Add support for additional numeric types in to_timestamp functions (#19663)

## Which issue does this PR close?

Closes #19117.

## Rationale for this change

The `to_timestamp` function family lacks consistency in supported
argument types. While `to_timestamp` accepts Float64 and Decimal128
types, the related functions (`to_timestamp_seconds`,
`to_timestamp_millis`, `to_timestamp_micros`, `to_timestamp_nanos`)
don't offer the same support. Additionally, the documentation claims
support for "unsigned integer" types, but this isn't fully implemented.

## What changes are included in this PR?

Standardizes all `to_timestamp` variants to uniformly support:

- All signed integer types: Int8, Int16, Int32, Int64
- All unsigned integer types: UInt8, UInt16, UInt32, UInt64
- Float32 and Float64
- Decimal128 (for millis/micros/nanos variants)

## Are these changes tested?

Yes, added comprehensive SQL logic tests in
`datafusion/sqllogictest/test_files/datetime/timestamps.slt`.

## Are there any user-facing changes?

Users can now pass additional numeric types to `to_timestamp` functions.
This is a backward-compatible enhancement.

Author: gokselk

datafusion/functions/src/datetime/to_timestamp.rs

@@ -19,16 +19,18 @@ use std::any::Any;
 use std::sync::Arc;
 
 use crate::datetime::common::*;
-use arrow::array::Float64Array;
 use arrow::array::timezone::Tz;
+use arrow::array::{
+    Array, Decimal128Array, Float16Array, Float32Array, Float64Array,
+    TimestampNanosecondArray,
+};
 use arrow::datatypes::DataType::*;
 use arrow::datatypes::TimeUnit::{Microsecond, Millisecond, Nanosecond, Second};
 use arrow::datatypes::{
     ArrowTimestampType, DataType, TimestampMicrosecondType, TimestampMillisecondType,
     TimestampNanosecondType, TimestampSecondType,
 };
 use datafusion_common::config::ConfigOptions;
-use datafusion_common::format::DEFAULT_CAST_OPTIONS;
 use datafusion_common::{Result, ScalarType, ScalarValue, exec_err};
 use datafusion_expr::{
     ColumnarValue, Documentation, ScalarUDF, ScalarUDFImpl, Signature, Volatility,
@@ -325,6 +327,45 @@ impl_to_timestamp_constructors!(ToTimestampMillisFunc);
 impl_to_timestamp_constructors!(ToTimestampMicrosFunc);
 impl_to_timestamp_constructors!(ToTimestampNanosFunc);
 
+fn decimal_to_nanoseconds(value: i128, scale: i8) -> i64 {
+    let nanos_exponent = 9_i16 - scale as i16;
+    let timestamp_nanos = if nanos_exponent >= 0 {
+        value * 10_i128.pow(nanos_exponent as u32)
+    } else {
+        value / 10_i128.pow(nanos_exponent.unsigned_abs() as u32)
+    };
+    timestamp_nanos as i64
+}
+
+fn decimal128_to_timestamp_nanos(
+    arg: &ColumnarValue,
+    tz: Option<Arc<str>>,
+) -> Result<ColumnarValue> {
+    match arg {
+        ColumnarValue::Scalar(ScalarValue::Decimal128(Some(value), _, scale)) => {
+            let timestamp_nanos = decimal_to_nanoseconds(*value, *scale);
+            Ok(ColumnarValue::Scalar(ScalarValue::TimestampNanosecond(
+                Some(timestamp_nanos),
+                tz,
+            )))
+        }
+        ColumnarValue::Scalar(ScalarValue::Decimal128(None, _, _)) => Ok(
+            ColumnarValue::Scalar(ScalarValue::TimestampNanosecond(None, tz)),
+        ),
+        ColumnarValue::Array(arr) => {
+            let decimal_arr = downcast_arg!(arr, Decimal128Array);
+            let scale = decimal_arr.scale();
+            let result: TimestampNanosecondArray = decimal_arr
+                .iter()
+                .map(|v| v.map(|val| decimal_to_nanoseconds(val, scale)))
+                .collect();
+            let result = result.with_timezone_opt(tz);
+            Ok(ColumnarValue::Array(Arc::new(result)))
+        }
+        _ => exec_err!("Invalid Decimal128 value for to_timestamp"),
+    }
+}
+
 /// to_timestamp SQL function
 ///
 /// Note: `to_timestamp` returns `Timestamp(Nanosecond)` though its arguments are interpreted as **seconds**.
@@ -380,48 +421,39 @@ impl ScalarUDFImpl for ToTimestampFunc {
         let tz = self.timezone.clone();
 
         match args[0].data_type() {
-            Int32 | Int64 => args[0]
+            Int8 | Int16 | Int32 | Int64 | UInt8 | UInt16 | UInt32 | UInt64 => args[0]
                 .cast_to(&Timestamp(Second, None), None)?
                 .cast_to(&Timestamp(Nanosecond, tz), None),
             Null | Timestamp(_, _) => args[0].cast_to(&Timestamp(Nanosecond, tz), None),
+            Float16 => {
+                let arr = args[0].to_array(1)?;
+                let f16_arr = downcast_arg!(&arr, Float16Array);
+                let result: TimestampNanosecondArray =
+                    f16_arr.unary(|x| (x.to_f64() * 1_000_000_000.0) as i64);
+                Ok(ColumnarValue::Array(Arc::new(result.with_timezone_opt(tz))))
+            }
+            Float32 => {
+                let arr = args[0].to_array(1)?;
+                let f32_arr = downcast_arg!(&arr, Float32Array);
+                let result: TimestampNanosecondArray =
+                    f32_arr.unary(|x| (x as f64 * 1_000_000_000.0) as i64);
+                Ok(ColumnarValue::Array(Arc::new(result.with_timezone_opt(tz))))
+            }
             Float64 => {
-                let rescaled = arrow::compute::kernels::numeric::mul(
-                    &args[0].to_array(1)?,
-                    &arrow::array::Scalar::new(Float64Array::from(vec![
-                        1_000_000_000f64,
-                    ])),
-                )?;
-                Ok(ColumnarValue::Array(arrow::compute::cast_with_options(
-                    &rescaled,
-                    &Timestamp(Nanosecond, tz),
-                    &DEFAULT_CAST_OPTIONS,
-                )?))
+                let arr = args[0].to_array(1)?;
+                let f64_arr = downcast_arg!(&arr, Float64Array);
+                let result: TimestampNanosecondArray =
+                    f64_arr.unary(|x| (x * 1_000_000_000.0) as i64);
+                Ok(ColumnarValue::Array(Arc::new(result.with_timezone_opt(tz))))
+            }
+            Decimal32(_, _) | Decimal64(_, _) | Decimal256(_, _) => {
+                let arg = args[0].cast_to(&Decimal128(38, 9), None)?;
+                decimal128_to_timestamp_nanos(&arg, tz)
             }
+            Decimal128(_, _) => decimal128_to_timestamp_nanos(&args[0], tz),
             Utf8View | LargeUtf8 | Utf8 => {
                 to_timestamp_impl::<TimestampNanosecondType>(&args, "to_timestamp", &tz)
             }
-            Decimal128(_, _) => {
-                match &args[0] {
-                    ColumnarValue::Scalar(ScalarValue::Decimal128(
-                        Some(value),
-                        _,
-                        scale,
-                    )) => {
-                        // Convert decimal to seconds and nanoseconds
-                        let scale_factor = 10_i128.pow(*scale as u32);
-                        let seconds = value / scale_factor;
-                        let fraction = value % scale_factor;
-                        let nanos = (fraction * 1_000_000_000) / scale_factor;
-                        let timestamp_nanos = seconds * 1_000_000_000 + nanos;
-
-                        Ok(ColumnarValue::Scalar(ScalarValue::TimestampNanosecond(
-                            Some(timestamp_nanos as i64),
-                            tz,
-                        )))
-                    }
-                    _ => exec_err!("Invalid decimal value"),
-                }
-            }
             other => {
                 exec_err!("Unsupported data type {other} for function to_timestamp")
             }
@@ -473,9 +505,23 @@ impl ScalarUDFImpl for ToTimestampSecondsFunc {
         let tz = self.timezone.clone();
 
         match args[0].data_type() {
-            Null | Int32 | Int64 | Timestamp(_, _) | Decimal128(_, _) => {
-                args[0].cast_to(&Timestamp(Second, tz), None)
-            }
+            Null
+            | Int8
+            | Int16
+            | Int32
+            | Int64
+            | UInt8
+            | UInt16
+            | UInt32
+            | UInt64
+            | Timestamp(_, _)
+            | Decimal32(_, _)
+            | Decimal64(_, _)
+            | Decimal128(_, _)
+            | Decimal256(_, _) => args[0].cast_to(&Timestamp(Second, tz), None),
+            Float16 | Float32 | Float64 => args[0]
+                .cast_to(&Int64, None)?
+                .cast_to(&Timestamp(Second, tz), None),
             Utf8View | LargeUtf8 | Utf8 => to_timestamp_impl::<TimestampSecondType>(
                 &args,
                 "to_timestamp_seconds",
@@ -533,9 +579,25 @@ impl ScalarUDFImpl for ToTimestampMillisFunc {
         }
 
         match args[0].data_type() {
-            Null | Int32 | Int64 | Timestamp(_, _) => {
+            Null
+            | Int8
+            | Int16
+            | Int32
+            | Int64
+            | UInt8
+            | UInt16
+            | UInt32
+            | UInt64
+            | Timestamp(_, _)
+            | Decimal32(_, _)
+            | Decimal64(_, _)
+            | Decimal128(_, _)
+            | Decimal256(_, _) => {
                 args[0].cast_to(&Timestamp(Millisecond, self.timezone.clone()), None)
             }
+            Float16 | Float32 | Float64 => args[0]
+                .cast_to(&Int64, None)?
+                .cast_to(&Timestamp(Millisecond, self.timezone.clone()), None),
             Utf8View | LargeUtf8 | Utf8 => to_timestamp_impl::<TimestampMillisecondType>(
                 &args,
                 "to_timestamp_millis",
@@ -593,9 +655,25 @@ impl ScalarUDFImpl for ToTimestampMicrosFunc {
         }
 
         match args[0].data_type() {
-            Null | Int32 | Int64 | Timestamp(_, _) => {
+            Null
+            | Int8
+            | Int16
+            | Int32
+            | Int64
+            | UInt8
+            | UInt16
+            | UInt32
+            | UInt64
+            | Timestamp(_, _)
+            | Decimal32(_, _)
+            | Decimal64(_, _)
+            | Decimal128(_, _)
+            | Decimal256(_, _) => {
                 args[0].cast_to(&Timestamp(Microsecond, self.timezone.clone()), None)
             }
+            Float16 | Float32 | Float64 => args[0]
+                .cast_to(&Int64, None)?
+                .cast_to(&Timestamp(Microsecond, self.timezone.clone()), None),
             Utf8View | LargeUtf8 | Utf8 => to_timestamp_impl::<TimestampMicrosecondType>(
                 &args,
                 "to_timestamp_micros",
@@ -653,9 +731,25 @@ impl ScalarUDFImpl for ToTimestampNanosFunc {
         }
 
         match args[0].data_type() {
-            Null | Int32 | Int64 | Timestamp(_, _) => {
+            Null
+            | Int8
+            | Int16
+            | Int32
+            | Int64
+            | UInt8
+            | UInt16
+            | UInt32
+            | UInt64
+            | Timestamp(_, _)
+            | Decimal32(_, _)
+            | Decimal64(_, _)
+            | Decimal128(_, _)
+            | Decimal256(_, _) => {
                 args[0].cast_to(&Timestamp(Nanosecond, self.timezone.clone()), None)
             }
+            Float16 | Float32 | Float64 => args[0]
+                .cast_to(&Int64, None)?
+                .cast_to(&Timestamp(Nanosecond, self.timezone.clone()), None),
             Utf8View | LargeUtf8 | Utf8 => to_timestamp_impl::<TimestampNanosecondType>(
                 &args,
                 "to_timestamp_nanos",
@@ -1735,4 +1829,23 @@ mod tests {
             assert_contains!(actual, expected);
         }
     }
+
+    #[test]
+    fn test_decimal_to_nanoseconds_negative_scale() {
+        // scale -2: internal value 5 represents 5 * 10^2 = 500 seconds
+        let nanos = decimal_to_nanoseconds(5, -2);
+        assert_eq!(nanos, 500_000_000_000); // 500 seconds in nanoseconds
+
+        // scale -1: internal value 10 represents 10 * 10^1 = 100 seconds
+        let nanos = decimal_to_nanoseconds(10, -1);
+        assert_eq!(nanos, 100_000_000_000);
+
+        // scale 0: internal value 5 represents 5 seconds
+        let nanos = decimal_to_nanoseconds(5, 0);
+        assert_eq!(nanos, 5_000_000_000);
+
+        // scale 3: internal value 1500 represents 1.5 seconds
+        let nanos = decimal_to_nanoseconds(1500, 3);
+        assert_eq!(nanos, 1_500_000_000);
+    }
 }