Struct WindowTopN 

pub struct WindowTopN;

Physical optimizer rule that converts per-partition ROW_NUMBER top-K queries into a more efficient plan using PartitionedTopKExec.

Pattern Detected

FilterExec(rn <= K)
  [optional ProjectionExec]
    BoundedWindowAggExec(ROW_NUMBER PARTITION BY ... ORDER BY ...)
      SortExec(partition_keys, order_keys)

Replacement

[optional ProjectionExec]
  BoundedWindowAggExec(ROW_NUMBER PARTITION BY ... ORDER BY ...)
    PartitionedTopKExec(partition_keys, order_keys, fetch=K)

The FilterExec is removed entirely (all output rows have rn ∈ {1..K}). The SortExec is replaced by PartitionedTopKExec which maintains a per-partition top-K heap instead of sorting the entire dataset.

Supported Predicates

• rn <= K → fetch = K
• rn < K → fetch = K - 1
• K >= rn (flipped) → fetch = K
• K > rn (flipped) → fetch = K - 1

When the Rule Fires

All of the following must be true:

• Config flag enable_window_topn is true
• The plan matches FilterExec → [ProjectionExec] → BoundedWindowAggExec → SortExec
• The window function is ROW_NUMBER (not RANK, DENSE_RANK, etc.)
• ROW_NUMBER has a PARTITION BY clause (global top-K is already handled by SortExec with fetch)
• The filter predicate compares the window output column to an integer literal using <=, <, >=, or >

Implementations

impl WindowTopN

pub fn new() -> Self

Trait Implementations

impl Clone for WindowTopN

fn clone(&self) -> WindowTopN

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for WindowTopN

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

Formats the value using the given formatter.

impl Default for WindowTopN

fn default() -> WindowTopN

Returns the “default value” for a type.

impl PhysicalOptimizerRule for WindowTopN

fn optimize( &self, plan: Arc<dyn ExecutionPlan>, config: &ConfigOptions, ) -> Result<Arc<dyn ExecutionPlan>>

Rewrite plan to an optimized form.

fn name(&self) -> &str

A human readable name for this optimizer rule

fn schema_check(&self) -> bool

A flag to indicate whether the physical planner should validate that the rule will not change the schema of the plan after the rewriting. Some of the optimization rules might change the nullable properties of the schema and should disable the schema check.

fn optimize_with_context( &self, plan: Arc<dyn ExecutionPlan>, context: &dyn PhysicalOptimizerContext, ) -> Result<Arc<dyn ExecutionPlan>>

Rewrite plan with access to extended context (statistics registry, etc.).