[GitHub] [spark] EnricoMi commented on a diff in pull request #38312: [SPARK-40819][SQL] address timestamp nanos behaviour regression

[GitBox <gi...@apache.org>]

EnricoMi commented on code in PR #38312:
URL: https://github.com/apache/spark/pull/38312#discussion_r1000224749


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sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/parquet/ParquetSchemaConverter.scala:
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@@ -271,6 +271,8 @@ class ParquetToSparkSchemaConverter(
             } else {
               TimestampNTZType
             }
+          case timestamp: TimestampLogicalTypeAnnotation if timestamp.getUnit == TimeUnit.NANOS =>

Review Comment:
   Ideally, this case would be merged with above case, but that would require `TimestampType` and `TimestampNTZType` to support nanos, which is a bigger change.
   
   This `case` deserves a comment that nanos are not supported as `TimestampType` but as `LongType`, without any timezone awareness.
   
   Supporting nanos as `TimestampType` in the future looks like a breaking change then (Spark 4.x?). Or another `TimestampNSType` like `TimstampNTZType` could be introduced.



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