Dragon: A distributed graph query engine

Introduced Dragon, a distributed graph query engine, to address the challenges of high-volume, multi-hop queries on Facebook's social graph. Dragon builds upon TAO by creating various indices to improve the efficiency of fetching, filtering, and reordering data, reducing network transfer and improving latency. It leverages techniques like socially aware inverted indices and optimized storage layouts based on query patterns, and supports functional programming primitives for complex filtering and ordering. Dragon aims to serve queries from cache with high availability and consistency, allowing applications to focus on business logic.