Following is the criteria:
ORC and Managed table
ACID enabled
HDFS directory should be owned by Hive
According to the shouldTableBeExternal method in HiveStrictMigration.java, a table is external if it is a StorageHandler table, or if it is an Avro/Text/Parquet table, or if it is a list bucketed table, or the directory is not owned by Hive.
Following is the codebase that describes the same:
String reason = shouldTableBeExternal(tableObj, ownerName, conf, hms, isPathOwnedByHive); if (reason != null) { LOG.debug("Converting {} to external table. {}", getQualifiedName(tableObj), reason); result = TableMigrationOption.EXTERNAL; } else { result = TableMigrationOption.MANAGED;
Reference: HiveStrictManagedMigration (GitHub)
It should be converted to an EXTERNAL table, in case it does not fit the criteria for the upgrade.
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