[jira] [Commented] (SPARK-15458) Disable schema inference for streaming datasets on file streams

["Apache Spark (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/SPARK-15458?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15294623#comment-15294623 ] 

Apache Spark commented on SPARK-15458:
--------------------------------------

User 'tdas' has created a pull request for this issue:
https://github.com/apache/spark/pull/13238

> Disable schema inference for streaming datasets on file streams
> ---------------------------------------------------------------
>
>                 Key: SPARK-15458
>                 URL: https://issues.apache.org/jira/browse/SPARK-15458
>             Project: Spark
>          Issue Type: Sub-task
>          Components: SQL
>            Reporter: Tathagata Das
>            Assignee: Tathagata Das
>
> If the user relies on the schema to be inferred in file streams can break easily for multiple reasons
> - accidentally running on a directory which has no data
> - schema changing underneath
> - on restart, the query will infer schema again, and may unexpectedly infer incorrect schema, as the file in the directory may be different at the time of the restart.
> To avoid these complicated scenarios, for Spark 2.0, we are going to disable schema inferencing by default with a config, so that user is forced to consider explicitly what is the schema it wants, rather than the system trying to infer it and run into weird corner cases.



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