[GitHub] [arrow] rdettai commented on a change in pull request #8525: ARROW-10387: [Rust][Parquet] Avoid call for file size metadata to read footer

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

rdettai commented on a change in pull request #8525:
URL: https://github.com/apache/arrow/pull/8525#discussion_r513240857



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File path: rust/parquet/src/file/footer.rs
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@@ -77,24 +78,31 @@ pub fn parse_metadata<R: ChunkReader>(chunk_reader: &R) -> Result<ParquetMetaDat
     let footer_metadata_len = FOOTER_SIZE + metadata_len as usize;
 
     // build up the reader covering the entire metadata
-    let mut default_end_cursor = Cursor::new(default_len_end_buf);
+    let mut first_end_cursor = Cursor::new(first_len_end_buf);
     let metadata_read: Box<dyn Read>;
-    if footer_metadata_len > file_size as usize {
+    if first_end_len < DEFAULT_FOOTER_READ_SIZE

Review comment:
       exactly, I should add a comment to explicit this




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