云原生多模数据库 Lindorm：通过Cassandra CQL非Java Driver的应用开发

前提条件

• 已获取Lindorm宽表引擎的CQL连接地址，具体如下图所示。

• 根据您使用的语言下载并安装驱动程序。更多信息请参见Cassandra client drivers。

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)
       }
   }