Design Facebook Search

Functional Requirements:

• Users can search for people, pages, groups, and posts using keywords.
• Search results should be ranked by relevance (e.g., connection, popularity, recency).
• Users can filter search results by type (people, posts, groups, pages), time, and other relevant filters.
• Search should support auto-suggestions as users type.
• Search should respect user privacy settings (only show results the user is allowed to see).

Non-Functional Requirements:

• The system should support high availability (99.9% uptime or better).
• Search queries should return results with low latency (ideally < 1 second).
• The system must be able to scale horizontally to handle large numbers of users and queries.
• Search results can be eventually consistent (minor delays in indexing new content are acceptable).
• The system should be fault tolerant and resilient to node failures.