[GitHub] [orc] sinkinben commented on issue #1237: The result is strange when casting `string` to `date` in ORC reading via spark (Schema Evolution)

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sinkinben commented on issue #1237:
URL: https://github.com/apache/orc/issues/1237#issuecomment-1229729122

   Hi, @dongjoon-hyun , many thx for you reply.
   
   I have made more tests after I set the conf `spark.sql.orc.impl`.
   
   ```shell
   scala> :paste
   // Entering paste mode (ctrl-D to finish)
   
   val data = Seq(
       ("", "2002-01-01"),
       ("", "2022-08-29"),
       ("", "2022-08-31")
   )
   val cols = Seq("str", "date_str")
   val df=spark.createDataFrame(data).toDF(cols:_*).repartition(1)
   df.printSchema()
   df.show(100)
   df.write.mode("overwrite").orc("/tmp/orc/data.orc")
   
   // Exiting paste mode, now interpreting.
   
   root
    |-- str: string (nullable = true)
    |-- date_str: string (nullable = true)
   
   +---+----------+
   |str|  date_str|
   +---+----------+
   |   |2002-01-01|
   |   |2022-08-29|
   |   |2022-08-31|
   +---+----------+
   
   data: Seq[(String, String)] = List(("",2002-01-01), ("",2022-08-29), ("",2022-08-31))
   cols: Seq[String] = List(str, date_str)
   df: org.apache.spark.sql.Dataset[org.apache.spark.sql.Row] = [str: string, date_str: string]
   
   scala> sql("set spark.sql.orc.impl=hive")
   res1: org.apache.spark.sql.DataFrame = [key: string, value: string]
   
   scala> var df = spark.read.schema("date_str date").orc("/tmp/orc/data.orc"); df.show()
   +--------+
   |date_str|
   +--------+
   |    null|
   |    null|
   |    null|
   +--------+
   
   df: org.apache.spark.sql.DataFrame = [date_str: date]
   ```
   
   These three cases are valid date, but why are they converted to `null`s?


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