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 ) -> Self

Create a new FIRST_VALUE window aggregate function

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

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<Self>

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

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 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)" or "RANK()". The default implementation returns placeholder text.

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

Create built-in window evaluator with a batch

fn supports_bounded_execution(&self) -> bool

fn uses_window_frame(&self) -> bool

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

Construct Reverse Expression that produces the same result on a reversed window. For example lead(10) –> lag(10)

fn evaluate_args(&self, batch: &RecordBatch) -> Result<Vec<ArrayRef>>

Evaluate window function arguments against the batch and return an array ref. Typically, the resulting vector is a single element vector.

impl Debug for NthValue

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

Formats the value using the given formatter.