Katkat
Back

Design Extensible Spreadsheet Aggregation APIs

GoogleSoftware Engineer · Other
MediumSoftware EngineerOtherSoftware Engineering Fundamentals

Last updated

Design reusable spreadsheet sum, minimum, and maximum APIs with operator state, shared cell evaluation, error policies, and extensible aggregation.

Design an extensible spreadsheet aggregation API supporting get_sum, get_max, and get_min. Explain how a new aggregate can be added without duplicating range traversal and cell evaluation logic.

Constraints & Assumptions

  • Cells may hold values or formulas; aggregation should consume computed values through one evaluation interface.
  • Specify how a range is represented and whether endpoints are inclusive before presenting the API.
  • The source names the three aggregate APIs but does not fix a formula grammar, empty-range policy, or numeric-error policy. State coherent choices rather than claiming those details are given.
  • Concentrate on interfaces, reuse, correctness, and complexity. No distribution or throughput requirement is supplied.

Clarifying Questions to Ask

  • Are aggregations over contiguous rectangular ranges, arbitrary cell lists, or both?
  • What should an empty range, unset cell, nonnumeric cell, or cyclic formula produce?
  • Should future operators include averages or operators that cannot be expressed as a simple binary reduction?

Hints

Hint 1

Separate fetching from reducing: One component should decide which cells are visited and how they are evaluated. Another should own the aggregate's state and its final result.

Follow-up questions

  • What additional property would allow an aggregate to combine partial results from disjoint chunks?
  • How would cached aggregate results become invalid after a referenced cell or formula changes?