tustvold commented on code in PR #2740:
URL: https://github.com/apache/arrow-rs/pull/2740#discussion_r973608091
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arrow/src/compute/kernels/arity.rs:
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@@ -298,36 +297,41 @@ where
let len = a.len();
if a.null_count() == 0 && b.null_count() == 0 {
- let values = a.values().iter().zip(b.values()).map(|(l, r)| op(*l,
*r));
- let buffer = unsafe { Buffer::try_from_trusted_len_iter(values) }?;
- // JUSTIFICATION
- // Benefit
- // ~75% speedup
- // Soundness
- // `values` is an iterator with a known size from a PrimitiveArray
- return Ok(unsafe { build_primitive_array(len, buffer, 0, None) });
+ let mut buffer = BufferBuilder::<O::Native>::new(len);
+ buffer.append_n_zeroed(len);
Review Comment:
It would be faster to reserve the correct capacity and use push_unchecked.
Avoids zero allocating.
As written I suspect this is a performance regression as this if block is
effectively identical to the one below now
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