Sets the output of the streaming query to be processed using the provided
function. This is supported only the in the micro-batch execution modes (that is, when the
trigger is not continuous). In every micro-batch, the provided function will be called in
every micro-batch with (i) the output rows as a DataFrame and (ii) the batch identifier.
The batchId can be used deduplicate and transactionally write the output
(that is, the provided Dataset) to external systems. The output DataFrame is guaranteed
to exactly same for the same batchId (assuming all operations are deterministic in the
New in version 2.4.0.
This API is evolving.
>>> import time
>>> df = spark.readStream.format("rate").load()
>>> def func(batch_df, batch_id):
>>> q = df.writeStream.foreachBatch(func).start()