Enum EvaluationType 

pub enum EvaluationType {
    Lazy,
    Eager,
}

Represents how an operator’s Stream implementation generates RecordBatches.

Most operators in DataFusion generate RecordBatches when asked to do so by a call to Stream::poll_next. This is known as demand-driven or lazy evaluation.

Some operators like Repartition need to drive RecordBatch generation themselves though. This is known as data-driven or eager evaluation.

Variants

Lazy

The stream generated by execute only generates RecordBatch instances when it is demanded by invoking Stream::poll_next. Filter, projection, and join are examples of such lazy operators.

Lazy operators are also known as demand-driven operators.

Eager

The stream generated by execute eagerly generates RecordBatch in one or more spawned Tokio tasks. Eager evaluation is only started the first time Stream::poll_next is called. Examples of eager operators are repartition, coalesce partitions, and sort preserving merge.

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 Debug for EvaluationType

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

Formats the value using the given formatter.

impl PartialEq for EvaluationType

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Copy for EvaluationType

impl Eq for EvaluationType

impl StructuralPartialEq for EvaluationType