The pagination part was fine, I've done that before.
Start by clarifying the API details (pagination style, rate limits, error handling) and the join key. Then outline a solution that fetches pages concurrently or sequentially, handles errors gracefully, and merges records with validation. Finally, discuss trade-offs like memory usage, concurrency, and data cleaning strategies.
Pro tip: Mention that you would use a streaming or generator-based approach to avoid loading all records into memory at once, and that you'd implement retry logic with exponential backoff for transient failures.
Ask about pagination type (offset, cursor), rate limits, authentication, and the expected size of data. Confirm the join key and what 'cleaned' means (e.g., remove nulls, deduplicate, normalize fields).
Decide whether to fetch pages sequentially or concurrently, and how to handle errors (retries, fallbacks). Use a loop or recursive function to retrieve all pages from each endpoint.
Validate each record's structure and the join key before merging. Skip or log invalid records, and handle missing fields by providing defaults or excluding them.
Use a hash map (dictionary) to index records from one endpoint by the join key, then iterate over the other to merge. Apply cleaning rules such as deduplication, type conversion, and filtering.
Talk about memory vs. speed, concurrency limits, and how to scale. Mention potential improvements like caching, batching, or using a streaming approach.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.