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https://issues.apache.org/jira/browse/SPARK-32582?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17175203#comment-17175203
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Lantao Jin commented on SPARK-32582:
------------------------------------

Maybe we could offer a new interface to break out in one iteration when 
mergeSchema is false. I am not sure.
{code}
  def inferSchema(
      sparkSession: SparkSession,
      options: Map[String, String],
      f: (FileIndex) => Seq[FileStatus]): Option[StructType]
{code}

Do you already have any fixing? PR is welcome.

> Spark SQL Infer Schema Performance
> ----------------------------------
>
>                 Key: SPARK-32582
>                 URL: https://issues.apache.org/jira/browse/SPARK-32582
>             Project: Spark
>          Issue Type: Improvement
>          Components: SQL
>    Affects Versions: 2.4.6, 3.0.0
>            Reporter: Jarred Li
>            Priority: Major
>
> When infer schema is enabled, it tries to list all the files in the table, 
> however only one of the file is used to read schema informaiton. The 
> performance is impacted due to list all the files in the table when the 
> number of partitions is larger.
>  
> See the code in 
> "[https://github.com/apache/spark/blob/master/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/orc/OrcUtils.scala#88]";,
>  all the files in the table are input, however only one of the file's schema 
> is used to infer schema.
>  



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