alamb commented on code in PR #8694:
URL: https://github.com/apache/arrow-rs/pull/8694#discussion_r2508178277
##########
arrow-array/src/array/byte_view_array.rs:
##########
@@ -512,18 +512,85 @@ impl<T: ByteViewType + ?Sized> GenericByteViewArray<T> {
};
}
- // 3) Allocate exactly capacity for all non-inline data
- let mut data_buf = Vec::with_capacity(total_large);
+ let (views_buf, data_blocks) = if total_large < i32::MAX as usize {
+ // fast path, the entire data fits in a single buffer
+ // 3) Allocate exactly capacity for all non-inline data
+ let mut data_buf = Vec::with_capacity(total_large);
+
+ // 4) Iterate over views and process each inline/non-inline view
+ let views_buf: Vec<u128> = (0..len)
+ .map(|i| unsafe { self.copy_view_to_buffer(i, 0, &mut
data_buf) })
+ .collect();
+ let data_block = Buffer::from_vec(data_buf);
+ let data_blocks = vec![data_block];
+ (views_buf, data_blocks)
+ } else {
+ // slow path, need to split into multiple buffers
Review Comment:
I think so!
##########
arrow-array/src/array/byte_view_array.rs:
##########
@@ -512,18 +512,85 @@ impl<T: ByteViewType + ?Sized> GenericByteViewArray<T> {
};
}
- // 3) Allocate exactly capacity for all non-inline data
- let mut data_buf = Vec::with_capacity(total_large);
+ let (views_buf, data_blocks) = if total_large < i32::MAX as usize {
+ // fast path, the entire data fits in a single buffer
+ // 3) Allocate exactly capacity for all non-inline data
+ let mut data_buf = Vec::with_capacity(total_large);
+
+ // 4) Iterate over views and process each inline/non-inline view
+ let views_buf: Vec<u128> = (0..len)
+ .map(|i| unsafe { self.copy_view_to_buffer(i, 0, &mut
data_buf) })
+ .collect();
+ let data_block = Buffer::from_vec(data_buf);
+ let data_blocks = vec![data_block];
+ (views_buf, data_blocks)
+ } else {
+ // slow path, need to split into multiple buffers
+
+ struct GcCopyGroup {
+ total_buffer_bytes: usize,
+ total_len: usize,
+ }
+
+ impl GcCopyGroup {
+ fn new(total_buffer_bytes: u32, total_len: usize) -> Self {
+ Self {
+ total_buffer_bytes: total_buffer_bytes as usize,
+ total_len,
+ }
+ }
+ }
- // 4) Iterate over views and process each inline/non-inline view
- let views_buf: Vec<u128> = (0..len)
- .map(|i| unsafe { self.copy_view_to_buffer(i, &mut data_buf) })
- .collect();
+ let mut groups = Vec::with_capacity(total_large / (i32::MAX as
usize) + 1);
+ let mut current_length = 0;
+ let mut current_elements = 0;
+
+ for view in self.views() {
+ let len = *view as u32;
+ if len > MAX_INLINE_VIEW_LEN {
+ if current_length + len > i32::MAX as u32 {
+ // Start a new group
+ groups.push(GcCopyGroup::new(current_length,
current_elements));
+ current_length = 0;
+ current_elements = 0;
+ }
+ current_length += len;
+ current_elements += 1;
+ }
+ }
+ if current_elements != 0 {
+ groups.push(GcCopyGroup::new(current_length,
current_elements));
+ }
+ debug_assert!(groups.len() <= i32::MAX as usize);
+
+ // 3) Copy the buffers group by group
+ let mut views_buf = Vec::with_capacity(len);
+ let mut data_blocks = Vec::with_capacity(groups.len());
+
+ let mut current_view_idx = 0;
+
+ for (group_idx, gc_copy_group) in groups.iter().enumerate() {
+ let mut data_buf =
Vec::with_capacity(gc_copy_group.total_buffer_bytes);
+
+ // Directly push views to avoid intermediate Vec allocation
+ let new_views = (current_view_idx..current_view_idx +
gc_copy_group.total_len).map(
+ |view_idx| {
+ // safety: the view index came from iterating over
valid range
+ unsafe {
+ self.copy_view_to_buffer(view_idx, group_idx as
i32, &mut data_buf)
+ }
+ },
+ );
+ views_buf.extend(new_views);
+
+ data_blocks.push(Buffer::from_vec(data_buf));
+ current_view_idx += gc_copy_group.total_len;
+ }
+ (views_buf, data_blocks)
+ };
// 5) Wrap up buffers
Review Comment:
to what?
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