摘要:超详细讲解Sqoop2应用与实践，从hdfs上的数据导入到postgreSQL中，再从postgreSQL数据库导入到hdfs上。详细讲解创建link和创建job的操作，以及如何查看sqoop2的工作状态。

1.准备，上一篇超详细讲解Sqoop2部署过程，Sqoop2自动部署源码

1.1.为了能查看sqoop2 status,编辑 mapred-site.xml

<property> <name>mapreduce.jobhistory.address</name> <value>localhost:10020</value> </property> sbin/mr-jobhistory-daemon.sh start historyserver

1.2.创建postgreSQL上的准备数据。创建表并填充数据-postgresql

CREATE TABLE products ( product_no integer PRIMARY KEY, name text, price numeric ); INSERT INTO products (product_no, name, price) VALUES (1,'Cheese',9.99);

1.3.创建hdfs上的准备数据

xiaolei@wang:~$ vim product.csv 2,'laoganma',13.5 xiaolei@wang:~$ hadoop fs -mkdir /hdfs2jdbc xiaolei@wang:~$ hadoop fs -put product.csv /hdfs2jdbc

1.3.配置sqoop2的server

sqoop:000> set server --host localhost --port 12000 --webapp sqoop

1.4.启动hadoop，特别是启动historyserver，启动sqoop2

sbin/start-dfs.sh $HADOOP_HOME/sbin/start-yarn.sh $HADOOP_HOME/sbin/mr-jobhistory-daemon.sh start historyserver sqoop2-server start

1.5.如果未安装Sqoop2或者部署有问题，上一篇超详细讲解Sqoop2部署过程，Sqoop2自动部署源码

2.通过sqoop2，hdfs上的数据导入到postgreSQL

sqoop:000> show connector

2.1.创建hdfs-link，注明（必填）的要写正确，其他的可以回车跳过。

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名称（必填） HDFS cluster URI: hdfs://localhost:9000 #hdfs的地址（必填） Conf directory: /opt/hadoop-2.7.3/etc/hadoop #hadoop的配置地址（必填） Additional configs:: There are currently 0 values in the map: entry# New link was successfully created with validation status OK and name hdfs-link

2.2.创建jdbc-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: jdbc-link #link名称（必填） Database connection Driver class: org.postgresql.Driver #jdbc驱动类（必填） Connection String: jdbc:postgresql://localhost:5432/whaleaidb # jdbc链接url（必填） Username: whaleai #数据库的用户（必填） Password: ****** #数据库密码（必填） Fetch Size: Connection Properties: There are currently 0 values in the map: entry# SQL Dialect Identifier enclose: New link was successfully created with validation status OK and name jdbc-link

2.3.查看已经创建好的hdfs-link和jdbc-link

sqoop:000> show link +----------------+------------------------+---------+ | Name | Connector Name | Enabled | +----------------+------------------------+---------+ | jdbc-link | generic-jdbc-connector | true | | hdfs-link | hdfs-connector | true | +----------------+------------------------+---------+

2.4.创建从hdfs导入到postgreSQL的job

sqoop:000> create job -f hdfs-link -t jdbc-link Creating job for links with from name hdfs-link and to name jdbc-link Please fill following values to create new job object Name: hdfs2jdbc #job 名称（必填） Input configuration Input directory: /hdfs2jdbc #hdfs的输入路径 （必填） Override null value: Null value: Incremental import Incremental type: 0 : NONE 1 : NEW_FILES Choose: 0 （必填） Last imported date: Database target Schema name: public #postgreSQL默认的public（必填） Table name: products #要导入的数据库表（必填） Column names: There are currently 0 values in the list: element# Staging table: Clear stage table: Throttling resources Incremental type: 0 : NONE 1 : NEW_FILES Choose: 0 #（必填） Last imported date: 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 hdfs2jdbc

2.5.启动 hdfs2jdbc job

sqoop:000> start job -name "hdfs2jdbc"

2.6.查看job执行状态，成功。

sqoop:000> status job -name "hdfs2jdbc"

3.通过sqoop2，postgreSQL上的数据导入到hdfs上

3.1.因为所需的link在第2部分已经，这里只需创建从postgreSQL导入到hdfs上的job。

sqoop:000> create job -f jdbc-link -t hdfs-link Creating job for links with from name jdbc-link and to name hdfs-link Please fill following values to create new job object Name: jdbc2hdfs #job 名称（必填） Database source Schema name: public #postgreSQL默认的为public（必填） Table name: products #数据源 数据库的表（必填） SQL statement: Column names: There are currently 0 values in the list: element# Partition column: 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 #（必填） Compression codec: 0 : NONE 1 : DEFAULT 2 : DEFLATE 3 : GZIP 4 : BZIP2 5 : LZO 6 : LZ4 7 : SNAPPY 8 : CUSTOM Choose: 0 #（必填） Custom codec: Output directory: /jdbc2hdfs #hdfs上的输出路径（必填） Append mode: 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 jdbc2hdfs

3.2. 启动jdbc2hdfs job

sqoop:000> start job -name "jdbc2hdfs" Submission details Job Name: jdbc2hdfs Server URL: http://localhost:12000/sqoop/ Created by: xiaolei Creation date: 2017-07-10 09:26:42 CST Lastly updated by: xiaolei External ID: job_1499648118116_0002 http://wang:8088/proxy/application_1499648118116_0002/ 2017-07-10 09:26:42 CST: BOOTING - Progress is not available

3.3.查看job执行状态，成功。

sqoop:000> status job -name "jdbc2hdfs"

3.4.查看hdfs上的数据已经存在

xiaolei@wang:~$ hadoop fs -ls /jdbc2hdfs Found 1 items -rw-r--r-- 1 xiaolei supergroup 30 2017-07-10 09:26 /jdbc2hdfs/4d2e5754-c587-4fcd-b1db-ca64fa545515.txt

3.5.通过web UI，可见两次执行的job都已成功 http://localhost:8088/cluster

上一篇超详细讲解Sqoop2部署过程，Sqoop2自动部署源码

完结-彩蛋

1.踩坑

sqoop:000> stop job -name joba Exception has occurred during processing command Exception: org.apache.sqoop.common.SqoopException Message: MAPREDUCE_0003:Can’t get RunningJob instance -

解决: 编辑 mapred-site.xml

<property> <name>mapreduce.jobhistory.address</name> <value>localhost:10020</value> </property>

2.踩坑

sbin/mr-jobhistory-daemon.sh start historyserver### Exception: org.apache.sqoop.common.SqoopException Message: GENERIC_JDBC_CONNECTOR_0001:Unable to get a connection -

解决: jdbc url写错，重新配置

3.踩坑

java.lang.Integer cannot be cast to java.math.BigDecimal

解决：数据库中的数据与hdfs上的数据无法转换，增加数据或者替换数据。