Cassandra SE: Internal error: 'TimedOutException: Default TException errors

It looks like CassandraSE has very small timeouts. Any operation that takes longer than a few seconds ends like this:

MariaDB [dbt3]> delete from customer ;
ERROR 1928 (HY000): Internal error: 'TimedOutException: Default TException.'
MariaDB [dbt3]> delete from lineitem ;
ERROR 1928 (HY000): Internal error: 'TimedOutException: Default TException.'
MariaDB [dbt3]> delete from nation ;
ERROR 1928 (HY000): Internal error: 'TimedOutException: Default TException.'
MariaDB [dbt3]> delete from orders ;

I added calls to

s->setConnTimeout(1000*1000);
s->setRecvTimeout(1000*1000);
s->setSendTimeout(1000*1000);

on a created TSocket object s, but this didn't seem to help.

This needs to be investigated.