Updating Object data in Apache Cassandra using Hector API example Archives

We already discussed the fundamentals of Apache Cassandra database.We discussed the basic operations like insert , read and delete . In the last few chapters we were discussing how object data is inserting into Apache Cassandra and how object data is retrieving from Apache Cassandra database using Hector API.In this chapter we will be updating the same object data we inserted before.

Updating Object data in Apache Cassandra using Hector API

In the previous chapter we inserted two Student objects into ‘myColumnFamily‘. Each object is having unique row key. The ‘id‘ of each object is using as row key.So our column family structure before update is :

Here we are updating the second object .We are simply changing the ‘name’ of the second object. The new column family structure after update will be like this:

Now lets see the Java code.Before Before running , the Apache Cassandra should be started and the ‘USERKEYSPACE‘ should be configured as explained in the previous discussion. Also we should include the libraries listed there in to the work space .

UpdateObjectsample.java

import java.util.HashMap; import java.util.Iterator; import java.util.Map; import java.util.Set; import com.cassandrasamples.beans.Student; import me.prettyprint.cassandra.model.HColumnImpl; import me.prettyprint.cassandra.serializers.StringSerializer; import me.prettyprint.cassandra.service.ColumnSliceIterator; import me.prettyprint.hector.api.Cluster; import me.prettyprint.hector.api.Keyspace; import me.prettyprint.hector.api.ddl.ColumnFamilyDefinition; import me.prettyprint.hector.api.ddl.ComparatorType; import me.prettyprint.hector.api.factory.HFactory; import me.prettyprint.hector.api.mutation.Mutator; import me.prettyprint.hector.api.query.SliceQuery;


public class UpdateObjectsample {

    Cluster cluster = null;

    Keyspace keySpace = null;
    public UpdateObjectsample() {
    }
    public void getConfig() {

        cluster = HFactory.getOrCreateCluster("Test Cluster", "localHost:9160");

        keySpace = HFactory.createKeyspace("USERKEYSPACE", cluster);

    }
    public void read(String rowKey) {

        if (null != cluster && null != keySpace) {

            ColumnFamilyDefinition columnFamily = HFactory

                    .createColumnFamilyDefinition("USERKEYSPACE",

                            "myColumnFamily", ComparatorType.UTF8TYPE);

            SliceQuery query = HFactory

                    .createSliceQuery(keySpace, StringSerializer.get(),

                            StringSerializer.get(), StringSerializer.get())

                    .setKey(rowKey).setColumnFamily(columnFamily.getName());

            ColumnSliceIterator iterator = new ColumnSliceIterator(

                    query, null, "\u00FFF", false);

            while (iterator.hasNext()) {

                HColumnImpl column = (HColumnImpl) iterator

                        .next();

                System.out

                        .println(column.getName() + " = " + column.getValue());

            }

        }
    }
    public void update(Student student) {

        if (null != cluster && null != keySpace) {

            ColumnFamilyDefinition columnFamily = HFactory

                    .createColumnFamilyDefinition("USERKEYSPACE",

                            "myColumnFamily", ComparatorType.UTF8TYPE);

            StringSerializer stringSerializer = StringSerializer.get();

            Mutator mutator = HFactory.createMutator(keySpace,stringSerializer);

            Map map = processKeyValueMap(student);

            Set set = map.entrySet();

            Iterator i = set.iterator();

            while (i.hasNext()) {

                Map.Entry entry = (Map.Entry) i.next();

                mutator.addInsertion(student.getId(), columnFamily

                        .getName(), HFactory.createStringColumn(entry

                        .getKey().toString(), entry.getValue().toString()));

                System.out.println("Updated..");

            }

            mutator.execute();

        }

    }
    public Map processKeyValueMap(Student student) {

        HashMap returnMap = new HashMap();

        if (null != student.getId() && null != student.getName()) {

            returnMap.put("id", student.getId());

            returnMap.put("name", student.getName());
        }

        return returnMap;
    }
    public static void main(String[] args) {

        UpdateObjectsample sample = new UpdateObjectsample();

        sample.getConfig();

        System.out.println("Before update..");

        sample.read("1");

        sample.read("2");

        Student student = new Student();

        student.setId("2");

        student.setName("JayaKrishnan");

        sample.update(student);

        System.out.println("After update..");

        sample.read("1");

        sample.read("2");

    }