Using Alternate Write Modes for HPE Ezmeral Data Fabric Database OJAI Connector

You can use alternate write modes supported by MapR Database OJAI Connector for Apache Spark to save an Apache Spark DataFrame to a MapR Database JSON table.

Normally, the Apache Spark DataFrameWriter class supports the following write modes:

Append
Overwrite
ErrorIfExists
Ignore

The HPE Ezmeral Data Fabric Database OJAI Connector for Apache Spark returns an OperationNotSupported exception if you attempt to use one of these modes. The following example returns the error:

Scala

import org.apache.spark.sql.SaveMode
import com.mapr.db.spark.sql._

df.write.mode(SaveMode.Append).saveToMapRDB("/tmp/userInfo")

The HPE Ezmeral Data Fabric Database OJAI Connector for Apache Spark provides the following alternative modes:

Insert: Inserts the data into the HPE Ezmeral Data Fabric Database table. Throws a DBException if a row with same _id value already exists in the table.
Overwrite: Overwrites the data in the table with the current DataFrame data. This operation drops the table and creates a new table with the data.
ErrorIfExists: Returns an exception (TableExistsException) if the table already exists. Otherwise, creates the table and inserts the data.
Ignore: Ignores the data in the table if the table already exists. Otherwise, creates the table and inserts the data.
InsertOrReplace: Replaces the row with the row in the DataFrame, if a row with the same _id already exists in the table. Otherwise, inserts the new row.

You cannot specify these modes using the Apache Spark SaveMode method. Doing so results in the same OperationNotSupported exception noted earlier. To use these modes, you must call the option method on a DataFrameWriter object. The following example sets the Insert mode:

Scala

df.write.option("Operation", "Insert").saveToMapRDB("/tmp/usersInfo")

Note: The UPDATE mode for HPE Ezmeral Data Fabric Database OJAI Connector is not supported and it results in an OperationNotSupported exception.