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複合列(Int32Type、BytesType、AsciiType)があり、その値を (基準に基づいて) 読み取り、変更して保存する必要があります (手動カウンター列のようなもの)。

クエリしている複合列が存在する場合と存在しない場合があります。

ヘクターでそれを行う最良の方法は何ですか?

4

2 に答える 2

4

次の解決策が最善であることを保証することはできませんが、複合列の作成などの基本的な機能を実行します。基本的に読み取りと書き込みを行います。これは、基本的に「（基準に基づいて）その値を読み取り、変更して保存し直す必要があります（手動カウンター列のようなもの）」にインラインで行われます。。しかし、このサンプルコードを使用すると、基本として機能し、あちこちで改善されて、最高になるはずだと思います。:-)空き時間があるときに徹底的にテストします。そうは言っても、以下は私の提案です。

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);
        }


    }

}
于 2012-07-03T13:43:44.017 に答える
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();
}
于 2012-07-03T13:56:54.320 に答える