Using Alternate Write Modes for MapR 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

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

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

The MapR Database OJAI Connector for Apache Spark provides the following alternative modes:

Insert

Inserts the data into the MapR 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")