在 AWS EMR 上将 Hadoop+Hive 与 MongoDB 连接（未找到类 com/mongodb/DBObject）

Question

我喜欢通过 MongoDB 连接（而不是通过 BSON 转储）将 EMR 集群连接到我们的 MongoDB。

为此，我通过 AWS 管理控制台生成了集群。在 Bootstrap 配置中，我指向了放置在 S3 上的这个文件：

#!/bin/sh

wget -P /home/hadoop/lib http://central.maven.org/maven2/org/mongodb/mongo-java-driver/2.13.0/mongo-java-driver-2.13.0.jar

wget -P /home/hadoop/lib https://github.com/mongodb/mongo-hadoop/releases/download/r1.3.2/mongo-hadoop-core-1.3.2.jar
wget -P /home/hadoop/lib https://github.com/mongodb/mongo-hadoop/releases/download/r1.3.2/mongo-hadoop-pig-1.3.2.jar
wget -P /home/hadoop/lib https://github.com/mongodb/mongo-hadoop/releases/download/r1.3.2/mongo-hadoop-hive-1.3.2.jar

当集群产生时，我进入主节点并看到它们已成功下载。

当我在 Hive shell 中执行此操作时：

CREATE TABLE nicks
( 
  id STRING,
  name STRING,
  business STRING,
  alias STRING
)
STORED BY 'com.mongodb.hadoop.hive.MongoStorageHandler'
TBLPROPERTIES('mongo.uri'='mongodb://54.93.123.123:27017/foo.aliases');

ADD JAR /home/hadoop/lib/mongo-hadoop-core-1.3.2.jar;
ADD JAR /home/hadoop/lib/mongo-hadoop-hive-1.3.2.jar;
ADD JAR /home/hadoop/lib/mongo-java-driver-2.13.0.jar;

Select * from nicks;

我得到这个例外：

Exception in thread "main" java.lang.NoClassDefFoundError: com/mongodb/DBObject
    at com.mongodb.hadoop.splitter.MongoSplitterFactory.getSplitterByClass(MongoSplitterFactory.java:41)
    at com.mongodb.hadoop.splitter.MongoSplitterFactory.getSplitter(MongoSplitterFactory.java:109)
    at com.mongodb.hadoop.hive.input.HiveMongoInputFormat.getSplits(HiveMongoInputFormat.java:64)
    at com.mongodb.hadoop.hive.input.HiveMongoInputFormat.getSplits(HiveMongoInputFormat.java:44)
    at org.apache.hadoop.hive.ql.exec.FetchOperator.getRecordReader(FetchOperator.java:418)
    at org.apache.hadoop.hive.ql.exec.FetchOperator.getNextRow(FetchOperator.java:561)
    at org.apache.hadoop.hive.ql.exec.FetchOperator.pushRow(FetchOperator.java:534)
    at org.apache.hadoop.hive.ql.exec.FetchTask.fetch(FetchTask.java:137)
    at org.apache.hadoop.hive.ql.Driver.getResults(Driver.java:1519)
    at org.apache.hadoop.hive.cli.CliDriver.processLocalCmd(CliDriver.java:292)
    at org.apache.hadoop.hive.cli.CliDriver.processCmd(CliDriver.java:227)
    at org.apache.hadoop.hive.cli.CliDriver.processLine(CliDriver.java:430)
    at org.apache.hadoop.hive.cli.CliDriver.executeDriver(CliDriver.java:803)
    at org.apache.hadoop.hive.cli.CliDriver.run(CliDriver.java:697)
    at org.apache.hadoop.hive.cli.CliDriver.main(CliDriver.java:636)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at org.apache.hadoop.util.RunJar.main(RunJar.java:212)
Caused by: java.lang.ClassNotFoundException: com.mongodb.DBObject
    at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
    ... 20 more

笔记：

• 我已经（使用 ssh）将所有 4 个库都放置在正确的文件夹中
• Mongo-Hive 连接器 JAR 似乎已加载，因为在通过执行“ADD JAR ...”修复之前我遇到了另一个异常。
• 我检查了 mongo-java-driver jar 的内容。它似乎是有效的（我在里面找到了 DBObject 类）

如何解决这个问题，或者我如何调试出了什么问题？

Answer 1

解决方案是将 libs 也放入/home/hadoop/hive/lib. 使用此脚本，它可以工作：

#!/bin/sh

wget -P /home/hadoop/lib http://central.maven.org/maven2/org/mongodb/mongo-java-driver/2.13.0/mongo-java-driver-2.13.0.jar

wget -P /home/hadoop/lib https://github.com/mongodb/mongo-hadoop/releases/download/r1.3.2/mongo-hadoop-core-1.3.2.jar
wget -P /home/hadoop/lib https://github.com/mongodb/mongo-hadoop/releases/download/r1.3.2/mongo-hadoop-pig-1.3.2.jar
wget -P /home/hadoop/lib https://github.com/mongodb/mongo-hadoop/releases/download/r1.3.2/mongo-hadoop-hive-1.3.2.jar

cp /home/hadoop/lib/mongo* /home/hadoop/hive/lib