Pass multiple values or string arrays in java as a parameter

I'm not a Java programmer but know enough to follow the code.  I also know nothing about Cassandra.

From a quick Google, it appears that you can create an ODBC connection to Cassandra.

If you can, I take a look at Oracle's Heterogeneous gateway to connect the Oracle database to the Cassandra and do everything in an "insert into select" query.

Heterogeneous gateway docs:
http://docs.oracle.com/database/121/HETER/toc.htm

If you cannot, then I think you are stuck with memory objects that hold lists of id's and abstract_html.  Then you should be able to do batch processing using the lists.

Step 1 in speeding things up is first figuring out which part is slow.

You should add:
                long startTime = System.currentTimeMillis() ;
                takeAction() ; <-- the thing you want to look at
                System.out.println("Step X took " + (System.currentTimeMillis() - startTime) + " ms") ;

with "X" replaced with some meaningful string
            
around each of your database/cassandra calls.

I.E. Before and after each of these:
rs = pstmt.executeQuery();  
or these
ResultSet rs = session.execute(stmt);

Then when you run it and it takes an hour, you'll see which of these statements is taking up the time.

I'd bet one of them is taking 55 mins of your hour.  That's the piece you need to optimize - but you need to find it first.

Doug