Using mybatis batch session template to copy data from a table having millions of records to another table in another oracle server.

@Bean(value = "batchSqlSession")
@Autowired
public SqlSessionTemplate batchSqlSession(SqlSessionFactory sqlSessionFactory) {       
    return new SqlSessionTemplate(sqlSessionFactory, ExecutorType.BATCH);
}

Repository Class

@Repository
@Slf4j
public class EmployeeDAO {
    private final SqlSessionTemplate sqlSessionTemplate;
    private final EmployeeMapper employeeSessionMapper;
    public EmployeeDAO (EmployeeMapper employeeSessionMapper,
                          @Qualifier("batchSqlSession") SqlSessionTemplate sqlSessionTemplate) {
        this.sqlSessionTemplate = sqlSessionTemplate;
        this.employeeSessionMapper = sqlSessionTemplate.getMapper(EmployeeMapper.class);
    }

    public List<EmployeeEnt> getEmployeeEnt() {
        return this.employeeSessionMapper.getEmployeeEnt();
    }

    @Transactional
    public void insertEmployeeEnt(List<EmployeeEnt> employeeEntList) {
        employeeEntList.stream().parallel().forEach(employeeEnt-> {
            try{
                employeeSessionMapper.insertEmployeeEnt(employeeEnt);
            } catch(Exception ex){
                log.error("Exception - {} while inserting data {}",ex.getMessage(),employeeEnt.toString());
            }
        });
        sqlSessionTemplate.flushStatements();
        sqlSessionTemplate.clearCache();
    }

    public void truncateEmployeeEnt() {
        this.employeeSessionMapper.truncateEmployeeEnt();
        sqlSessionTemplate.flushStatements();
        sqlSessionTemplate.clearCache();
    }
}

From service class

new EmployeeDAO().truncateEmployeeEnt();
new EmployeeDAO().insertEmployeeEnt(employeeDAO.getEmployeeEnt());

Mapper

<insert id="employeeEnt" parameterType="EmployeeEnt">        
            Insert into EMPLOYEE_DET(..) values {#{empId},#{empName},...
</insert>

getEmployeeEnt() from source Database server is returning 1 Million records and i truncate the target database before inserting the 1 million records. Insert is taking more than 2 hours and it never completes. But if i run this in copying data between 2 schemas of same database server, it takes less than 10 minutes, but if it is 2 different oracle servers, it never completes.

Is there anything i am doing wrong to correct and speed up the inserts? I cannot create database links because source is production data and link creation is not allowed. Exporting the data as CSV and then using sqlldr in java to load is an option?