Enum AggregateMode 

pub enum AggregateMode {
    Partial,
    Final,
    FinalPartitioned,
    Single,
    SinglePartitioned,
}

Aggregation modes

See Accumulator::state for background information on multi-phase aggregation and how these modes are used.

Variants

Partial

One of multiple layers of aggregation, any input partitioning

Partial aggregate that can be applied in parallel across input partitions.

This is the first phase of a multi-phase aggregation.

Final

Final of multiple layers of aggregation, in exactly one partition

Final aggregate that produces a single partition of output by combining the output of multiple partial aggregates.

This is the second phase of a multi-phase aggregation.

This mode requires that the input is a single partition

Note: Adjacent Partial and Final mode aggregation is equivalent to a Single mode aggregation node. The Final mode is required since this is used in an intermediate step. The CombinePartialFinalAggregate physical optimizer rule will replace this combination with Single mode for more efficient execution.

FinalPartitioned

Final of multiple layers of aggregation, input is Partitioned

Final aggregate that works on pre-partitioned data.

This mode requires that all rows with a particular grouping key are in the same partitions, such as is the case with Hash repartitioning on the group keys. If a group key is duplicated, duplicate groups would be produced

Single

Single layer of Aggregation, input is exactly one partition

Applies the entire logical aggregation operation in a single operator, as opposed to Partial / Final modes which apply the logical aggregation using two operators.

This mode requires that the input is a single partition (like Final)

SinglePartitioned

Single layer of Aggregation, input is Partitioned

Applies the entire logical aggregation operation in a single operator, as opposed to Partial / Final modes which apply the logical aggregation using two operators.

This mode requires that the input has more than one partition, and is partitioned by group key (like FinalPartitioned).

Implementations

impl AggregateMode

pub fn is_first_stage(&self) -> bool

Checks whether this aggregation step describes a “first stage” calculation. In other words, its input is not another aggregation result and the merge_batch method will not be called for these modes.

Trait Implementations

impl Clone for AggregateMode

fn clone(&self) -> AggregateMode

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for AggregateMode

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

Formats the value using the given formatter.

impl PartialEq for AggregateMode

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

impl Eq for AggregateMode

impl StructuralPartialEq for AggregateMode