HOW DOORDASH'S IN-HOUSE SEARCH ENGINE ACHIEVED A 50% DROP IN LATENCY

Summary from the TLDR Web Dev newsletter

DoorDash replaced Elasticsearch with a custom-built search engine using Apache Lucene to better handle complex relationships, custom ranking, and large-scale indexing needs. Its architecture separates indexing and search, supports fast segment replication, and includes a declarative schema system with query planning.