ExternalDataSourceType
The enumeration specifies the external data source type for external tables
Currently, we support HADOOP, RDBMS, and SHARD_MAP_MANAGER. EXTERNAL_GENERICS only works
for SQL150 and DW, in DW it is called Native external data source.
BLOB_STORAGE = 3
BLOB_STORAGE external data source type.
EXTERNAL_GENERICS external data source type.
HADOOP = 0
HADOOP external data source type.
RDBMS = 1
RDBMS external data source type.
SHARD_MAP_MANAGER external data source type.