October 2025 performance summary for apache/calcite. Focused on strengthening query robustness in complex join scenarios by addressing edge cases in correlated subqueries. Delivered a critical bug fix that prevents IllegalArgumentException when correlating subqueries in JOIN ON clauses, particularly when referencing right-hand side columns. The change, tracked under CALCITE-7034, was implemented in commit ff319cf753dbbc122822308fd34ce3b3e3329a84 and accompanied by targeted tests to prevent regressions. This work significantly reduces production failures for complex analytic workloads and improves overall reliability of Calcite's query planning. Technologies demonstrated include Java-based optimizer internals, SQL planning, and test-driven development for subquery correlation scenarios.