Enum datafusion_expr::AggregateState

pub enum AggregateState {
    Scalar(ScalarValue),
    Array(ArrayRef),
}

Representation of internal accumulator state. Accumulators can potentially have a mix of scalar and array values. It may be desirable to add custom aggregator states here as well in the future (perhaps Custom(Box<dyn Any>)?).

Variants

Scalar(ScalarValue)

Simple scalar value. Note that ScalarValue::List can be used to pass multiple values around

Array(ArrayRef)

Arrays can be used instead of ScalarValue::List and could potentially have better performance with large data sets, although this has not been verified. It also allows for use of arrow kernels with less overhead.

Implementations

impl AggregateState

pub fn as_scalar(&self) -> Result<&ScalarValue>

Access the aggregate state as a scalar value. An error will occur if the state is not a scalar value.

pub fn to_array(&self) -> ArrayRef

Access the aggregate state as an array value.

Trait Implementations

impl Debug for AggregateState

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.