong to the same clan.
The Character Map - easy - Every character leaves a trace. Add them up.
The Chunked Reader - medium - Too big for one payload. Ship it in pieces.
The Cipher Wheel - easy - Every letter has an alias - you just need the right codebook.
The Clock Examiner - medium - Two hands on a clock: how wide is the gap?
The Code Expander - easy - Compressed messages need a decoder to come alive.
The Coin Vault - medium - Exact change only - and you want to use as few coins as possible.
The Column Shuffle - medium - Rows in, columns out. Number them.
The Column Transformer - easy - Each column gets its function.
The Complement Hunt - easy - Every number is looking for its other half.
The Config Blender - easy - Config collision. The surviving values after a merge.
The Counting Machine - medium - It knows where it stopped last time.
The Crowd Favorite Eatery - easy - One restaurant clearly won the most hearts.
The Crowd Pleaser - easy - One value shows up more than all others combined.
The Crowd Splitter - easy - The middle holds even with a dominant outlier.
The Custom Iterator - medium - Some sequences follow their own rules.
The Date Sorter - medium - Jumbled calendar. Sort it first.
The Decomposer - easy - Every composite thing can be broken down to its simplest parts.
The Deep Config - medium - Every setting has a path. Trace it down to the value.
The Deep Dictionary - easy - One key goes further than the rest.
The Deep Dive - easy - A specific position in the unsorted pile.
The Deep Selector - easy - Tell it what you want. It knows where to look.
The Deep Unpacker - easy - Boxes inside boxes. Eventually you reach the bottom.
The Dependency Resolver - medium - Everything depends on everything.
The Depth of Field - easy - Some containers hold containers that hold containers.
The Diagonal Accountant - easy - Two diagonals cross in the center of every square.
The Dict Comparator - medium - Two dictionaries. Subtle differences.
The Disputed Fare - medium - One charge, two legs. Finance needs to know which two.
The Dominant Signal - easy - Hottest items in the transaction log. Ties included.
The Double-Ended Gateway - medium - Some queues let you skip the line from both ends.
The Dynamic Container - hard - Grow your own storage before the standard library does it for you.
The Elevator Trace - medium - Nested floors. One path through.
The Email Ranker - medium - Some inboxes see more action.
The Encoded Signal - medium - Letters folded into digits, counts hidden in the punctuation.
The Even Checkpoint - easy - Is this number in the even club? Prove it the fast way.
The Event Bucketer - easy - Logs slotted into buckets.
The Event Window - medium - A five-minute window is all that matters.
The Eviction Policy - medium - Fixed capacity. The key left idle longest is the one that goes.
The Exception Handler - medium - Good code handles failure as gracefully as success.
The Expander - easy - What goes in small comes out big.
The Face That Breaks the Bank - medium - Roll enough dice and one number always runs away with it.
The Fallback Layer - easy - When the live values come back empty, something has to stand in.
The Family Reunion - medium - Two cousins share a common ancestor somewhere above.
The Fast Climber - medium - Some routes up the mountain are faster than others.
The Field Counter - easy - Some fields speak louder than others.
The File Size Profiler - medium - File types and their disk footprint. One type dominates.
The Fine Print - medium - Risk rules nest deep. Decide which transactions clear them.
The Firehose - medium - A stream arrives out of order. Roll it up, one time window at a time.
The First Class Function - medium - Functions travel as values - prove you can pass one around.
The First Encounter - easy - Every character has a story - but only if you remember where it started.
The First of Their Kind - easy - When the same record arrives twice, only the first one survives.
The First Stranger - easy - In a crowd, the unique ones stand out first.
The Flat Mapper - medium - Nested values. One flat stream out.
The Forbidden Ceiling - easy - Round up. But not the obvious way.
The Forbidden Sorter - medium - Put the letters in order without the obvious tool.
The Forgetful Machine - medium - It remembers everything, until it does not.
The Forward Fill - easy - Patch the gaps in a noisy sensor stream.
The Frequency Eviction - hard - When storage is tight, something has to go.
The Fuller Copy - medium - The same listing lands twice, half-filled each time. Keep what is whole.
The Gap Filler - easy - Fill the Nones with the last real value.
The Gaps Between - hard - The data is not as clean as it looks.
The Gate Keeper - easy - Not all openings have a closing.
The Generous Ones - medium - The generous ones are obvious.
The Grid Pivot - easy - A different angle reveals a completely different picture.
The Half-Life Search - medium - Every guess cuts the problem in half.
The Halftime Score - easy - Middle value of a dataset. No built-in shortcuts.
The Hash Stamper - easy - One input, one irreversible output - the foundation of every secret.
The High Mark - easy - Scan the list. Report the max.
The High Rollers - medium - Not every gambler bets the same - some wager far more than others.
The Horizon Scanner - medium - For each position, what is coming up ahead?
The Hostile Takeover - medium - One dict eats another.
The Hourly Bucket - medium - Timestamps belong somewhere.
The Indivisibles - easy - Numbers that yield only to themselves.
The Infection Spread - hard - It starts with one, and then it spreads.
The Integer Sieve - easy - Not everything in this list belongs here.
The Intervals - medium - Timestamps in buckets.
The IP Validator - easy - Real and fake, mixed together.
The Island Counter - medium - Surrounded by water, connected by land - how many separate landmasses?
The Last Instance - easy - When duplicates appear, only the last one counts.
The Last Known Good - medium - When a column goes quiet, its last reading keeps standing.
The Last Seen Map - easy - For each character, where did it appear last?
The Lazy Squares - easy - A sequence that never fully reveals itself.
The Lazy Stream - hard - Some slots hold one value, some hold a batch. Level them out.
The Lazy Unpacker - medium - Peel back every layer until only the values remain.
The Letter Census - easy - Every crowd has its share of talkers and quiet ones.
The Letter Frequency Map - easy - Count every character in the string and report the results.
The Letter Kin - medium - Words that share the same letters belong together.
The Letter Ledger - easy - Every character has a count to answer for.
The Letter Mapper - medium - A consistent substitution, or not.
The Letter Tally - easy - Each character in the string has a count to answer for.
The Level Inspector - medium - Each floor of the tower tells a different story.
The Level Summer - medium - Every tier of the hierarchy keeps its own total.
The Line Cutter - easy - Did everyone with an A-pass get through before the B-crowd arrived?
The Line Splitter - easy - Comma-separated truths, one at a time.
The Link Shrinker - medium - Long addresses have aliases - you give them out, you keep the map.
The Listeners - medium - Subscribers show up, listen, and sometimes leave.
The List Merger - easy - No shortcuts.
The Log Decoder - easy - Every line holds a secret.
The Log Pulse - easy - Some lines repeat themselves.
The Lone Character - easy - It appeared exactly one time. That made it special.
The Lone Traveler - easy - One character stands apart from the crowd.
The Long Run - easy - Say it once, then say how many times it kept saying it.
The Long Way Around - easy - Anyone can call the function. Order it by hand.
The Loudest Voice - medium - One event type is drowning out the rest. Find it.
The Low That Came Too Late - easy - You only get to buy before you sell. Find the biggest gain the day allowed.
The Map Reducer - medium - Map it. Reduce it. One answer.
The Market Streak - medium - Some stocks run longer than you think.
The Market Timer - medium - Buy low, sell later. The whole game is when.
The Matching Manifest - easy - Two warehouses, one shipment - only load what's in both.
The Merge - easy - Chaos in. Order out.
The Merge Champion - medium - Many sorted rivers flowing into one.
The Messy Pipeline - easy - The upstream API has no idea what a schema is.
The Middle Ground - hard - The middle value keeps moving.
The Min Tracker - medium - The stack remembers the best it ever saw.
The Minutes Tracker - easy - Some activities eat more time than others.
The Mirror Flip - easy - Sometimes the fastest fix is to swap everything.
The Mirror Image - easy - Flip the tape backwards - start from the end.
The Mirror Index - easy - Every value remembers who pointed to it.
The Mirror Test - easy - Check if a string reads the same forwards and backwards.
The Mirror Words - easy - Each word looks back at itself.
The Missing Number - easy - Something is missing from the sequence.
The Molecule Report - easy - Four letters. A lot of math hidden in the sequence.
The Month-by-Month Snapshot - medium - Every salesperson has a story. The months just tell it sideways.
The Multiplication Trail - easy - Each step multiplies the whole journey.
The Multiplier Rush - medium - Negatives cancel negatives - but only if you keep both in view.
The Narrow Lens - medium - A narrow timeframe. Everything inside matters.
The Nearest Value Mapper - medium - Close enough counts. Ties go low.
The Never-Ending Sequence - easy - Sequence that keeps going. Follow it.
The Numbered Chair - easy - A standing list. Position n holds one entry.
The Number Miner - medium - JSON strings are hiding numeric secrets. Dig them out.
The Number Narrator - medium - Every number has a story in words.
The Number Screen - easy - Some numbers make the cut. Most do not.
The Odd Digits - easy - Hidden inside a mess of characters are a few odd numbers.
The Odd Extractor - easy - Not all numbers from a string are welcome here.
The Ones That Come Back - easy - In a column that promised uniqueness, some values kept their seat. Name them.
The Ones That Count - easy - Not every minute counts. Add up the ones that do.
The One-Timers - easy - Values that never repeated.
The One-Way Street - easy - The longest stretch that never turns around.
The Onion Layer - hard - Peel from the outside in - one ring at a time.
The Online Elite - medium - The top performers are hiding in the data.
The Only Difference - easy - Two versions of the same line. Surface only what changed.
The OOP Pillars Exam - medium - Four principles, one class hierarchy - show you know all of them.
The Op Dispatcher - easy - Name the operation, apply it everywhere.
The Order Enforcer - easy - Some rules say every A must come before every B.
The Order Inspector - medium - A binary tree has rules - is this one actually following them?
The Original Keeper - easy - Clean up duplicate events without losing the timeline.
The Output Peak - hard - One stretch outpaced all the others.
The Overlap - hard - Overlapping windows are one outage. Collapse them into the truth.
The Overlap Finder - easy - Two guest lists - who made it onto both?
The Overwritten Hour - medium - The log wrapped on itself. The order is still there, just not where you would look.
The Page Turner - medium - Nobody loads everything at once.
The Paired Doors - easy - Every door you open is a promise to close it, in order.
The Parentheses Factory - medium - Building balanced brackets is an art form.
The Pascal Row - easy - Each number is the sum of two numbers above it.
The Password Builder - easy - Random characters, fixed rules.
The Password Forge - easy - Does this password pass the strength gate?
The Path Inward - medium - Every setting hides a few levels down. Follow the route, or come back empty.
The Pay Ladder - medium - Climb the ladder the hard way. No shortcuts allowed.
The Peak Finder - easy - Largest number in the list. Max() is not an option.
The Perfect Match - medium - Two numbers walk into an interview...
The Placement Fixer - medium - Each value belongs in exactly one spot.
The Portfolio - medium - Count every bed under a name. The largest holdings rise first.
The Postfix Processor - medium - Math without parentheses - the operators come after the numbers.
The Precision Hunt - medium - Some answers need no decimal point.
The Price Bander - easy - Different prices, different treatment.
The Priority Queue - medium - When two things tie, something has to break the deadlock.
The Progress Meter - medium - Ten glimpses of a run, no matter how long it ran.
The Progress Parade - easy - Just tell them how far along you are.
The Quarter Turn - medium - One rotation changes everything.
The Queue Disguise - medium - A queue in sheep's clothing.
The Quiet Drift - medium - Two versions of the same truth.
The Quiet Hours - medium - Overlapping outages hide how much time is really dark. Collapse them into the truth.
The Ranked Dict - easy - Values deserve order too.
The Repeat Offenders - easy - Repetition is a clue.
The Repeat Review - medium - The echo came back.
The Repeat Visitor - medium - Loyal customers come back sooner than expected.
The Response Aggregator - medium - Multiple result pages. One clean summary.
The Resume Sifter - medium - Pull what's useful. Skip what you know.
The Roll Call - easy - Every value is waiting for its name.
The Rolling Peak - medium - The sweetest stretch in the sequence.
The Roman Converter - easy - Roman numerals decoded.
The Rotated Array - medium - Someone shuffled it. Now locate what you came for.
The Runaway Leader - easy - Noise scatters in every direction; the true reading is the one that keeps coming back.
The Runner-Up - easy - Not the winner. The one just behind it.
The Running Total - easy - Each position holds the sum of everything before it.
The Safe Caster - easy - Type conversion is easy, until it is not.
The Schedule Cleaner - medium - Overlapping sessions. One clean line.
The Schema Diff - medium - Two versions of the same config - what changed between them?
The Scoreboard Race - medium - The first to cross the line ends the game, mid-round or not.
The Score Sorter - easy - Points on the board, sorted by who earned the most.
The Scramble Check - easy - Same letters, different order - are these two strings secret twins?
The Second Summit - easy - Not the top of the mountain - just below it.
The Secret Twins - easy - Same letters, different disguises.
The Self-Portrait Number - easy - Some numbers describe themselves perfectly.
The Sequel Spotter - easy - Spot the sequels hiding in the catalog.
The Shadow Cleaner - easy - Remove the repeats. No shortcuts.
The Shape They All Share - medium - A pile of exports, no two quite alike. Keep only what every record agrees on.
The Shifting Standard - medium - A benchmark in motion.
The Short Address - medium - Every link needs a slug small enough to type by hand.
The Shortest Path Home - medium - Every leaf remembers the road it came from. Bring them all back on one line.
The Shortest Route - medium - Fewer hops is always better.
The Shortlist - medium - In every field, only a few rise to the top. Keep them.
The Silent Locator - easy - Every lookup should cost you less than the one before it.
The Silver Screen Summit - medium - Box office totals decide who makes the top of the marquee.
The Single Bit - easy - One particular pattern hides in plain sight.
The Slow Leak - medium - Nested groups. One flat stream.
The Sneaky Twins - medium - They look different but they are the same inside.
The Social Graph - easy - Everyone knows someone.
The Solo Act - easy - One-and-done values only.
The Spaces Between - medium - Every voided trip leaves a hole in the sequence. Find the one that matters.
The Spin Doctor - medium - Ninety degrees, but which way?
The Spiral Harvest - medium - The snail reads the grid in its own special order.
The Spread - easy - Data spread around a center. The range matters.
The Squeeze - easy - aaabbb gets old fast. Shrink it.
The Staircase Problem - medium - One step or two, the choices add up.
The Status Board - medium - A pile of raw access logs, and two numbers that matter hiding inside the quotes.
The Step Counter - easy - You can hop one step or two - how many ways to reach the top?
The Streak Breaker - easy - It has a problem with repetition.
The Stream Joiner - hard - Events don't wait for each other. This does.
The String Shrinker - easy - Compress the string. Shorter wins.
The Style Guide - easy - Not every word deserves the same treatment.
The Sum of Its Parts - medium - Every assembly hides smaller ones. Count what it really takes to build.
The Syntax Sentinel - easy - Brackets opened and closed. The nesting might be off.
The Table Thief - medium - Somewhere in that query, tables are hiding.
The Tag Analyst - medium - Two sets of labels, one analysis.
The Tail End - easy - Push, pop, peek. The basics that break people.
The Tail Finder - medium - Navigate to the end of a linked list using recursion.
The Tail Trimmer - easy - Remove the k-th item from the back without counting forward first.
The Tallest Stacks - medium - Every terminal has its records. Find the two that stand tallest.
The Tally Counter - easy - How many times does a single guest show up to the party?
The Target Hunt - medium - Pairs that hit a target. Every one of them.
The Throttle Ceiling - medium - Too many requests in too short a timeframe. Throttle it.
The Throttle Wall - hard - Stop the abusers. Let the rest through.
The Timezone Trap - medium - Trip data and timezones. They're not the same thing.
The Timing Decorator - medium - Wrap any function to capture how long it takes.
The Title Ladder - medium - Job titles and the salary tier they belong to.
The Top Reviewer - easy - One restaurant receives the most feedback - which one?
The Top Words - medium - In every document, some words dominate the conversation.
The Trade Signal - easy - Buy low, sell high. Identify the ideal moment.
The Traffic Director - easy - Spread the load evenly - nobody should be doing all the work.
The Trapped Pool - hard - What collects in the valleys after the rain?
The Tree Measurer - easy - How deep does the rabbit hole go?
The Trip Aggregator - medium - Travel records hold patterns waiting to be surfaced.
The Trip Grouper - easy - Where did everyone go, and for how long?
The Triple Alliance - hard - Three numbers, one target.
The Triplet Hunt - medium - Every path that works gets a seat at the table.
The Type Sorter - easy - A mixed list is hiding its numbers - extract them.
The Unbroken Line - medium - The longest stretch that never repeats itself.
The Value Sorter - easy - The order was always negotiable.
The Velvet Rope - medium - Some users get in. Others wait outside until the window resets.
The Version Parade - easy - 1.0 before 2.0. Don't let the dots confuse you.
The Version Ranker - medium - Software versions follow their own ordering rules.
The Vocabulary Test - medium - Every character has to come from a word you already know.
The Vowel Hunt - easy - Just the vowels. All of them.
The Waiting Game - medium - Patience has a price - and a count.
The Water Collector - hard - Two walls, one sky, and a very important question.
The Water Gauge - medium - Elevation bars trap water in the dips. Total the volume.
The Weight of the Book - medium - Every holding pulls its weight. Order the asset classes by what they carry, and let the ties settle by name.
The Wide View - hard - Long format is easy. Wide format is useful.
The Window Cleaner - medium - Keep it fresh, keep it unique.
The Word Census - easy - Who said what - and how many times?
The Word Counter - easy - How many times does each word show up in a file?
The Word Families - medium - Different spellings, same letters - they belong together.
The Word Flipper - easy - The sentence stays, the words surrender.
The Word Inventory - easy - Every word, twice over.
The Word Map - easy - Language, quantified.
The Yahtzee Engine - hard - Five dice. Six faces. Score it.
The Yahtzee Scorer - medium - Dice scoring. Multiple categories evaluated.
The Zero Propagator - medium - One zero can change the whole picture.
The Zigzag Encoder - medium - The message snakes its way across the rails.
Three That Hold - medium - Not every triangle is a triangle.
Threshold Filter - medium - Above the line or below it.
Top-Heavy - medium - The widest row leads, and everything below it narrows.
Top N Keys - medium - Most of them do not matter. The few that do stand out.
Transform Column - easy - Same data, new shape.
Twice on the Wire - easy - A dropped ACK makes the reader say it again. Keep the signal, drop the echo.
Unbroken - easy - A single dip resets the clock. Find the longest the machine held steady.
Unique Values - easy - Duplicates are noise. Remove them.
Validate Email - medium - Looks like an email. But is it?
Value Count - easy - How many of each? Count them.
Ways of Reading - medium - One key, no separators, and more than one story it could tell.
What Changed Overnight - medium - Schema from yesterday vs today. Something changed.
What's Left Standing - medium - They only meet head-on, and only mass decides who keeps going.
What Stays Warm - medium - Memory is small and the stream never stops. Keep only what was just asked for, in the order it was asked.
What the Card Remembers - medium - A hold on your money is never a single moment. Rebuild the windows it actually lived in.
What the Day Left Open - medium - Every fill moves a position. Reconstruct where the book settled by the close.
What the Night Changed - hard - Two photographs of the same table, a day apart. Account for everything that moved.
What Won't Convert - easy - Some values become numbers. The rest become nothing.
When Hours Collide - medium - Two reservations, one slot. Find every clash.
When the Hours Touch - medium - Two sessions that overlap are really one. Find the windows a driver was actually online.
Where the Buck Stops - hard - A pile of reporting lines, no order to them. Somewhere in the bag sits the one with no boss.
Where the Deltas Settle - medium - Every stretch of the stream tells its own story. Count the ones that settle to your number.
Where the Line Breaks - easy - Every batch has a last piece. Mark it right.
Where the Lines Break - easy - Every record hides its fields behind noise. Pull the real ones loose.
Where the Numbers Settle - easy - The answer moves with the data.
Where They Part - hard - They all start the same way. How far?
Who Came First - easy - The feed repeats itself. Keep each member only the first time it speaks.
Who Gets In - medium - When the roster changes, does access follow?
Zip to Record - easy - Two lists become one record.

Data Modeling (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 Counts - medium - Every beep at the register. Coupons, returns, all of it.
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.
Insurance Claims Lifecycle - hard - A claim gets filed. Then it gets complicated. Then it gets reassigned. Then it loops back.
Lateral Paths - medium - People switch teams. HR loses track.
Marketplace Sales Warehouse - hard - No schema given. The interviewer is watching.
Metric Definition Reverse Engineering - hard - Five numbers on a dashboard. Your job: figure out where they come from.
Multiplayer Game Match History - medium - Millions of matches. The leaderboard refreshes in fifteen minutes.
One Door Each - medium - Every user picks a lane and stays in it. Model the world so the numbers stay honest.
Online Marketplace - Seller Payouts - hard - The buyer paid one number. The seller got a different one.
Open Threads - medium - Every minute tracked. Every app accounted for.
Personal Best - easy - Reps, sets, streaks, and personal bests. Gym rats love their stats.
Property Booking Platform - hard - Five-star listing. Three-star reality.
Retailer Data Warehouse Design - medium - Queries are crawling. The analysts are not happy.
Signal and Silence - medium - They opened the assignment. Did they actually read it?
Telecom Network Connectivity Warehouse - hard - One device goes down. The ripple keeps going.
The Anonymous Majority - medium - Millions of clicks, mostly anonymous.
The Balance Always Reconciles - easy - Money out, payments back. The balance has to be exact.
The Celebrity Problem - medium - One post. A million notifications. Something has to give.
The Churner Who Came Back - hard - They cancelled. They came back. The report has to tell both stories correctly.
The Credits Roll - hard - Searchable from every angle. Design it so nothing gets lost.
The Customer Who Changed - hard - She moved. She upgraded. She became someone new. The record has to keep up.
The Double Count - medium - One flight carries hundreds of seats; one ticket spans many flights. Model them so neither gets counted twice.
The Endless Thread - medium - Follows, likes, replies to replies. It never stops.
The Float - medium
The Gaps Between Clicks - hard - A visit is a story with a start and an end. Draw the model that finds where one ends and who was really there.
The Gift Economy - medium - Someone goes live, thousands tune in, chat explodes, and virtual gifts start flying.
The Heat of the Map - hard
The Hunger Shift - medium - What's everyone eating? The answer changes hourly.
The JSON Files That Became a Data Mart - medium - Three semi-structured inputs. One queryable warehouse.
The Last Mile - medium - Order placed. Now track it to the door.
The League With Too Many Loyalties - hard - A player can belong to many teams. The schema must agree.
The Long Play - medium - They pressed play. What happened next is the whole question.
The Long Route - hard - A package splits, reroutes, and (maybe) arrives.
The Meter's Running - medium - Riders, drivers, and fares. Everyone takes a cut.
The No-Show - easy - Every reserved seat ends one of five ways. Build the model that can tell them apart.
The Other Seat - hard
The Person They Were Then - easy
The Plan That Changed Twice This Month - medium - Subscribers come, go, downgrade, and share. The schema has to keep up.
The Rate That Was - medium
The Retail Blueprint - medium - One business. A thousand transactions. Only one layout survives the analytics layer.
The Sales Architecture - medium - Numbers are easy. Making them queryable at scale is the real job.
The Schema That Could Not Answer Back - hard - Forty columns in. Zero useful answers out.
The Shape of a Run - medium - Two log lines bracket every process. Pair them and the fleet's rhythm appears.
The Slow Yes - hard
The Table That Lies - medium - Every query comes out wrong. The data is all there.
The Talent Funnel - medium - Thousands applied. One accepted. Where did the rest go?
The Territory That Keeps Moving - hard - Reps get reassigned. The receipts have to survive.
The Transfer Request - medium - Apply, wait, get approved or denied. Track all of it.
The Vanishing State - easy - A status column forgets the moment it changes. Model the schema that remembers.
The Vital Few - medium - Two terabytes a day, and the lines that matter are a rounding error in the noise.
Three-Sided Marketplace Delivery Schema - hard - One order. Two deliveries. Revenue counted twice. Where is the bug in your schema?
Time in Force - medium
Trees Within Trees - hard - A file is also a folder. A folder is also a file.
Two Wallets - medium - Two user types. Multiple payment methods. One messy billing table.
When the Music Stops - medium - Subscribers are leaving. The data knows why.
Where Everyone Was - easy - People move. Sometimes twice in a month. How do you remember where everyone was, and when?
Where They Used to Live - medium - They moved. The data stayed behind.
Who Comes Back - medium