Method FirstValIgnoreNullsUpdate

be/src/exprs/aggregate-functions-ir.cc:3631–3637

template <typename T>
void AggregateFunctions::FirstValIgnoreNullsUpdate(FunctionContext*, const T& src,
    T* dst) {
  // Store the first non-null value encountered, unlike FirstValUpdate which always stores
  // the first value even if it is null.
  if (!dst->is_null || src.is_null) return;
  *dst = src;
}

template <>
void AggregateFunctions::FirstValIgnoreNullsUpdate(FunctionContext* ctx,