[GitHub] [hudi] umehrot2 commented on issue #2180: [SUPPORT] Unable to read MERGE ON READ table with Snapshot option using Databricks.

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umehrot2 commented on issue #2180:
URL: https://github.com/apache/hudi/issues/2180#issuecomment-709480582


   This is strange. The exception appears to be happening at https://github.com/apache/hudi/blob/master/hudi-spark/src/main/scala/org/apache/hudi/MergeOnReadSnapshotRelation.scala#L138 while doing `fileStatuses.toArray`.
   
   Now it is an `java.lang.ArrayStoreException` which indicates that it is possibly trying to store a wrong type of object `org.apache.spark.sql.execution.datasources.SerializableFileStatus` in an array of `FileStatus`. This would mean that Spark itself is returning `Seq[SerializableFileStatus]` instead of `Seq[FileStatus]` which is not possible on open source spark.
   
   In open source spark they always convert `SerializableFileStatus` to `FileStatus` before returning and thats the contract: https://github.com/apache/spark/blob/v2.4.5/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/InMemoryFileIndex.scala#L246 . `SerializableFileStatus` is private to that class. So my guess is that databricks Spark implementation differs here and its possibly returning `Seq[SerializableFileStatus]` and thats why this is happening. Not sure whether this is something we want to consider fixing and how. @bvaradar @garyli1019 @vinothchandar 
   


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