MaxCompute Lightning是MaxCompute产品的交互式查询服务，支持以PostgreSQL协议及语法连接访问Maxcompute项目，让您使用熟悉的工具以标准 SQL查询分析MaxCompute项目中的数据，快速获取查询结果。
很多开发者希望利用Lightning的特性来开发数据应用，本文将结合示例来介绍Java和Python如何连接访问Lightning进行应用开发(参考时需要替换为您项目所在region的Endpoint及用户认证信息)。
一、Java使用JDBC访问Lightning
示例如下：

import java.sql.*;public class Main {private static Connection connection;public static void main(String[] args) throws SQLException {String url = "jdbc:postgresql://lightning.cn-shanghai.maxcompute.aliyun.com:443/your_project_name?prepareThreshold=0&sslmode=require";String accessId = "<your_maxcompute_access_id>";String accessKey = "<your_maxcompute_access_key>";String sql = "select * from dual";try {Connection conn = getCon(url, accessId, accessKey);Statement st = conn.createStatement();System.out.println("Send Lightning query");ResultSet rs = st.executeQuery(sql);while (rs.next()) {System.out.println(rs.getString(1)+ "\t");}System.out.println("End Lightning query");conn.close();} catch (SQLException e) {e.printStackTrace();}}public static Connection getCon(String lightningsHost, String lightningUser, String lightningPwd) {try {if (connection == null || connection.isClosed()) {try {Class.forName("org.postgresql.Driver").newInstance();DriverManager.setLoginTimeout(1);connection = DriverManager.getConnection(lightningsHost, lightningUser, lightningPwd);} catch (Exception ex) {ex.printStackTrace();}}} catch (Exception ex) {ex.printStackTrace();}return connection;}
}复制代码

二、Java使用druid访问Lightning
1.pom依赖

<dependency><groupId>com.alibaba</groupId><artifactId>druid</artifactId><version>1.0.23</version></dependency><dependency><groupId>org.postgresql</groupId><artifactId>postgresql</artifactId><version>9.3-1101-jdbc4</version></dependency>
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2.spring配置

    <bean id="LightningDataSource" class="com.alibaba.druid.pool.DruidDataSource" init-method="init" destroy-method="close"><property name="url" value="jdbc:postgresql://lightning.cn-shanghai.maxcompute.aliyun.com:443/project_name?prepareThreshold=0&sslmode=require”/> <!--替换成自己project所在region的Endpoint—><property name="username" value=“访问用户的Access Key ID"/><property name="password" value="访问用户的Access Key Secret"/><property name="driverClassName" value="org.postgresql.Driver"/><property name="dbType" value="postgresql"/><property name="initialSize" value="1" />  <property name="minIdle" value="1" /><property name="maxActive" value="5" />  <!—Lightning服务每个project的连接数限制20，所以不要配置过大，按需配置，否则容易出现query_wait_timeout错误 --><!--以下两个配置，检测连接有效性，修复偶尔出现create connection holder error错误 --><property name="testWhileIdle" value="true" /><property name="validationQuery" value="SELECT 1" /></bean><bean class="com.xxx.xxx.LightningProvider"><property name="druidDataSource" ref="LightningDataSource"/></bean>复制代码

3.代码访问

public class LightningProvider {DruidDataSource druidDataSource;/*** 执行sql* @param sql* @return* @throws Exception*/public void execute(String sql) throws SQLException {DruidPooledConnection connection = null ;Statement st = null;try{connection = druidDataSource.getConnection();st = connection.createStatement();ResultSet resultSet = st.executeQuery(sql);//对返回值的解析和处理的代码//按行处理，每行的数据放到一个map中ResultSetMetaData metaData = resultSet.getMetaData();int columnCount = metaData.getColumnCount();List<LinkedHashMap> rows = Lists.newArrayList();while(resultSet.next()){LinkedHashMap map = Maps.newLinkedHashMap();for(int i=1;i<=columnCount;i++){String label = resultSet.getMetaData().getColumnLabel(i);map.put(label,resultSet.getString(i));}rows.add(map);}   }catch (Exception e){e.printStackTrace();}finally {try {if(st!=null) {st.close();}} catch (SQLException e) {e.printStackTrace();}try {if(connection!=null) {connection.close();}} catch (SQLException e) {e.printStackTrace();}}}
}复制代码

三、Python使用pyscopg2访问Lightning
示例如下：

#!/usr/bin/env python
# coding=utf-8import psycopg2
import sysdef query_lightning(lightning_conf, sql):"""Query data through Lightning by sqlArgs:lightning_conf: a map contains settings of 'dbname', 'user', 'password', 'host', 'port'sql:  query submit to LightningReturns:result: the query result in format of list of rows"""result = Noneconn = Noneconn_str = Nonetry:conn_str = ("dbname={dbname} ""user={user} ""password={password} ""host={host} ""port={port}").format(**lightning_conf)except Exception, e:print >> sys.stderr, ("Invalid Lightning' configuration ""{}".format(e))sys.exit(1)try:conn = psycopg2.connect(conn_str)conn.set_session(autocommit=True) # This will disable transaction# started with keyword BEGIN,# which is currently not# supported by Lightning’ public servicecur = conn.cursor()# execute Lightning' querycur.execute(sql)# get resultresult = cur.fetchall()except Exception, e:print >> sys.stderr, ("Failed to query data through ""Lightning: {}".format(e))finally:if conn:conn.close()return resultif __name__ == "__main__":# step1. setup configurationlightning_conf = {"dbname": “your_project_name”,"user": "<your_maxcompute_access_id>", "password": "<your_maxcompute_access_key>", "host": "lightning.cn-shanghai.maxcompute.aliyun.com",  #your region lightning endpoint"port": 443}# step2. issue a queryresult = query_lightning(lightning_conf, "select * from test”)# step3. print resultif result:for i in xrange(0, len(result)):print "Got %d row from Lightning:%s" % (i + 1, result[i])复制代码

四、Python使用ODBC访问Lightning
您需要现在电脑上安装并和配置odbc驱动。代码示例如下：

import pyodbc
conn_str = ("DRIVER={PostgreSQL Unicode};""DATABASE=your_project_name;""UID=your_maxcompute_access_id;""PWD=your_maxcompute_access_key;""SERVER=lightning.cn-shanghai.maxcompute.aliyun.com;" #your region lightning endpoint"PORT=443;")
conn = pyodbc.connect(conn_str)
crsr = conn.execute("SELECT * from test”)
row = crsr.fetchone()
print(row)
crsr.close()
conn.close()复制代码

由于Lightning提供了PostgreSQL兼容的接口，您可以像开发PostgreSQL的应用一样开发Lightning应用程序。