How to read a composite column that might/might not be existing, get its value to update it and save it back?

Question

I have a composite column (Int32Type,BytesType,AsciiType) that I need to read its value (based on criteria), modify it and save it back (something like manual counter column).

The composite column that I'm querying might exist or it may not.

What is the best way to do that in Hector?

Answer 1

Composite col = new Composite(yourInt, yourBytes, yourString);

ColumnSlice<Composite, valueType> result = HFactory.createSliceQuery(keyspace, keySerializer, compositeSerializer, intSerializer)    
                                                   .setColumnFamily(columnFamily)
                                                   .setKey(key)
                                                   .setRange(col, col, false, 1)
                                                   .execute()
                                                   .get();


if (result.getColumns().isEmpty()) {
      // do whatever you need to do if there's no value
} else {
      int value = result.getColumns().get(0).getValue();
      int newValue = //some modification to value
      Mutator<keyType> mutator = HFactory.createMutator(keyspace, keySerializer);
      HColumn<Composite, int> column = HFactory.createColumn(col, newValue, CompositeSerializer, intSerializer);
      mutator.addInsertion(key, columnFamily, column);
      mutator.execute();
}

Answer 2

I cannot vouch the following solution is the best but it does the basic functionality like creating composite columns. It basically does reading and writing which essentially inline to "I need to read its value (based on criteria), modify it and save it back (something like manual counter column)." . But I think with this sample codes, it should be able to serve as a basic and improve here and there and so that it become the best. :-) Will test it thoroughly when there is free time. With that said, the following is my suggestion.

package com.hector.dataTypes;

import java.util.Iterator;

import me.prettyprint.cassandra.serializers.ByteBufferSerializer;
import me.prettyprint.cassandra.serializers.CompositeSerializer;
import me.prettyprint.cassandra.serializers.IntegerSerializer;
import me.prettyprint.cassandra.serializers.StringSerializer;
import me.prettyprint.cassandra.service.CassandraHostConfigurator;
import me.prettyprint.cassandra.service.ColumnSliceIterator;
import me.prettyprint.cassandra.service.ThriftCluster;
import me.prettyprint.hector.api.Cluster;
import me.prettyprint.hector.api.Keyspace;
import me.prettyprint.hector.api.beans.AbstractComposite.ComponentEquality;
import me.prettyprint.hector.api.beans.ColumnSlice;
import me.prettyprint.hector.api.beans.Composite;
import me.prettyprint.hector.api.beans.HColumn;
import me.prettyprint.hector.api.ddl.ColumnFamilyDefinition;
import me.prettyprint.hector.api.ddl.ColumnType;
import me.prettyprint.hector.api.ddl.ComparatorType;
import me.prettyprint.hector.api.exceptions.HectorException;
import me.prettyprint.hector.api.factory.HFactory;
import me.prettyprint.hector.api.mutation.Mutator;
import me.prettyprint.hector.api.query.QueryResult;
import me.prettyprint.hector.api.query.SliceQuery;

import org.apache.cassandra.db.marshal.Int32Type;
import org.apache.cassandra.utils.ByteBufferUtil;

import com.google.common.base.Joiner;

/**
 *
 * @author jasonw
 *
 */
public class CompositeExample
{
    private String m_node;
    private String m_keyspace;
    private String m_column_family;
    private ThriftCluster m_cassandraCluster;
    private CassandraHostConfigurator m_cassandraHostConfigurator;
    private Mutator<String> mutator;
    private SliceQuery<String, Composite, String> sliceQuery;

    public CompositeExample(String p_node, String p_keyspace, String p_column_family, String p_cluster)
    {
        m_node = p_node;
        m_keyspace = p_keyspace;
        m_column_family = p_column_family;
        m_cassandraHostConfigurator = new CassandraHostConfigurator(m_node);
        m_cassandraCluster = new ThriftCluster(p_cluster, m_cassandraHostConfigurator);
        Cluster cluster = HFactory.getOrCreateCluster(p_cluster, m_cassandraHostConfigurator);
        Keyspace keyspace = HFactory.createKeyspace(m_keyspace, cluster);
        mutator = HFactory.createMutator(keyspace, StringSerializer.get());
        sliceQuery = HFactory.createSliceQuery(keyspace, StringSerializer.get(), CompositeSerializer.get(), StringSerializer.get());
    }

    public boolean createCompositeColumn(String... p_new_columns)
    {
        try
        {
            ColumnFamilyDefinition cfDef = HFactory.createColumnFamilyDefinition(m_keyspace, m_column_family, ComparatorType.COMPOSITETYPE);
            cfDef.setColumnType(ColumnType.STANDARD);
            cfDef.setComparatorTypeAlias("(".concat(Joiner.on(",").join(p_new_columns)).concat(")"));
            cfDef.setKeyValidationClass("UTF8Type");
            cfDef.setDefaultValidationClass("UTF8Type");
            m_cassandraCluster.addColumnFamily(cfDef, true);           
            return true;
        }
        catch (HectorException e)
        {
            e.printStackTrace();
        }

        return false;

    }

    public boolean saveColumn(String p_field_one, String p_field_two, String p_field_three)
    {

        try
        {
            Composite c = new Composite();
            c.addComponent(Int32Type.instance.fromString(p_field_one), ByteBufferSerializer.get());
            c.addComponent(ByteBufferUtil.bytes(p_field_two), ByteBufferSerializer.get());
            c.addComponent(p_field_three, StringSerializer.get());
            HColumn<Composite, String> col = HFactory.createColumn(c, "composite_value", CompositeSerializer.get(), StringSerializer.get());
            mutator.addInsertion("key", m_column_family, col);
            mutator.execute();                   
            return true;

        }
        catch (HectorException e)
        {
            e.printStackTrace();           
        }

        return false;

    }

    public boolean readColumn(String p_key, int p_column_number, ComponentEquality p_equality, int p_value)
    {
        if (p_column_number < 0 || p_column_number > 2)
        {
            return false;
        }

        try
        {
            sliceQuery.setColumnFamily(m_column_family);
            sliceQuery.setKey(p_key);       


            Composite start = new Composite();
            start.addComponent(0, p_value, p_equality);
            Composite end = new Composite();
            end.addComponent(0, p_value, ComponentEquality.GREATER_THAN_EQUAL);         
            sliceQuery.setRange(start, end, false, 1000);

            QueryResult<ColumnSlice<Composite, String>> qr = sliceQuery.execute();

            System.out.println("size = " + qr.get().getColumns().size());

            Iterator<HColumn<Composite, String>> iter = qr.get().getColumns().iterator();

            while (iter.hasNext())
            {
                HColumn<Composite, String> column = iter.next();
                System.out.print(column.getName().get(0, IntegerSerializer.get()));
                System.out.print(":");
                System.out.print(column.getName().get(1, StringSerializer.get()));
                System.out.print(":");
                System.out.print(column.getName().get(2, StringSerializer.get()));
                System.out.println("=" + column.getValue());
            }

            return true;
        }
        catch (HectorException e)
        {
            e.printStackTrace();
        }
        catch (Exception why)
        {
            why.printStackTrace();
        }

        return false;

    }

    public static void main(String[] args)
    {
        boolean isSuccess = false;
        String node_ip = "192.168.0.1";
        String keyspace_name = "mykeyspace";
        String column_family_name = "compositecf";
        String cluster_name = "Test Cluster";

        CompositeExample test1 = new CompositeExample(node_ip, keyspace_name, column_family_name, cluster_name);

        isSuccess = test1.createCompositeColumn("Int32Type", "BytesType", "AsciiType");       
        if (!isSuccess)
        {
            System.err.println("failed to create cf");
            System.exit(-1);
        }

        isSuccess = test1.saveColumn("1027", "blablabla", "this is ascii field");
        if (!isSuccess)
        {
            System.err.println("failed to write");
            System.exit(-1);
        }

        isSuccess = test1.readColumn("key", 0, ComponentEquality.EQUAL, 1027);
        if (!isSuccess)
        {
            System.err.println("failed to read");
            System.exit(-1);
        }


    }

}