Struct datafusion::physical_expr::expressions::NthValue

pub struct NthValue { /* private fields */ }

nth_value expression

Implementations

impl NthValue

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

Create a new FIRST_VALUE window aggregate function

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

Create a new LAST_VALUE window aggregate function

pub fn nth( name: impl Into<String>, expr: Arc<dyn PhysicalExpr>, data_type: DataType, n: u32 ) -> Result<NthValue, DataFusionError>

Create a new NTH_VALUE window aggregate function

pub fn get_kind(&self) -> NthValueKind

Get nth_value kind

Trait Implementations

impl BuiltInWindowFunctionExpr for NthValue

fn as_any(&self) -> &(dyn Any + 'static)

Return a reference to Any that can be used for downcasting

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

The field of the final result of evaluating this window function.

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

Expressions that are passed to the PartitionEvaluator.

fn name(&self) -> &str

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

fn create_evaluator( &self ) -> Result<Box<dyn PartitionEvaluator, Global>, DataFusionError>

Create a PartitionEvaluator for evaluating the function on a particular partition.

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

Construct a new BuiltInWindowFunctionExpr that produces the same result as this function on a window with reverse order. The return value of this function is used by the DataFusion optimizer to avoid re-sorting the data when possible.

fn evaluate_args( &self, batch: &RecordBatch ) -> Result<Vec<Arc<dyn Array>, Global>, DataFusionError>

Evaluate window function’s arguments against the input window batch and return an ArrayRef.

fn add_equal_orderings(&self, _builder: &mut OrderingEquivalenceBuilder)

Adds any equivalent orderings generated by this expression to builder.

impl Debug for NthValue

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

Formats the value using the given formatter.