Question

以下代码有什么问题，为什么Cassandra中的负载平衡不起作用？

const cassandra = require('cassandra-driver');
const client = new cassandra.Client({ contactPoints: ['172.30.56.63','172.30.36.129'], keyspace: 'qnapstat',
                                      policies : { loadBalancing : new cassandra.policies.loadBalancing.RoundRobinPolicy } });

const query = 'SELECT * FROM nodedata WHERE partitionkey = ?';

async function read() {
    console.log(client.options.policies.loadBalancing);
    const params = ['testdata'];
    var response = await client.execute(query, params, { prepare: true, consistency: cassandra.types.consistencies.quorum });
    console.log(response.info);
    process.exit();
}

read();

我打印了尝试过的主机，我能够看到它总是试图将172.30.36.129作为协调器，而不是另一个。

Answer 1

我误解了，只有使用相同的客户端连接才能使用该策略，为了明确以下代码按预期工作，

const cassandra = require('cassandra-driver');
const client = new cassandra.Client({ contactPoints: ['172.30.56.60','172.30.56.61,172.30.56.62'], keyspace: 'qnapstat', 
                                      policies : { loadBalancing : new cassandra.policies.loadBalancing.RoundRobinPolicy
                         } });

var index = 0;
var totalcount = 10;

const query = 'SELECT readiops FROM nodedata where nodeip = ?';

async function read() {
    console.log(client.options.policies.loadBalancing);
    console.log(client.options.policies.retry);

    while(index < totalcount) {
       const params = ['testdata'];
       var response = await client.execute(query, params, { prepare: true, consistency: cassandra.types.consistencies.quorum });
       console.log(response.info);
       index = index + 1;
    }
       process.exit();
}

read();

谢谢，

哈利

cassandra中的负载均衡策略

1 个答案: