zhuqi-lucas commented on issue #7744:
URL: https://github.com/apache/arrow-rs/issues/7744#issuecomment-3002839353
@Dandandan @alamb
I tried the patch for this ticket:
```rust
diff --git a/arrow-array/src/array/byte_view_array.rs
b/arrow-array/src/array/byte_view_array.rs
index 713e275d18..20962abc9b 100644
--- a/arrow-array/src/array/byte_view_array.rs
+++ b/arrow-array/src/array/byte_view_array.rs
@@ -338,6 +338,15 @@ impl<T: ByteViewType + ?Sized> GenericByteViewArray<T> {
std::slice::from_raw_parts((view as *const u128 as *const
u8).wrapping_add(4), len)
}
+
+ /// Returns the first 4-byte prefix of the inline value of the view.
+ /// # Safety
+ /// - The `view` must be a valid element from `Self::views()` that
adheres to the view layout.
+ #[inline(always)]
+ pub unsafe fn inline_prefix(view: &u128) -> &[u32] {
+ std::slice::from_raw_parts((view as *const u128 as *const
u32).wrapping_add(1), 1)
+ }
+
/// Constructs a new iterator for iterating over the values of this
array
pub fn iter(&self) -> ArrayIter<&Self> {
ArrayIter::new(self)
@@ -552,8 +561,8 @@ impl<T: ByteViewType + ?Sized> GenericByteViewArray<T> {
// one of the string is larger than 12 bytes,
// we then try to compare the inlined data first
- let l_inlined_data = unsafe {
GenericByteViewArray::<T>::inline_value(l_view, 4) };
- let r_inlined_data = unsafe {
GenericByteViewArray::<T>::inline_value(r_view, 4) };
+ let l_inlined_data = unsafe {
GenericByteViewArray::<T>::inline_prefix(l_view) };
+ let r_inlined_data = unsafe {
GenericByteViewArray::<T>::inline_prefix(r_view) };
if r_inlined_data != l_inlined_data {
return l_inlined_data.cmp(r_inlined_data);
}
```
But no performance improvement for benchmark, currently our code already
using 4 bytes inline to check:
```rust
// one of the string is larger than 12 bytes,
// we then try to compare the inlined data first
let l_inlined_data = unsafe {
GenericByteViewArray::<T>::inline_value(l_view, 4) };
let r_inlined_data = unsafe {
GenericByteViewArray::<T>::inline_value(r_view, 4) };
if r_inlined_data != l_inlined_data {
return l_inlined_data.cmp(r_inlined_data);
}
```
As a try to change to u8 compare to u32 for the 4 bytes, we don't see
performance improvement in the benchmark.
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