Join rides and users to find percentile rank
Last updated: May 14, 2026
Quick Overview
Write a query joining rides and transactions to produce the combined percentile rank.
MongoDB
May 14, 202613
12
1,285 solved
Write a query joining rides and transactions to produce the combined percentile rank.
Data manipulation questions at MongoDB test your ability to work with real-world datasets. This Onsite question evaluates your SQL proficiency, understanding of data modeling, and ability to derive insights from raw data.
What the Interviewer Expects
- Write syntactically correct SQL with proper JOIN and WHERE clauses
- Use GROUP BY and aggregate functions appropriately
- Handle NULL values correctly in your queries
- Explain the query execution plan at a high level
Key Topics to Cover
How to Approach This
- Clarify the schema and expected output format before writing queries.
- Use CTEs (WITH clauses) to break complex queries into readable steps.
- Consider window functions (ROW_NUMBER, RANK, LAG, LEAD) for ranking and sequential analysis.
- Watch for NULLs, duplicates, and edge cases in JOINs and GROUP BY.
- For pandas, prefer vectorized operations over row-by-row iteration.
Possible Follow-up Questions
- How would you optimize this query for a table with 100 million rows?
- How would you handle slowly changing dimensions in this scenario?
- What would you do if this query needs to run every 5 minutes?
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Practice SQL ProblemsSample Answer
Problem Understanding
In this problem, we have two tables: rides and users. The rides table contains information about ride transactions, including ride IDs, user IDs, and ride durations, while the users table incl...
Approach
Step 1: Begin by performing an INNER JOIN on the rides and users tables using the user ID to combine the relevant information.
Step 2: Use a Common Table Expression (CTE) to first calculate the d...
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