Dandandan commented on a change in pull request #9016:
URL: https://github.com/apache/arrow/pull/9016#discussion_r549109977
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File path: rust/arrow/src/array/array_string.rs
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@@ -126,25 +126,28 @@ impl<OffsetSize: StringOffsetSizeTrait>
GenericStringArray<OffsetSize> {
}
pub(crate) fn from_vec(v: Vec<&str>) -> Self {
- let mut offsets = Vec::with_capacity(v.len() + 1);
- let mut values = Vec::new();
+ let mut offsets =
+ MutableBuffer::new((v.len() + 1) *
std::mem::size_of::<OffsetSize>());
+ let mut values = MutableBuffer::new(0);
Review comment:
So something like
```rust
for s in &v {
length_so_far = length_so_far +
OffsetSize::from_usize(s.len()).unwrap();
offsets.extend_from_slice(length_so_far.to_byte_slice());
}
let mut values = MutableBuffer::new(length_so_far);
for s in &v {
values.extend_from_slice(s.as_bytes());
}
```
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