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List:       hadoop-user
Subject:    Re: jdbc in Hadoop mapper
From:       Shi Yu <shiyu () uchicago ! edu>
Date:       2010-09-24 21:07:45
Message-ID: 4C9D1321.2080903 () uchicago ! edu
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You are right. I ran stop-all.sh and start-all.sh, now it works fine. 
Thanks!

On 2010-9-24 15:30, Harsh J wrote:
> My guess: Either you haven't put the JAR in all the tasktracker
> machines, or you have not restarted your tasktrackers and jobtracker
> after doing so.
>
> On Sat, Sep 25, 2010 at 1:47 AM, Shi Yu<shiyu@uchicago.edu>  wrote:
>    
>> Hi,
>>
>> I tried to combine in memory mysql database with Mapreduce to do some value
>> exchanges. In the Mapper, I declare the mysql driver like this
>>             import com.mysql.jdbc.*;
>>             import java.sql.DriverManager;
>>             import java.sql.SQLException;
>>
>>               String driver = "com.mysql.jdbc.Driver";
>>                 try{
>>                     Class.forName(driver);
>>                 }...
>>
>> but it returns an error: java.lang.ClassNotFoundException:
>> com.mysql.jdbc.Driver
>> It looks like the class file cannot be found. I put the mysql jdbc jar file
>> under hadoop\lib\ folder.  This error only occurs when the jdbc connection
>> is declared in the Mapper, all the other functions outside of the mapper
>> work fine. I also tried to ant the jdbc jar file together with my class in a
>> same jar file, but still get the error. Is there any special configuration
>> required for jdbc connections in Mapper class?
>>
>> Thanks.
>>
>> BR,
>>
>> Shi
>>
>> --
>> Postdoctoral Scholar
>> Institute for Genomics and Systems Biology
>> Department of Medicine, the University of Chicago
>> Knapp Center for Biomedical Discovery
>> 900 E. 57th St. Room 10148
>> Chicago, IL 60637, US
>> Tel: 773-702-6799
>>
>>
>>      
>
>
>    


-- 
Postdoctoral Scholar
Institute for Genomics and Systems Biology
Department of Medicine, the University of Chicago
Knapp Center for Biomedical Discovery
900 E. 57th St. Room 10148
Chicago, IL 60637, US
Tel: 773-702-6799

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