Preferred Max Bytes: The preferred

Preferred Max Bytes: The preferred maximum number of bytes allowed for the serialized messages in a batch. Roughly, this field may be considered the best effort maximum size of a batch. A batch will fill with messages until this size is reached (or the max message count, or batch timeout is exceeded). If adding a new message to the batch would cause the batch to exceed the preferred max bytes, then the current batch is closed and written to a block, and a new batch containing the new message is created. If a message larger than the preferred max bytes is received, then its batch will contain only that message. Because messages may be larger than preferred max bytes (up to AbsoluteMaxBytes), some batches may exceed the preferred max bytes, but will always contain exactly one transaction.