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Reduce number of traversals per node in PhysicalExprSimplifier #20082

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Merged
adriangb merged 2 commits into from
Jan 30, 2026
Merged

Reduce number of traversals per node in PhysicalExprSimplifier #20082

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bbda191
Reduce number of traversals per node in physical expr simplification
AdamGS Jan 29, 2026
328b36b
TIL how is implemented
AdamGS Jan 30, 2026
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19 changes: 17 additions & 2 deletions datafusion/physical-expr/src/simplifier/const_evaluator.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -25,7 +25,6 @@ use arrow::record_batch::RecordBatch;
use datafusion_common::tree_node::{Transformed, TreeNode, TreeNodeRecursion};
use datafusion_common::{Result, ScalarValue};
use datafusion_expr_common::columnar_value::ColumnarValue;
use datafusion_physical_expr_common::physical_expr::is_volatile;

use crate::PhysicalExpr;
use crate::expressions::{Column, Literal};
Expand All @@ -43,7 +42,7 @@ use crate::expressions::{Column, Literal};
pub fn simplify_const_expr(
expr: &Arc<dyn PhysicalExpr>,
) -> Result<Transformed<Arc<dyn PhysicalExpr>>> {
if is_volatile(expr) || has_column_references(expr) {
if !can_evaluate_as_constant(expr) {
return Ok(Transformed::no(Arc::clone(expr)));
}

Expand Down Expand Up @@ -73,6 +72,22 @@ pub fn simplify_const_expr(
}
}

fn can_evaluate_as_constant(expr: &Arc<dyn PhysicalExpr>) -> bool {
let mut can_evaluate = true;

expr.apply(|e| {
if e.as_any().is::<Column>() || e.is_volatile_node() {
can_evaluate = false;
Ok(TreeNodeRecursion::Stop)
} else {
Ok(TreeNodeRecursion::Continue)
}
})
.expect("apply should not fail");

can_evaluate
}

/// Create a 1-row dummy RecordBatch for evaluating constant expressions.
///
/// The batch is never actually accessed for data - it's just needed because
Expand Down
4 changes: 2 additions & 2 deletions datafusion/physical-expr/src/simplifier/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -53,7 +53,7 @@ impl<'a> PhysicalExprSimplifier<'a> {
while count < MAX_LOOP_COUNT {
count += 1;
let result = current_expr.transform(|node| {
#[cfg(test)]
#[cfg(debug_assertions)]
let original_type = node.data_type(schema).unwrap();

// Apply NOT expression simplification first, then unwrap cast optimization,
Expand All @@ -64,7 +64,7 @@ impl<'a> PhysicalExprSimplifier<'a> {
})?
.transform_data(|node| const_evaluator::simplify_const_expr(&node))?;

#[cfg(test)]
#[cfg(debug_assertions)]
assert_eq!(
rewritten.data.data_type(schema).unwrap(),
original_type,
Expand Down