Add customizable equality and hash functions to UDFs (apache#11392)

* Add customizable equality and hash functions to UDFs

* Improve equals and hash_value documentation

* Add tests for parameterized UDFs

datafusion/core/tests/user_defined/user_defined_aggregates.rs

@@ -18,14 +18,19 @@
 //! This module contains end to end demonstrations of creating
 //! user defined aggregate functions
 
-use arrow::{array::AsArray, datatypes::Fields};
-use arrow_array::{types::UInt64Type, Int32Array, PrimitiveArray, StructArray};
-use arrow_schema::Schema;
+use std::hash::{DefaultHasher, Hash, Hasher};
 use std::sync::{
     atomic::{AtomicBool, Ordering},
     Arc,
 };
 
+use arrow::{array::AsArray, datatypes::Fields};
+use arrow_array::{
+    types::UInt64Type, Int32Array, PrimitiveArray, StringArray, StructArray,
+};
+use arrow_schema::Schema;
+
+use datafusion::dataframe::DataFrame;
 use datafusion::datasource::MemTable;
 use datafusion::test_util::plan_and_collect;
 use datafusion::{
@@ -45,8 +50,8 @@ use datafusion::{
 };
 use datafusion_common::{assert_contains, cast::as_primitive_array, exec_err};
 use datafusion_expr::{
-    create_udaf, function::AccumulatorArgs, AggregateUDFImpl, GroupsAccumulator,
-    SimpleAggregateUDF,
+    col, create_udaf, function::AccumulatorArgs, AggregateUDFImpl, GroupsAccumulator,
+    LogicalPlanBuilder, SimpleAggregateUDF,
 };
 use datafusion_functions_aggregate::average::AvgAccumulator;
 
@@ -377,6 +382,55 @@ async fn test_groups_accumulator() -> Result<()> {
     Ok(())
 }
 
+#[tokio::test]
+async fn test_parameterized_aggregate_udf() -> Result<()> {
+    let batch = RecordBatch::try_from_iter([(
+        "text",
+        Arc::new(StringArray::from(vec!["foo"])) as ArrayRef,
+    )])?;
+
+    let ctx = SessionContext::new();
+    ctx.register_batch("t", batch)?;
+    let t = ctx.table("t").await?;
+    let signature = Signature::exact(vec![DataType::Utf8], Volatility::Immutable);
+    let udf1 = AggregateUDF::from(TestGroupsAccumulator {
+        signature: signature.clone(),
+        result: 1,
+    });
+    let udf2 = AggregateUDF::from(TestGroupsAccumulator {
+        signature: signature.clone(),
+        result: 2,
+    });
+
+    let plan = LogicalPlanBuilder::from(t.into_optimized_plan()?)
+        .aggregate(
+            [col("text")],
+            [
+                udf1.call(vec![col("text")]).alias("a"),
+                udf2.call(vec![col("text")]).alias("b"),
+            ],
+        )?
+        .build()?;
+
+    assert_eq!(
+        format!("{plan:?}"),
+        "Aggregate: groupBy=[[t.text]], aggr=[[geo_mean(t.text) AS a, geo_mean(t.text) AS b]]\n  TableScan: t projection=[text]"
+    );
+
+    let actual = DataFrame::new(ctx.state(), plan).collect().await?;
+    let expected = [
+        "+------+---+---+",
+        "| text | a | b |",
+        "+------+---+---+",
+        "| foo  | 1 | 2 |",
+        "+------+---+---+",
+    ];
+    assert_batches_eq!(expected, &actual);
+
+    ctx.deregister_table("t")?;
+    Ok(())
+}
+
 /// Returns an context with a table "t" and the "first" and "time_sum"
 /// aggregate functions registered.
 ///
@@ -735,6 +789,21 @@ impl AggregateUDFImpl for TestGroupsAccumulator {
     ) -> Result<Box<dyn GroupsAccumulator>> {
         Ok(Box::new(self.clone()))
     }
+
+    fn equals(&self, other: &dyn AggregateUDFImpl) -> bool {
+        if let Some(other) = other.as_any().downcast_ref::<TestGroupsAccumulator>() {
+            self.result == other.result && self.signature == other.signature
+        } else {
+            false
+        }
+    }
+
+    fn hash_value(&self) -> u64 {
+        let hasher = &mut DefaultHasher::new();
+        self.signature.hash(hasher);
+        self.result.hash(hasher);
+        hasher.finish()
+    }
 }
 
 impl Accumulator for TestGroupsAccumulator {

datafusion/core/tests/user_defined/user_defined_scalar_functions.rs

@@ -16,11 +16,20 @@
 // under the License.
 
 use std::any::Any;
+use std::hash::{DefaultHasher, Hash, Hasher};
 use std::sync::Arc;
 
 use arrow::compute::kernels::numeric::add;
-use arrow_array::{ArrayRef, Float32Array, Float64Array, Int32Array, RecordBatch};
+use arrow_array::builder::BooleanBuilder;
+use arrow_array::cast::AsArray;
+use arrow_array::{
+    Array, ArrayRef, Float32Array, Float64Array, Int32Array, RecordBatch, StringArray,
+};
 use arrow_schema::{DataType, Field, Schema};
+use parking_lot::Mutex;
+use regex::Regex;
+use sqlparser::ast::Ident;
+
 use datafusion::execution::context::{FunctionFactory, RegisterFunction, SessionState};
 use datafusion::prelude::*;
 use datafusion::{execution::registry::FunctionRegistry, test_util};
@@ -37,8 +46,6 @@ use datafusion_expr::{
     Volatility,
 };
 use datafusion_functions_array::range::range_udf;
-use parking_lot::Mutex;
-use sqlparser::ast::Ident;
 
 /// test that casting happens on udfs.
 /// c11 is f32, but `custom_sqrt` requires f64. Casting happens but the logical plan and
@@ -1021,6 +1028,121 @@ async fn create_scalar_function_from_sql_statement_postgres_syntax() -> Result<(
     Ok(())
 }
 
+#[derive(Debug)]
+struct MyRegexUdf {
+    signature: Signature,
+    regex: Regex,
+}
+
+impl MyRegexUdf {
+    fn new(pattern: &str) -> Self {
+        Self {
+            signature: Signature::exact(vec![DataType::Utf8], Volatility::Immutable),
+            regex: Regex::new(pattern).expect("regex"),
+        }
+    }
+
+    fn matches(&self, value: Option<&str>) -> Option<bool> {
+        Some(self.regex.is_match(value?))
+    }
+}
+
+impl ScalarUDFImpl for MyRegexUdf {
+    fn as_any(&self) -> &dyn Any {
+        self
+    }
+
+    fn name(&self) -> &str {
+        "regex_udf"
+    }
+
+    fn signature(&self) -> &Signature {
+        &self.signature
+    }
+
+    fn return_type(&self, args: &[DataType]) -> Result<DataType> {
+        if matches!(args, [DataType::Utf8]) {
+            Ok(DataType::Boolean)
+        } else {
+            plan_err!("regex_udf only accepts a Utf8 argument")
+        }
+    }
+
+    fn invoke(&self, args: &[ColumnarValue]) -> Result<ColumnarValue> {
+        match args {
+            [ColumnarValue::Scalar(ScalarValue::Utf8(value))] => {
+                Ok(ColumnarValue::Scalar(ScalarValue::Boolean(
+                    self.matches(value.as_deref()),
+                )))
+            }
+            [ColumnarValue::Array(values)] => {
+                let mut builder = BooleanBuilder::with_capacity(values.len());
+                for value in values.as_string::<i32>() {
+                    builder.append_option(self.matches(value))
+                }
+                Ok(ColumnarValue::Array(Arc::new(builder.finish())))
+            }
+            _ => exec_err!("regex_udf only accepts a Utf8 arguments"),
+        }
+    }
+
+    fn equals(&self, other: &dyn ScalarUDFImpl) -> bool {
+        if let Some(other) = other.as_any().downcast_ref::<MyRegexUdf>() {
+            self.regex.as_str() == other.regex.as_str()
+        } else {
+            false
+        }
+    }
+
+    fn hash_value(&self) -> u64 {
+        let hasher = &mut DefaultHasher::new();
+        self.regex.as_str().hash(hasher);
+        hasher.finish()
+    }
+}
+
+#[tokio::test]
+async fn test_parameterized_scalar_udf() -> Result<()> {
+    let batch = RecordBatch::try_from_iter([(
+        "text",
+        Arc::new(StringArray::from(vec!["foo", "bar", "foobar", "barfoo"])) as ArrayRef,
+    )])?;
+
+    let ctx = SessionContext::new();
+    ctx.register_batch("t", batch)?;
+    let t = ctx.table("t").await?;
+    let foo_udf = ScalarUDF::from(MyRegexUdf::new("fo{2}"));
+    let bar_udf = ScalarUDF::from(MyRegexUdf::new("[Bb]ar"));
+
+    let plan = LogicalPlanBuilder::from(t.into_optimized_plan()?)
+        .filter(
+            foo_udf
+                .call(vec![col("text")])
+                .and(bar_udf.call(vec![col("text")])),
+        )?
+        .filter(col("text").is_not_null())?
+        .build()?;
+
+    assert_eq!(
+        format!("{plan:?}"),
+        "Filter: t.text IS NOT NULL\n  Filter: regex_udf(t.text) AND regex_udf(t.text)\n    TableScan: t projection=[text]"
+    );
+
+    let actual = DataFrame::new(ctx.state(), plan).collect().await?;
+    let expected = [
+        "+--------+",
+        "| text   |",
+        "+--------+",
+        "| foobar |",
+        "| barfoo |",
+        "+--------+",
+    ];
+    assert_batches_eq!(expected, &actual);
+
+    ctx.deregister_table("t")?;
+    Ok(())
+}
+
 fn create_udf_context() -> SessionContext {
     let ctx = SessionContext::new();
     // register a custom UDF

datafusion/expr/src/udaf.rs

@@ -17,6 +17,17 @@
 
 //! [`AggregateUDF`]: User Defined Aggregate Functions
 
+use std::any::Any;
+use std::fmt::{self, Debug, Formatter};
+use std::hash::{DefaultHasher, Hash, Hasher};
+use std::sync::Arc;
+use std::vec;
+
+use arrow::datatypes::{DataType, Field};
+use sqlparser::ast::NullTreatment;
+
+use datafusion_common::{exec_err, not_impl_err, plan_err, Result};
+
 use crate::expr::AggregateFunction;
 use crate::function::{
     AccumulatorArgs, AggregateFunctionSimplification, StateFieldsArgs,
@@ -26,13 +37,6 @@ use crate::utils::format_state_name;
 use crate::utils::AggregateOrderSensitivity;
 use crate::{Accumulator, Expr};
 use crate::{AccumulatorFactoryFunction, ReturnTypeFunction, Signature};
-use arrow::datatypes::{DataType, Field};
-use datafusion_common::{exec_err, not_impl_err, plan_err, Result};
-use sqlparser::ast::NullTreatment;
-use std::any::Any;
-use std::fmt::{self, Debug, Formatter};
-use std::sync::Arc;
-use std::vec;
 
 /// Logical representation of a user-defined [aggregate function] (UDAF).
 ///
@@ -72,20 +76,19 @@ pub struct AggregateUDF {
 
 impl PartialEq for AggregateUDF {
     fn eq(&self, other: &Self) -> bool {
-        self.name() == other.name() && self.signature() == other.signature()
+        self.inner.equals(other.inner.as_ref())
     }
 }
 
 impl Eq for AggregateUDF {}
 
-impl std::hash::Hash for AggregateUDF {
-    fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
-        self.name().hash(state);
-        self.signature().hash(state);
+impl Hash for AggregateUDF {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        self.inner.hash_value().hash(state)
     }
 }
 
-impl std::fmt::Display for AggregateUDF {
+impl fmt::Display for AggregateUDF {
     fn fmt(&self, f: &mut Formatter) -> fmt::Result {
         write!(f, "{}", self.name())
     }
@@ -280,7 +283,7 @@ where
 /// #[derive(Debug, Clone)]
 /// struct GeoMeanUdf {
 ///   signature: Signature
-/// };
+/// }
 ///
 /// impl GeoMeanUdf {
 ///   fn new() -> Self {
@@ -507,6 +510,33 @@ pub trait AggregateUDFImpl: Debug + Send + Sync {
     fn coerce_types(&self, _arg_types: &[DataType]) -> Result<Vec<DataType>> {
         not_impl_err!("Function {} does not implement coerce_types", self.name())
     }
+
+    /// Return true if this aggregate UDF is equal to the other.
+    ///
+    /// Allows customizing the equality of aggregate UDFs.
+    /// Must be consistent with [`Self::hash_value`] and follow the same rules as [`Eq`]:
+    ///
+    /// - reflexive: `a.equals(a)`;
+    /// - symmetric: `a.equals(b)` implies `b.equals(a)`;
+    /// - transitive: `a.equals(b)` and `b.equals(c)` implies `a.equals(c)`.
+    ///
+    /// By default, compares [`Self::name`] and [`Self::signature`].
+    fn equals(&self, other: &dyn AggregateUDFImpl) -> bool {
+        self.name() == other.name() && self.signature() == other.signature()
+    }
+
+    /// Returns a hash value for this aggregate UDF.
+    ///
+    /// Allows customizing the hash code of aggregate UDFs. Similarly to [`Hash`] and [`Eq`],
+    /// if [`Self::equals`] returns true for two UDFs, their `hash_value`s must be the same.
+    ///
+    /// By default, hashes [`Self::name`] and [`Self::signature`].
+    fn hash_value(&self) -> u64 {
+        let hasher = &mut DefaultHasher::new();
+        self.name().hash(hasher);
+        self.signature().hash(hasher);
+        hasher.finish()
+    }
 }
 
 pub enum ReversedUDAF {
@@ -562,6 +592,21 @@ impl AggregateUDFImpl for AliasedAggregateUDFImpl {
     fn aliases(&self) -> &[String] {
         &self.aliases
     }
+
+    fn equals(&self, other: &dyn AggregateUDFImpl) -> bool {
+        if let Some(other) = other.as_any().downcast_ref::<AliasedAggregateUDFImpl>() {
+            self.inner.equals(other.inner.as_ref()) && self.aliases == other.aliases
+        } else {
+            false
+        }
+    }
+
+    fn hash_value(&self) -> u64 {
+        let hasher = &mut DefaultHasher::new();
+        self.inner.hash_value().hash(hasher);
+        self.aliases.hash(hasher);
+        hasher.finish()
+    }
 }
 
 /// Implementation of [`AggregateUDFImpl`] that wraps the function style pointers