mapleFU commented on code in PR #8694:
URL: https://github.com/apache/arrow-rs/pull/8694#discussion_r2476188161
##########
arrow-array/src/array/byte_view_array.rs:
##########
@@ -512,18 +512,71 @@ impl<T: ByteViewType + ?Sized> GenericByteViewArray<T> {
};
}
- // 3) Allocate exactly capacity for all non-inline data
- let mut data_buf = Vec::with_capacity(total_large);
+ struct GcCopyGroup {
+ total_buffer_bytes: usize,
+ total_len: usize,
+ }
+
+ let mut groups = vec![];
+ let one_group = [GcCopyGroup {
+ total_buffer_bytes: total_large,
+ total_len: len,
+ }];
+ let gc_copy_groups = if total_large > i32::MAX as usize {
+ // Slow-path: need to split into multiple copy groups
+ 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 {
+ total_buffer_bytes: current_length as usize,
+ total_len: current_elements,
+ });
+ current_length = 0;
+ current_elements = 0;
+ }
+ current_length += len;
+ current_elements += 1;
+ }
+ }
+ if current_elements != 0 {
+ groups.push(GcCopyGroup {
+ total_buffer_bytes: current_length as usize,
+ total_len: current_elements,
+ });
+ }
+ &groups
+ } else {
+ one_group.as_slice()
Review Comment:
I've add a `one_group` for gc-copy-group in stack, hopefully this avoids
allocation
```rust
let one_group = [GcCopyGroup {
total_buffer_bytes: total_large,
total_len: len,
}];
```
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