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Google·Software Engineer·Technical Phone Screen·Senior

Senior
May 2026

Summary

Interviewed for a data engineer role at Google. The content was pretty sparse so there's not much to go on, just a topic that came up around top earning employees, probably a SQL or analytics question of some kind.

Questions Asked (1)

Q1

Given an employee dataset, how would you identify or retrieve the top earning employees?

Algorithms & Data StructuresData Modeling
Author's notes

Classic SQL territory.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the problem: what defines 'top earning' (e.g., top N, top 10%, or above a threshold), and what data structures are available (array, SQL table, etc.). Then propose an efficient algorithm, such as using a min-heap of size N for top N, or sorting if N is large, and discuss trade-offs in time/space complexity. Finally, consider edge cases like ties, missing data, and scalability.

Pro tip: Mention that for large datasets, a single-pass heap-based approach is often preferred over full sorting because it runs in O(M log N) time and O(N) space, where M is the number of employees and N is the number of top earners. Also, clarify whether the data fits in memory or requires a distributed approach like MapReduce.

1. Clarify requirements

Ask questions to understand what 'top earning' means: top N, top percentile, or threshold? Also confirm the data format (array, SQL table, stream) and constraints (memory, time).

2. Choose data structure and algorithm

Select an appropriate approach: for top N, use a min-heap of size N; for top percentile, sort or use quickselect; for SQL, use ORDER BY with LIMIT. Discuss trade-offs.

3. Analyze complexity and scalability

Explain time and space complexity of your chosen method. If data is huge, mention distributed processing (e.g., MapReduce) or external sorting.

4. Handle edge cases

Address ties (e.g., multiple employees with same salary), missing or negative salaries, and empty dataset. Decide how to break ties (e.g., by employee ID).

5. Summarize and conclude

Restate your solution, emphasizing efficiency and correctness. Offer to code it if needed.

Key Points to Mention

  • Time and space complexity of heap vs. sorting vs. quickselect
  • Use of a min-heap for top N to avoid sorting the entire dataset
  • SQL approach: SELECT * FROM employees ORDER BY salary DESC LIMIT N
  • Handling ties and defining a tie-breaking rule
  • Scalability: distributed algorithms like MapReduce or using a database with indexes
  • Edge cases: empty dataset, N larger than dataset size, negative salaries

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.