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首页 云原生多模数据库 Lindorm 操作指南 宽表引擎（兼容HBase或Cassandra） 应用开发教程 基于Cassandra CQL的应用开发 通过Cassandra CQL非Java Driver的应用开发

通过Cassandra CQL非Java Driver的应用开发

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本文介绍多语言Driver（例如C++、Python、Nodejs和Go）通过Cassandra CQL访问云原生多模数据库 Lindorm宽表引擎的操作方法。

前提条件

Cassandra CQL Python Driver访问Lindorm宽表

  1. 安装Datastax Python依赖包，具体操作请参见安装Python SDK。

    # 指定版本安装（建议安装3.x版本）
pip install cassandra-driver==3.19.0
# 安装最新版本
pip install cassandra-driver

  2. 访问Lindorm宽表的示例代码。

    #!/usr/bin/env python
# -*- coding: UTF-8 -*-
import logging
import sys
from cassandra.cluster import Cluster
from cassandra.auth import PlainTextAuthProvider

logging.basicConfig(stream=sys.stdout, level=logging.INFO)

cluster = Cluster(
    # 填写Lindorm宽表引擎的CQL连接地址，不用填端口
    contact_points=["ld-bp17j28j2y7pm****-proxy-lindorm.lindorm.rds.aliyuncs.com"],
    # 填写用户名和密码，默认为root
    auth_provider=PlainTextAuthProvider("cassandra", "****"))

session = cluster.connect()
# 创建keyspace
session.execute(
                "CREATE KEYSPACE IF NOT EXISTS testKeyspace WITH replication = {'class':'SimpleStrategy', 'replication_factor':1};");

# 创建table
session.execute(
                "CREATE TABLE IF NOT EXISTS testKeyspace.testTable (id int PRIMARY KEY, name text,age int,address text);");

# 插入数据
session.execute(
                "INSERT INTO testKeyspace.testTable (id, name, age, address) VALUES ( 1, 'testname', 11, 'hangzhou');");

# 查询数据
rows = session.execute(
                "SELECT * FROM testKeyspace.testTable ;");

# 打印每行数据到控制台
for row in rows:
    print("# row: {}".format(row))

# 关闭Session
session.shutdown()

# 关闭
cluster.shutdown()

Cassandra CQL C++ Driver访问Lindorm宽表

  1. 下载C++依赖包，下载链接请参见Datastax c++。

  2. 访问Lindorm宽表的示例代码。

    CassFuture* connect_future = NULL;
CassCluster* cluster = cass_cluster_new();
CassSession* session = cass_session_new();
//填写Lindorm宽表引擎的CQL连接地址，不用填端口
char* hosts = "ld-bp17j28j2y7pm****-proxy-lindorm.lindorm.rds.aliyuncs.com";

//建立连接
cass_cluster_set_contact_points(cluster, hosts);
connect_future = cass_session_connect(session, cluster);

//DDL操作
if (cass_future_error_code(connect_future) == CASS_OK) {
    CassFuture* close_future = NULL;

    
    const char* query = "SELECT  name FROM testKeyspace.testTable ";
    CassStatement* statement = cass_statement_new(query, 0);

    CassFuture* result_future = cass_session_execute(session, statement);

    if (cass_future_error_code(result_future) == CASS_OK) {
      //获取查询结果
      const CassResult* result = cass_future_get_result(result_future);
      const CassRow* row = cass_result_first_row(result);

      if (row) {
        const CassValue* value = cass_row_get_column_by_name(row, "name");
        //打印结果
        const char* name;
        size_t name_length;
        cass_value_get_string(value, &name, &name_length);
        printf("release_version: '%.*s'\n", (int)name_length, name);
      }

      cass_result_free(result);
    } else {
      //异常处理
      const char* message;
      size_t message_length;
      cass_future_error_message(result_future, &message, &message_length);
      fprintf(stderr, "Unable to run query: '%.*s'\n", (int)message_length, message);
    }

    cass_statement_free(statement);
    cass_future_free(result_future);

    //手动释放资源信息
    close_future = cass_session_close(session);
    cass_future_wait(close_future);
    cass_future_free(close_future);
  } else {
    //异常处理
    const char* message;
    size_t message_length;
    cass_future_error_message(connect_future, &message, &message_length);
    fprintf(stderr, "Unable to connect: '%.*s'\n", (int)message_length, message);
  }

  cass_future_free(connect_future);
  cass_cluster_free(cluster);
  cass_session_free(session);

Cassandra CQL Nodejs Driver访问Lindorm宽表

  1. 安装Node.js依赖包。

    npm install cassandra-driver

  2. 访问Lindorm宽表的示例代码。

    const cassandra = require('cassandra-driver');

/**
* 填写Lindorm宽表引擎的CQL连接地址，不用填端口。dc名字填datacenter1
* 填写用户名和密码，默认为root
*/
const client = new cassandra.Client({ contactPoints: ['ld-bp17j28j2y7pm****-proxy-lindorm.lindorm.rds.aliyuncs.com'], localDataCenter: 'datacenter1', credentials: { username: '用户名', password: '密码' } });

client.connect()
.then(() => client.execute("CREATE KEYSPACE IF NOT EXISTS lindormtest WITH replication = {'class': 'SimpleStrategy', 'replication_factor': '2' }"))
.then(() => client.execute("CREATE TABLE IF NOT EXISTS lindormtest.nodejs (name text PRIMARY KEY, age int)"))
.then(() => {
 return client.execute("INSERT INTO lindormtest.nodejs (name, age) VALUES ('lindorm', 10)");
})
.then(() => {
 return client.execute("SELECT name, age FROM lindormtest.nodejs WHERE name = 'lindorm' ");
})
.then(result => {
 const row = result.first();
 console.log('Obtained row: ', row);
 const p = row.age;
})
.finally(() => client.shutdown());

Cassandra CQL go Driver访问Lindorm宽表

  1. 安装GoCQL。

    go get github.com/gocql/gocql

  2. 访问Lindorm宽表的示例代码。

    package main

import (
    "fmt"
    "log"

    "github.com/gocql/gocql"
)

func main() {
    // 填写Lindorm宽表引擎的CQL连接地址，不用填端口
    cluster := gocql.NewCluster("ld-bp17j28j2y7pm****-proxy-lindorm.lindorm.rds.aliyuncs.com")
    cluster.Authenticator = gocql.PasswordAuthenticator{
        Username:"用户名",
        Password: "密码",
    }

    session, _ := cluster.CreateSession()
    defer session.Close()

    //create keyspace
    if err := session.Query(`CREATE KEYSPACE ks WITH replication = {'class': 'SimpleStrategy', 'replication_factor': 2}`).Exec(); err != nil {
        log.Fatal(err)
    }

    // create table
    if err := session.Query(`CREATE TABLE ks.tb (cn1 text PRIMARY KEY, cn2 text, cn3 text)`).Exec(); err != nil {
        log.Fatal(err)
    }

    // insert value
    if err := session.Query(`INSERT INTO ks.tb (cn1, cn2, cn3) VALUES (?, ?, ?)`,
        "v11", "v12", "v13").Exec(); err != nil {
        log.Fatal(err)
    }

    var column1 string
    var column2 string

    if err := session.Query(`SELECT cn1, cn2 FROM ks.tb WHERE cn1 = ?`,
        "v11").Consistency(gocql.One).Scan(&column1, &column2); err != nil {
        log.Fatal(err)
    }
    fmt.Println("ALL values:", column1, column2)

    var column3 string
    // list all tweets
    iter := session.Query(`SELECT * FROM ks.tb WHERE cn1 = ? `, "v11").Iter()
    for iter.Scan(&column1, &column2, &column3) {
        fmt.Println("ALL value:", column1, column2, column3)
    }
    if err := iter.Close(); err != nil {
        log.Fatal(err)
    }
}
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