[GitHub] [spark] MaxGekk edited a comment on issue #25230: [SPARK-28471][SQL] Replace `yyyy` by `uuuu` in date-timestamp patterns without era

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MaxGekk edited a comment on issue #25230: [SPARK-28471][SQL] Replace `yyyy` by `uuuu` in date-timestamp patterns without era
URL: https://github.com/apache/spark/pull/25230#issuecomment-514516270
 
 
   > is this a breaking change though?
   
   @felixcheung No, negative years are out of the valid range for the `DATE` type: https://github.com/apache/spark/blob/4cb1cd6ab7b7bffd045a786b0ddb7c7783afdf46/sql/catalyst/src/main/scala/org/apache/spark/sql/types/DateType.scala#L27
   
   It could be considered as a fix for correctness issue.
   
   Before: written -99 year was loaded back as 100. That's incorrect.
   ```Scala
   scala> Seq(java.time.LocalDate.of(-99, 1, 1)).toDF("d").write.mode("overwrite").json("neg_year2")
   scala> spark.read.schema("d date").json("/Users/maxim/tmp/neg_year2").show
   +----------+
   |         d|
   +----------+
   |0100-01-01|
   +----------+
   ```
   After:
   ```Scala
   scala> Seq(java.time.LocalDate.of(-99, 1, 1)).toDF("d").write.mode("overwrite").json("neg_year")
   scala> spark.read.schema("d date").json("neg_year").show
   +----+
   |   d|
   +----+
   |null|
   +----+
   ```

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