Enum datafusion_expr::ColumnarValue

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

Represents the result of evaluating an expression: either a single ScalarValue or an ArrayRef.

While a ColumnarValue can always be converted into an array for convenience, it is often much more performant to provide an optimized path for scalar values.

Variants

Array(ArrayRef)

Array of values

Scalar(ScalarValue)

A single value

Implementations

impl ColumnarValue

pub fn data_type(&self) -> DataType

pub fn into_array(self, num_rows: usize) -> Result<ArrayRef>

Convert a columnar value into an ArrayRef. Self::Scalar is converted by repeating the same scalar multiple times.

Errors

Errors if self is a Scalar that fails to be converted into an array of size

pub fn create_null_array(num_rows: usize) -> Self

null columnar values are implemented as a null array in order to pass batch num_rows

pub fn values_to_arrays(args: &[ColumnarValue]) -> Result<Vec<ArrayRef>>

Converts ColumnarValues to ArrayRefs with the same length.

Performance Note

This function expands any ScalarValue to an array. This expansion permits using a single function in terms of arrays, but it can be inefficient compared to handling the scalar value directly.

Thus, it is recommended to provide specialized implementations for scalar values if performance is a concern.

Errors

If there are multiple array arguments that have different lengths

Trait Implementations

impl Clone for ColumnarValue

fn clone(&self) -> ColumnarValue

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for ColumnarValue

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

Formats the value using the given formatter.

impl From<Arc<dyn Array>> for ColumnarValue

fn from(value: ArrayRef) -> Self

Converts to this type from the input type.

impl From<ScalarValue> for ColumnarValue

fn from(value: ScalarValue) -> Self

Converts to this type from the input type.