public interface StreamingDataWriterFactory
DataWriter returned by
StreamingWrite.createStreamingWriterFactory(PhysicalWriteInfo), which is responsible for
creating and initializing the actual data writer at executor side.
Note that, the writer factory will be serialized and sent to executors, then the data writer
will be created on executors and do the actual writing. So this interface must be
DataWriter doesn't need to be.
DataWriter<org.apache.spark.sql.catalyst.InternalRow> createWriter(int partitionId, long taskId, long epochId)
If this method fails (by throwing an exception), the corresponding Spark write task would fail and get retried until hitting the maximum retry times.
partitionId - A unique id of the RDD partition that the returned writer will process.
Usually Spark processes many RDD partitions at the same time,
implementations should use the partition id to distinguish writers for
taskId - The task id returned by
TaskContext.taskAttemptId(). Spark may run
multiple tasks for the same partition (due to speculation or task failures,
epochId - A monotonically increasing id for streaming queries that are split in to
discrete periods of execution.