Amazon DynamoDB | Global tables Flashcards
What is a maintenance window? Will my DAX cluster be available during software maintenance?
Global tables
Amazon DynamoDB | Database
You can think of the DAX maintenance window as an opportunity to control when cluster modifications such as software patching occur. If a “maintenance” event is scheduled for a given week, it will be initiated and completed at some point during the maintenance window you identify.
Required patching is automatically scheduled only for patches that are security and reliability related. Such patching occurs infrequently (typically once every few months). If you do not specify a preferred weekly maintenance window when creating your cluster, a default value will be assigned. If you wish to modify when maintenance is performed on your behalf, you can do so by modifying your cluster in the AWS Management Console or by using the UpdateCluster API. Each of your clusters can have different preferred maintenance windows.
For multi-node clusters, updates in the cluster are performed serially, and one node will be updated at a time. After the node is updated, it will sync with one of the peers in the cluster so that the node has the current working set of data. For a single-node cluster, we will provision a replica (at no charge to you), sync the replica with the latest data, and then perform a failover to make the new replica the primary node. This way, you don’t lose any data during an upgrade for a one-node cluster.
What is DynamoDB Global Tables?
Global tables
Amazon DynamoDB | Database
DynamoDB Global Tables is a new multi-master, cross-region replication capability of DynamoDB to support data access locality and regional fault tolerance for database workloads. Applications can now perform reads and writes to DynamoDB in AWS regions around the world, with changes in any region propagated to every region where a table is replicated.
Why should I use Global Tables?
Global tables
Amazon DynamoDB | Database
Global Tables enable you to build applications that take advantage of data locality to reduce overall latency. Your applications can read/write data to the region closest to your end users, thereby improving the overall responsiveness of your application. In addition, Global Tables enables your applications to stay highly available even in the unlikely event of isolation or degradation of an entire region.
Which AWS regions support Global Tables?
Global tables
Amazon DynamoDB | Database
Global Tables is currently supported in five regions: US East (Ohio), US East (N. Virginia), US West (Oregon), EU (Ireland), and EU (Frankfurt).
How many AWS regions can I replicate to?
Global tables
Amazon DynamoDB | Database
You can have one replica table per region, for as many regions in which Global Tables is supported.
What consistency guarantees does Global Table provide?
Global tables
Amazon DynamoDB | Database
Global Tables ensures eventual consistency, meaning that any update made to any item in any replica table will be replicated to all other replicas in the same global table. If there are multiple updates to the same item, all replicas in the global table will agree on the latest update, and hence all replicas will converge continually towards a state in which they store identical data.
What latency can I expect when accessing a replica table?
Global tables
Amazon DynamoDB | Database
If your application is hosted in a region with a global table, accessing the local replica table through its regional endpoint will exhibit the same single-digit millisecond latencies that you have come to expect from DynamoDB.
What is the pricing for Global Tables?
Global tables
Amazon DynamoDB | Database
Please refer to the pricing page for details.
Can I use Global Tables with DynamoDB’s free tier?
Global tables
Amazon DynamoDB | Database
Yes. You can create a global table with replica tables that each fall within free tier, as long as it is replicated in no more than two AWS regions.
