Enum EmissionType

pub enum EmissionType {
    Incremental,
    Final,
    Both,
}

Represents how an operator emits its output records.

This is used to determine whether an operator emits records incrementally as they arrive, only emits a final result at the end, or can do both. Note that it generates the output – record batch with batch_size rows but it may still buffer data internally until it has enough data to emit a record batch or the source is exhausted.

For example, in the following plan:

  SortExec [EmissionType::Final]
    |_ on: [col1 ASC]
    FilterExec [EmissionType::Incremental]
      |_ pred: col2 > 100
      CsvExec [EmissionType::Incremental]
        |_ file: "data.csv"

• CsvExec emits records incrementally as it reads from the file
• FilterExec processes and emits filtered records incrementally as they arrive
• SortExec must wait for all input records before it can emit the sorted result, since it needs to see all values to determine their final order

Left joins can emit both incrementally and finally:

• Incrementally emit matches as they are found
• Finally emit non-matches after all input is processed

Variants

Incremental

Records are emitted incrementally as they arrive and are processed

Final

Records are only emitted once all input has been processed

Both

Records can be emitted both incrementally and as a final result

Trait Implementations

impl Clone for EmissionType

fn clone(&self) -> EmissionType

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for EmissionType

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

Formats the value using the given formatter.

impl PartialEq for EmissionType

fn eq(&self, other: &EmissionType) -> 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 EmissionType

impl Eq for EmissionType

impl StructuralPartialEq for EmissionType