[GitHub] [arrow] ritchie46 commented on a change in pull request #8803: ARROW-10772: [Rust] Speed up take by writing to buffer

[GitBox <gi...@apache.org>]

ritchie46 commented on a change in pull request #8803:
URL: https://github.com/apache/arrow/pull/8803#discussion_r532413954



##########
File path: rust/arrow/src/compute/kernels/take.rs
##########
@@ -214,19 +215,20 @@ where
 
     let null_count = array.null_count();
 
-    // This iteration is implemented with a while loop, rather than a
-    // map()/collect(), since the while loop performs better in the benchmarks.
-    let mut new_values: Vec<T::Native> = Vec::with_capacity(data_len);
+    let mut buffer = MutableBuffer::new(data_len * std::mem::size_of::<T::Native>());
+    buffer.resize(data_len * std::mem::size_of::<T::Native>());
+    let data = buffer.typed_data_mut();
+
     let nulls;
 
     if null_count == 0 {
         // Take indices without null checking
-        for i in 0..data_len {
+        for (i, elem) in data.iter_mut().enumerate() {

Review comment:
       Nice! This feels more safe than indexing.




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