Amazon Neptune now supports Streams, an easy way to capture changes in your graph. When enabled, Neptune Streams logs changes to your graph (change-log data) as they happen. Neptune Streams are useful when you want to notify processes (e.g. trigger a lambda) as changes occur in your graph. Streams can also be useful to maintain a current version of your graph in a different region or service such as Amazon Elasticsearch, Amazon ElastiCache, or Amazon Simple Storage Service.

from Recent Announcements https://aws.amazon.com/about-aws/whats-new/2019/10/amazon-neptune-now-supports-streams-to-capture-graph-data-changes/