cloud-fan commented on a change in pull request #27622: [SPARK-27528][followup] improve migration guide URL: https://github.com/apache/spark/pull/27622#discussion_r381224166
########## File path: docs/sql-migration-guide.md ########## @@ -87,7 +87,7 @@ license: | - In Spark version 2.4, when a spark session is created via `cloneSession()`, the newly created spark session inherits its configuration from its parent `SparkContext` even though the same configuration may exist with a different value in its parent spark session. Since Spark 3.0, the configurations of a parent `SparkSession` have a higher precedence over the parent `SparkContext`. The old behavior can be restored by setting `spark.sql.legacy.sessionInitWithConfigDefaults` to `true`. - - Since Spark 3.0, parquet logical type `TIMESTAMP_MICROS` is used by default while saving `TIMESTAMP` columns. In Spark version 2.4 and earlier, `TIMESTAMP` columns are saved as `INT96` in parquet files. To set `INT96` to `spark.sql.parquet.outputTimestampType` restores the previous behavior. + - Since Spark 3.0, parquet logical type `TIMESTAMP_MICROS` is used by default while saving `TIMESTAMP` columns. In Spark version 2.4 and earlier, `TIMESTAMP` columns are saved as `INT96` in parquet files. Note that, some SQL systems such as Hive 1.x and Impala 2.x can only read `INT96` timestamps, you can set `spark.sql.parquet.outputTimestampType` as `INT96` to restore the previous behavior and keep interoperability. Review comment: Actually, there may be a problem: In `HiveExternalCatalog.createTable`, we claim a parquet table is hive-compatible but it's actually not if the timestamp column is written as parquet logical timestamp. @MaxGekk can you look into it? ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected] With regards, Apache Git Services --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
