Function unified_plan_contains_volatile_function 

pub fn unified_plan_contains_volatile_function(
    catalog: &dyn VolatilityCatalog,
    plan: &UnifiedPlan,
) -> bool

Whether scalar optimizer rewrites or DPccp join enumeration must be kept away from a plan. rewrite_scalar_expressions is exhaustive over query, mutation, CTE, prepared/explained, and expression-plan children.