Perf: Optimize CursorValues compare performance for StringViewArray (1.4X faster for sort-tpch Q11) (#16509)

* Perf: Optimize CursorValues compare performance for StringViewArray

* fix

Author: zhuqi-lucas

datafusion/physical-plan/src/sorts/cursor.rs

@@ -293,14 +293,19 @@ impl CursorValues for StringViewArray {
         self.views().len()
     }
 
+    #[inline(always)]
     fn eq(l: &Self, l_idx: usize, r: &Self, r_idx: usize) -> bool {
         // SAFETY: Both l_idx and r_idx are guaranteed to be within bounds,
         // and any null-checks are handled in the outer layers.
         // Fast path: Compare the lengths before full byte comparison.
-
         let l_view = unsafe { l.views().get_unchecked(l_idx) };
-        let l_len = *l_view as u32;
         let r_view = unsafe { r.views().get_unchecked(r_idx) };
+
+        if l.data_buffers().is_empty() && r.data_buffers().is_empty() {
+            return l_view.eq(r_view);
+        }
+
+        let l_len = *l_view as u32;
         let r_len = *r_view as u32;
         if l_len != r_len {
             return false;
@@ -309,13 +314,19 @@ impl CursorValues for StringViewArray {
         unsafe { GenericByteViewArray::compare_unchecked(l, l_idx, r, r_idx).is_eq() }
     }
 
+    #[inline(always)]
     fn eq_to_previous(cursor: &Self, idx: usize) -> bool {
         // SAFETY: The caller guarantees that idx > 0 and the indices are valid.
         // Already checked it in is_eq_to_prev_one function
         // Fast path: Compare the lengths of the current and previous views.
         let l_view = unsafe { cursor.views().get_unchecked(idx) };
-        let l_len = *l_view as u32;
         let r_view = unsafe { cursor.views().get_unchecked(idx - 1) };
+        if cursor.data_buffers().is_empty() {
+            return l_view.eq(r_view);
+        }
+
+        let l_len = *l_view as u32;
+
         let r_len = *r_view as u32;
         if l_len != r_len {
             return false;
@@ -326,10 +337,21 @@ impl CursorValues for StringViewArray {
         }
     }
 
+    #[inline(always)]
     fn compare(l: &Self, l_idx: usize, r: &Self, r_idx: usize) -> Ordering {
         // SAFETY: Prior assertions guarantee that l_idx and r_idx are valid indices.
         // Null-checks are assumed to have been handled in the wrapper (e.g., ArrayValues).
         // And the bound is checked in is_finished, it is safe to call get_unchecked
+        if l.data_buffers().is_empty() && r.data_buffers().is_empty() {
+            let l_view = unsafe { l.views().get_unchecked(l_idx) };
+            let r_view = unsafe { r.views().get_unchecked(r_idx) };
+            let l_len = *l_view as u32;
+            let r_len = *r_view as u32;
+            let l_data = unsafe { StringViewArray::inline_value(l_view, l_len as usize) };
+            let r_data = unsafe { StringViewArray::inline_value(r_view, r_len as usize) };
+            return l_data.cmp(r_data);
+        }
+
         unsafe { GenericByteViewArray::compare_unchecked(l, l_idx, r, r_idx) }
     }
 }