cloud-fan commented on a change in pull request #28137: [SPARK-31361][SQL]
Rebase datetime in parquet/avro according to file written Spark version
URL: https://github.com/apache/spark/pull/28137#discussion_r404582477
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File path:
sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/DataSourceUtils.scala
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@@ -64,4 +66,10 @@ object DataSourceUtils {
private[sql] def isDataFile(fileName: String) =
!(fileName.startsWith("_") || fileName.startsWith("."))
+
+ def needRebaseDateTime(lookupFileMeta: String => String): Option[Boolean] = {
+ // If there is no version, we return None and let the caller side to
decide.
+ // Files written by Spark 3.0 and later follow the new calendar and don't
need to rebase.
+ Option(lookupFileMeta(SPARK_VERSION_METADATA_KEY)).map(_ < "3.0")
Review comment:
I think the use case you pointed out (write with 3.0 and read with 2.4) is a
bit artificial. If someone develops a data pipeline, it's very tricky if some
parts of the pipeline use 3.0 and some parts use 2.4. IMO the more common
problem is to deal with legacy data files.
BTW we can support this use case by creating a new metadata entry to record
the calendar, but I think it's too complicated and not worth it.
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