Struct datafusion_physical_expr::expressions::Avg

pub struct Avg { /* private fields */ }

AVG aggregate expression

Implementations

impl Avg

pub fn new(
    expr: Arc<dyn PhysicalExpr>,
    name: impl Into<String>,
    data_type: DataType
) -> Self

Create a new AVG aggregate function

Trait Implementations

impl AggregateExpr for Avg

fn as_any(&self) -> &dyn Any

Return a reference to Any that can be used for downcasting

fn field(&self) -> Result<Field>

the field of the final result of this aggregation.

fn create_accumulator(&self) -> Result<Box<dyn Accumulator>>

the accumulator used to accumulate values from the expressions. the accumulator expects the same number of arguments as expressions and must return states with the same description as state_fields

fn state_fields(&self) -> Result<Vec<Field>>

the fields that encapsulate the Accumulator’s state the number of fields here equals the number of states that the accumulator contains

fn expressions(&self) -> Vec<Arc<dyn PhysicalExpr>>

expressions that are passed to the Accumulator. Single-column aggregations such as sum return a single value, others (e.g. cov) return many.

fn name(&self) -> &str

Human readable name such as "MIN(c2)". The default implementation returns placeholder text.

fn row_accumulator_supported(&self) -> bool

If the aggregate expression is supported by row format

fn supports_bounded_execution(&self) -> bool

Specifies whether this aggregate function can run using bounded memory. Any accumulator returning “true” needs to implement retract_batch.

fn create_row_accumulator(
    &self,
    start_index: usize
) -> Result<Box<dyn RowAccumulator>>

RowAccumulator to access/update row-based aggregation state in-place. Currently, row accumulator only supports states of fixed-sized type.

fn reverse_expr(&self) -> Option<Arc<dyn AggregateExpr>>

Construct an expression that calculates the aggregate in reverse. Typically the “reverse” expression is itself (e.g. SUM, COUNT). For aggregates that do not support calculation in reverse, returns None (which is the default value).

fn create_sliding_accumulator(&self) -> Result<Box<dyn Accumulator>>

Creates accumulator implementation that supports retract

impl Clone for Avg

fn clone(&self) -> Avg

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for Avg

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

Formats the value using the given formatter.