Struct datafusion::physical_expr::expressions::ApproxMedian
source · pub struct ApproxMedian { /* private fields */ }
Expand description
MEDIAN aggregate expression
Implementations§
source§impl ApproxMedian
impl ApproxMedian
sourcepub fn try_new(
expr: Arc<dyn PhysicalExpr>,
name: impl Into<String>,
data_type: DataType
) -> Result<ApproxMedian, DataFusionError>
pub fn try_new( expr: Arc<dyn PhysicalExpr>, name: impl Into<String>, data_type: DataType ) -> Result<ApproxMedian, DataFusionError>
Create a new APPROX_MEDIAN aggregate function
Trait Implementations§
source§impl AggregateExpr for ApproxMedian
impl AggregateExpr for ApproxMedian
source§fn as_any(&self) -> &(dyn Any + 'static)
fn as_any(&self) -> &(dyn Any + 'static)
Return a reference to Any that can be used for downcasting
source§fn field(&self) -> Result<Field, DataFusionError>
fn field(&self) -> Result<Field, DataFusionError>
the field of the final result of this aggregation.
source§fn create_accumulator(
&self
) -> Result<Box<dyn Accumulator, Global>, DataFusionError>
fn create_accumulator( &self ) -> Result<Box<dyn Accumulator, Global>, DataFusionError>
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
source§fn state_fields(&self) -> Result<Vec<Field, Global>, DataFusionError>
fn state_fields(&self) -> Result<Vec<Field, Global>, DataFusionError>
the fields that encapsulate the Accumulator’s state
the number of fields here equals the number of states that the accumulator contains
source§fn expressions(&self) -> Vec<Arc<dyn PhysicalExpr>, Global>
fn expressions(&self) -> Vec<Arc<dyn PhysicalExpr>, Global>
expressions that are passed to the Accumulator.
Single-column aggregations such as
sum
return a single value, others (e.g. cov
) return many.source§fn name(&self) -> &str
fn name(&self) -> &str
Human readable name such as
"MIN(c2)"
. The default
implementation returns placeholder text.source§fn order_bys(&self) -> Option<&[PhysicalSortExpr]>
fn order_bys(&self) -> Option<&[PhysicalSortExpr]>
Order by requirements for the aggregate function
By default it is
None
(there is no requirement)
Order-sensitive aggregators, such as FIRST_VALUE(x ORDER BY y)
should implement thissource§fn row_accumulator_supported(&self) -> bool
fn row_accumulator_supported(&self) -> bool
If the aggregate expression is supported by row format
source§fn create_row_accumulator(
&self,
_start_index: usize
) -> Result<Box<dyn RowAccumulator, Global>, DataFusionError>
fn create_row_accumulator( &self, _start_index: usize ) -> Result<Box<dyn RowAccumulator, Global>, DataFusionError>
RowAccumulator to access/update row-based aggregation state in-place.
Currently, row accumulator only supports states of fixed-sized type. Read more
source§fn reverse_expr(&self) -> Option<Arc<dyn AggregateExpr>>
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).
source§fn create_sliding_accumulator(
&self
) -> Result<Box<dyn Accumulator, Global>, DataFusionError>
fn create_sliding_accumulator( &self ) -> Result<Box<dyn Accumulator, Global>, DataFusionError>
Creates accumulator implementation that supports retract
source§impl Debug for ApproxMedian
impl Debug for ApproxMedian
Auto Trait Implementations§
impl !RefUnwindSafe for ApproxMedian
impl Send for ApproxMedian
impl Sync for ApproxMedian
impl Unpin for ApproxMedian
impl !UnwindSafe for ApproxMedian
Blanket Implementations§
source§impl<T> BorrowMut<T> for Twhere
T: ?Sized,
impl<T> BorrowMut<T> for Twhere T: ?Sized,
source§fn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more