Github user gvramana commented on a diff in the pull request:

    https://github.com/apache/carbondata/pull/1002#discussion_r120927111
  
    --- Diff: 
integration/spark-common/src/main/scala/org/apache/carbondata/spark/rdd/CarbonMergerRDD.scala
 ---
    @@ -405,11 +411,16 @@ class CarbonMergerRDD[K, V](
               NodeInfo(splitsPerNode.getTaskId, 
splitsPerNode.getCarbonInputSplitList.size()))
     
             if (blockletCount != 0) {
    +          val taskInfo = splitInfo.asInstanceOf[CarbonInputSplitTaskInfo]
               val multiBlockSplit = new 
CarbonMultiBlockSplit(absoluteTableIdentifier,
    -            
splitInfo.asInstanceOf[CarbonInputSplitTaskInfo].getCarbonInputSplitList,
    +            taskInfo.getCarbonInputSplitList,
                 Array(nodeName))
    -          result.add(new CarbonSparkPartition(id, partitionNo, 
multiBlockSplit))
    -          partitionNo += 1
    +          if (isPartitionTable) {
    --- End diff --
    
    This handling will not be sufficient, 
    When number of partitions(Example:100) is not equal to number of 
nodes(Example:5) , getPartitions will divide total blocks among available 
nodes. Then each node will get more than one taskno/partitionNo to handle.
    Compute function in executor just merges all the given btrees(segid+taskid) 
into one task. So multiple taskids/partitions will be merged to one. This 
disturbs partition mapping.


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