上一篇已经完成了sqoop2的安装，本篇文章介绍sqoop2将数据从Oracle导入hdfs已经从hdfs导入Oracle
sqoop的使用，主要分为以下几个部分
- 连接服务器
- 搜索connectors
- 创建Link
- 创建Job
- 执行Job
- 查看Job运行信息
在使用sqoop2之前，还需要对hadoop的配置文件做以下修改并启动jobhistory服务，否则，job只能运行一次，第二次运行就会报错
1）配置mapred-site.xml：（namenode节点即可）
<property>
<name>mapreduce.jobhistory.address</name>
<value>192.168.101.11:10020</value>
</property>
2）启动jobhistory服务
sbin/mr-jobhistory-daemon.sh start historyserver
1、连接sqoop2服务器
sqoop2是c/s模式，之前安装并启动的是sqoop的服务端，如果想要使用和操作sqoop2，需要通过客户端连接到服务端，然后使用。只要保证服务端正常处于运行状态，客户端可以从任意终端发起。也就是说，客户端可以是一台只解压了sqoop2安装包的机器中启动，无需hadoop和sqoopserver。
启动客户端bin/sqoop2-shell
[hadoop@hadoop01 sqoop-1.99.7-bin-hadoop200]$ bin/sqoop2-shell
Setting conf dir: /home/hadoop/sqoop-1.99.7-bin-hadoop200/bin/../conf
Sqoop home directory: /home/hadoop/sqoop-1.99.7-bin-hadoop200
Sqoop Shell: Type 'help' or '\h' for help.
sqoop:000> \h
For information about Sqoop, visit: http://sqoop.apache.org/
Available commands:
:exit (:x ) Exit the shell
:history (:H ) Display, manage and recall edit-line history
help (\h ) Display this help message
set (\st ) Configure various client options and settings
show (\sh ) Display various objects and configuration options
create (\cr ) Create new object in Sqoop repository
delete (\d ) Delete existing object in Sqoop repository
update (\up ) Update objects in Sqoop repository
clone (\cl ) Create new object based on existing one
start (\sta) Start job
stop (\stp) Stop job
status (\stu) Display status of a job
enable (\en ) Enable object in Sqoop repository
disable (\di ) Disable object in Sqoop repository
grant (\g ) Grant access to roles and assign privileges
revoke (\r ) Revoke access from roles and remove privileges
For help on a specific command type: help command
sqoop:000>
此时只是启动了客户端，还没有连接服务端，如果测试创建link或者job，那么默认会连接localhost。所以，要先设置连接服务器：
sqoop:000> set server --host 192.168.101.12 --port 12000 --webapp sqoop
Server is set successfully
sqoop:000>
2、搜索connector
connector是用于创建link的模板，例如要创建hdfs的link，则使用hdfs-connector，要创建Oracle的link，则使用oracle-jdbc-connector或者generic-jdbc-connector
如果所设置的服务端连接是正常可用的，那么执行show connector 命令后，会显示如下：
sqoop:000> show connector
+------------------------+---------+------------------------------------------------------------+----------------------+
| Name | Version | Class | Supported Directions |
+------------------------+---------+------------------------------------------------------------+----------------------+
| generic-jdbc-connector | 1.99.7 | org.apache.sqoop.connector.jdbc.GenericJdbcConnector | FROM/TO |
| kite-connector | 1.99.7 | org.apache.sqoop.connector.kite.KiteConnector | FROM/TO |
| oracle-jdbc-connector | 1.99.7 | org.apache.sqoop.connector.jdbc.oracle.OracleJdbcConnector | FROM/TO |
| ftp-connector | 1.99.7 | org.apache.sqoop.connector.ftp.FtpConnector | TO |
| hdfs-connector | 1.99.7 | org.apache.sqoop.connector.hdfs.HdfsConnector | FROM/TO |
| kafka-connector | 1.99.7 | org.apache.sqoop.connector.kafka.KafkaConnector | TO |
| sftp-connector | 1.99.7 | org.apache.sqoop.connector.sftp.SftpConnector | TO |
+------------------------+---------+------------------------------------------------------------+----------------------+
否则，会提示拒绝连接
sqoop:000> show connector
Exception has occurred during processing command
Exception: java.net.ConnectException Message: 拒绝连接 (Connection refused)
3、创建link
顾名思义，就是创建到各个源或目标存储的连接。可创建的link类型，在上一个步骤show connector中已经列出
1）创建hdfs link
sqoop:000> create link --connector hdfs-connector
Creating link for connector with name hdfs-connector
Please fill following values to create new link object
Name: hdfs-link ##link的名称，可以随意起
HDFS cluster
URI: hdfs://192.168.101.11:9000 ##hdfs地址，在hadoop配置文件core-site.xml中查看
Conf directory: /home/hadoop/hadoop-2.6.5/etc/hadoop ##hadoop配置文件目录
Additional configs::
There are currently 0 values in the map:
entry# ##直接回车即可
New link was successfully created with validation status OK and name hdfs-link
sqoop:000> show link
+-----------+----------------+---------+
| Name | Connector Name | Enabled |
+-----------+----------------+---------+
| hdfs-link | hdfs-connector | true |
+-----------+----------------+---------+
2）创建Oracle link
sqoop:000> create link --connector generic-jdbc-connector
Creating link for connector with name generic-jdbc-connector
Please fill following values to create new link object
Name: oracle-link ##link的名称，可以随意起
Database connection
Driver class: oracle.jdbc.driver.OracleDriver ##Oracle jdbc驱动
Connection String: jdbc:oracle:thin:@192.168.101.9:1521:orcl ##Oracle连接字符串
Username: scott ##Oracle用户名
Password: ***** #密码
Fetch Size: #以下直接回车，默认即可
Connection Properties:
There are currently 0 values in the map:
entry#
SQL Dialect
Identifier enclose: ##sql定界符，为避免错误，需要打一个空格
New link was successfully created with validation status OK and name oracle-link
sqoop:000> show link
+-------------+------------------------+---------+
| Name | Connector Name | Enabled |
+-------------+------------------------+---------+
| oracle-link | generic-jdbc-connector | true |
| hdfs-link | hdfs-connector | true |
+-------------+------------------------+---------+
3、创建从oracle向hdfs导入数据的job
sqoop:000> create job -f oracle-link -t hdfs-link
Creating job for links with from name oracle-link and to name hdfs-link
Please fill following values to create new job object
Name: oracle2hdfs #job名称
Database source
Schema name: scott #oracle的schema，即用户名
Table name: emp #需要导入的表名
SQL statement: ##SQL，默认导入整张表
Column names:
There are currently 0 values in the list:
element#
Partition column: empno ##指定一个列名即可，一般可以用主键，或者时间列，以便mapper任务的切分
Partition column nullable:
Boundary query:
Incremental read
Check column:
Last value:
Target configuration
Override null value:
Null value:
File format:
0 : TEXT_FILE
1 : SEQUENCE_FILE
2 : PARQUET_FILE
Choose: 0 #选择导入hdfs的一种格式，选择txt即可
Compression codec:
0 : NONE
1 : DEFAULT
2 : DEFLATE
3 : GZIP
4 : BZIP2
5 : LZO
6 : LZ4
7 : SNAPPY
8 : CUSTOM
Choose: 0 #默认无压缩
Custom codec:
Output directory: /data ##导入到hdfs的目录，注意，全量导入时，该目录需要为空
Append mode: ##追加模式，默认为全量
Throttling resources
Extractors:
Loaders:
Classpath configuration
Extra mapper jars:
There are currently 0 values in the list:
element#
New job was successfully created with validation status OK and name oracle2hdfs
sqoop:000>
4、创建从hdfs向oracle导入的job
sqoop:000> create job -f hdfs-link -t oracle-link
Creating job for links with from name hdfs-link and to name oracle-link
Please fill following values to create new job object
Name: hdfs2oracle
Input configuration
Input directory: /data ##hdfs 的导入目录
Override null value:
Null value:
Incremental import
Incremental type:
0 : NONE
1 : NEW_FILES
Choose: 0 #默认选0即可，应该是配合上一个参数，Incremental import，设置增量导入模式
Last imported date:
Database target
Schema name: scott #oracle用户
Table name: emp2 #oracle表名，需要提前创建好表结构
Column names:
There are currently 0 values in the list:
element#
Staging table:
Clear stage table:
Throttling resources
Extractors:
Loaders:
Classpath configuration
Extra mapper jars:
There are currently 0 values in the list:
element#
New job was successfully created with validation status OK and name hdfs2oracle
sqoop:000>
sqoop:000> show job
+----+-------------+--------------------------------------+--------------------------------------+---------+
| Id | Name | From Connector | To Connector | Enabled |
+----+-------------+--------------------------------------+--------------------------------------+---------+
| 8 | oracle2hdfs | oracle-link (generic-jdbc-connector) | hdfs-link (hdfs-connector) | true |
| 9 | hdfs2oracle | hdfs-link (hdfs-connector) | oracle-link (generic-jdbc-connector) | true |
+----+-------------+--------------------------------------+--------------------------------------+---------+
sqoop:000>
5、运行作业
start job -name oracle2hdfs
sqoop:000> start job -name oracle2hdfs
Submission details
Job Name: oracle2hdfs
Server URL: http://192.168.101.12:12000/sqoop/
Created by: hadoop
Creation date: 2017-10-17 17:24:23 CST
Lastly updated by: hadoop
External ID: job_1508227894698_0001
http://hadoop01:8088/proxy/application_1508227894698_0001/
2017-10-17 17:24:23 CST: BOOTING - Progress is not available
sqoop:000>
sqoop:000> start job -name hdfs2oracle
Submission details
Job Name: hdfs2oracle
Server URL: http://192.168.101.12:12000/sqoop/
Created by: hadoop
Creation date: 2017-10-17 17:25:38 CST
Lastly updated by: hadoop
External ID: job_1508227894698_0002
http://hadoop01:8088/proxy/application_1508227894698_0002/
2017-10-17 17:25:38 CST: BOOTING - Progress is not available
由于sqoop2的job提交后，是运行在hadoop集群上的mapreduce任务，所以可以通过hadoop的web管理界面来查看，地址为：http://namenode:8088/cluster，对应的id就是External ID.
如下图所示：
7、验证结果
hdfs
[hadoop@hadoop02 bin]$ ./hadoop fs -ls /data/
Found 13 items
-rw-r--r-- 2 hadoop supergroup 172 2017-10-17 17:40 /data/129d2e07-1a0f-44ec-bbcd-299985b6972d.txt
-rw-r--r-- 2 hadoop supergroup 119 2017-10-17 17:40 /data/1fffd203-a20f-4925-a328-8fe05994b80a.txt
-rw-r--r-- 2 hadoop supergroup 119 2017-10-17 17:36 /data/2b8c5cd1-9ec2-4ae7-8683-a4587def6b74.txt
-rw-r--r-- 2 hadoop supergroup 0 2017-10-17 17:40 /data/31b026a3-697c-4b11-a49d-4c02adfaf847.txt
-rw-r--r-- 2 hadoop supergroup 0 2017-10-17 17:35 /data/3f6b78a3-a4ee-43ea-b4f3-fb46ae1a4ce0.txt
-rw-r--r-- 2 hadoop supergroup 0 2017-10-17 17:37 /data/7ed1cc68-a1c7-4c98-ac25-c2d9d2ce1a54.txt
-rw-r--r-- 2 hadoop supergroup 0 2017-10-17 17:33 /data/8ca051dd-6d80-4663-b062-931683d01026.txt
-rw-r--r-- 2 hadoop supergroup 0 2017-10-17 17:40 /data/95cedc62-7355-4408-8361-cbf875645e94.txt
-rw-r--r-- 2 hadoop supergroup 54 2017-10-17 17:37 /data/9e59a5b9-90d3-4b04-aa59-d20302e4ee2b.txt
-rw-r--r-- 2 hadoop supergroup 0 2017-10-17 17:34 /data/b3229660-0409-4d33-9b2f-df9cdb2549ec.txt
-rw-r--r-- 2 hadoop supergroup 166 2017-10-17 17:40 /data/b59fa170-7c5e-4b1e-8ca3-083bb09a9544.txt
-rw-r--r-- 2 hadoop supergroup 57 2017-10-17 17:40 /data/cf92a71a-8528-4842-8a88-c4b4ea4b96e2.txt
-rw-r--r-- 2 hadoop supergroup 114 2017-10-17 17:36 /data/dda07b7d-01a8-420d-964b-d2a5bee35168.txt
[hadoop@hadoop02 bin]$ ./hadoop fs -cat /data/dda07b7d-01a8-420d-964b-d2a5bee35168.txt
7782,'CLARK','MANAGER',7839,'1981-06-09',2450.00,NULL,10
7788,'SCOTT','ANALYST',7566,'1987-04-19',3000.00,NULL,20
[hadoop@hadoop02 bin]$
oracle
后记：
途中遇到不少报错，记录如下：
--报错1
[hadoop@hadoop01 sqoop-1.99.7-bin-hadoop200]$ ./bin/sqoop.sh server start
Setting conf dir: ./bin/../conf
Sqoop home directory: /home/hadoop/sqoop-1.99.7-bin-hadoop200
Starting the Sqoop2 server...
1 [main] INFO org.apache.sqoop.core.SqoopServer - Initializing Sqoop server.
20 [main] INFO org.apache.sqoop.core.PropertiesConfigurationProvider - Starting config file poller thread
Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/hadoop/conf/Configuration
at org.apache.sqoop.security.authentication.SimpleAuthenticationHandler.secureLogin(SimpleAuthenticationHandler.java:36)
at org.apache.sqoop.security.AuthenticationManager.initialize(AuthenticationManager.java:98)
at org.apache.sqoop.core.SqoopServer.initialize(SqoopServer.java:57)
at org.apache.sqoop.server.SqoopJettyServer.<init>(SqoopJettyServer.java:67)
at org.apache.sqoop.server.SqoopJettyServer.main(SqoopJettyServer.java:177)
Caused by: java.lang.ClassNotFoundException: org.apache.hadoop.conf.Configuration
at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:335)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
... 5 more
原因：sqoop没有正确的找的hadoop的jar包,因为在安装hadoop时，配置了HADOOP_COMMON_HOME、HADOOP_HDFS_HOME、HADOOP_MAPRED_HOME、HADOOP_YARN_HOME四个环境变量
解决方法：
修改bin/sqoop.sh
将以下四行注释
HADOOP_COMMON_HOME=${HADOOP_COMMON_HOME:-${HADOOP_HOME}/share/hadoop/common}
HADOOP_HDFS_HOME=${HADOOP_HDFS_HOME:-${HADOOP_HOME}/share/hadoop/hdfs}
HADOOP_MAPRED_HOME=${HADOOP_MAPRED_HOME:-${HADOOP_HOME}/share/hadoop/mapreduce}
HADOOP_YARN_HOME=${HADOOP_YARN_HOME:-${HADOOP_HOME}/share/hadoop/yarn}
新增以下四行，也可以把${HADOOP_HOME}换成绝对路径
HADOOP_COMMON_HOME=${HADOOP_HOME}/share/hadoop/common
HADOOP_HDFS_HOME=${HADOOP_HOME}/share/hadoop/hdfs
HADOOP_MAPRED_HOME=${HADOOP_HOME}/share/hadoop/mapreduce
HADOOP_YARN_HOME=${HADOOP_HOME}/share/hadoop/yarn
----报错2
GENERIC_JDBC_CONNECTOR_0025:No primary key - Please specify partition column.
原因：在创建关系型数据库到hdfs的job时Partition column: 参数没有指定
解决方法：指定一个列名即可，一般可以用主键，或者时间列，以便mapper任务的切分
PS：由于sqoop会以此列作为mapper的划分，如果此列数据分布存在倾斜，会导致某几个mapper负载过重，而其他mapper无数据可跑的问题，所以尽量选择数据均匀分布的类作为Partition column
--报错3
GENERIC_HDFS_CONNECTOR_0007:Invalid input/output directory - Unexpected exception
GENERIC_HDFS_CONNECTOR_0007:Invalid input/output directory - Output directory is not empty
原因：hdfs输出目录必须为空，从关系型数据库将数据到入到hdfs中时，所指定的hdfs目录必须为空
解决方法：新建一个hdfs目录，或者将旧目录清空即可
--报错4
Exception: org.apache.sqoop.common.SqoopException Message: DRIVER_0002:Given job is already running - Job with name hdfs2orcl_3
原因：
没有启动hadoop的jobhistory服务
解决方法：
配置mapred-site.xml：（namenode节点即可）
<property>
<name>mapreduce.jobhistory.address</name>
<value>192.168.101.11:10020</value>
</property>
启动jobhistory服务
sbin/mr-jobhistory-daemon.sh start historyserver
创建generic-jdbc-connector link 时：
--报错5
Exception: org.apache.sqoop.common.SqoopException Message: GENERIC_JDBC_CONNECTOR_0016:Can't fetch schema -
Identifier enclose：指定SQL中标识符的定界符，有的SQL标示符是一个引号，这个属性默认值就是双引号,例如oracle数据库，你在输入表名和schema的时候，用的是小写的emp和scoot，那么sql就会转化成 SELECT * FROM "scott"."emp" ，从而导致报错