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。

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

mapreduce.jobhistory.address

localhost:10020

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

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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

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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"

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2.6.查看job执行状态，成功。

sqoop:000> status job -name "hdfs2jdbc"

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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"

1

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

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

mapreduce.jobhistory.address

localhost:10020

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。