Intro to Facebook Search

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This post introduces Facebook Search, detailing its evolution from a basic search function to a sophisticated, user-centric system. It explains the complexities of serving over 150 million queries daily and the decision to build an in-house search service. Key technical challenges discussed include: ranking on the critical path due to the need for real-time personal and social context, the absence of traditional query caching due to the unique [user, query] nature of requests, maintaining a large 'hot' index because most results are relevant to specific users, and the necessity of live updates to reflect constant user profile and connection changes. The post also highlights the growing use of search for discovering entities beyond people, such as bands and applications, and the infrastructure challenges of indexing and filtering recent public and friend content.