[GitHub] [arrow-datafusion] tustvold opened a new issue, #5562: Push Down Offset to TableScan

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

tustvold opened a new issue, #5562:
URL: https://github.com/apache/arrow-datafusion/issues/5562

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   TableScan currently contains a single `fetch` parameter, that acts as an overall limit.
   
   The PushDownLimit optimizer rule is therefore forced to push down the `limit + offset`, even though it determines both separately.
   
   Pushing down the offset separately allows formats to skip decoding lines in the case of CSV or JSON, or skip even fetching the corresponding bytes in the case of parquet.
   
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   I would suggest removing `TableScan::fetch` and replacing it with separate limit and offset fields. These could then be pushed down in TableProvider, and FileScanConfig. This would likely need to be a breaking change.
   
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