sqoop数据迁移（基于Hadoop和关系数据库服务器之间传送数据）

1：sqoop的概述：

（1）：sqoop是apache旗下一款“Hadoop和关系数据库服务器之间传送数据”的工具。
（2）：导入数据：MySQL，Oracle导入数据到Hadoop的HDFS、HIVE、HBASE等数据存储系统；
（3）：导出数据：从Hadoop的文件系统中导出数据到关系数据库

（4）：工作机制：

　　将导入或导出命令翻译成mapreduce程序来实现；
　　在翻译出的mapreduce中主要是对inputformat和outputformat进行定制；

（5）：Sqoop的原理：

　　Sqoop的原理其实就是将导入导出命令转化为mapreduce程序来执行，sqoop在接收到命令后，都要生成mapreduce程序；
　　使用sqoop的代码生成工具可以方便查看到sqoop所生成的java代码，并可在此基础之上进行深入定制开发；

2：sqoop安装：

　　安装sqoop的前提是已经具备java和hadoop的环境；

第一步：下载并解压，下载以后，上传到自己的虚拟机上面，过程省略，然后解压缩操作：

　　最新版下载地址：http://ftp.wayne.edu/apache/sqoop/1.4.6/

　　Sqoop的官方网址：http://sqoop.apache.org/

[root@master package]# tar -zxvf sqoop-1.4.6.bin__hadoop-2.0.4-alpha.tar.gz -C /home/hadoop/

第二步：修改配置文件：

可以修改一下sqoop的名称，因为解压缩的太长了。然后你也可以配置sqoop的环境变量，这样可以方便访问；

[root@master hadoop]# mv sqoop-1.4.6.bin__hadoop-2.0.4-alpha/ sqoop

配置Sqoop的环境变量操作，如下所示：

[root@master hadoop]# vim /etc/profile
[root@master hadoop]# source /etc/profile

修改sqoop的配置文件名称如下所示：

[root@master hadoop]# cd $SQOOP_HOME/conf
[root@master conf]# ls
oraoop-site-template.xml  sqoop-env-template.sh    sqoop-site.xml
sqoop-env-template.cmd    sqoop-site-template.xml
[root@master conf]# mv sqoop-env-template.sh sqoop-env.sh

修改sqoop的配置文件如下所示，打开sqoop-env.sh并编辑下面几行（根据需求，可以修改hadoop，hive，hbase的配置文件）：

第三步：加入mysql的jdbc驱动包（自己必须提前将mysql的jar包上传到虚拟机上面）：

[root@master package]# cp mysql-connector-java-5.1.28.jar $SQOOP_HOME/lib/

第四步：验证启动，如下所示（由于未配置$HBASE_HOME等等这些的配置，所以发出Warning，不是Error）：

[root@master conf]# cd $SQOOP_HOME/bin

 [root@master bin]# sqoop-version
 Warning: /home/hadoop/soft/sqoop/../hbase does not exist! HBase imports will fail.
 Please set $HBASE_HOME to the root of your HBase installation.
 Warning: /home/hadoop/soft/sqoop/../hcatalog does not exist! HCatalog jobs will fail.
 Please set $HCAT_HOME to the root of your HCatalog installation.
 Warning: /home/hadoop/soft/sqoop/../accumulo does not exist! Accumulo imports will fail.
 Please set $ACCUMULO_HOME to the root of your Accumulo installation.
 // :: INFO sqoop.Sqoop: Running Sqoop version: 1.4.
 Sqoop 1.4.
 git commit id c0c5a81723759fa575844a0a1eae8f510fa32c25
 Compiled by root on Mon Apr  :: CST 

到这里，整个Sqoop安装工作完成。下面可以尽情的和Sqoop玩耍了。

---

3：Sqoop的数据导入：

　　“导入工具”导入单个表从RDBMS到HDFS。表中的每一行被视为HDFS的记录。所有记录都存储为文本文件的文本数据（或者Avro、sequence文件等二进制数据）

下面的语法用于将数据导入HDFS。

 $ sqoop import (generic-args) (import-args) 

导入表表数据到HDFS
下面的命令用于从MySQL数据库服务器中的emp表导入HDFS。

 $bin/sqoop import   \
 --connect jdbc:mysql://localhost:3306/test   \ #指定主机名称和数据库
 --username root  \   #mysql的账号
 --password root   \  #mysql的密码
 --table emp   \      #导入的数据表
 --m    #多少个mapreduce跑，这里是一个mapreduce

或者使用下面的命令进行导入：

 [root@master sqoop]# bin/sqoop import --connect jdbc:mysql://localhost:3306/test --username root --password 123456 --table emp --m 1

开始将mysql的数据导入到sqoop的时候出现下面的错误，贴一下，希望可以帮到看到的人：

 [root@master sqoop]# bin/sqoop import   \
 > --connect jdbc:mysql://localhost:3306/test   \
 > --username root  \
 > --password 123456   \
 > --table emp   \
 > --m
 Warning: /home/hadoop/sqoop/../hbase does not exist! HBase imports will fail.
 Please set $HBASE_HOME to the root of your HBase installation.
 Warning: /home/hadoop/sqoop/../hcatalog does not exist! HCatalog jobs will fail.
 Please set $HCAT_HOME to the root of your HCatalog installation.
 Warning: /home/hadoop/sqoop/../accumulo does not exist! Accumulo imports will fail.
 Please set $ACCUMULO_HOME to the root of your Accumulo installation.
 Warning: /home/hadoop/sqoop/../zookeeper does not exist! Accumulo imports will fail.
 Please set $ZOOKEEPER_HOME to the root of your Zookeeper installation.
 // :: INFO sqoop.Sqoop: Running Sqoop version: 1.4.
 // :: WARN tool.BaseSqoopTool: Setting your password on the command-line is insecure. Consider using -P instead.
 // :: INFO manager.MySQLManager: Preparing to use a MySQL streaming resultset.
 // :: INFO tool.CodeGenTool: Beginning code generation
 // :: INFO manager.SqlManager: Executing SQL statement: SELECT t.* FROM `emp` AS t LIMIT
 // :: INFO manager.SqlManager: Executing SQL statement: SELECT t.* FROM `emp` AS t LIMIT
 // :: INFO orm.CompilationManager: HADOOP_MAPRED_HOME is /home/hadoop/hadoop-2.4.
 Note: /tmp/sqoop-root/compile/2df9072831c26203712cd4da683c50d9/emp.java uses or overrides a deprecated API.
 Note: Recompile with -Xlint:deprecation for details.
 // :: INFO orm.CompilationManager: Writing jar file: /tmp/sqoop-root/compile/2df9072831c26203712cd4da683c50d9/emp.jar
 // :: WARN manager.MySQLManager: It looks like you are importing from mysql.
 // :: WARN manager.MySQLManager: This transfer can be faster! Use the --direct
 // :: WARN manager.MySQLManager: option to exercise a MySQL-specific fast path.
 // :: INFO manager.MySQLManager: Setting zero DATETIME behavior to convertToNull (mysql)
 // :: INFO mapreduce.ImportJobBase: Beginning import of emp
 // :: INFO Configuration.deprecation: mapred.jar is deprecated. Instead, use mapreduce.job.jar
 // :: INFO Configuration.deprecation: mapred.map.tasks is deprecated. Instead, use mapreduce.job.maps
 // :: INFO client.RMProxy: Connecting to ResourceManager at master/192.168.3.129:
 // :: ERROR tool.ImportTool: Encountered IOException running import job: java.net.ConnectException: Call From master/192.168.3.129 to master: failed on connection exception: java.net.ConnectException: Connection refused; For more details see:  http://wiki.apache.org/hadoop/ConnectionRefused
     at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
     at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:)
     at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:)
     at java.lang.reflect.Constructor.newInstance(Constructor.java:)
     at org.apache.hadoop.net.NetUtils.wrapWithMessage(NetUtils.java:)
     at org.apache.hadoop.net.NetUtils.wrapException(NetUtils.java:)
     at org.apache.hadoop.ipc.Client.call(Client.java:)
     at org.apache.hadoop.ipc.Client.call(Client.java:)
     at org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:)
     at com.sun.proxy.$Proxy14.getFileInfo(Unknown Source)
     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
     at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:)
     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:)
     at java.lang.reflect.Method.invoke(Method.java:)
     at org.apache.hadoop.io.retry.RetryInvocationHandler.invokeMethod(RetryInvocationHandler.java:)
     at org.apache.hadoop.io.retry.RetryInvocationHandler.invoke(RetryInvocationHandler.java:)
     at com.sun.proxy.$Proxy14.getFileInfo(Unknown Source)
     at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolTranslatorPB.getFileInfo(ClientNamenodeProtocolTranslatorPB.java:)
     at org.apache.hadoop.hdfs.DFSClient.getFileInfo(DFSClient.java:)
     at org.apache.hadoop.hdfs.DistributedFileSystem$.doCall(DistributedFileSystem.java:)
     at org.apache.hadoop.hdfs.DistributedFileSystem$.doCall(DistributedFileSystem.java:)
     at org.apache.hadoop.fs.FileSystemLinkResolver.resolve(FileSystemLinkResolver.java:)
     at org.apache.hadoop.hdfs.DistributedFileSystem.getFileStatus(DistributedFileSystem.java:)
     at org.apache.hadoop.fs.FileSystem.exists(FileSystem.java:)
     at org.apache.hadoop.mapreduce.lib.output.FileOutputFormat.checkOutputSpecs(FileOutputFormat.java:)
     at org.apache.hadoop.mapreduce.JobSubmitter.checkSpecs(JobSubmitter.java:)
     at org.apache.hadoop.mapreduce.JobSubmitter.submitJobInternal(JobSubmitter.java:)
     at org.apache.hadoop.mapreduce.Job$.run(Job.java:)
     at org.apache.hadoop.mapreduce.Job$.run(Job.java:)
     at java.security.AccessController.doPrivileged(Native Method)
     at javax.security.auth.Subject.doAs(Subject.java:)
     at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:)
     at org.apache.hadoop.mapreduce.Job.submit(Job.java:)
     at org.apache.hadoop.mapreduce.Job.waitForCompletion(Job.java:)
     at org.apache.sqoop.mapreduce.ImportJobBase.doSubmitJob(ImportJobBase.java:)
     at org.apache.sqoop.mapreduce.ImportJobBase.runJob(ImportJobBase.java:)
     at org.apache.sqoop.mapreduce.ImportJobBase.runImport(ImportJobBase.java:)
     at org.apache.sqoop.manager.SqlManager.importTable(SqlManager.java:)
     at org.apache.sqoop.manager.MySQLManager.importTable(MySQLManager.java:)
     at org.apache.sqoop.tool.ImportTool.importTable(ImportTool.java:)
     at org.apache.sqoop.tool.ImportTool.run(ImportTool.java:)
     at org.apache.sqoop.Sqoop.run(Sqoop.java:)
     at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:)
     at org.apache.sqoop.Sqoop.runSqoop(Sqoop.java:)
     at org.apache.sqoop.Sqoop.runTool(Sqoop.java:)
     at org.apache.sqoop.Sqoop.runTool(Sqoop.java:)
     at org.apache.sqoop.Sqoop.main(Sqoop.java:)
 Caused by: java.net.ConnectException: Connection refused
     at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
     at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:)
     at org.apache.hadoop.net.SocketIOWithTimeout.connect(SocketIOWithTimeout.java:)
     at org.apache.hadoop.net.NetUtils.connect(NetUtils.java:)
     at org.apache.hadoop.net.NetUtils.connect(NetUtils.java:)
     at org.apache.hadoop.ipc.Client$Connection.setupConnection(Client.java:)
     at org.apache.hadoop.ipc.Client$Connection.setupIOstreams(Client.java:)
     at org.apache.hadoop.ipc.Client$Connection.access$(Client.java:)
     at org.apache.hadoop.ipc.Client.getConnection(Client.java:)
     at org.apache.hadoop.ipc.Client.call(Client.java:)
     ...  more

 [root@master sqoop]#  service iptables status
 iptables: Firewall is not running.
 [root@master sqoop]# cat /etc/hosts
 127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4
 ::         localhost localhost.localdomain localhost6 localhost6.localdomain6

 192.168.3.129 master
 192.168.3.130 slaver1
 192.168.3.131 slaver2
 192.168.3.132 slaver3
 192.168.3.133 slaver4
 192.168.3.134 slaver5
 192.168.3.135 slaver6
 192.168.3.136 slaver7

 [root@master sqoop]# jps
  Jps
 [root@master sqoop]# sqoop import --connect jdbc:mysql://localhost:3306/test --username root --password 123456 --table emp --m 1
 Warning: /home/hadoop/sqoop/../hbase does not exist! HBase imports will fail.
 Please set $HBASE_HOME to the root of your HBase installation.
 Warning: /home/hadoop/sqoop/../hcatalog does not exist! HCatalog jobs will fail.
 Please set $HCAT_HOME to the root of your HCatalog installation.
 Warning: /home/hadoop/sqoop/../accumulo does not exist! Accumulo imports will fail.
 Please set $ACCUMULO_HOME to the root of your Accumulo installation.
 Warning: /home/hadoop/sqoop/../zookeeper does not exist! Accumulo imports will fail.
 Please set $ZOOKEEPER_HOME to the root of your Zookeeper installation.
 // :: INFO sqoop.Sqoop: Running Sqoop version: 1.4.
 // :: WARN tool.BaseSqoopTool: Setting your password on the command-line is insecure. Consider using -P instead.
 // :: INFO manager.MySQLManager: Preparing to use a MySQL streaming resultset.
 // :: INFO tool.CodeGenTool: Beginning code generation
 // :: INFO manager.SqlManager: Executing SQL statement: SELECT t.* FROM `emp` AS t LIMIT
 // :: INFO manager.SqlManager: Executing SQL statement: SELECT t.* FROM `emp` AS t LIMIT
 // :: INFO orm.CompilationManager: HADOOP_MAPRED_HOME is /home/hadoop/hadoop-2.4.
 Note: /tmp/sqoop-root/compile/3748127f0b101bfa0fd892963bea25dd/emp.java uses or overrides a deprecated API.
 Note: Recompile with -Xlint:deprecation for details.
 // :: INFO orm.CompilationManager: Writing jar file: /tmp/sqoop-root/compile/3748127f0b101bfa0fd892963bea25dd/emp.jar
 // :: WARN manager.MySQLManager: It looks like you are importing from mysql.
 // :: WARN manager.MySQLManager: This transfer can be faster! Use the --direct
 // :: WARN manager.MySQLManager: option to exercise a MySQL-specific fast path.
 // :: INFO manager.MySQLManager: Setting zero DATETIME behavior to convertToNull (mysql)
 // :: INFO mapreduce.ImportJobBase: Beginning import of emp
 // :: INFO Configuration.deprecation: mapred.jar is deprecated. Instead, use mapreduce.job.jar
 // :: INFO Configuration.deprecation: mapred.map.tasks is deprecated. Instead, use mapreduce.job.maps
 // :: INFO client.RMProxy: Connecting to ResourceManager at master/192.168.3.129:
 // :: ERROR tool.ImportTool: Encountered IOException running import job: java.net.ConnectException: Call From master/192.168.3.129 to master: failed on connection exception: java.net.ConnectException: Connection refused; For more details see:  http://wiki.apache.org/hadoop/ConnectionRefused
     at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
     at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:)
     at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:)
     at java.lang.reflect.Constructor.newInstance(Constructor.java:)
     at org.apache.hadoop.net.NetUtils.wrapWithMessage(NetUtils.java:)
     at org.apache.hadoop.net.NetUtils.wrapException(NetUtils.java:)
     at org.apache.hadoop.ipc.Client.call(Client.java:)
     at org.apache.hadoop.ipc.Client.call(Client.java:)
     at org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:)
     at com.sun.proxy.$Proxy14.getFileInfo(Unknown Source)
     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
     at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:)
     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:)
     at java.lang.reflect.Method.invoke(Method.java:)
     at org.apache.hadoop.io.retry.RetryInvocationHandler.invokeMethod(RetryInvocationHandler.java:)
     at org.apache.hadoop.io.retry.RetryInvocationHandler.invoke(RetryInvocationHandler.java:)
     at com.sun.proxy.$Proxy14.getFileInfo(Unknown Source)
     at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolTranslatorPB.getFileInfo(ClientNamenodeProtocolTranslatorPB.java:)
     at org.apache.hadoop.hdfs.DFSClient.getFileInfo(DFSClient.java:)
     at org.apache.hadoop.hdfs.DistributedFileSystem$.doCall(DistributedFileSystem.java:)
     at org.apache.hadoop.hdfs.DistributedFileSystem$.doCall(DistributedFileSystem.java:)
     at org.apache.hadoop.fs.FileSystemLinkResolver.resolve(FileSystemLinkResolver.java:)
     at org.apache.hadoop.hdfs.DistributedFileSystem.getFileStatus(DistributedFileSystem.java:)
     at org.apache.hadoop.fs.FileSystem.exists(FileSystem.java:)
     at org.apache.hadoop.mapreduce.lib.output.FileOutputFormat.checkOutputSpecs(FileOutputFormat.java:)
     at org.apache.hadoop.mapreduce.JobSubmitter.checkSpecs(JobSubmitter.java:)
     at org.apache.hadoop.mapreduce.JobSubmitter.submitJobInternal(JobSubmitter.java:)
     at org.apache.hadoop.mapreduce.Job$.run(Job.java:)
     at org.apache.hadoop.mapreduce.Job$.run(Job.java:)
     at java.security.AccessController.doPrivileged(Native Method)
     at javax.security.auth.Subject.doAs(Subject.java:)
     at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:)
     at org.apache.hadoop.mapreduce.Job.submit(Job.java:)
     at org.apache.hadoop.mapreduce.Job.waitForCompletion(Job.java:)
     at org.apache.sqoop.mapreduce.ImportJobBase.doSubmitJob(ImportJobBase.java:)
     at org.apache.sqoop.mapreduce.ImportJobBase.runJob(ImportJobBase.java:)
     at org.apache.sqoop.mapreduce.ImportJobBase.runImport(ImportJobBase.java:)
     at org.apache.sqoop.manager.SqlManager.importTable(SqlManager.java:)
     at org.apache.sqoop.manager.MySQLManager.importTable(MySQLManager.java:)
     at org.apache.sqoop.tool.ImportTool.importTable(ImportTool.java:)
     at org.apache.sqoop.tool.ImportTool.run(ImportTool.java:)
     at org.apache.sqoop.Sqoop.run(Sqoop.java:)
     at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:)
     at org.apache.sqoop.Sqoop.runSqoop(Sqoop.java:)
     at org.apache.sqoop.Sqoop.runTool(Sqoop.java:)
     at org.apache.sqoop.Sqoop.runTool(Sqoop.java:)
     at org.apache.sqoop.Sqoop.main(Sqoop.java:)
 Caused by: java.net.ConnectException: Connection refused
     at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
     at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:)
     at org.apache.hadoop.net.SocketIOWithTimeout.connect(SocketIOWithTimeout.java:)
     at org.apache.hadoop.net.NetUtils.connect(NetUtils.java:)
     at org.apache.hadoop.net.NetUtils.connect(NetUtils.java:)
     at org.apache.hadoop.ipc.Client$Connection.setupConnection(Client.java:)
     at org.apache.hadoop.ipc.Client$Connection.setupIOstreams(Client.java:)
     at org.apache.hadoop.ipc.Client$Connection.access$(Client.java:)
     at org.apache.hadoop.ipc.Client.getConnection(Client.java:)
     at org.apache.hadoop.ipc.Client.call(Client.java:)
     ...  more

 [root@master sqoop]# 

出现上面错误的原因是因为你的集群没有开，start-dfs.sh和start-yarn.sh开启你的集群即可：

正常运行如下所示：

 [root@master sqoop]# bin/sqoop import --connect jdbc:mysql://localhost:3306/test --username root --password 123456 --table emp --m 1
 Warning: /home/hadoop/sqoop/../hbase does not exist! HBase imports will fail.
 Please set $HBASE_HOME to the root of your HBase installation.
 Warning: /home/hadoop/sqoop/../hcatalog does not exist! HCatalog jobs will fail.
 Please set $HCAT_HOME to the root of your HCatalog installation.
 Warning: /home/hadoop/sqoop/../accumulo does not exist! Accumulo imports will fail.
 Please set $ACCUMULO_HOME to the root of your Accumulo installation.
 Warning: /home/hadoop/sqoop/../zookeeper does not exist! Accumulo imports will fail.
 Please set $ZOOKEEPER_HOME to the root of your Zookeeper installation.
 // :: INFO sqoop.Sqoop: Running Sqoop version: 1.4.
 // :: WARN tool.BaseSqoopTool: Setting your password on the command-line is insecure. Consider using -P instead.
 // :: INFO manager.MySQLManager: Preparing to use a MySQL streaming resultset.
 // :: INFO tool.CodeGenTool: Beginning code generation
 // :: INFO manager.SqlManager: Executing SQL statement: SELECT t.* FROM `emp` AS t LIMIT
 // :: INFO manager.SqlManager: Executing SQL statement: SELECT t.* FROM `emp` AS t LIMIT
 // :: INFO orm.CompilationManager: HADOOP_MAPRED_HOME is /home/hadoop/hadoop-2.4.
 Note: /tmp/sqoop-root/compile/60ee51250c5c6b5f5598392e068ce2d0/emp.java uses or overrides a deprecated API.
 Note: Recompile with -Xlint:deprecation for details.
 // :: INFO orm.CompilationManager: Writing jar file: /tmp/sqoop-root/compile/60ee51250c5c6b5f5598392e068ce2d0/emp.jar
 // :: WARN manager.MySQLManager: It looks like you are importing from mysql.
 // :: WARN manager.MySQLManager: This transfer can be faster! Use the --direct
 // :: WARN manager.MySQLManager: option to exercise a MySQL-specific fast path.
 // :: INFO manager.MySQLManager: Setting zero DATETIME behavior to convertToNull (mysql)
 // :: INFO mapreduce.ImportJobBase: Beginning import of emp
 // :: INFO Configuration.deprecation: mapred.jar is deprecated. Instead, use mapreduce.job.jar
 // :: INFO Configuration.deprecation: mapred.map.tasks is deprecated. Instead, use mapreduce.job.maps
 // :: INFO client.RMProxy: Connecting to ResourceManager at master/192.168.3.129:
 // :: INFO db.DBInputFormat: Using read commited transaction isolation
 // :: INFO mapreduce.JobSubmitter: number of splits:
 // :: INFO mapreduce.JobSubmitter: Submitting tokens for job: job_1513306156301_0001
 // :: INFO impl.YarnClientImpl: Submitted application application_1513306156301_0001
 // :: INFO mapreduce.Job: The url to track the job: http://master:8088/proxy/application_1513306156301_0001/
 // :: INFO mapreduce.Job: Running job: job_1513306156301_0001
 // :: INFO mapreduce.Job: Job job_1513306156301_0001 running in uber mode : false
 // :: INFO mapreduce.Job:  map % reduce %
 // :: INFO mapreduce.Job:  map % reduce %
 // :: INFO mapreduce.Job: Job job_1513306156301_0001 completed successfully
 // :: INFO mapreduce.Job: Counters:
     File System Counters
         FILE: Number of bytes read=
         FILE: Number of bytes written=
         FILE: Number of read operations=
         FILE: Number of large read operations=
         FILE: Number of write operations=
         HDFS: Number of bytes read=
         HDFS: Number of bytes written=
         HDFS: Number of read operations=
         HDFS: Number of large read operations=
         HDFS: Number of write operations=
     Job Counters
         Launched map tasks=
         Other local map tasks=
         Total time spent by all maps in occupied slots (ms)=
         Total time spent by all reduces in occupied slots (ms)=
         Total time spent by all map tasks (ms)=
         Total vcore-seconds taken by all map tasks=
         Total megabyte-seconds taken by all map tasks=
     Map-Reduce Framework
         Map input records=
         Map output records=
         Input split bytes=
         Spilled Records=
         Failed Shuffles=
         Merged Map outputs=
         GC time elapsed (ms)=
         CPU time spent (ms)=
         Physical memory (bytes) snapshot=
         Virtual memory (bytes) snapshot=
         Total committed heap usage (bytes)=
     File Input Format Counters
         Bytes Read=
     File Output Format Counters
         Bytes Written=
 // :: INFO mapreduce.ImportJobBase: Transferred  bytes in 90.4093 seconds (0.5088 bytes/sec)
 // :: INFO mapreduce.ImportJobBase: Retrieved  records.
 [root@master sqoop]# 

为了验证在HDFS导入的数据，请使用以下命令查看导入的数据，如下所示：

总之，遇到很多问题，当我我没有指定导入到的目录的时候，我去hdfs查看的时候竟然没有我导入的mysql数据表。郁闷。先记录一下。如果查看成功的话，数据表的数据和字段之间用逗号(,)表示。

4：导入关系表到HIVE：

 bin/sqoop import --connect jdbc:mysql://localhost:3306/test --username root --password 123456 --table emp --hive-import --m 1

5：导入到HDFS指定目录：
在导入表数据到HDFS使用Sqoop导入工具，我们可以指定目标目录。
以下是指定目标目录选项的Sqoop导入命令的语法。

 --target-dir <new or exist directory in HDFS>

 下面的命令是用来导入emp表数据到'/sqoop'目录。
 bin/sqoop import \
 --connect jdbc:mysql://localhost:3306/test \
 --username root \
 --password  \
 --target-dir /sqoop \
 --table emp \
 --m 

 [root@master sqoop]# bin/sqoop import --connect jdbc:mysql://localhost:3306/test --username root --password 123456 --target-dir /sqoop --table emp --m 1

如果你指定的目录存在的话，将会报如下的错误：

 // :: ERROR tool.ImportTool: Encountered IOException running import job: org.apache.hadoop.mapred.FileAlreadyExistsException: Output directory hdfs://master:9000/wordcount already exists
     at org.apache.hadoop.mapreduce.lib.output.FileOutputFormat.checkOutputSpecs(FileOutputFormat.java:)
     at org.apache.hadoop.mapreduce.JobSubmitter.checkSpecs(JobSubmitter.java:)
     at org.apache.hadoop.mapreduce.JobSubmitter.submitJobInternal(JobSubmitter.java:)
     at org.apache.hadoop.mapreduce.Job$.run(Job.java:)
     at org.apache.hadoop.mapreduce.Job$.run(Job.java:)
     at java.security.AccessController.doPrivileged(Native Method)
     at javax.security.auth.Subject.doAs(Subject.java:)
     at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:)
     at org.apache.hadoop.mapreduce.Job.submit(Job.java:)
     at org.apache.hadoop.mapreduce.Job.waitForCompletion(Job.java:)
     at org.apache.sqoop.mapreduce.ImportJobBase.doSubmitJob(ImportJobBase.java:)
     at org.apache.sqoop.mapreduce.ImportJobBase.runJob(ImportJobBase.java:)
     at org.apache.sqoop.mapreduce.ImportJobBase.runImport(ImportJobBase.java:)
     at org.apache.sqoop.manager.SqlManager.importTable(SqlManager.java:)
     at org.apache.sqoop.manager.MySQLManager.importTable(MySQLManager.java:)
     at org.apache.sqoop.tool.ImportTool.importTable(ImportTool.java:)
     at org.apache.sqoop.tool.ImportTool.run(ImportTool.java:)
     at org.apache.sqoop.Sqoop.run(Sqoop.java:)
     at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:)
     at org.apache.sqoop.Sqoop.runSqoop(Sqoop.java:)
     at org.apache.sqoop.Sqoop.runTool(Sqoop.java:)
     at org.apache.sqoop.Sqoop.runTool(Sqoop.java:)
     at org.apache.sqoop.Sqoop.main(Sqoop.java:)

导入到指定的目录，如果成功的话，会显示出你的mysql数据表的数据，字段之间以逗号分隔。

使用如下的命令是用来验证 /sqoop 目录中 emp数据表导入的数据形式。它会用逗号,分隔emp数据表的数据和字段。

 [root@master sqoop]# hadoop fs -cat /sqoop/part-m-
 ,zhangsan,,yi
 ,lisi,,er
 ,wangwu,,san
 [root@master sqoop]#

6：导入表数据子集：

我们可以导入表的使用Sqoop导入工具，"where"子句的一个子集。它执行在各自的数据库服务器相应的SQL查询，并将结果存储在HDFS的目标目录。
where子句的语法如下。

 --where <condition>

 #下面的命令用来导入emp表数据的子集。子集查询检索员工ID和地址，居住城市为：city；
 #方式一
 bin/sqoop import \
 --connect jdbc:mysql://localhost:3306/test \
 --username root \
 --password  \
 --where "city ='zhengzhou'" \
 --target-dir /sqoop02 \
 --table emp \
 --m 

 #方式二
 [root@master sqoop]# bin/sqoop import --connect jdbc:mysql://localhost:3306/test --username root --password 123456 --where "city ='zhengzhou'" --target-dir /sqoop02 --table emp --m 1

7：sqoop的按需导入：

可以如上面演示使用命令用来验证数据从emp数据表导入/sqoop03 目录
它用逗号'\t'分隔 emp数据表数据和字段。

 #sqoop按需导入
 #方式一
 bin/sqoop import \
 --connect jdbc:mysql://localhost:3306/test \
 --username root \        #mysql的账号
 --password  \        #mysql的密码
 --target-dir /sqoop03 \ #指定存放的目录
 --query 'select id,name,age,dept from emp WHERE  id>0 and $CONDITIONS' \  #灵活的mysql语句,且必须加and $CONDITIONS'
 --split-by id \    #按照那个字段做切片,id做切片
 --fields-terminated-by '\t' \ #导入到我的文件系统中为'\t',默认为逗号。
 --m 

 #方式二
 [root@master sqoop]# bin/sqoop import --connect jdbc:mysql://localhost:3306/test --username root --password 123456 --target-dir /sqoop03 --query 'select id,name,age,dept from emp WHERE  id>0 and $CONDITIONS' --split-by id --fields-terminated-by '\t' --m 1

7：sqoop的增量导入，增量导入是仅导入新添加的表中的行的技术：

它需要添加‘incremental’, ‘check-column’, 和 ‘last-value’选项来执行增量导入。
下面的语法用于Sqoop导入命令增量选项。

 --incremental <mode>
 --check-column <column name>
 --last value <last check column value>

 下面的命令用于在EMP表执行增量导入。

 #方式一
 bin/sqoop import \
 --connect jdbc:mysql://localhost:3306/test \
 --username root \
 --password  \
 --table emp \
 --m  \
 --incremental append \ #追加导入
 --check-column id \    #根据id字段来判断从哪里开始导入
 --last-value 6　　　　　#根据id字段，从7开始导入　　　　　　　

 #方式二
 [root@master sqoop]# bin/sqoop import --connect jdbc:mysql://localhost:3306/test --username root --password 123456 --m 1 --incremental append --check-column id --last-value 6

8：Sqoop的数据导出：

将数据从HDFS导出到RDBMS数据库，导出前，目标表必须存在于目标数据库中。默认操作是从将文件中的数据使用INSERT语句插入到表中，更新模式下，是生成UPDATE语句更新表数据；

 以下是export命令语法。
 $ sqoop export (generic-args) (export-args) 

具体操作如下所示：

首先，数据是在HDFS 中"/sqoop"目录的part-m-00000文件中。

第一步：首先需要手动创建mysql中的目标表：

  [root@master hadoop]# mysql -uroot -p123456

  mysql> show databases;

  mysql> use test;

  mysql> CREATE TABLE `emp` (
     ->   `id` int() NOT NULL AUTO_INCREMENT,
     ->   `name` varchar() DEFAULT NULL,
     ->   `age` int() DEFAULT NULL,
     ->   `dept` varchar() DEFAULT NULL,
     ->   PRIMARY KEY (`id`)
     -> ) ENGINE=MyISAM AUTO_INCREMENT= DEFAULT CHARSET=latin1;

如果不事先创建好数据表会报如下错误：

 // :: ERROR manager.SqlManager: Error executing statement: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Table 'test.emp' doesn't exist
 com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Table 'test.emp' doesn't exist
     at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
     at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:)
     at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:)
     at java.lang.reflect.Constructor.newInstance(Constructor.java:)
     at com.mysql.jdbc.Util.handleNewInstance(Util.java:)
     at com.mysql.jdbc.Util.getInstance(Util.java:)
     at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:)
     at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:)
     at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:)
     at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:)
     at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:)
     at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:)
     at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:)
     at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:)
     at org.apache.sqoop.manager.SqlManager.execute(SqlManager.java:)
     at org.apache.sqoop.manager.SqlManager.execute(SqlManager.java:)
     at org.apache.sqoop.manager.SqlManager.getColumnInfoForRawQuery(SqlManager.java:)
     at org.apache.sqoop.manager.SqlManager.getColumnTypesForRawQuery(SqlManager.java:)
     at org.apache.sqoop.manager.SqlManager.getColumnTypes(SqlManager.java:)
     at org.apache.sqoop.manager.ConnManager.getColumnTypes(ConnManager.java:)
     at org.apache.sqoop.orm.ClassWriter.getColumnTypes(ClassWriter.java:)
     at org.apache.sqoop.orm.ClassWriter.generate(ClassWriter.java:)
     at org.apache.sqoop.tool.CodeGenTool.generateORM(CodeGenTool.java:)
     at org.apache.sqoop.tool.ExportTool.exportTable(ExportTool.java:)
     at org.apache.sqoop.tool.ExportTool.run(ExportTool.java:)
     at org.apache.sqoop.Sqoop.run(Sqoop.java:)
     at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:)
     at org.apache.sqoop.Sqoop.runSqoop(Sqoop.java:)
     at org.apache.sqoop.Sqoop.runTool(Sqoop.java:)
     at org.apache.sqoop.Sqoop.runTool(Sqoop.java:)
     at org.apache.sqoop.Sqoop.main(Sqoop.java:)

第二步：然后执行导出命令（如果localhost不好使，可以换成ip试一下）：

 #方式一
 bin/sqoop export \
 --connect jdbc:mysql://192.168.3.129:3306/test \
 --username root \
 --password  \
 --table emp \ #导入的数据表
 --export-dir /sqoop/ #导出的目录

 #方式二
 bin/sqoop export --connect jdbc:mysql://localhost:3306/test --username root --password 123456 --table emp --export-dir /sqoop

第三步：验证表mysql命令行（或者使用图形化工具查看是否有数据导入）：

mysql>select * from emp;
如果给定的数据存储成功，那么可以找到符合的数据。

待续......