The DataStream API's BATCH execution mode first sorts by key, and within
each key, it sorts by timestamp. By operating this way, it only needs to
keep state for one key at a time, so this keeps the runtime simple and
efficient.
Regards,
David
P.S. I see you also asked this question on stack
I have a custom flink Source, and I have a SerializableTimestampAssigner that
assigns event timestamps to records emitted by the source. The source may emit
records out of order because of the nature of the underlying data storage,
however with BATCH mode, I expect Flink to sort these records
