Oracle Big Data SQL provides external tables with extreme performance gains. An external table is an Oracle Database object that identifies and describes the location of data outside of a database. You can query an external table using the same SQL SELECT syntax that you use for any other database tables.

Big Data SQL uses fan out parallelism to offer highly scalable processing with external tables. For example, a serial query against a Big Data SQL external table takes advantage of the Hadoop cluster parallel processing capacity.

External tables use access drivers to parse the data outside the database. There are multiple external data drivers to process data from different sources. The first, ORACLE_HIVE, leverages metadata defined in Apache Hive. The second, ORACLE_HDFS, accesses data directly in HDFS - with metadata specified as part of the external table definition. And the third, ORACLE_BIGDATA, accesses data in Object Storage; similar to HDFS, the metadata is part of the table definition.