From Presto to Prestissimo: A Velox-Powered Modernization Journey

Presto is a widely adopted, open-source distributed SQL query engine that has powered Meta's exabyte-scale data analytics for over a decade. Over time, as data volumes and workload diversity consistently increased, the original Java-based Presto worker fleet started facing challenges in reliability, performance, and operational efficiency, despite continuous upgrades and enhancements. To overcome these challenges, we created Prestissimo (open-sourced under Presto), a more modern version of Presto, re-engineered to use the Velox open-source composable library; Prestissimo provides a drop-in C++ worker replacement, delivering substantial improvements in query latency, hardware efficiency, and reliability. In this paper, we outline the phased, in-place migration journey that resulted in a full and seamless transition of hundreds of millions of daily large-scale analytic queries, without service interruption or additional hardware. To ensure correctness and reliability, we developed a comprehensive suite of verification tools and testing frameworks, including randomized fuzzers, end-to-end verifiers, and production traffic shadowing. We discuss the challenges of achieving feature parity at scale across different programming languages, how we handled backward compatibility, how pipeline migration was prioritized, and how operational excellence was achieved in a multi-tenant, business-critical environment. The complete Prestissimo migration took about two years, alongside substantial development in both Prestissimo and Velox. With this journey, we have fully decommissioned the legacy Java worker fleet, achieving broad gains including 2–5x faster queries while at the same time cutting down the hardware footprint significantly, and reducing the number of reliability issues in production by an order of magnitude. Prestissimo is today fully rolled out at Meta, and has replaced Presto Java workers in many other deployments across the industry.