Willem Verstraeten focused on improving SQL string matching correctness in the tarantool/datafusion repository, addressing a subtle bug in the StartsWith function. He enhanced the function’s handling of SQL LIKE patterns by implementing proper escaping for underscores, complementing existing percent-sign escapes to prevent unintended wildcard matches. Using Rust and SQL, Willem also expanded the suite of logic tests to cover starts_with with various literals and patterns, increasing test coverage and regression safety. His work did not introduce user-facing changes but improved the accuracy and reliability of string manipulation, reflecting careful attention to data safety and robust testing practices.