anchor.diff:  
   === Upsert option in Kudu Spark
   The upsert operation in kudu-spark supports an extra write option of `ignoreNull`. If set to true,
  -it will avoid setting existing column values in Kudu table to Null if the corresponding dataframe
  +it will avoid setting existing column values in Kudu table to Null if the corresponding DataFrame
   column values are Null. If unspecified, `ignoreNull` is false by default.
   [source,scala]
   ----
  -val dataDF = spark.read
  +val dataFrame = spark.read
     .options(Map("kudu.master" -> "kudu.master:7051", "kudu.table" -> simpleTableName))
     .format("kudu").load
  -dataDF.registerTempTable(simpleTableName)
  -dataDF.show()
  +dataFrame.createOrReplaceTempView(simpleTableName)
  +dataFrame.show()
   // Below is the original data in the table 'simpleTableName'
   +---+---+
   |key|val|
  
positive.code: val wo = new KuduWriteOptions
  wo.ignoreNull = true
  kuduContext.upsertRows(nullDF, simpleTableName, wo)
  dataDF.show()
  // The val field stays unchanged
  +---+---+
  |key|val|
  
negative.code: spark-shell --packages org.apache.kudu:kudu-spark2_2.11:1.10.0
  ----
  
  Below is a minimal Spark SQL "select" example for a Kudu table created with
  Impala in the "default" database. We first import the kudu spark package,
  then create a DataFrame, and then create a view from the DataFrame. After those
  steps, the table is accessible from Spark SQL.
  
  [source,scala]
  ----
  import org.apache.kudu.spark.kudu._
  
  // Create a DataFrame that points to the Kudu table we want to query.
  val df = spark.read.options(Map("kudu.master" -> "master1.foo.com,master2.foo.com,master3.foo.com",
                                  "kudu.table" -> "default.my_table")).kudu
  // Create a view from the DataFrame to make it accessible from Spark SQL.
  df.createOrReplaceTempView("my_table")
  // Now we can run Spark SQL queries against our view of the Kudu table.
  spark.sql("select * from my_table").show()
  ----
  
  Below is a more sophisticated example that includes both reads and writes:
  
  [source,scala]
  ----
  import org.apache.kudu.client._
  