使用Pelops客户端连接到Cassandra数据库的高效方法 [英] Efficient way to connect to Cassandra database using Pelops client

问题描述

我正在开发一个项目，我需要使用 Cassandra数据库。我有一个示例程序，将数据填充到 Cassandra数据库。我现在使用 Pelops客户

I am working on a project in which I need to use Cassandra Database. I have a sample program that will populate data into Cassandra database. I am using Pelops client for that.

现在我正在考虑制作一个对于 Cassandra数据库的 > 使用 Singelton类到我的 CassandraDAO 中的实例插入到Cassandra数据库，并从Cassandra数据库检索数据。

So now I am thinking of making a Singleton class for Cassandra database that will make a connection to Cassandra database and then I be using that instance from Singelton class into my CassandraDAO to insert into Cassandra database and retrieve the data from Cassandra database as well.

下面是我到目前为止构建的Singleton类，它将连接到Cassandra数据库 -

Below is my Singleton class that I have built so far which will make a connection to Cassandra database-

public class CassandraConnection {

    private static CassandraConnection _instance;
    private String keyspace;
    private String[] seeds;
    private int port;
    private String poolName;

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

    private CassandraConnection() {
        setKeyspace(ICassandraDo.KEYSPACE_NAME);
        setSeeds(ICassandraDo.NODES).split(",");
        setPort(ICassandraDo.CASSANDRA_PORT);
        setPoolName(ICassandraDo.THRIFT_CONNECTION_POOL);

        createPool();
    }

    //This is the right way to `addPool` in pelops?
    private void createPool() {
        Pelops.addPool(getPoolName(), getSeeds(), getPort(),
                false, getKeyspace(), new Policy());

    }

    private String setSeeds(String nodes) {

    // I am not sure what I am supposed to do here? 
    // Any guidance will be of great help

    }

    private void setPoolName(String thriftConnectionPool) {
        this.poolName = thriftConnectionPool;
    }

    private void setPort(int cassandraPort) {
        this.port = cassandraPort;
    }

    private void setKeyspace(String keyspaceName) {
        this.keyspace = keyspaceName;

    }

    public void setSeeds(String[] seeds) {
        this.seeds = seeds;
    }

    public String[] getSeeds() {
        return seeds;
    }

    public int getPort() {
        return port;
    }

    public String getKeyspace() {
        return keyspace;
    }

    public String getPoolName() {
        return poolName;
    }
}

问题陈述：

我在上面的代码中几乎没有怀疑。

I have few doubts in my above code.

1. 我应该在 setSeeds 方法在我上面的类吗？任何指针或示例都会有很大的帮助。


2. 其次，我不知道这是否是正确的方法，因为我创建一个Singleton类？我想知道什么是最好的方法是使用pelops客户端管理集群连接。


3. 还有，使用 addPool的最好方法是方法在我上面的代码？我想，我在那里搞砸了一些东西吗？我在 Pelops类中继续看到不同的 addPool 方法？

1. Firstly, what I am supposed to do in setSeeds method in my above class? Any pointers or example will be of great help.
2. Secondly, I am not sure whether this is the right way to do this as I am creating a Singleton class? I am wondering what's the best approach is for managing a cluster connection with pelops client.
3. And also, what's the best way of using addPool method in my above code? I guess, I messed up something over there as well? As I keep on seeing different addPool methods in Pelops class? So which method I should be using keeping in mind as I will be running this in Production environment.

在上面的Singleton类之后，准备好，我打算在我的 DAO 代码中使用上面的类，像这样 -

And after the above Singleton class is ready, I am planning to use the above class in my DAO code, something like this-

Mutator mutator = Pelops.createMutator（CassandraConnection.getInstance（）。getPoolName（））;
mutator.writeColumns $ c>;

Mutator mutator = Pelops.createMutator(CassandraConnection.getInstance().getPoolName()); mutator.writeColumns(other data inside);

然后选择器也用于检索数据。

And then do the selector as well for retrieving the data.

只是FYI我正在使用 Cassandra 1.2.3 和 Scale 7 pelops客户端。

Just FYI, I am working with Cassandra 1.2.3 and Scale 7 pelops client.

任何帮助将不胜感激。提前感谢。

Any help will be appreciated. Thanks in advance.

更新代码：

public class CassandraConnection {

    private static CassandraConnection _instance;
    private String keyspace;
    private String[] nodes;
    private int port;
    private String poolName;


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

    private CassandraConnection() {
        setKeyspace(ICassandraDo.KEYSPACE_NAME);
        setNodes(ICassandraDo.NODES);
        setPort(ICassandraDo.CASSANDRA_PORT);
        setPoolName(ICassandraDo.THRIFT_CONNECTION_POOL);

        createPool();
    }


    private void createPool() {
        Pelops.addPool(getPoolName(), getCluster(), getKeyspace());

    }

    private Cluster getCluster() {

        Config casconf = new Config(ICassandraDo.CASSANDRA_PORT, true, 0); 

        Cluster cluster= new Cluster(nodes, casconf, ICassandraDo.NODE_DISCOVERY);

        return cluster; 
    }


    private void setPoolName(String thriftConnectionPool) {
        this.poolName = thriftConnectionPool;
    }

    private void setPort(int cassandraPort) {
        this.port = cassandraPort;
    }

    private void setKeyspace(String keyspaceName) {
        this.keyspace = keyspaceName;

    }

    private void setNodes(String nodes) {
        this.nodes = nodes.split(",");
    }

    public int getPort() {
        return port;
    }

    public String getKeyspace() {
        return keyspace;
    }

    public String getPoolName() {
        return poolName;
    }
}

任何人都可以看看，让我知道我的一切正确吗？感谢您的帮助。

Can anyone take a look and let me know I got everything correctly? Thanks for the help.

推荐答案

种子节点是两个（或更多，但2是Cassandra文档的建议数）节点您的群集。在每个Cassandra节点配置文件（cassandra.yaml）中，存在该簇的种子节点的地址。假设您有5个节点的集群

Seeds nodes are two (or more, but 2 is the suggested number from Cassandra documentation) nodes of your cluster. In each cassandra-node configuration file (cassandra.yaml) there is the address of the seeds nodes for the cluster. Imagine you have cluster of 5 nodes

192.168.1.100
192.168.1.101
192.168.1.102
192.168.1.103
192.168.1.104

192.168.1.100 192.168.1.101 192.168.1.102 192.168.1.103 192.168.1.104

种子
192.168。在每个配置文件中将有

in each config file there will be, for instance

1.101
192.168.1.103

Seeds 192.168.1.101 192.168.1.103

对于这个集群，这两个地址是种子节点。启动时集群的每个节点将联系这2个节点并获取必要的信息。在你的例子中，你可以传递在配置中找到的地址或只是对群集的地址节点的配对

For this cluster these 2 addresses are the seed nodes. Each node of the cluster at the startup will contact these 2 nodes and get the necessary information. In your example you can pass the addresses found in the configuration or just couple of address nodes of the cluster

String[] nodes = new String[2];
nodes[1] = "192.168.1.101";
nodes[2] = "192.168.1.103";

2）Singleton是绝对不必要的，因为Pelops类只由静态元素构成。如果您的应用程序中有一个Init / Startup，那么只需声明与Cassandra的连接，它将在您的所有代码中可用。

2) The Singleton is absolutely unnecessary since the Pelops class is made only by static elements. If you have an Init/Startup in your application just declare there the connection to Cassandra and it will be available in all your code

3）没有正确的答案，正确的方式连接到群集取决于群集。
您可能需要设置您的自定义参数或由Pelops保留一个。在我的生产env（5个节点，RF = 3）我使用默认参数没有问题。

3) There is no correct answer, the right way to connect to a cluster depends on the cluster. You may need to set your custom parameters or leave the one by Pelops. In my production env (5 nodes, RF=3) I'm using default params without problems.

Ciao

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