Window function: rank over date
Last updated: March 18, 2026
Quick Overview
Use window functions to compute rank partitioned by date.
Figma
Data Manipulation (SQL/Python)
Data Scientist
Figma
March 18, 2026Data Scientist
Onsite
Data Manipulation (SQL/Python)
Medium
5
4
3,080 solved
Use window functions to compute rank partitioned by date.
Figma asks this during the Onsite because data engineering skills are critical for the role. You should be comfortable with complex joins, window functions, CTEs, and performance optimization.
What the Interviewer Expects
- Use advanced SQL features: window functions, CTEs, subqueries
- Write efficient queries that avoid common performance pitfalls
- Handle complex data transformations with multiple joins and aggregations
- Discuss indexing strategy and query optimization
- Address data quality issues: duplicates, missing values, outliers
Key Topics to Cover
JOIN types and when to use each
Date/time manipulation
Pandas vectorized operations and groupby
Common Table Expressions (CTEs)
Index optimization and query performance
Subqueries and correlated subqueries
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
- Can you rewrite this without using subqueries?
- How would you validate the correctness of your query results?
- What would you do if this query needs to run every 5 minutes?
- How would you handle slowly changing dimensions in this scenario?
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Practice SQL ProblemsSample Answer
Problem Understanding
The task requires us to compute the rank of records partitioned by date. The dataset likely contains at least a 'date' column along with a value column that we will use for ranking. For example, a tab...
Approach
- Identify the Dataset: Determine the structure of the 'sales' table, including relevant columns for ranking.
- Define the Ranking Criteria: Decide which column to rank by (e.g., 'amount') a...
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