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

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 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.