[
https://issues.apache.org/jira/browse/SPARK-32582?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17175197#comment-17175197
]
Lantao Jin commented on SPARK-32582:
------------------------------------
I see. The implementation of {{inferSchema}} method depends on the underlay
file format. Even for Orc, we still need all files since the given Orc files
can have different schemas and we want to get a merged schema.
> 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.
>
--
This message was sent by Atlassian Jira
(v8.3.4#803005)
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
