我正在使用hadoop处理xml文件,所以我已经在python中编写了mapper文件,reducer文件.
假设需要处理的输入是test.xml
mapper.py文件
import sys
import cStringIO
import xml.etree.ElementTree as xml
if __name__ == ‘__main__’:
buff = None
intext = False
for line in sys.stdin:
line = line.strip()
if line.find("
…
…
…
print ‘%s%s’%(campaignID,adGroupID )
reducer.py文件
import sys
if __name__ == ‘__main__’:
for line in sys.stdin:
print line.strip()
我已经使用以下命令运行了hadoop
bin/hadoop jar contrib/streaming/hadoop-streaming-1.0.4.jar
- file /path/to/mapper.py file -mapper /path/to/mapper.py file
-file /path/to/reducer.py file -reducer /path/to/reducer.py file
-input /path/to/input_file/test.xml
-output /path/to/output_folder/to/store/file
当我运行以上命令时,hadoop正在以我们在reducer.py文件中正确提及的格式与所需数据在输出路径中创建输出文件
现在毕竟我想做的是,当我运行上述命令时,我不想将输出数据存储在haddop默认创建的文本文件中,而是想将数据保存到MYSQL数据库中
所以我在reducer.py文件中写了一些python代码,将数据直接写到MYSQL数据库,并尝试通过删除如下所示的输出路径来运行上述命令
bin/hadoop jar contrib/streaming/hadoop-streaming-1.0.4.jar
- file /path/to/mapper.py file -mapper /path/to/mapper.py file
-file /path/to/reducer.py file -reducer /path/to/reducer.py file
-input /path/to/input_file/test.xml
而且我收到以下类似的错误
12/11/08 15:20:49 ERROR streaming.StreamJob: Missing required option: output
Usage: $HADOOP_HOME/bin/hadoop jar $HADOOP_HOME/hadoop-streaming.jar [options]
Options:
-input DFS input file(s) for the Map step
-output DFS output directory for the Reduce step
-mapper The streaming command to run
-combiner The streaming command to run
-reducer The streaming command to run
-file File/dir to be shipped in the Job jar file
-inputformat TextInputFormat(default)|SequenceFileAsTextInputFormat|JavaClassName Optional.
-outputformat TextOutputFormat(default)|JavaClassName Optional.
…
…
>毕竟我怀疑在处理文件后如何将数据保存在数据库中？
>我们可以在哪个文件(mapper.py/reducer.py？)中编写将数据写入数据库的代码
>该命令用于运行hadoop以将数据保存到数据库中,因为当我在hadoop命令中删除了输出文件夹路径时,它显示了一个错误.
谁能帮我解决以上问题………….
已编辑
已处理
>如上所述创建的映射器和化简器文件,可通过hadoop命令读取xml文件并在某个文件夹中创建文本文件
例如：文本文件(使用hadoop命令处理xml文件的结果)位于以下文件夹
/ home / local / user / Hadoop / xml_processing / xml_output / part-00000
这里的xml文件大小为1.3 GB,使用hadoop处理后,创建的文本文件的大小为345 MB
现在,我要做的就是读取上述路径中的文本文件,并尽快将数据保存到mysql数据库中.
我已经使用基本的python进行了尝试,但是要花费350秒来处理文本文件并将其保存到mysql数据库.
>现在,如nichole所示,下载了sqoop并解压缩到如下所示的某个路径
/home/local/user/sqoop-1.4.2.bin__hadoop-0.20
并输入到bin文件夹并键入./sqoop,我收到以下错误
sh-4.2$./sqoop
Warning: /usr/lib/hbase does not exist! HBase imports will fail.
Please set $HBASE_HOME to the root of your HBase installation.
Warning: $HADOOP_HOME is deprecated.
Try ‘sqoop help’ for usage.
我也在下面尝试过
./sqoop export --connect jdbc:mysql://localhost/Xml_Data --username root --table PerformaceReport --export-dir /home/local/user/Hadoop/xml_processing/xml_output/part-00000 --input-fields-terminated-by ‘’
结果
Warning: /usr/lib/hbase does not exist! HBase imports will fail.
Please set $HBASE_HOME to the root of your HBase installation.
Warning: $HADOOP_HOME is deprecated.
12/11/27 11:54:57 INFO manager.MySQLManager: Preparing to use a MySQL streaming resultset.
12/11/27 11:54:57 INFO tool.CodeGenTool: Beginning code generation
12/11/27 11:54:57 ERROR sqoop.Sqoop: Got exception running Sqoop: java.lang.RuntimeException: Could not load db driver class: com.mysql.jdbc.Driver
java.lang.RuntimeException: Could not load db driver class: com.mysql.jdbc.Driver
at org.apache.sqoop.manager.SqlManager.makeConnection(SqlManager.java:636)
at org.apache.sqoop.manager.GenericJdbcManager.getConnection(GenericJdbcManager.java:52)
at org.apache.sqoop.manager.SqlManager.execute(SqlManager.java:525)
at org.apache.sqoop.manager.SqlManager.execute(SqlManager.java:548)
at org.apache.sqoop.manager.SqlManager.getColumnTypesForRawQuery(SqlManager.java:191)
at org.apache.sqoop.manager.SqlManager.getColumnTypes(SqlManager.java:175)
at org.apache.sqoop.manager.ConnManager.getColumnTypes(ConnManager.java:262)
at org.apache.sqoop.orm.ClassWriter.getColumnTypes(ClassWriter.java:1235)
at org.apache.sqoop.orm.ClassWriter.generate(ClassWriter.java:1060)
at org.apache.sqoop.tool.CodeGenTool.generateORM(CodeGenTool.java:82)
at org.apache.sqoop.tool.ExportTool.exportTable(ExportTool.java:64)
at org.apache.sqoop.tool.ExportTool.run(ExportTool.java:97)
at org.apache.sqoop.Sqoop.run(Sqoop.java:145)
at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:65)
at org.apache.sqoop.Sqoop.runSqoop(Sqoop.java:181)
at org.apache.sqoop.Sqoop.runTool(Sqoop.java:220)
at org.apache.sqoop.Sqoop.runTool(Sqoop.java:229)
at org.apache.sqoop.Sqoop.main(Sqoop.java:238)
at com.cloudera.sqoop.Sqoop.main(Sqoop.java:57)
上面的sqoop命令对于读取文本文件并将其保存到数据库的功能是否有用？ ,因为我们必须处理文本文件并将其插入数据库！