/** Exercise 4 - Read a list of people from Cassandra */
private static void readPeopleFromCassandra(JavaSparkContext javaSparkContext) {
SparkContextJavaFunctions sparkContextJavaFunctions =
CassandraJavaUtil.javaFunctions(javaSparkContext);
CassandraJavaRDD<Person> personCassandraJavaRDD =
sparkContextJavaFunctions.cassandraTable(
"test", "people", CassandraJavaUtil.mapRowTo(Person.class));
JavaRDD<String> readPeopleRDD = personCassandraJavaRDD.map(Person::toString);
System.out.println(
"Data as Person beans: \n" + StringUtils.join("\n", readPeopleRDD.collect()));
// select id from test.people where id=45;
JavaRDD<String> rdd4 =
sparkContextJavaFunctions
.cassandraTable("test", "people")
.select("id")
.where("id = 45")
.map(CassandraRow::toString);
System.out.println(
"Data with only 'id' column fetched: \n" + StringUtils.join("\n", rdd4.collect()));
}
/** Exercise 3 - Save a list of people to Cassandra */
private static void writePeopleToCassandra(JavaSparkContext javaSparkContext) {
// here we are going to save some data to Cassandra...
List<Person> people =
Arrays.asList(
Person.newInstance(1, "John", new Date()),
Person.newInstance(2, "Anna", new Date()),
Person.newInstance(3, "Andrew", new Date()));
JavaRDD<Person> peopleRDD = javaSparkContext.parallelize(people);
JavaPairRDD<Integer, Person> integerPersonJavaPairRDD = peopleRDD.keyBy(np -> np.getId());
RDDJavaFunctions<Person> cassandraPersonRDD = CassandraJavaUtil.javaFunctions(peopleRDD);
cassandraPersonRDD
.writerBuilder("test", "people", CassandraJavaUtil.mapToRow(Person.class))
.saveToCassandra();
}