Enum EvaluationType 

pub enum EvaluationType {
    Lazy,
    Eager,
}

Represents how an operator’s stream drives RecordBatch production relative to downstream demand.

This is execution-topology metadata for optimizers. It distinguishes streams whose batch production is driven directly by downstream calls to Stream::poll_next from streams that may also drive input or output production independently, such as by spawning tasks or buffering batches ahead of demand.

Variants

Lazy

The stream generated by execute is demand-driven: it produces RecordBatches in response to downstream calls to Stream::poll_next.

Filter, projection, and join operators are examples of lazy operators.

Lazy operators are also known as demand-driven operators.

Eager

The stream generated by execute may drive input or output RecordBatch production ahead of, or independently from, downstream calls to Stream::poll_next.

Eager operators commonly poll input streams from spawned Tokio tasks, buffer batches ahead of demand, or otherwise create an independent child-polling pipeline. Eager work may start when execute creates the stream or when the returned stream is first polled; that timing is an implementation detail.

Repartition, coalesce partitions, sort-preserving merge, buffer, and analyze operators are examples of eager operators.

Eager operators are also known as a data-driven operators.

Trait Implementations

impl Clone for EvaluationType

fn clone(&self) -> EvaluationType

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for EvaluationType

impl Debug for EvaluationType

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

Formats the value using the given formatter.

impl Eq for EvaluationType

impl PartialEq for EvaluationType

fn eq(&self, other: &EvaluationType) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for EvaluationType