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 <[email protected]> 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 > > -- Harsh J www.harshj.com
