Walk VarBinView rows directly in row encoder hot loop

vortex-row/src/codec.rs

@@ -530,17 +530,33 @@ fn encode_varbinview(
 ) -> VortexResult<()> {
     let non_null = field.non_null_sentinel();
     let descending = field.descending;
+    let views = arr.views();
+    let n_buffers = arr.data_buffers().len();
     match resolve_validity(arr.as_ref().validity()?, arr.len(), ctx)? {
         ValidityKind::AllValid => {
-            arr.with_iterator(|iter| {
-                for (i, maybe) in iter.enumerate() {
-                    let pos = (row_offsets[i] + col_offset[i]) as usize;
-                    let bytes: &[u8] = maybe.unwrap_or(&[]);
-                    out[pos] = non_null;
-                    let written = encode_varlen_value(bytes, &mut out[pos + 1..], descending);
-                    col_offset[i] += 1 + written;
-                }
-            });
+            // Cache data-buffer slices once. For inlined views (len <= 12), bytes live
+            // inside the view itself.
+            let buffers: smallvec::SmallVec<[&[u8]; 4]> =
+                (0..n_buffers).map(|i| arr.buffer(i).as_slice()).collect();
+            for (i, view) in views.iter().enumerate() {
+                let pos = (row_offsets[i] + col_offset[i]) as usize;
+                out[pos] = non_null;
+                let len = view.len() as usize;
+                // SAFETY: BinaryView's inlined-vs-ref discriminant is its `size` field
+                // (read by `view.len()`); for len <= 12 the bytes are inline in the view
+                // (we read from `as_inlined().value()`); for larger we index into the
+                // pre-validated buffer at `view_ref.offset..offset+size`. Both reads
+                // produce a slice of exactly `len` valid bytes.
+                let bytes: &[u8] = if view.is_inlined() {
+                    view.as_inlined().value()
+                } else {
+                    let r = view.as_view();
+                    let off = r.offset as usize;
+                    &buffers[r.buffer_index as usize][off..off + len]
+                };
+                let written = encode_varlen_value(bytes, &mut out[pos + 1..], descending);
+                col_offset[i] += 1 + written;
+            }
         }
         ValidityKind::Mask(mask) => {
             let null = field.null_sentinel();