Under the Hood: Building out the infrastructure for Graph Search

What this post added

This post details the development of Unicorn, a unified, scalable inverted-index search engine designed to support Graph Search. It describes the migration of legacy search systems (PPS, Typeahead) to Unicorn, the challenges of indexing the Facebook graph (nodes and edges with metadata), and the design of Unicorn's index structure (posting lists, static rank) and query language. It highlights Unicorn's ability to handle multi-hop queries and the real-time update pipeline for indexing over 2.5 billion new pieces of content daily.