HiveServer2

HiveServer 2(HS2)是一种服务，使客户端能够对Hive执行查询。HiveServer 2是HiveServer 1的继承者，HiveServer 1已被废弃。HS2支持多客户端并发和身份验证。它的设计是为了更好地支持开放API客户机，如JDBC和ODBC。HS2是一个作为复合服务运行的单个进程，它包括基于Thwift的Hive服务(TCP或HTTP)和用于WebUI的JettyWeb服务器。

启动HiveServer2

[root@hadoop-senior hive-0.13.1]# bin/hiveserver2

servier2启动成功

说明：如果不启动此服务或者服务启动失败，客户端beeline会报错.
Error: Invalid URL: jdbc:hive2://hadoop-senior.beifeng.com:10000 (state=08S01,code=0)

使用客户端连接Hiveserver2

1、启用客户端[root@hadoop-senior hive-0.13.1]# bin/beeline

2、连接服务器端

连接服务器命令：
beeline>!connect jdbc:hive2://hadoop-senior.beifeng.com:10000
scan complete in 2ms
Connecting to jdbc:hive2://hadoop-senior.beifeng.com:10000
Enter username for jdbc:hive2://hadoop-senior.beifeng.com:10000: root
Enter password for jdbc:hive2://hadoop-senior.beifeng.com:10000: 123456

beeline 连接成功后的信息

测试结果

beeline 和 bing/hive 中的命令都是一样的，但是beeline 使用起来更人性化，查询数据的时候展现方式内容比较齐全，数据存在格式。

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Hive的JDBC使用

HiveServer 2有一个JDBC驱动程序。它既支持嵌入式访问，也支持远程访问HiveServer 2。建议生产使用Remote HiveServer 2模式，因为它更安全，并且不需要为用户提供直接的HDFS/亚稳访问。

步骤如下：
You can use JDBC to access data stored in a relational database or other tabular format.

1. Load the HiveServer2 JDBC driver. As of 1.2.0 applications no longer need to explicitly load JDBC drivers using Class.forName().

For example:

Class.forName("org.apache.hive.jdbc.HiveDriver");

2. Connect to the database by creating a Connection object with the JDBC driver.

For example:

Connection cnct = DriverManager.getConnection("jdbc:hive2://<host>:<port>", "<user>", "<password>");

The default <port> is 10000. In non-secure configurations, specify a <user> for the query to run as. The <password> field value is ignored in non-secure mode.

Connection cnct = DriverManager.getConnection("jdbc:hive2://<host>:<port>", "<user>", "");

In Kerberos secure mode, the user information is based on the Kerberos credentials.

3. Submit SQL to the database by creating a Statement object and using its executeQuery() method.

For example:

Statement stmt = cnct.createStatement();

ResultSet rset = stmt.executeQuery("SELECT foo FROM bar");

4. Process the result set, if necessary.

These steps are illustrated in the sample code below.

JDBC Client 样例代码

import java.sql.SQLException;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.Statement;
import java.sql.DriverManager;
 
public class HiveJdbcClient {
  private static String driverName = "org.apache.hive.jdbc.HiveDriver";
 
  /**
   * @param args
   * @throws SQLException
   */
  public static void main(String[] args) throws SQLException {
      try {
      Class.forName(driverName);
    } catch (ClassNotFoundException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
      System.exit(1);
    }
    //replace "hive" here with the name of the user the queries should run as
    Connection con = DriverManager.getConnection("jdbc:hive2://hadoop-senior.beifeng.com:10000/default", "root", "123456");
    Statement stmt = con.createStatement();
    String tableName = "emp";
    stmt.execute("drop table if exists " + tableName);
    stmt.execute("create table " + tableName + " (key int, value string)");
    // show tables
    String sql = "show tables '" + tableName + "'";
    System.out.println("Running: " + sql);
    ResultSet res = stmt.executeQuery(sql);
    if (res.next()) {
      System.out.println(res.getString(1));
    }
       // describe table
    sql = "describe " + tableName;
    System.out.println("Running: " + sql);
    res = stmt.executeQuery(sql);
    while (res.next()) {
      System.out.println(res.getString(1) + "\t" + res.getString(2));
    }
 
    // load data into table
    // NOTE: filepath has to be local to the hive server
    // NOTE: /tmp/a.txt is a ctrl-A separated file with two fields per line
    String filepath = "/tmp/a.txt";
    sql = "load data local inpath '" + filepath + "' into table " + tableName;
    System.out.println("Running: " + sql);
    stmt.execute(sql);
 
    // select * query
    sql = "select * from " + tableName;
    System.out.println("Running: " + sql);
    res = stmt.executeQuery(sql);
    while (res.next()) {
      System.out.println(String.valueOf(res.getInt(1)) + "\t" + res.getString(2));
    }
 
    // regular hive query
    sql = "select count(1) from " + tableName;
    System.out.println("Running: " + sql);
    res = stmt.executeQuery(sql);
    while (res.next()) {
      System.out.println(res.getString(1));
    }
  }
}

Hive使用JDBC的原因