title: Duplication Id creation Error Mongodb
body: <p>I am using pentaho data integration tool to populate Mongodb collection from a SQL Server database. There are no indexes defined in the mongodb collection.The job is getting failed because of the creation of duplicate ids in the collection. </p>
  
  <p>I would want to know in which scenario it could cause the issue. Any advise would be really helpful.</p>
  
  <pre><code>occurred during write: com.mongodb.MongoException$Network: Write operation to server /myhost:27017 failed on database transactions
  
      ERROR (version 5.0.1-stable, build 1 from 2013-11-15_16-08-58 by buildguy) : An error     occurred during write: com.mongodb.MongoException$DuplicateKey:
     { "serverUsed" : "/myhost:27017" , "connectionId" : 186 , "err" :
     "insertDocument :: caused by :: 11000 E11000 duplicate key error
     index: transactions.datacollection.$_id_  dup key: { :
     ObjectId('534fe5644503839b0f6d47a2') }" , "code" : 11000 , "n" : 0 ,
     "ok" : 1.0} 
  
  ERROR (version 5.0.1-stable, build 1 from 2013-11-15_16-08-58 by buildguy)
     : An error occurred during write:
     com.mongodb.MongoException$DuplicateKey: { "serverUsed" :
     "/myhost:27017" , "connectionId" : 186 , "err" : "insertDocument ::
     caused by :: 11000 E11000 duplicate key error index:
     transactions.datacollection.$_id_  dup key: { :
     ObjectId('534fe5644503839b0f6d47a2') }" , "code" : 11000 , "n" : 0 ,
     "ok" : 1.0}  
  
     ERROR (version 5.0.1-stable, build 1 from 2013-11-15_16-08-58 by buildguy)
     : An error occurred during write: com.mongodb.MongoException$Network:
     Write operation to server /myhost:27017 failed on database
     transactions
  
     MongoDB Output.0 - ERROR (version 5.0.1-stable, build 1 from
     2013-11-15_16-08-58 by buildguy) : An error occurred during write:
     com.mongodb.MongoException$DuplicateKey: { "serverUsed" :
     "/myhost:27017" , "connectionId" : 187 , "err" : "insertDocument ::
     caused by :: 11000 E11000 duplicate key error index:
     transactions.datacollection.$_id_  dup key: { :
     ObjectId('534fe5644503839b0f6d47a2') }" , "code" : 11000 , "n" : 0 ,
     "ok" : 1.0}
  
     ERROR (version 5.0.1-stable, build 1 from 2013-11-15_16-08-58 by buildguy) : Unexpected   error ERROR (version 5.0.1-stable, build 1 from
     2013-11-15_16-08-58 by buildguy) :
  </code></pre>