Unraveling the Non Deterministic Query Conundrum for Prestissimo Verification

We will present our work on enabling the correctness verification of Prestissimo on non-deterministic queries for Meta’s Presto production release. Non-deterministic queries constitute a large portion of production traffic, yet their results are not comparable between engines and between engine versions, hence posing a big challenge to the correctness verification for Prestissimo. In this talk, we will share how we divide the problem and leverage Presto Verifier and Velox Fuzzer to rewrite non-deterministic queries and verify correctness at the query level and expression level.