看起來 MySQL 系的 Global Database 就是跨區的 master-slave 架構 (所以標榜降低了 read latency，但沒有提到 write latency)：
An Amazon Aurora Global Database is a single database that spans multiple AWS regions, enabling low latency global reads and disaster recovery from region-wide outages.
另外可以看到是 1 秒，所以應該是 async replication：
Aurora Global Database replicates writes in the primary region with typical latency of <1 second to secondary regions, for low latency global reads.
然後可以跨區切換：
In disaster recovery situations, you can promote the secondary region to take full read-write responsibilities in under a minute.
Now you can invoke Lambda functions directly from within an Aurora database via stored procedures or user-defined functions. Lambda integration allows you to extend the capabilities of the database and invoke external applications to act upon data changes. For example, you can create a Lambda function that sends emails to customers whenever their address in the database is updated.
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.
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.
看起來像是某個情況的 optimization，將可能的 random access 換成 sequential access 而得到大量的效能：
This feature applies to queries that require use of the Batched Key Access (BKA) join algorithm and Multi-Range Read (MRR) optimization, and improves performance when the underlying data set is not in the main memory buffer pool or query cache.
Logical backup size is much smaller. 3x-10x size difference is not uncommon.
備份出來的資料會變小，而且宣稱 1/3 到 1/10 不是罕見情況... -_-
With logical readahead, our full table scan speed improved 9~10 times than before under usual production workloads. Under heavy production workloads, full table scan speed became 15~20 times faster.
