Upsert /使用Datastax API读取/读取Cassandra数据库（使用新的二进制协议） [英] Upsert/Read into/from Cassandra database using Datastax API (using new Binary protocol)

问题描述

我开始使用 Cassandra数据库。我计划使用 Datastax API 来 upsert / read into / from Cassandra数据库。我完全是新的 Datastax API （它使用新的二进制协议），我不能找到很多文档以及一些适当的例子。

I have started working with Cassandra database. I am planning to use Datastax API to upsert/read into/from Cassandra database. I am totally new to this Datastax API (which uses new Binary protocol) and I am not able to find lot of documentations as well which have some proper examples.

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'}
      ];

下面是 Singleton类已使用 Datastax API 创建连接到Cassandra数据库，该数据库使用新的二进制协议 -

Now below is the Singleton class that I have created for connecting to Cassandra database using Datastax API which uses new Binary protocol-

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 - let我知道如果在使用新的二进制协议的Datastax API连接到Cassandra数据库时，我在上面的 singleton类中缺少任何东西。

First question- let me know if I am missing anything in the above singleton class while making connection to Cassandra database using Datastax API which uses new Binary protocol.

第二个问题现在我试图从/从Cassandra数据库

Second question- Now I am trying to upsert and read data into/from Cassandra database-

这些是我在我的DAO中使用上面的Singleton类的方法 -

These are the methods I have in my DAO's which will use the above Singleton class-

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.

}

任何人都可以帮助我吗？我完全是新的Datastax API，它使用新的二进制协议，因此有很多问题。

Can anyone help me with this? I am totally new to this Datastax API which is using new Binary protocol so having lot of problem on this.

感谢您的帮助。

推荐答案

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

In your cassandra.yaml file look for the tag start_native_transport, by default its disabled, enable it.

使用Datastax Java Driver与jdbc driver非常相似。

Playing with Datastax Java Driver is quite similar like jdbc driver.

插入代码

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

从Cassandra读取

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

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