Struct StreamingScanExec 

pub struct StreamingScanExec { /* private fields */ }

A DataFusion execution plan that scans from a streaming source.

This is a leaf node in the query plan tree that pulls data from a StreamSource implementation. It handles projection and filter pushdown to the source when supported.

Properties

• Single partition (streaming sources are typically not partitioned)
• Unbounded execution mode (streaming)
• No inherent ordering (unless specified by source)

Implementations

impl StreamingScanExec

pub fn new( source: StreamSourceRef, projection: Option<Vec<usize>>, filters: Vec<Expr>, ) -> Self

Creates a new streaming scan execution plan.

If the source declares an output_ordering, the plan’s EquivalenceProperties will include it so DataFusion can elide SortExec for matching ORDER BY queries.

pub fn with_watermark_filter(self, filter: Arc<WatermarkDynamicFilter>) -> Self

Attaches a watermark filter that drops late rows at scan time.

When set, execute() wraps the inner stream with a WatermarkFilterStream that applies ts >= watermark before any downstream processing.

pub fn watermark_filter(&self) -> Option<&Arc<WatermarkDynamicFilter>>

Returns the watermark filter, if set.

pub fn source(&self) -> &StreamSourceRef

Returns the streaming source.

pub fn projection(&self) -> Option<&[usize]>

Returns the column projection.

pub fn filters(&self) -> &[Expr]

Returns the pushed-down filters.

Trait Implementations

impl Debug for StreamingScanExec

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

Formats the value using the given formatter.

impl DisplayAs for StreamingScanExec

fn fmt_as(&self, t: DisplayFormatType, f: &mut Formatter<'_>) -> Result

Format according to DisplayFormatType, used when verbose representation looks different from the default one

impl ExecutionPlan for StreamingScanExec

fn name(&self) -> &'static str

Short name for the ExecutionPlan, such as ‘DataSourceExec’.

fn as_any(&self) -> &dyn Any

Returns the execution plan as Any so that it can be downcast to a specific implementation.

fn schema(&self) -> SchemaRef

Get the schema for this execution plan

fn properties(&self) -> &PlanProperties

Return properties of the output of the ExecutionPlan, such as output ordering(s), partitioning information etc.

fn children(&self) -> Vec<&Arc<dyn ExecutionPlan>>

Get a list of children ExecutionPlans that act as inputs to this plan. The returned list will be empty for leaf nodes such as scans, will contain a single value for unary nodes, or two values for binary nodes (such as joins).

fn with_new_children( self: Arc<Self>, children: Vec<Arc<dyn ExecutionPlan>>, ) -> Result<Arc<dyn ExecutionPlan>, DataFusionError>

Returns a new ExecutionPlan where all existing children were replaced by the children, in order

fn execute( &self, partition: usize, _context: Arc<TaskContext>, ) -> Result<SendableRecordBatchStream, DataFusionError>

Begin execution of partition, returning a Stream of RecordBatches.

fn static_name() -> &'static str

where Self: Sized,

Short name for the ExecutionPlan, such as ‘DataSourceExec’. Like name but can be called without an instance.

fn check_invariants(&self, check: InvariantLevel) -> Result<(), DataFusionError>

Returns an error if this individual node does not conform to its invariants. These invariants are typically only checked in debug mode.

fn required_input_distribution(&self) -> Vec<Distribution>

Specifies the data distribution requirements for all the children for this ExecutionPlan, By default it’s [Distribution::UnspecifiedDistribution] for each child,

fn required_input_ordering(&self) -> Vec<Option<OrderingRequirements>>

Specifies the ordering required for all of the children of this ExecutionPlan.

fn maintains_input_order(&self) -> Vec<bool>

Returns false if this ExecutionPlan’s implementation may reorder rows within or between partitions.

fn benefits_from_input_partitioning(&self) -> Vec<bool>

Specifies whether the ExecutionPlan benefits from increased parallelization at its input for each child.

fn reset_state( self: Arc<Self>, ) -> Result<Arc<dyn ExecutionPlan>, DataFusionError>

Reset any internal state within this ExecutionPlan.

fn repartitioned( &self, _target_partitions: usize, _config: &ConfigOptions, ) -> Result<Option<Arc<dyn ExecutionPlan>>, DataFusionError>

If supported, attempt to increase the partitioning of this ExecutionPlan to produce target_partitions partitions.

fn metrics(&self) -> Option<MetricsSet>

Return a snapshot of the set of Metrics for this ExecutionPlan. If no Metrics are available, return None.

fn statistics(&self) -> Result<Statistics, DataFusionError>

👎Deprecated since 48.0.0:

Use partition_statistics method instead

Returns statistics for this ExecutionPlan node. If statistics are not available, should return Statistics::new_unknown (the default), not an error.

fn partition_statistics( &self, partition: Option<usize>, ) -> Result<Statistics, DataFusionError>

Returns statistics for a specific partition of this ExecutionPlan node. If statistics are not available, should return Statistics::new_unknown (the default), not an error. If partition is None, it returns statistics for the entire plan.

fn supports_limit_pushdown(&self) -> bool

Returns true if a limit can be safely pushed down through this ExecutionPlan node.

fn with_fetch(&self, _limit: Option<usize>) -> Option<Arc<dyn ExecutionPlan>>

Returns a fetching variant of this ExecutionPlan node, if it supports fetch limits. Returns None otherwise.

fn fetch(&self) -> Option<usize>

Gets the fetch count for the operator, None means there is no fetch.

fn cardinality_effect(&self) -> CardinalityEffect

Gets the effect on cardinality, if known

fn try_swapping_with_projection( &self, _projection: &ProjectionExec, ) -> Result<Option<Arc<dyn ExecutionPlan>>, DataFusionError>

Attempts to push down the given projection into the input of this ExecutionPlan.

fn gather_filters_for_pushdown( &self, _phase: FilterPushdownPhase, parent_filters: Vec<Arc<dyn PhysicalExpr>>, _config: &ConfigOptions, ) -> Result<FilterDescription, DataFusionError>

Collect filters that this node can push down to its children. Filters that are being pushed down from parents are passed in, and the node may generate additional filters to push down. For example, given the plan FilterExec -> HashJoinExec -> DataSourceExec, what will happen is that we recurse down the plan calling ExecutionPlan::gather_filters_for_pushdown:

fn handle_child_pushdown_result( &self, _phase: FilterPushdownPhase, child_pushdown_result: ChildPushdownResult, _config: &ConfigOptions, ) -> Result<FilterPushdownPropagation<Arc<dyn ExecutionPlan>>, DataFusionError>

Handle the result of a child pushdown. This method is called as we recurse back up the plan tree after pushing filters down to child nodes via ExecutionPlan::gather_filters_for_pushdown. It allows the current node to process the results of filter pushdown from its children, deciding whether to absorb filters, modify the plan, or pass filters back up to its parent.

fn with_new_state( &self, _state: Arc<dyn Any + Sync + Send>, ) -> Option<Arc<dyn ExecutionPlan>>

Injects arbitrary run-time state into this execution plan, returning a new plan instance that incorporates that state if it is relevant to the concrete node implementation.

fn try_pushdown_sort( &self, _order: &[PhysicalSortExpr], ) -> Result<SortOrderPushdownResult<Arc<dyn ExecutionPlan>>, DataFusionError>

Try to push down sort ordering requirements to this node.

impl ExecutionPlanProperties for StreamingScanExec

fn output_partitioning(&self) -> &Partitioning

Specifies how the output of this ExecutionPlan is split into partitions.

fn output_ordering(&self) -> Option<&LexOrdering>

If the output of this ExecutionPlan within each partition is sorted, returns Some(keys) describing the ordering. A None return value indicates no assumptions should be made on the output ordering.

fn boundedness(&self) -> Boundedness

Boundedness information of the stream corresponding to this ExecutionPlan. For more details, see Boundedness.

fn pipeline_behavior(&self) -> EmissionType

Indicates how the stream of this ExecutionPlan emits its results. For more details, see EmissionType.

fn equivalence_properties(&self) -> &EquivalenceProperties

Get the EquivalenceProperties within the plan.