title: hadoop: sqoop- why jdbc code is written in reducers?
body: <p>I am newbie to hadoop and its eco-systems. 
  Sqoop : imports/exports data from/to hdfs - RDBMS. Sqoop compatible with JDBC related databases. </p>
  
  <p>Why is that all the jdbc code written in reducers rather in mappers while importing and exporting the data from /to hdfs - RDBMS ? Some say to avoid Ddos (Distributed Denial of service). </p>