IsSortedKernel

Signed-off-by: Nicholas Gates <nick@nickgates.com>

Author: gatesn

vortex-array/src/aggregate_fn/fns/is_sorted/mod.rs

@@ -175,15 +175,18 @@ impl IsSorted {
         }
         let first_value = batch.scalar_at(0)?.into_nullable();
         let last_value = batch.scalar_at(batch.len() - 1)?.into_nullable();
-        Ok(Scalar::struct_(
-            partial_dtype,
-            vec![
-                Scalar::bool(is_sorted, Nullability::NonNullable),
-                Scalar::bool(strict, Nullability::NonNullable),
-                first_value,
-                last_value,
-            ],
-        ))
+        // SAFETY: We constructed partial_dtype and the children match its field dtypes exactly.
+        Ok(unsafe {
+            Scalar::struct_unchecked(
+                partial_dtype,
+                [
+                    Scalar::bool(is_sorted, Nullability::NonNullable),
+                    Scalar::bool(strict, Nullability::NonNullable),
+                    first_value,
+                    last_value,
+                ],
+            )
+        })
     }
 }
 
@@ -314,44 +317,53 @@ impl AggregateFnVTable for IsSorted {
 
     fn flush(&self, partial: &mut Self::Partial) -> VortexResult<Scalar> {
         let dtype = make_is_sorted_partial_dtype(&partial.element_dtype);
-        let result = match (&partial.first_value, &partial.last_value) {
+
+        // Take ownership of the values to avoid cloning.
+        let first = partial.first_value.take();
+        let last = partial.last_value.take();
+        let is_sorted = partial.is_sorted;
+        let strict = partial.strict;
+
+        // Reset state.
+        partial.is_sorted = true;
+
+        let result = match (first, last) {
             (None, _) => {
                 // Empty accumulator — return null struct.
                 Scalar::null(dtype)
             }
-            (Some(first_value), Some(last_value)) => Scalar::struct_(
-                dtype,
-                vec![
-                    Scalar::bool(partial.is_sorted, Nullability::NonNullable),
-                    Scalar::bool(partial.strict, Nullability::NonNullable),
-                    first_value
-                        .clone()
-                        .cast(&partial.element_dtype.as_nullable())?,
-                    last_value
-                        .clone()
-                        .cast(&partial.element_dtype.as_nullable())?,
-                ],
-            ),
-            (Some(first_value), None) => Scalar::struct_(
-                dtype,
-                vec![
-                    Scalar::bool(partial.is_sorted, Nullability::NonNullable),
-                    Scalar::bool(partial.strict, Nullability::NonNullable),
-                    first_value
-                        .clone()
-                        .cast(&partial.element_dtype.as_nullable())?,
-                    first_value
-                        .clone()
-                        .cast(&partial.element_dtype.as_nullable())?,
-                ],
-            ),
+            (Some(first_value), Some(last_value)) => {
+                // Values are already nullable from into_nullable_unchecked in accumulate.
+                // SAFETY: We constructed partial_dtype and the children match its field dtypes.
+                unsafe {
+                    Scalar::struct_unchecked(
+                        dtype,
+                        [
+                            Scalar::bool(is_sorted, Nullability::NonNullable),
+                            Scalar::bool(strict, Nullability::NonNullable),
+                            first_value,
+                            last_value,
+                        ],
+                    )
+                }
+            }
+            (Some(first_value), None) => {
+                let cloned = first_value.clone();
+                // SAFETY: We constructed partial_dtype and the children match its field dtypes.
+                unsafe {
+                    Scalar::struct_unchecked(
+                        dtype,
+                        [
+                            Scalar::bool(is_sorted, Nullability::NonNullable),
+                            Scalar::bool(strict, Nullability::NonNullable),
+                            first_value,
+                            cloned,
+                        ],
+                    )
+                }
+            }
         };
 
-        // Reset state.
-        partial.is_sorted = true;
-        partial.first_value = None;
-        partial.last_value = None;
-
         Ok(result)
     }
 
@@ -449,7 +461,7 @@ impl AggregateFnVTable for IsSorted {
                     Canonical::Extension(e) => check_extension_sorted(e, partial.strict, ctx)?,
                     Canonical::Null(_) => !partial.strict,
                     // Struct, List, FixedSizeList should have been filtered out by return_dtype
-                    _ => false,
+                    _ => unreachable!(),
                 };
 
                 if !batch_is_sorted {