Design a Top-K search words service

## Scenario Design a service that tracks user search queries and returns the **Top-K most searched words/queries**. ## Requirements ### Functional - API to **record** a search query event (e.g., user searches "iphone 16"). - API to fetch **Top-K** queries. - Support a time window variant: - (a) all-time Top-K - (b) Top-K over the last **N minutes/hours** (trending) ### Non-functional - High write QPS (search events), low latency reads for Top-K. - Scalable horizontally. - Reasonable correctness (define whether exact or approximate is acceptable). ## Clarifications to address - What is a “word” vs “query” (full string)? - Case-folding, normalization, stop words, punctuation. - Deduping (e.g., multiple searches by same user) or count every event. - Multi-region and eventual consistency expectations.