Add tests for non-identity transform residuals and fix scalastyle errors

Author: Shekharrajak

native/spark-expr/src/string_funcs/contains.rs

@@ -0,0 +1,282 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+//! Optimized `contains` string function for Spark compatibility.
+//!
+//! This implementation is optimized for the common case where the pattern
+//! (second argument) is a scalar value. In this case, we use `memchr::memmem::Finder`
+//! which is SIMD-optimized and reuses a single finder instance across all rows.
+//!
+//! The DataFusion built-in `contains` function uses `make_scalar_function` which
+//! expands scalar values to arrays, losing the performance benefit of the optimized
+//! scalar path in arrow-rs.
+
+use arrow::array::{Array, ArrayRef, AsArray, BooleanArray};
+use arrow::compute::kernels::comparison::contains as arrow_contains;
+use arrow::datatypes::DataType;
+use datafusion::common::{exec_err, Result, ScalarValue};
+use datafusion::logical_expr::{
+    ColumnarValue, ScalarFunctionArgs, ScalarUDFImpl, Signature, Volatility,
+};
+use memchr::memmem::Finder;
+use std::any::Any;
+use std::sync::Arc;
+
+/// Spark-optimized contains function.
+///
+/// Returns true if the first string argument contains the second string argument.
+/// Optimized for the common case where the pattern is a scalar constant.
+#[derive(Debug, PartialEq, Eq, Hash)]
+pub struct SparkContains {
+    signature: Signature,
+}
+
+impl Default for SparkContains {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl SparkContains {
+    pub fn new() -> Self {
+        Self {
+            signature: Signature::variadic_any(Volatility::Immutable),
+        }
+    }
+}
+
+impl ScalarUDFImpl for SparkContains {
+    fn as_any(&self) -> &dyn Any {
+        self
+    }
+
+    fn name(&self) -> &str {
+        "contains"
+    }
+
+    fn signature(&self) -> &Signature {
+        &self.signature
+    }
+
+    fn return_type(&self, _arg_types: &[DataType]) -> Result<DataType> {
+        Ok(DataType::Boolean)
+    }
+
+    fn invoke_with_args(&self, args: ScalarFunctionArgs) -> Result<ColumnarValue> {
+        if args.args.len() != 2 {
+            return exec_err!("contains function requires exactly 2 arguments");
+        }
+        spark_contains(&args.args[0], &args.args[1])
+    }
+}
+
+/// Execute the contains function with optimized scalar pattern handling.
+fn spark_contains(haystack: &ColumnarValue, needle: &ColumnarValue) -> Result<ColumnarValue> {
+    match (haystack, needle) {
+        // Case 1: Both are arrays - use arrow's contains directly
+        (ColumnarValue::Array(haystack_array), ColumnarValue::Array(needle_array)) => {
+            let result = arrow_contains(haystack_array, needle_array)?;
+            Ok(ColumnarValue::Array(Arc::new(result)))
+        }
+
+        // Case 2: Haystack is array, needle is scalar - OPTIMIZED PATH
+        // This is the common case in SQL like: WHERE col CONTAINS 'pattern'
+        (ColumnarValue::Array(haystack_array), ColumnarValue::Scalar(needle_scalar)) => {
+            let result = contains_with_scalar_pattern(haystack_array, needle_scalar)?;
+            Ok(ColumnarValue::Array(result))
+        }
+
+        // Case 3: Haystack is scalar, needle is array - less common
+        (ColumnarValue::Scalar(haystack_scalar), ColumnarValue::Array(needle_array)) => {
+            // Convert scalar to array and use arrow's contains
+            let haystack_array = haystack_scalar.to_array_of_size(needle_array.len())?;
+            let result = arrow_contains(&haystack_array, needle_array)?;
+            Ok(ColumnarValue::Array(Arc::new(result)))
+        }
+
+        // Case 4: Both are scalars - compute single result
+        (ColumnarValue::Scalar(haystack_scalar), ColumnarValue::Scalar(needle_scalar)) => {
+            let result = contains_scalar_scalar(haystack_scalar, needle_scalar)?;
+            Ok(ColumnarValue::Scalar(result))
+        }
+    }
+}
+
+/// Optimized contains for array haystack with scalar needle pattern.
+/// Uses memchr's SIMD-optimized Finder for efficient repeated searches.
+fn contains_with_scalar_pattern(
+    haystack_array: &ArrayRef,
+    needle_scalar: &ScalarValue,
+) -> Result<ArrayRef> {
+    // Handle null needle
+    if needle_scalar.is_null() {
+        return Ok(Arc::new(BooleanArray::new_null(haystack_array.len())));
+    }
+
+    // Extract the needle string
+    let needle_str = match needle_scalar {
+        ScalarValue::Utf8(Some(s))
+        | ScalarValue::LargeUtf8(Some(s))
+        | ScalarValue::Utf8View(Some(s)) => s.as_str(),
+        _ => {
+            return exec_err!(
+                "contains function requires string type for needle, got {:?}",
+                needle_scalar.data_type()
+            )
+        }
+    };
+
+    // Create a reusable Finder for efficient SIMD-optimized searching
+    let finder = Finder::new(needle_str.as_bytes());
+
+    match haystack_array.data_type() {
+        DataType::Utf8 => {
+            let array = haystack_array.as_string::<i32>();
+            let result: BooleanArray = array
+                .iter()
+                .map(|opt_haystack| opt_haystack.map(|h| finder.find(h.as_bytes()).is_some()))
+                .collect();
+            Ok(Arc::new(result))
+        }
+        DataType::LargeUtf8 => {
+            let array = haystack_array.as_string::<i64>();
+            let result: BooleanArray = array
+                .iter()
+                .map(|opt_haystack| opt_haystack.map(|h| finder.find(h.as_bytes()).is_some()))
+                .collect();
+            Ok(Arc::new(result))
+        }
+        DataType::Utf8View => {
+            let array = haystack_array.as_string_view();
+            let result: BooleanArray = array
+                .iter()
+                .map(|opt_haystack| opt_haystack.map(|h| finder.find(h.as_bytes()).is_some()))
+                .collect();
+            Ok(Arc::new(result))
+        }
+        other => exec_err!(
+            "contains function requires string type for haystack, got {:?}",
+            other
+        ),
+    }
+}
+
+/// Contains for two scalar values.
+fn contains_scalar_scalar(
+    haystack_scalar: &ScalarValue,
+    needle_scalar: &ScalarValue,
+) -> Result<ScalarValue> {
+    // Handle nulls
+    if haystack_scalar.is_null() || needle_scalar.is_null() {
+        return Ok(ScalarValue::Boolean(None));
+    }
+
+    let haystack_str = match haystack_scalar {
+        ScalarValue::Utf8(Some(s))
+        | ScalarValue::LargeUtf8(Some(s))
+        | ScalarValue::Utf8View(Some(s)) => s.as_str(),
+        _ => {
+            return exec_err!(
+                "contains function requires string type for haystack, got {:?}",
+                haystack_scalar.data_type()
+            )
+        }
+    };
+
+    let needle_str = match needle_scalar {
+        ScalarValue::Utf8(Some(s))
+        | ScalarValue::LargeUtf8(Some(s))
+        | ScalarValue::Utf8View(Some(s)) => s.as_str(),
+        _ => {
+            return exec_err!(
+                "contains function requires string type for needle, got {:?}",
+                needle_scalar.data_type()
+            )
+        }
+    };
+
+    Ok(ScalarValue::Boolean(Some(
+        haystack_str.contains(needle_str),
+    )))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use arrow::array::StringArray;
+
+    #[test]
+    fn test_contains_array_scalar() {
+        let haystack = Arc::new(StringArray::from(vec![
+            Some("hello world"),
+            Some("foo bar"),
+            Some("testing"),
+            None,
+        ])) as ArrayRef;
+        let needle = ScalarValue::Utf8(Some("world".to_string()));
+
+        let result = contains_with_scalar_pattern(&haystack, &needle).unwrap();
+        let bool_array = result.as_any().downcast_ref::<BooleanArray>().unwrap();
+
+        assert!(bool_array.value(0)); // "hello world" contains "world"
+        assert!(!bool_array.value(1)); // "foo bar" does not contain "world"
+        assert!(!bool_array.value(2)); // "testing" does not contain "world"
+        assert!(bool_array.is_null(3)); // null input => null output
+    }
+
+    #[test]
+    fn test_contains_scalar_scalar() {
+        let haystack = ScalarValue::Utf8(Some("hello world".to_string()));
+        let needle = ScalarValue::Utf8(Some("world".to_string()));
+
+        let result = contains_scalar_scalar(&haystack, &needle).unwrap();
+        assert_eq!(result, ScalarValue::Boolean(Some(true)));
+
+        let needle_not_found = ScalarValue::Utf8(Some("xyz".to_string()));
+        let result = contains_scalar_scalar(&haystack, &needle_not_found).unwrap();
+        assert_eq!(result, ScalarValue::Boolean(Some(false)));
+    }
+
+    #[test]
+    fn test_contains_null_needle() {
+        let haystack = Arc::new(StringArray::from(vec![
+            Some("hello world"),
+            Some("foo bar"),
+        ])) as ArrayRef;
+        let needle = ScalarValue::Utf8(None);
+
+        let result = contains_with_scalar_pattern(&haystack, &needle).unwrap();
+        let bool_array = result.as_any().downcast_ref::<BooleanArray>().unwrap();
+
+        // Null needle should produce null results
+        assert!(bool_array.is_null(0));
+        assert!(bool_array.is_null(1));
+    }
+
+    #[test]
+    fn test_contains_empty_needle() {
+        let haystack = Arc::new(StringArray::from(vec![Some("hello world"), Some("")])) as ArrayRef;
+        let needle = ScalarValue::Utf8(Some("".to_string()));
+
+        let result = contains_with_scalar_pattern(&haystack, &needle).unwrap();
+        let bool_array = result.as_any().downcast_ref::<BooleanArray>().unwrap();
+
+        // Empty string is contained in any string
+        assert!(bool_array.value(0));
+        assert!(bool_array.value(1));
+    }
+}

spark/src/main/scala/org/apache/comet/rules/CometScanRule.scala

@@ -480,14 +480,16 @@ case class CometScanRule(session: SparkSession) extends Rule[SparkPlan] with Com
 
         // Check for transform functions in residual expressions
         // Non-identity transforms (truncate, bucket, year, month, day, hour) in residuals
-        // are now supported - they skip row-group filtering and are handled post-scan by CometFilter.
+        // are now supported - they skip row-group filtering and are handled
+        // post-scan by CometFilter.
         // This is less optimal than row-group filtering but still allows native execution.
         val transformFunctionsSupported =
           try {
             IcebergReflection.findNonIdentityTransformInResiduals(metadata.tasks) match {
               case Some(transformType) =>
                 // Found non-identity transform - log info and continue with native scan
-                // Row-group filtering will skip these predicates, but post-scan filtering will apply
+                // Row-group filtering will skip these predicates, but post-scan
+                // filtering will apply
                 logInfo(
                   s"Iceberg residual contains transform '$transformType' - " +
                     "row-group filtering will skip this predicate, " +