From 5a9d08875119479300eca374244d1b72d0333ebd Mon Sep 17 00:00:00 2001
From: Liam Bao <liam.zw.bao@gmail.com>
Date: Wed, 1 Apr 2026 11:25:17 -0400
Subject: [PATCH 1/2] Support `GenericListViewArray::new_unchecked` and
 refactor ListView json decoder

---
 arrow-array/src/array/list_view_array.rs | 28 ++++++++++++++++++++++++
 arrow-json/src/reader/list_array.rs      | 28 ++++++++++--------------
 2 files changed, 39 insertions(+), 17 deletions(-)

diff --git a/arrow-array/src/array/list_view_array.rs b/arrow-array/src/array/list_view_array.rs
index 75ff6117eeba..9f8f0b147c08 100644
--- a/arrow-array/src/array/list_view_array.rs
+++ b/arrow-array/src/array/list_view_array.rs
@@ -223,6 +223,34 @@ impl<OffsetSize: OffsetSizeTrait> GenericListViewArray<OffsetSize> {
         Self::try_new(field, offsets, sizes, values, nulls).unwrap()
     }
 
+    /// Create a new [`GenericListViewArray`] from the provided parts without validation
+    ///
+    /// See [`Self::try_new`] for the checked version of this function, and the
+    /// documentation of that function for the invariants that must be upheld.
+    ///
+    /// # Safety
+    ///
+    /// Safe if [`Self::new`] would not panic with the given arguments
+    pub unsafe fn new_unchecked(
+        field: FieldRef,
+        offsets: ScalarBuffer<OffsetSize>,
+        sizes: ScalarBuffer<OffsetSize>,
+        values: ArrayRef,
+        nulls: Option<NullBuffer>,
+    ) -> Self {
+        if cfg!(feature = "force_validate") {
+            return Self::new(field, offsets, sizes, values, nulls);
+        }
+
+        Self {
+            data_type: Self::DATA_TYPE_CONSTRUCTOR(field),
+            nulls,
+            values,
+            value_offsets: offsets,
+            value_sizes: sizes,
+        }
+    }
+
     /// Create a new [`GenericListViewArray`] of length `len` where all values are null
     pub fn new_null(field: FieldRef, len: usize) -> Self {
         let values = new_empty_array(field.data_type());
diff --git a/arrow-json/src/reader/list_array.rs b/arrow-json/src/reader/list_array.rs
index b11124576df2..0ee1b5af1cd9 100644
--- a/arrow-json/src/reader/list_array.rs
+++ b/arrow-json/src/reader/list_array.rs
@@ -19,10 +19,9 @@ use std::marker::PhantomData;
 use std::sync::Arc;
 
 use arrow_array::builder::BooleanBufferBuilder;
-use arrow_array::{ArrayRef, GenericListArray, OffsetSizeTrait, make_array};
+use arrow_array::{ArrayRef, GenericListArray, GenericListViewArray, OffsetSizeTrait};
 use arrow_buffer::buffer::NullBuffer;
-use arrow_buffer::{Buffer, OffsetBuffer, ScalarBuffer};
-use arrow_data::ArrayDataBuilder;
+use arrow_buffer::{OffsetBuffer, ScalarBuffer};
 use arrow_schema::{ArrowError, DataType, FieldRef};
 
 use crate::reader::tape::{Tape, TapeElement};
@@ -109,22 +108,17 @@ impl<O: OffsetSizeTrait, const IS_VIEW: bool> ArrayDecoder for ListLikeArrayDeco
                 sizes.push(offsets[i] - offsets[i - 1]);
             }
             offsets.pop();
-            let data_type = if O::IS_LARGE {
-                DataType::LargeListView(self.field.clone())
-            } else {
-                DataType::ListView(self.field.clone())
-            };
             // SAFETY: offsets and sizes are constructed correctly from the tape
-            let array_data = unsafe {
-                ArrayDataBuilder::new(data_type)
-                    .len(pos.len())
-                    .nulls(nulls)
-                    .child_data(vec![values.to_data()])
-                    .add_buffer(Buffer::from_vec(offsets))
-                    .add_buffer(Buffer::from_vec(sizes))
-                    .build_unchecked()
+            let array = unsafe {
+                GenericListViewArray::<O>::new_unchecked(
+                    self.field.clone(),
+                    ScalarBuffer::from(offsets),
+                    ScalarBuffer::from(sizes),
+                    values,
+                    nulls,
+                )
             };
-            Ok(make_array(array_data))
+            Ok(Arc::new(array))
         } else {
             // SAFETY: offsets are built monotonically starting from 0
             let offsets = unsafe { OffsetBuffer::<O>::new_unchecked(ScalarBuffer::from(offsets)) };

From e44308e60eb628807c05c591c5664e3c29ba40f5 Mon Sep 17 00:00:00 2001
From: Liam Bao <liam.zw.bao@gmail.com>
Date: Tue, 14 Apr 2026 18:39:08 -0400
Subject: [PATCH 2/2] Improve doc

---
 arrow-array/src/array/list_view_array.rs | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arrow-array/src/array/list_view_array.rs b/arrow-array/src/array/list_view_array.rs
index 9f8f0b147c08..a032d8715a90 100644
--- a/arrow-array/src/array/list_view_array.rs
+++ b/arrow-array/src/array/list_view_array.rs
@@ -230,7 +230,8 @@ impl<OffsetSize: OffsetSizeTrait> GenericListViewArray<OffsetSize> {
     ///
     /// # Safety
     ///
-    /// Safe if [`Self::new`] would not panic with the given arguments
+    /// The parts must form a valid [`ListViewArray`] or [`LargeListViewArray`] according
+    /// to the Arrow spec.
     pub unsafe fn new_unchecked(
         field: FieldRef,
         offsets: ScalarBuffer<OffsetSize>,