[GitHub] [spark] viirya commented on a diff in pull request #36851: [SPARK-39535][SQL] Make `SchemaPruning` only pruning if it contains nested column

[GitBox <gi...@apache.org>]

viirya commented on code in PR #36851:
URL: https://github.com/apache/spark/pull/36851#discussion_r906323749


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sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/SchemaPruning.scala:
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@@ -103,8 +104,14 @@ object SchemaPruning extends Rule[LogicalPlan] {
     }
   }
 
+  private def containsNestedColumn(fsRelation: HadoopFsRelation): Boolean =

Review Comment:
   Hmm, does nested column pruning work for metadata columns? Nested column pruning is basically to update required schema for file datasource like parquet. 
   
   I think metadata columns are directly reported from datasource to Spark. For example, `FileFormat` adds metadata columns separately during reading data. It is not covered by the nested column pruning logic.
   
    



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