[GitHub] [spark] timarmstrong edited a comment on pull request #33639: [SPARK-36645][SQL] Aggregate (Min/Max/Count) push down for Parquet

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timarmstrong edited a comment on pull request #33639:
URL: https://github.com/apache/spark/pull/33639#issuecomment-942489610


   > If the aggregate column is on partition column, only Count will be pushed, Min or Max will not be pushed down because Parquet doesn't return max/min for partition column.
   
   In the traditional Hive table layout partition columns are not stored in the files at all and the reader needs to materialise the partition column values via a different mechanism (e.g. the partition column value is included in plan metadata somewhere). I don't know the spark readers well but I think the spark parquet reader must have access to the partition values.
   
   I.e. so the min/max could be materialised from the partition column too, it just needs to use a different mechanism.


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