gszadovszky commented on pull request #164: URL: https://github.com/apache/parquet-format/pull/164#issuecomment-770716726
@emkornfield, in parquet-mr there was another reason to use the `file_path` in the footer. The feature is called _summary files_. The idea was to have a separate file containing a summarized footer of several parquet files so you might do filtering and pruning without even checking a file's own footer. As far as I know this implementation exists in parquet-mr only and there are no specification for it in parquet-format. This feature is more or less abandoned meaning during the development of some newer features (e.g. column indexes, bloom filters) the related parts might not updated properly. There were a couple of discussions about this topic in the dev list: [here](https://lists.apache.org/thread.html/fb232d024d3ca0f3900b76fb884b55fad11dffafb182d6f336b37a69%40%3Cdev.parquet.apache.org%3E) and [here](https://lists.apache.org/thread.html/r2e539c50c1cc818304de2b7dc28a4109aaa529955a42664e3073f811%40%3Cdev.parquet.apache.org%3E). Because non of the ideas of _external column chunks_ nor the _summary files_ were spread across the different implementations (because of the lack of specification) I think we should not include the usage of the field `file_path` in this document or even explicitly specify that this field is not supported. I am open to specify such features properly and after the required demonstration we may include them in a later version of the core features. However, I think these requirements (e.g. snapshot API, summary files) are not necessarily needed by all of our clients or already implemented in some ways (e.g. storing statistics in HMS, Iceberg). ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected]
