Method evaluate

datafusion/core/tests/user_defined/user_defined_aggregates.rs:627–629

(&mut self)

    }

    fn evaluate(&mut self) -> Result<ScalarValue> {
        Ok(ScalarValue::TimestampNanosecond(Some(self.sum), None))
    }

    fn size(&self) -> usize {
        // accurate size estimates are not important for this example