Add array_product UDF

datafusion/functions-nested/src/array_product.rs

@@ -0,0 +1,185 @@
+// 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.
+
+//! [`ScalarUDFImpl`] definitions for array_product function.
+
+use crate::utils::make_scalar_function;
+use arrow::array::{Array, ArrayRef, Float64Array, OffsetSizeTrait};
+use arrow::datatypes::{
+    DataType,
+    DataType::{FixedSizeList, LargeList, List, Null},
+    Field,
+};
+use datafusion_common::cast::{as_float64_array, as_generic_list_array};
+use datafusion_common::utils::{ListCoercion, coerced_type_with_base_type_only};
+use datafusion_common::{Result, internal_err, plan_err, utils::take_function_args};
+use datafusion_expr::{
+    ColumnarValue, Documentation, ScalarFunctionArgs, ScalarUDFImpl, Signature,
+    Volatility,
+};
+use datafusion_macros::user_doc;
+use std::sync::Arc;
+
+make_udf_expr_and_func!(
+    ArrayProduct,
+    array_product,
+    array,
+    "returns the product of the elements of a numeric array.",
+    array_product_udf
+);
+
+#[user_doc(
+    doc_section(label = "Array Functions"),
+    description = "Returns the product of the elements in the input numeric array. \
+                   NULL elements inside the array are skipped (matching SQL aggregate \
+                   convention). Returns NULL if the whole input is NULL or if every \
+                   element is NULL. Returns 1.0 for an empty array (multiplicative \
+                   identity). The result is always returned as `Float64`.",
+    syntax_example = "array_product(array)",
+    sql_example = r#"```sql
+> select array_product([1.0, 2.0, 3.0]);
++------------------------------------+
+| array_product(List([1.0,2.0,3.0])) |
++------------------------------------+
+| 6.0                                |
++------------------------------------+
+```"#,
+    argument(
+        name = "array",
+        description = "Array expression. Can be a constant, column, or function, and any combination of array operators."
+    )
+)]
+#[derive(Debug, PartialEq, Eq, Hash)]
+pub struct ArrayProduct {
+    signature: Signature,
+    aliases: Vec<String>,
+}
+
+impl Default for ArrayProduct {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl ArrayProduct {
+    pub fn new() -> Self {
+        Self {
+            signature: Signature::user_defined(Volatility::Immutable),
+            aliases: vec!["list_product".to_string()],
+        }
+    }
+}
+
+impl ScalarUDFImpl for ArrayProduct {
+    fn name(&self) -> &str {
+        "array_product"
+    }
+
+    fn signature(&self) -> &Signature {
+        &self.signature
+    }
+
+    fn return_type(&self, _arg_types: &[DataType]) -> Result<DataType> {
+        Ok(DataType::Float64)
+    }
+
+    fn coerce_types(&self, arg_types: &[DataType]) -> Result<Vec<DataType>> {
+        let [arg_type] = take_function_args(self.name(), arg_types)?;
+        let coercion = Some(&ListCoercion::FixedSizedListToList);
+
+        if !matches!(arg_type, Null | List(_) | LargeList(_) | FixedSizeList(..)) {
+            return plan_err!("{} does not support type {arg_type}", self.name());
+        }
+
+        let coerced = if matches!(arg_type, Null) {
+            List(Arc::new(Field::new_list_field(DataType::Float64, true)))
+        } else {
+            coerced_type_with_base_type_only(arg_type, &DataType::Float64, coercion)
+        };
+
+        Ok(vec![coerced])
+    }
+
+    fn invoke_with_args(&self, args: ScalarFunctionArgs) -> Result<ColumnarValue> {
+        make_scalar_function(array_product_inner)(&args.args)
+    }
+
+    fn aliases(&self) -> &[String] {
+        &self.aliases
+    }
+
+    fn documentation(&self) -> Option<&Documentation> {
+        self.doc()
+    }
+}
+
+fn array_product_inner(args: &[ArrayRef]) -> Result<ArrayRef> {
+    let [array] = take_function_args("array_product", args)?;
+    match array.data_type() {
+        List(_) => general_array_product::<i32>(args),
+        LargeList(_) => general_array_product::<i64>(args),
+        arg_type => internal_err!(
+            "array_product received unexpected type after coercion: {arg_type}"
+        ),
+    }
+}
+
+fn general_array_product<O: OffsetSizeTrait>(arrays: &[ArrayRef]) -> Result<ArrayRef> {
+    let list_array = as_generic_list_array::<O>(&arrays[0])?;
+    let values = as_float64_array(list_array.values())?;
+    let offsets = list_array.value_offsets();
+
+    let mut builder = Float64Array::builder(list_array.len());
+
+    for row in 0..list_array.len() {
+        if list_array.is_null(row) {
+            builder.append_null();
+            continue;
+        }
+
+        let start = offsets[row].as_usize();
+        let end = offsets[row + 1].as_usize();
+        let len = end - start;
+
+        // Empty list -> multiplicative identity. Distinguished here from
+        // all-NULL elements (which yield NULL): we have no data either way,
+        // but `[]` is structurally a known-empty product, while `[NULL,NULL]`
+        // means every value was unknown.
+        if len == 0 {
+            builder.append_value(1.0);
+            continue;
+        }
+
+        let slice = values.slice(start, len);
+        let mut prod = 1.0_f64;
+        let mut any_valid = false;
+        for i in 0..len {
+            if slice.is_valid(i) {
+                prod *= slice.value(i);
+                any_valid = true;
+            }
+        }
+
+        if any_valid {
+            builder.append_value(prod);
+        } else {
+            builder.append_null();
+        }
+    }
+
+    Ok(Arc::new(builder.finish()))
+}

datafusion/functions-nested/src/lib.rs

@@ -46,6 +46,7 @@ pub mod array_compact;
 pub mod array_filter;
 pub mod array_has;
 pub mod array_normalize;
+pub mod array_product;
 pub mod array_scale;
 pub mod array_subtract;
 pub mod array_transform;
@@ -99,6 +100,7 @@ pub mod expr_fn {
     pub use super::array_has::array_has_all;
     pub use super::array_has::array_has_any;
     pub use super::array_normalize::array_normalize;
+    pub use super::array_product::array_product;
     pub use super::array_scale::array_scale;
     pub use super::array_subtract::array_subtract;
     pub use super::array_transform::array_transform;
@@ -177,6 +179,7 @@ pub fn all_default_nested_functions() -> Vec<Arc<ScalarUDF>> {
         length::array_length_udf(),
         array_normalize::array_normalize_udf(),
         array_add::array_add_udf(),
+        array_product::array_product_udf(),
         array_scale::array_scale_udf(),
         array_subtract::array_subtract_udf(),
         cosine_distance::cosine_distance_udf(),

datafusion/sqllogictest/test_files/array_product.slt

@@ -0,0 +1,145 @@
+# 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.
+
+## array_product
+
+# Basic product of three floats
+query R
+select array_product([1.0, 2.0, 3.0]);
+----
+6
+
+# Negative values: signs multiply
+query R
+select array_product([-2.0, 3.0]);
+----
+-6
+
+# Single element returns itself
+query R
+select array_product([5.0]);
+----
+5
+
+# Zero element produces zero (no short-circuit; we still multiply)
+query R
+select array_product([0.0, 3.0, 4.0]);
+----
+0
+
+# NULL elements inside the list are skipped (SQL aggregate convention)
+query R
+select array_product([2.0, NULL, 3.0]);
+----
+6
+
+# All-NULL elements: no data to reduce, returns NULL
+query R
+select array_product([CAST(NULL AS DOUBLE), CAST(NULL AS DOUBLE)]);
+----
+NULL
+
+# Bare NULL input returns NULL
+query R
+select array_product(NULL);
+----
+NULL
+
+# Empty array: returns 1.0 (multiplicative identity)
+query R
+select array_product(arrow_cast(make_array(), 'List(Float64)'));
+----
+1
+
+# LargeList input
+query R
+select array_product(arrow_cast([2.0, 3.0, 4.0], 'LargeList(Float64)'));
+----
+24
+
+# FixedSizeList input (coerced to List)
+query R
+select array_product(arrow_cast([2.0, 3.0, 4.0], 'FixedSizeList(3, Float64)'));
+----
+24
+
+# Float32 inner type (coerced to Float64)
+query R
+select array_product(arrow_cast([2.0, 3.0, 4.0], 'List(Float32)'));
+----
+24
+
+# Int64 inner type (coerced to Float64)
+query R
+select array_product(arrow_cast([2, 3, 4], 'List(Int64)'));
+----
+24
+
+# Integer literals (coerced to Float64)
+query R
+select array_product([2, 3, 4]);
+----
+24
+
+# Unsupported non-list input (plan error)
+query error array_product does not support type
+select array_product(1);
+
+# No arguments error
+query error array_product function requires 1 argument, got 0
+select array_product();
+
+# Multi-row query: normal row, NULL row, empty list, all-NULL elements,
+# element-NULL skip, single zero
+query R
+select array_product(column1) from (values
+    (make_array(2.0, 3.0, 4.0)),
+    (NULL),
+    (arrow_cast(make_array(), 'List(Float64)')),
+    (make_array(CAST(NULL AS DOUBLE), CAST(NULL AS DOUBLE))),
+    (make_array(CAST(2.0 AS DOUBLE), CAST(NULL AS DOUBLE), CAST(5.0 AS DOUBLE))),
+    (make_array(0.0, 7.0))
+) as t(column1);
+----
+24
+NULL
+1
+NULL
+10
+0
+
+# Return type is always Float64 (scalar, not List)
+query RT
+select array_product([2.0, 3.0]), arrow_typeof(array_product([2.0, 3.0]));
+----
+6 Float64
+
+# list_product alias produces the same result
+query R
+select list_product([2.0, 3.0, 4.0]);
+----
+24
+
+# list_product alias multi-row
+query R
+select list_product(column1) from (values
+    (make_array(2.0, 3.0)),
+    (NULL)
+) as t(column1);
+----
+6
+NULL