troychiu commented on code in PR #5281:
URL: https://github.com/apache/arrow-rs/pull/5281#discussion_r1443021578


##########
object_store/src/local.rs:
##########
@@ -1082,6 +1097,58 @@ fn convert_walkdir_result(
     }
 }
 
+
+/// Download a remote object to a local [`File`]
+pub async fn upload(store: &dyn ObjectStore, location: &Path, opts: 
PutOptions, file: &mut std::fs::File) -> Result<()> {
+    // Determine file size
+    let metadata = file.metadata().map_err(|e| Error::FileMetadata {
+        source: e.into(),
+    })?;
+    let file_size = metadata.len();
+
+    // Set a threshold for when to switch to multipart_put
+    let multipart_threshold: u64 = 50 * 1024 * 1024;
+
+    if file_size <= multipart_threshold {
+        let mut buffer = Vec::with_capacity(file_size as usize);
+        file.read_to_end(&mut buffer).map_err(|e| 
Error::UnableToReadBytesFromFile{
+            source: e
+        })?;
+        let bytes = Bytes::from(buffer);
+        store.put_opts(&location, bytes, opts).await?;
+        Ok(())
+    } else {
+        let (_id, mut writer) =  store.put_multipart(&location).await?;
+        let mut buffer = vec![0u8; 5 * 1024 * 1024];
+        while let Ok(size) = file.read(&mut buffer) {
+            if size == 0 {
+                break;
+            }
+            writer.write_all(&buffer[..size]).await.unwrap();
+        }
+
+        writer.flush().await.unwrap();
+        writer.shutdown().await.unwrap();
+        Ok(())
+    }
+}
+
+
+/// Upload a local [`File`] to a remote object store
+pub async fn download(store: &dyn ObjectStore, location: &Path, opts: 
GetOptions, file: &mut File) -> Result<()> {
+    let get_result = store.get_opts(location, opts).await?;
+    let mut stream = get_result.into_stream();
+
+    while let Some(bytes_result) = stream.next().await {
+        let bytes = bytes_result?;
+        file.write_all(&bytes).map_err(|e| Error::UnableToWriteBytesToFile{
+            source: e.into()
+        })?;
+    }

Review Comment:
   That will be great if you can provide an example. Thank you!



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