Question

我需要编写一个API来从Hive表中获取数据，以便我可以处理它，我试图使用Jdbc访问Hive表。一个简单的“Select * from table”工作正常，但“从表中选择count（*）会引发错误：

2017-04-20 18:05:57,709 INFO  [main] jdbc.Utils (Utils.java:parseURL(310)) - Supplied authorities: 10.94.154.125:10000
2017-04-20 18:05:57,712 INFO  [main] jdbc.Utils (Utils.java:parseURL(397)) - Resolved authority: 10.94.154.125:10000
SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.
2017-04-20 18:05:57,790 INFO  [main] jdbc.HiveConnection (HiveConnection.java:openTransport(203)) - Will try to open client transport with JDBC Uri: jdbc:hive2://10.94.154.125:10000/CloudData
Running: select count(*) from  ipticket
java.sql.SQLException: Error while processing statement: FAILED: Execution Error, return code 1 from org.apache.hadoop.hive.ql.exec.mr.MapRedTask
    at org.apache.hive.jdbc.HiveStatement.execute(HiveStatement.java:296)
    at org.apache.hive.jdbc.HiveStatement.executeQuery(HiveStatement.java:392)
    at HiveJdbcClient.main(HiveJdbcClient.java:35)

代码：

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";

  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);
    }
    Connection con = DriverManager.getConnection("jdbc:hive2://localhost:10000/CloudData", "", "");
    Statement stmt = con.createStatement();
    String tableName = "table1";
  String  sql = "select count(*) from  " + tableName;
    System.out.println("Running: " + sql);
    try{
         ResultSet res = stmt.executeQuery(sql);
         while (res.next()) {
              System.out.println(res.getString(1) + "\t" + res.getString(2)+"\t"+res.getString(3) + "\t" + res.getString(4));
            }

    }catch (SQLException f){
        f.printStackTrace();
    }

  }
}

Answer 1

由于Select count（）启动了MapReduce作业，因此您的配置文件可能存在问题尝试测试群集上的地图减少作业执行此操作并改变hadoop-mapreduce-examples - 。。 .jar与你的mapreduce例子的jar版本（如果你有hadoop 2.6，它将看起来像/hadoop-mapreduce-examples-2.6。 0.jar）

cd $ HADOOP_HOME 然后 hadoop jar ./share/hadoop/mapreduce/hadoop-mapreduce-examples-..*.jar pi 2 5

如果您有错误，则MR未配置为正常工作

尝试使用Jdbc访问Hive表时出错

1 个答案: