There are several ways to go about loading data from Oracle to DSE Cassandra, depending on how much data you intend to load. The first would be to extract a table from Oracle into a CSV file and load it using CQLSH "Copy" command: https://docs.datastax.com/en/dse/6.7/cql/cql/cql_reference/cqlsh_commands/cqlshCopyFrom.html

The second way would be to extract the data from Oracle and use the Bulkloader: https://www.datastax.com/blog/2018/05/introducing-datastax-bulk-loader

A third way may be to support a more complex ingestion process supporting multiple tables that can be mapped into the ingestion process: https://docs.datastax.com/en/dse/6.7/dse-dev/datastax_enterprise/graph/dgl/dglCSV.html

These are for fairly straight forward copying of data into Cassandra, however, moving data from a relational environment to a distributed partitioned database has additional considerations around partitioning, data distribution and creating efficient collections of data within a partition for efficient querying. This is done through data modeling and when loading more complex data you can use DSE Analytics spark engine to read from Oracle, map the data or enhance it prior to storing it in Cassandra. For example, you might read data from 3 tables in Oracle and merge them into a single data stream in Cassandra that supports the partition stored data that encapsulates the relationship of the data into the partition. This discussion can help you get started down that path: https://www.datastax.com/blog/2012/03/how-move-data-relational-databases-datastax-enterprise-cassandra-using-sqoop

And this: http://ntier-db.com/index.php/2016/09/14/migrating-relational-data-from-oracle-to-cassandra/

You can always reach out to your Sales team or Services team members for deeper dive discussion to address specifics around what you are trying to achieve.