Convert nth_value builtIn function to User Defined Window Function

datafusion/core/src/dataframe/mod.rs

@@ -1946,12 +1946,12 @@ mod tests {
     use datafusion_common_runtime::SpawnedTask;
     use datafusion_expr::expr::WindowFunction;
     use datafusion_expr::{
-        cast, create_udf, lit, BuiltInWindowFunction, ExprFunctionExt,
-        ScalarFunctionImplementation, Volatility, WindowFrame, WindowFrameBound,
-        WindowFrameUnits, WindowFunctionDefinition,
+        cast, create_udf, lit, ExprFunctionExt, ScalarFunctionImplementation, Volatility,
+        WindowFrame, WindowFrameBound, WindowFrameUnits, WindowFunctionDefinition,
     };
     use datafusion_functions_aggregate::expr_fn::{array_agg, count_distinct};
     use datafusion_functions_window::expr_fn::row_number;
+    use datafusion_functions_window::nth_value::first_value_udwf;
     use datafusion_physical_expr::expressions::Column;
     use datafusion_physical_plan::{get_plan_string, ExecutionPlanProperties};
     use sqlparser::ast::NullTreatment;
@@ -2177,9 +2177,7 @@ mod tests {
         // build plan using Table API
         let t = test_table().await?;
         let first_row = Expr::WindowFunction(WindowFunction::new(
-            WindowFunctionDefinition::BuiltInWindowFunction(
-                BuiltInWindowFunction::FirstValue,
-            ),
+            WindowFunctionDefinition::WindowUDF(first_value_udwf()),
             vec![col("aggregate_test_100.c1")],
         ))
         .partition_by(vec![col("aggregate_test_100.c2")])

datafusion/core/tests/fuzz_cases/window_fuzz.rs

@@ -34,8 +34,7 @@ use datafusion_common::{Result, ScalarValue};
 use datafusion_common_runtime::SpawnedTask;
 use datafusion_expr::type_coercion::functions::data_types_with_aggregate_udf;
 use datafusion_expr::{
-    BuiltInWindowFunction, WindowFrame, WindowFrameBound, WindowFrameUnits,
-    WindowFunctionDefinition,
+    WindowFrame, WindowFrameBound, WindowFrameUnits, WindowFunctionDefinition,
 };
 use datafusion_functions_aggregate::count::count_udaf;
 use datafusion_functions_aggregate::min_max::{max_udaf, min_udaf};
@@ -47,6 +46,9 @@ use test_utils::add_empty_batches;
 use datafusion::functions_window::row_number::row_number_udwf;
 use datafusion_common::HashMap;
 use datafusion_functions_window::lead_lag::{lag_udwf, lead_udwf};
+use datafusion_functions_window::nth_value::{
+    first_value_udwf, last_value_udwf, nth_value_udwf,
+};
 use datafusion_functions_window::rank::{dense_rank_udwf, rank_udwf};
 use datafusion_physical_expr_common::sort_expr::LexOrdering;
 use rand::distributions::Alphanumeric;
@@ -418,27 +420,21 @@ fn get_random_function(
     window_fn_map.insert(
         "first_value",
         (
-            WindowFunctionDefinition::BuiltInWindowFunction(
-                BuiltInWindowFunction::FirstValue,
-            ),
+            WindowFunctionDefinition::WindowUDF(first_value_udwf()),
             vec![arg.clone()],
         ),
     );
     window_fn_map.insert(
         "last_value",
         (
-            WindowFunctionDefinition::BuiltInWindowFunction(
-                BuiltInWindowFunction::LastValue,
-            ),
+            WindowFunctionDefinition::WindowUDF(last_value_udwf()),
             vec![arg.clone()],
         ),
     );
     window_fn_map.insert(
         "nth_value",
         (
-            WindowFunctionDefinition::BuiltInWindowFunction(
-                BuiltInWindowFunction::NthValue,
-            ),
+            WindowFunctionDefinition::WindowUDF(nth_value_udwf()),
             vec![
                 arg.clone(),
                 lit(ScalarValue::Int64(Some(rng.gen_range(1..10)))),

datafusion/expr/src/expr.rs

@@ -21,7 +21,6 @@ use std::collections::HashSet;
 use std::fmt::{self, Display, Formatter, Write};
 use std::hash::{Hash, Hasher};
 use std::mem;
-use std::str::FromStr;
 use std::sync::Arc;
 
 use crate::expr_fn::binary_expr;
@@ -832,23 +831,6 @@ impl WindowFunction {
     }
 }
 
-/// Find DataFusion's built-in window function by name.
-pub fn find_df_window_func(name: &str) -> Option<WindowFunctionDefinition> {
-    let name = name.to_lowercase();
-    // Code paths for window functions leveraging ordinary aggregators and
-    // built-in window functions are quite different, and the same function
-    // may have different implementations for these cases. If the sought
-    // function is not found among built-in window functions, we search for
-    // it among aggregate functions.
-    if let Ok(built_in_function) = BuiltInWindowFunction::from_str(name.as_str()) {
-        Some(WindowFunctionDefinition::BuiltInWindowFunction(
-            built_in_function,
-        ))
-    } else {
-        None
-    }
-}
-
 /// EXISTS expression
 #[derive(Clone, PartialEq, Eq, PartialOrd, Hash, Debug)]
 pub struct Exists {
@@ -2548,77 +2530,6 @@ mod test {
 
     use super::*;
 
-    #[test]
-    fn test_first_value_return_type() -> Result<()> {
-        let fun = find_df_window_func("first_value").unwrap();
-        let observed = fun.return_type(&[DataType::Utf8], &[true], "")?;
-        assert_eq!(DataType::Utf8, observed);
-
-        let observed = fun.return_type(&[DataType::UInt64], &[true], "")?;
-        assert_eq!(DataType::UInt64, observed);
-
-        Ok(())
-    }
-
-    #[test]
-    fn test_last_value_return_type() -> Result<()> {
-        let fun = find_df_window_func("last_value").unwrap();
-        let observed = fun.return_type(&[DataType::Utf8], &[true], "")?;
-        assert_eq!(DataType::Utf8, observed);
-
-        let observed = fun.return_type(&[DataType::Float64], &[true], "")?;
-        assert_eq!(DataType::Float64, observed);
-
-        Ok(())
-    }
-
-    #[test]
-    fn test_nth_value_return_type() -> Result<()> {
-        let fun = find_df_window_func("nth_value").unwrap();
-        let observed =
-            fun.return_type(&[DataType::Utf8, DataType::UInt64], &[true, true], "")?;
-        assert_eq!(DataType::Utf8, observed);
-
-        let observed =
-            fun.return_type(&[DataType::Float64, DataType::UInt64], &[true, true], "")?;
-        assert_eq!(DataType::Float64, observed);
-
-        Ok(())
-    }
-
-    #[test]
-    fn test_window_function_case_insensitive() -> Result<()> {
-        let names = vec!["first_value", "last_value", "nth_value"];
-        for name in names {
-            let fun = find_df_window_func(name).unwrap();
-            let fun2 = find_df_window_func(name.to_uppercase().as_str()).unwrap();
-            assert_eq!(fun, fun2);
-            if fun.to_string() == "first_value" || fun.to_string() == "last_value" {
-                assert_eq!(fun.to_string(), name);
-            } else {
-                assert_eq!(fun.to_string(), name.to_uppercase());
-            }
-        }
-        Ok(())
-    }
-
-    #[test]
-    fn test_find_df_window_function() {
-        assert_eq!(
-            find_df_window_func("first_value"),
-            Some(WindowFunctionDefinition::BuiltInWindowFunction(
-                BuiltInWindowFunction::FirstValue
-            ))
-        );
-        assert_eq!(
-            find_df_window_func("LAST_value"),
-            Some(WindowFunctionDefinition::BuiltInWindowFunction(
-                BuiltInWindowFunction::LastValue
-            ))
-        );
-        assert_eq!(find_df_window_func("not_exist"), None)
-    }
-
     #[test]
     fn test_display_wildcard() {
         assert_eq!(format!("{}", wildcard()), "*");

datafusion/expr/src/lib.rs

@@ -65,7 +65,6 @@ pub mod type_coercion;
 pub mod utils;
 pub mod var_provider;
 pub mod window_frame;
-pub mod window_function;
 pub mod window_state;
 
 pub use built_in_window_function::BuiltInWindowFunction;

datafusion/functions-window/src/lib.rs

@@ -22,6 +22,7 @@
 //!
 //! [DataFusion]: https://crates.io/crates/datafusion
 //!
+
 use std::sync::Arc;
 
 use log::debug;
@@ -34,6 +35,7 @@ pub mod macros;
 
 pub mod cume_dist;
 pub mod lead_lag;
+pub mod nth_value;
 pub mod ntile;
 pub mod rank;
 pub mod row_number;
@@ -44,6 +46,7 @@ pub mod expr_fn {
     pub use super::cume_dist::cume_dist;
     pub use super::lead_lag::lag;
     pub use super::lead_lag::lead;
+    pub use super::nth_value::{first_value, last_value, nth_value};
     pub use super::ntile::ntile;
     pub use super::rank::{dense_rank, percent_rank, rank};
     pub use super::row_number::row_number;
@@ -60,6 +63,9 @@ pub fn all_default_window_functions() -> Vec<Arc<WindowUDF>> {
         rank::dense_rank_udwf(),
         rank::percent_rank_udwf(),
         ntile::ntile_udwf(),
+        nth_value::first_value_udwf(),
+        nth_value::last_value_udwf(),
+        nth_value::nth_value_udwf(),
     ]
 }
 /// Registers all enabled packages with a [`FunctionRegistry`]