Amazon DynamoDB 實做了全球性的 replication，以及備份功能：「Amazon DynamoDB Update – Global Tables and On-Demand Backup」。
跨區 replication 的功能讓每個 region 都可以存取當地機房的 DynamoDB：
Global Tables – You can now create tables that are automatically replicated across two or more AWS Regions, with full support for multi-master writes, with a couple of clicks. This gives you the ability to build fast, massively scaled applications for a global user base without having to manage the replication process.
這有點類似 Google 的 Cloud Spanner 在前陣子也推出全球性服務，但 DynamoDB 提供的比較偏向 NoSQL 而不是 RDBMS。
另外一個限制是跨區同步是 async，會有 replication lag 的問題：
Updates are propagated to other Regions asynchronously via DynamoDB Streams and are typically complete within one second (you can track this using the new ReplicationLatency and PendingReplicationCount metrics).
不過如果是這樣的機制，conflict 的問題不知道怎麼解決... 文章裡面沒看到。
然後目前支援的區域還是有限：
Global Tables are available in the US East (Ohio), US East (N. Virginia), US West (Oregon), EU (Ireland), and EU (Frankfurt) Regions today, with more Regions in the works for 2018.
另外一個是備份與還原機制，有這樣的功能對很多計畫方便不少：
On-Demand Backup – You can now create full backups of your DynamoDB tables with a single click, and with zero impact on performance or availability. Your application remains online and runs at full speed. Backups are suitable for long-term retention and archival, and can help you to comply with regulatory requirements.
而備份還原機制是陸陸續續開放的，區域也有限：
We are rolling this new feature out on an account-by-account basis as quickly as possible, with initial availability in the US East (Northern Virginia), US East (Ohio), US West (Oregon), and EU (Ireland) Regions.
