[I] Improve Parquet metadata reads by avoiding fixed-size prefetch [paimon-rust]

["JunRuiLee (via GitHub)" <gi...@apache.org>]

JunRuiLee opened a new issue, #687:
URL: https://github.com/apache/paimon-rust/issues/687

   ### Problem
   
   The async Parquet reader currently uses a fixed 512 KiB metadata prefetch hint. This can read substantially more data than the footer metadata requires.
   
   For HDFS through OpenDAL's native service, positioned reads reuse a file-scoped reader. A local HDFS comparison showed better read performance when following parquet-hadoop's seek-based sequence instead: read the 8-byte footer, then fetch the exact footer metadata and requested page-index range.
   
   ### Proposed change
   
   - Remove the fixed 512 KiB metadata prefetch hint.
   - Keep page-index loading demand-driven.
   - Avoid loading OffsetIndex for an empty external row selection.
   - Add range-tracking tests for footer, metadata, and OffsetIndex reads.
   
   ### Validation
   
   Before the implementation PR is marked ready, document the HDFS comparison with:
   
   - the same dataset and query/read path for both variants;
   - file count and representative footer-metadata sizes;
   - repeated wall-clock results for fixed prefetch versus exact reads;
   - any available bytes-read or range-request counts.
   
   Implementation: #686
   


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Re: [I] Improve Parquet metadata reads by avoiding fixed-size prefetch [paimon-rust]

["JingsongLi (via GitHub) via issues" <is...@paimon.apache.org>]

JingsongLi closed issue #687: Improve Parquet metadata reads by avoiding fixed-size prefetch
URL: https://github.com/apache/paimon-rust/issues/687


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