Question

我已开始使用Cassandra database。我打算将Datastax API用于upsert/read进/出Cassandra database。我对这个Datastax API（它使用新的二进制协议）完全不熟悉，我也找不到很多具有适当例子的文档。

create column family profile
    with key_validation_class = 'UTF8Type'
    and comparator = 'UTF8Type'
    and default_validation_class = 'UTF8Type'
    and column_metadata = [
      {column_name : crd, validation_class : 'DateType'}
      {column_name : lmd, validation_class : 'DateType'}
      {column_name : account, validation_class : 'UTF8Type'}
      {column_name : advertising, validation_class : 'UTF8Type'}
      {column_name : behavior, validation_class : 'UTF8Type'}
      {column_name : info, validation_class : 'UTF8Type'}
      ];

现在，下面是我使用Singleton class连接到Cassandra数据库创建的Datastax API，它使用了新的二进制协议 -

public class CassandraDatastaxConnection {

    private static CassandraDatastaxConnection _instance;
    protected static Cluster cluster;
    protected static Session session;


    public static synchronized CassandraDatastaxConnection getInstance() {
        if (_instance == null) {
            _instance = new CassandraDatastaxConnection();
        }
        return _instance;
    }

    /**
     * Creating Cassandra connection using Datastax API
     *
     */
    private CassandraDatastaxConnection() {

        try{
            cluster = Cluster.builder().addContactPoint("localhost").build();
            session = cluster.connect("my_keyspace");           
        } catch (NoHostAvailableException e) {
            throw new RuntimeException(e);
        }
    }

    public static Cluster getCluster() {
        return cluster;
    }

    public static Session getSession() {
        return session;
    }
}

第一个问题 - 让我知道在使用使用新二进制协议的Datastax API与Cassandra数据库建立连接时，我是否遗漏了上述singleton class中的任何内容。

第二个问题 - 现在我正试图upsert and read data进入/来自Cassandra数据库 -

这些是我在DAO中使用的方法，它将使用上面的Singleton类 -

public Map<String, String> getColumnNames(final String userId, final Collection<String> columnNames) {

    //I am not sure what I am supposed to do here?
    //Given a userId, I need to retrieve those columnNames from the Cassandra database
    //And then put it in the map with column name and its value and then finally return the map

    Map<String, String> attributes = new ConcurrentHashMap<String, String>();

    for(String col : columnNames ) {
        attributes.put(col, colValue);
    }

    return attributes;
}


/**
 * Performs an upsert of the specified attributes for the specified id.
 */
public void upsertAttributes(final String userId, final Map<String, String> columnNameAndValue) {

    //I am not sure what I am supposed to do here to upsert the data in Cassandra database.
    //Given a userId, I need to upsert the columns values into Cassandra database.
    //columnNameAndValue is the map which will have column name as the key and corresponding column value as the value.

}

任何人都可以帮我吗？我对这个使用新二进制协议的Datastax API完全不熟悉，因此在这方面存在很多问题。

感谢您的帮助。

Answer 1

在您的cassandra.yaml文件中查找标记 start_native_transport ，默认情况下已禁用，启用它。

使用Datastax Java Driver非常类似于jdbc驱动程序。

广告代码

 String query = "insert into test(key,col1,col2) values('1','value1','value2')";
 session.execute(query);

阅读Cassandra

 String query="select * from test;";
 ResultSet result = session.execute(query);
 for (Row rows: result){
     System.out.println(rows.getString("key"));
 }

使用Datastax API（使用新的二进制协议）升级/读入/读取Cassandra数据库

1 个答案: