shangxinli commented on PR #14435: URL: https://github.com/apache/iceberg/pull/14435#issuecomment-3864662074
> > > "When used to merge many small files, the resulting file will still contain small row groups and one loses most of the advantages of larger files." > > > > > > This could negatively impact read performance (predicate pushdown efficiency, vectorized read benefits, etc.). > > This can have mixed effects on read performance. In Iceberg’s Java readers, filtering is applied at the row‑group level, so smaller row groups can improve predicate pruning. However, this comes at the cost of full scan read efficiency and compression. @pvary the compression is at page level instead of row group (column chunk). @lintingbin the read/filtering can be at page level as well. Checkout the page skipping (column index) https://parquet.apache.org/docs/file-format/pageindex/. -- 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. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
