Spark Kudu Rdd/Dataframe upsert

Applying Upserting kuduRdd into existing Kudu table is not clear how to apply.
You mention in the documentation under "Kudu integration with Spark":
some possible operations to perform:
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// then we can insert data into the kudu table
df.write.options(Map("kudu.master" -> "your.kudu.master.here","kudu.table"-> "your.kudu.table.here")).mode("append").kudu

// to update existing data change the mode to 'overwrite'
df.write.options(Map("kudu.master" -> "your.kudu.master.here","kudu.table"-> "your.kudu.table.here")).mode("overwrite").kudu
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But there is no possibility to perform:
kuduDataFrame.write.options(Map("kudu.master" -> Kudu_Master,"kudu.table"-> TargetTable)).mode("upsert").kudu
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the current solution which is quit slow is:
Call DataFrame.foreachpartition

• open the table
• create session
  --For each row in this partition
  • • create upsert operation
    • get row from the operation
    • add all fields and values to this row
    • perform this operation
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      this solution is quit slow! so adding upsert mode to Dataframe writing function for Kudu tables could be better than open sessions and create operations as the previous solution.
      kuduDataFrame.write.options(Map("kudu.master" -> Kudu_Master,"kudu.table"-> TargetTable)).mode("upsert").kudu