perf: use foldhash for BoundedWindowAggExec partition state maps

PartitionWindowAggStates and PartitionBatches were using IndexMap's
default SipHash hasher. Switching to foldhash yields a small but
measurable performance improvement.

This improves performance in linear mode for 10k partitions by ~6%.

Author: neilconway

datafusion/physical-expr/src/window/window_expr.rs

@@ -30,6 +30,7 @@ use arrow::compute::kernels::sort::SortColumn;
 use arrow::datatypes::FieldRef;
 use arrow::record_batch::RecordBatch;
 use datafusion_common::cast::as_boolean_array;
+use datafusion_common::hash_utils::RandomState;
 use datafusion_common::utils::compare_rows;
 use datafusion_common::{
     Result, ScalarValue, arrow_datafusion_err, exec_datafusion_err, internal_err,
@@ -609,10 +610,10 @@ pub struct WindowState {
     pub state: WindowAggState,
     pub window_fn: WindowFn,
 }
-pub type PartitionWindowAggStates = IndexMap<PartitionKey, WindowState>;
+pub type PartitionWindowAggStates = IndexMap<PartitionKey, WindowState, RandomState>;
 
 /// The IndexMap (i.e. an ordered HashMap) where record batches are separated for each partition.
-pub type PartitionBatches = IndexMap<PartitionKey, PartitionBatchState>;
+pub type PartitionBatches = IndexMap<PartitionKey, PartitionBatchState, RandomState>;
 
 #[cfg(test)]
 mod tests {

datafusion/physical-plan/src/windows/bounded_window_agg_exec.rs

@@ -1054,13 +1054,13 @@ impl BoundedWindowAggStream {
         baseline_metrics: BaselineMetrics,
         search_mode: Box<dyn PartitionSearcher>,
     ) -> Result<Self> {
-        let state = window_expr.iter().map(|_| IndexMap::new()).collect();
+        let state = window_expr.iter().map(|_| IndexMap::default()).collect();
         let empty_batch = RecordBatch::new_empty(Arc::clone(&schema));
         Ok(Self {
             schema,
             input,
             input_buffer: empty_batch,
-            partition_buffers: IndexMap::new(),
+            partition_buffers: IndexMap::default(),
             window_agg_states: state,
             finished: false,
             window_expr,