Struct SlidingAggregateWindowExpr

pub struct SlidingAggregateWindowExpr { /* private fields */ }

A window expr that takes the form of an aggregate function that can be incrementally computed over sliding windows.

See comments on WindowExpr for more details.

Implementations

impl SlidingAggregateWindowExpr

pub fn new( aggregate: Arc<AggregateFunctionExpr>, partition_by: &[Arc<dyn PhysicalExpr>], order_by: LexOrderingRef<'_>, window_frame: Arc<WindowFrame>, ) -> Self

Create a new (sliding) aggregate window function expression.

pub fn get_aggregate_expr(&self) -> &AggregateFunctionExpr

Get the AggregateFunctionExpr of this object.

Trait Implementations

impl Debug for SlidingAggregateWindowExpr

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

Formats the value using the given formatter.

impl WindowExpr for SlidingAggregateWindowExpr

Incrementally update window function using the fact that batch is pre-sorted given the sort columns and then per partition point.

Evaluates the peer group (e.g. SUM or MAX gives the same results for peers) and concatenate the results.

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 window function.

fn name(&self) -> &str

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

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

Expressions that are passed to the WindowAccumulator. Functions which take a single input argument, such as sum, return a single datafusion_expr::expr::Expr, others (e.g. cov) return many.

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

Evaluate the window function values against the batch

fn evaluate_stateful( &self, partition_batches: &PartitionBatches, window_agg_state: &mut PartitionWindowAggStates, ) -> Result<()>

Evaluate the window function against the batch. This function facilitates stateful, bounded-memory implementations.

fn partition_by(&self) -> &[Arc<dyn PhysicalExpr>]

Expressions that’s from the window function’s partition by clause, empty if absent

fn order_by(&self) -> LexOrderingRef<'_>

Expressions that’s from the window function’s order by clause, empty if absent

fn get_window_frame(&self) -> &Arc<WindowFrame>

Get the window frame of this WindowExpr.

fn get_reverse_expr(&self) -> Option<Arc<dyn WindowExpr>>

Get the reverse expression of this WindowExpr.

fn uses_bounded_memory(&self) -> bool

Return a flag indicating whether this WindowExpr can run with bounded memory.

fn with_new_expressions( &self, args: Vec<Arc<dyn PhysicalExpr>>, partition_bys: Vec<Arc<dyn PhysicalExpr>>, order_by_exprs: Vec<Arc<dyn PhysicalExpr>>, ) -> Option<Arc<dyn WindowExpr>>

Rewrites WindowExpr, with new expressions given. The argument should be consistent with the return value of the WindowExpr::all_expressions method. Returns Some(Arc<dyn WindowExpr>) if re-write is supported, otherwise returns None.

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

Evaluate the window function arguments against the batch and return array ref, normally the resulting Vec is a single element one.

fn order_by_columns(&self, batch: &RecordBatch) -> Result<Vec<SortColumn>>

Get order by columns, empty if absent

fn all_expressions(&self) -> WindowPhysicalExpressions

Returns all expressions used in the WindowExpr. These expressions are (1) function arguments, (2) partition by expressions, (3) order by expressions.