Design keyword search for social posts
Company: Meta
Role: Software Engineer
Category: System Design
Difficulty: medium
Interview Round: Technical Screen
Design a Facebook-like **post search** feature:
- Input: one or more **keywords**.
- Output: all (or top-K) posts that **contain** the keyword(s).
- Assume posts are created/updated/deleted continuously and the corpus is very large.
Define APIs, indexing strategy, ranking, and how you would scale the system. You may assume you can build something similar to an Elasticsearch-style solution (inverted index), but describe the components yourself.
Quick Answer: This question evaluates a candidate's skills in large-scale system design, information retrieval and indexing, API design, ranking strategies, and handling real-time updates and consistency for search features.