perf: Improve hive partition pruning with datetime predicates from SQL

crates/polars-expr/src/expressions/alias.rs

@@ -33,6 +33,13 @@ impl PhysicalExpr for AliasExpr {
         Ok(self.finish(series))
     }
 
+    fn evaluate_inline_impl(&self, depth_limit: u8) -> Option<Column> {
+        let depth_limit = depth_limit.checked_sub(1)?;
+        self.physical_expr
+            .evaluate_inline_impl(depth_limit)
+            .map(|s| self.finish(s))
+    }
+
     #[allow(clippy::ptr_arg)]
     fn evaluate_on_groups<'a>(
         &self,

crates/polars-expr/src/expressions/apply.rs

@@ -1,4 +1,5 @@
 use std::borrow::Cow;
+use std::sync::OnceLock;
 
 use polars_core::chunked_array::builder::get_list_builder;
 use polars_core::prelude::*;
@@ -28,6 +29,7 @@ pub struct ApplyExpr {
     check_lengths: bool,
     allow_group_aware: bool,
     output_field: Field,
+    inlined_eval: OnceLock<Option<Column>>,
 }
 
 impl ApplyExpr {
@@ -63,6 +65,7 @@ impl ApplyExpr {
             check_lengths: options.check_lengths(),
             allow_group_aware: options.flags.contains(FunctionFlags::ALLOW_GROUP_AWARE),
             output_field,
+            inlined_eval: Default::default(),
         }
     }
 
@@ -347,6 +350,24 @@ impl PhysicalExpr for ApplyExpr {
         }
     }
 
+    fn evaluate_inline_impl(&self, depth_limit: u8) -> Option<Column> {
+        // For predicate evaluation at I/O of:
+        // `lit("2024-01-01").str.strptime()`
+
+        self.inlined_eval
+            .get_or_init(|| {
+                let depth_limit = depth_limit.checked_sub(1)?;
+                let mut inputs = self
+                    .inputs
+                    .iter()
+                    .map(|x| x.evaluate_inline_impl(depth_limit).filter(|s| s.len() == 1))
+                    .collect::<Option<Vec<_>>>()?;
+
+                self.eval_and_flatten(&mut inputs).ok()
+            })
+            .clone()
+    }
+
     #[allow(clippy::ptr_arg)]
     fn evaluate_on_groups<'a>(
         &self,
@@ -576,11 +597,10 @@ impl ApplyExpr {
             FunctionExpr::Boolean(BooleanFunction::IsIn) => {
                 let should_read = || -> Option<bool> {
                     let root = expr_to_leaf_column_name(&input[0]).ok()?;
-                    let Expr::Literal(LiteralValue::Series(input)) = &input[1] else {
-                        return None;
-                    };
-                    #[allow(clippy::explicit_auto_deref)]
-                    let input: &Series = &**input;
+
+                    let input = self.inputs[1].evaluate_inline()?;
+                    let input = input.as_materialized_series();
+
                     let st = stats.get_stats(&root).ok()?;
                     let min = st.to_min()?;
                     let max = st.to_max()?;
@@ -603,35 +623,20 @@ impl ApplyExpr {
             FunctionExpr::Boolean(BooleanFunction::IsBetween { closed }) => {
                 let should_read = || -> Option<bool> {
                     let root: PlSmallStr = expr_to_leaf_column_name(&input[0]).ok()?;
-                    let Expr::Literal(left) = &input[1] else {
-                        return None;
-                    };
-                    let Expr::Literal(right) = &input[2] else {
-                        return None;
-                    };
+
+                    let left = self.inputs[1]
+                        .evaluate_inline()?
+                        .as_materialized_series()
+                        .clone();
+                    let right = self.inputs[2]
+                        .evaluate_inline()?
+                        .as_materialized_series()
+                        .clone();
 
                     let st = stats.get_stats(&root).ok()?;
                     let min = st.to_min()?;
                     let max = st.to_max()?;
 
-                    let (left, left_dtype) = (left.to_any_value()?, left.get_datatype());
-                    let (right, right_dtype) = (right.to_any_value()?, right.get_datatype());
-
-                    let left = Series::from_any_values_and_dtype(
-                        PlSmallStr::EMPTY,
-                        &[left],
-                        &left_dtype,
-                        false,
-                    )
-                    .ok()?;
-                    let right = Series::from_any_values_and_dtype(
-                        PlSmallStr::EMPTY,
-                        &[right],
-                        &right_dtype,
-                        false,
-                    )
-                    .ok()?;
-
                     // don't read the row_group anyways as
                     // the condition will evaluate to false.
                     // e.g. in_between(10, 5)

crates/polars-expr/src/expressions/binary.rs

@@ -392,17 +392,26 @@ mod stats {
     impl BinaryExpr {
         fn impl_should_read(&self, stats: &BatchStats) -> PolarsResult<bool> {
             // See: #5864 for the rationale behind this.
-            use Expr::*;
-            use Operator::*;
-            if !self.expr.into_iter().all(|e| match e {
-                BinaryExpr { op, .. } => {
-                    !matches!(op, Multiply | Divide | TrueDivide | FloorDivide | Modulus)
-                },
-                Column(_) | Literal(_) | Alias(_, _) => true,
-                _ => false,
-            }) {
-                return Ok(true);
+            {
+                use Operator::*;
+
+                match self.op {
+                    // These don't result in a boolean output
+                    Multiply | Divide | TrueDivide | FloorDivide | Modulus => return Ok(true),
+                    _ => {},
+                }
+
+                let Expr::BinaryExpr { left, right, .. } = &self.expr else {
+                    unreachable!()
+                };
+
+                match (left.as_ref(), right.as_ref()) {
+                    // The logic below assumes one side is a column
+                    (Expr::Column(_), _) | (_, Expr::Column(_)) => {},
+                    _ => return Ok(true),
+                }
             }
+
             let schema = stats.schema();
             let Some(fld_l) = self.left.to_field(schema).ok() else {
                 return Ok(true);
@@ -423,18 +432,16 @@ mod stats {
                 }
             }
 
-            let dummy = DataFrame::empty();
             let state = ExecutionState::new();
 
-            let out = match (self.left.is_literal(), self.right.is_literal()) {
-                (false, true) => {
+            let out = match (self.left.evaluate_inline(), self.right.evaluate_inline()) {
+                (None, Some(lit_s)) => {
                     let l = stats.get_stats(fld_l.name())?;
                     match l.to_min_max() {
                         None => Ok(true),
                         Some(min_max_s) => {
                             // will be incorrect if not
                             debug_assert_eq!(min_max_s.null_count(), 0);
-                            let lit_s = self.right.evaluate(&dummy, &state).unwrap();
                             Ok(apply_operator_stats_rhs_lit(
                                 &min_max_s.into_column(),
                                 &lit_s,
@@ -443,14 +450,13 @@ mod stats {
                         },
                     }
                 },
-                (true, false) => {
+                (Some(lit_s), None) => {
                     let r = stats.get_stats(fld_r.name())?;
                     match r.to_min_max() {
                         None => Ok(true),
                         Some(min_max_s) => {
                             // will be incorrect if not
                             debug_assert_eq!(min_max_s.null_count(), 0);
-                            let lit_s = self.left.evaluate(&dummy, &state).unwrap();
                             Ok(apply_operator_stats_lhs_lit(
                                 &lit_s,
                                 &min_max_s.into_column(),

crates/polars-expr/src/expressions/cast.rs

@@ -1,3 +1,5 @@
+use std::sync::OnceLock;
+
 use polars_core::chunked_array::cast::CastOptions;
 use polars_core::prelude::*;
 
@@ -9,6 +11,7 @@ pub struct CastExpr {
     pub(crate) dtype: DataType,
     pub(crate) expr: Expr,
     pub(crate) options: CastOptions,
+    pub(crate) inlined_eval: OnceLock<Option<Column>>,
 }
 
 impl CastExpr {
@@ -27,6 +30,18 @@ impl PhysicalExpr for CastExpr {
         self.finish(&column)
     }
 
+    fn evaluate_inline_impl(&self, depth_limit: u8) -> Option<Column> {
+        self.inlined_eval
+            .get_or_init(|| {
+                let depth_limit = depth_limit.checked_sub(1)?;
+                self.input
+                    .evaluate_inline_impl(depth_limit)
+                    .filter(|x| x.len() == 1)
+                    .and_then(|x| self.finish(&x).ok())
+            })
+            .clone()
+    }
+
     #[allow(clippy::ptr_arg)]
     fn evaluate_on_groups<'a>(
         &self,

crates/polars-expr/src/expressions/literal.rs

@@ -15,13 +15,8 @@ impl LiteralExpr {
     pub fn new(value: LiteralValue, expr: Expr) -> Self {
         Self(value, expr)
     }
-}
 
-impl PhysicalExpr for LiteralExpr {
-    fn as_expression(&self) -> Option<&Expr> {
-        Some(&self.1)
-    }
-    fn evaluate(&self, _df: &DataFrame, _state: &ExecutionState) -> PolarsResult<Column> {
+    fn as_column(&self) -> PolarsResult<Column> {
         use LiteralValue::*;
         let s = match &self.0 {
             #[cfg(feature = "dtype-i8")]
@@ -118,6 +113,23 @@ impl PhysicalExpr for LiteralExpr {
         };
         Ok(s)
     }
+}
+
+impl PhysicalExpr for LiteralExpr {
+    fn as_expression(&self) -> Option<&Expr> {
+        Some(&self.1)
+    }
+    fn evaluate(&self, _df: &DataFrame, _state: &ExecutionState) -> PolarsResult<Column> {
+        self.as_column()
+    }
+
+    fn evaluate_inline_impl(&self, _depth_limit: u8) -> Option<Column> {
+        use LiteralValue::*;
+        match &self.0 {
+            Range { .. } => None,
+            _ => self.as_column().ok(),
+        }
+    }
 
     #[allow(clippy::ptr_arg)]
     fn evaluate_on_groups<'a>(

crates/polars-expr/src/expressions/mod.rs

@@ -538,6 +538,20 @@ pub trait PhysicalExpr: Send + Sync {
     /// Take a DataFrame and evaluate the expression.
     fn evaluate(&self, df: &DataFrame, _state: &ExecutionState) -> PolarsResult<Column>;
 
+    /// Attempt to cheaply evaluate this expression in-line without a DataFrame context.
+    /// This is used by StatsEvaluator when skipping files / row groups using a predicate.
+    /// TODO: Maybe in the future we can do this evaluation in-line at the optimizer stage?
+    ///
+    /// Do not implement this directly - instead implement `evaluate_inline_impl`
+    fn evaluate_inline(&self) -> Option<Column> {
+        self.evaluate_inline_impl(4)
+    }
+
+    /// Implementation of `evaluate_inline`
+    fn evaluate_inline_impl(&self, _depth_limit: u8) -> Option<Column> {
+        None
+    }
+
     /// Some expression that are not aggregations can be done per group
     /// Think of sort, slice, filter, shift, etc.
     /// defaults to ignoring the group

crates/polars-expr/src/planner.rs

@@ -438,6 +438,7 @@ fn create_physical_expr_inner(
                 dtype: dtype.clone(),
                 expr: node_to_expr(expression, expr_arena),
                 options: *options,
+                inlined_eval: Default::default(),
             }))
         },
         Ternary {

crates/polars-io/src/predicates.rs

@@ -159,6 +159,7 @@ impl ColumnStats {
     ///
     /// Returns `None` if no maximum value is available.
     pub fn to_min(&self) -> Option<&Series> {
+        // @scalar-opt
         let min_val = self.min_value.as_ref()?;
         let dtype = min_val.dtype();
 
@@ -177,6 +178,7 @@ impl ColumnStats {
     ///
     /// Returns `None` if no maximum value is available.
     pub fn to_max(&self) -> Option<&Series> {
+        // @scalar-opt
         let max_val = self.max_value.as_ref()?;
         let dtype = max_val.dtype();
 

py-polars/tests/unit/io/test_scan.py

@@ -2,6 +2,7 @@
 
 import io
 from dataclasses import dataclass
+from datetime import datetime
 from functools import partial
 from math import ceil
 from pathlib import Path
@@ -835,3 +836,74 @@ def test_streaming_scan_csv_with_row_index_19172(io_files_path: Path) -> None:
             schema={"calories": pl.String, "index": pl.UInt32},
         ),
     )
+
+
+@pytest.mark.write_disk
+def test_predicate_hive_pruning_with_cast(tmp_path: Path) -> None:
+    tmp_path.mkdir(exist_ok=True)
+
+    df = pl.DataFrame({"x": 1})
+
+    (p := (tmp_path / "date=2024-01-01")).mkdir()
+
+    df.write_parquet(p / "1")
+
+    (p := (tmp_path / "date=2024-01-02")).mkdir()
+
+    # Write an invalid parquet file that will cause errors if polars attempts to
+    # read it.
+    # This works because `scan_parquet()` only looks at the first file during
+    # schema inference.
+    (p / "1").write_text("not a parquet file")
+
+    expect = pl.DataFrame({"x": 1, "date": datetime(2024, 1, 1).date()})
+
+    lf = pl.scan_parquet(tmp_path)
+
+    q = lf.filter(pl.col("date") < datetime(2024, 1, 2).date())
+
+    assert_frame_equal(q.collect(), expect)
+
+    # This filter expr with stprtime is effectively what LazyFrame.sql()
+    # generates
+    q = lf.filter(
+        pl.col("date")
+        < pl.lit("2024-01-02").str.strptime(
+            dtype=pl.Date, format="%Y-%m-%d", ambiguous="latest"
+        )
+    )
+
+    assert_frame_equal(q.collect(), expect)
+
+    q = lf.sql("select * from self where date < '2024-01-02'")
+    assert_frame_equal(q.collect(), expect)
+
+
+def test_predicate_stats_eval_nested_binary() -> None:
+    bufs: list[bytes] = []
+
+    for i in range(10):
+        b = io.BytesIO()
+        pl.DataFrame({"x": i}).write_parquet(b)
+        b.seek(0)
+        bufs.append(b.read())
+
+    assert_frame_equal(
+        (
+            pl.scan_parquet(bufs)
+            .filter(pl.col("x") % 2 == 0)
+            .collect(no_optimization=True)
+        ),
+        pl.DataFrame({"x": [0, 2, 4, 6, 8]}),
+    )
+
+    assert_frame_equal(
+        (
+            pl.scan_parquet(bufs)
+            # The literal eval depth limit is 4 -
+            # * crates/polars-expr/src/expressions/mod.rs::PhysicalExpr::evaluate_inline
+            .filter(pl.col("x") == pl.lit("222").str.slice(0, 1).cast(pl.Int64))
+            .collect()
+        ),
+        pl.DataFrame({"x": [2]}),
+    )