DynamoDB Global Tables - The Ultimate Guide

What are DynamoDB Global Tables?

DynamoDB Global Tables are globally available, fully-managed, multi-master, multi-region DynamoDB tables with eventual cross-region replication. With global tables, you get a replica of your table in each of the desired regions. Once you write data to one of the replicas, it will be eventually replicated to the rest of the tables. This ensures high availability and low-latency access to data across different geographical locations.

How to Create Global Tables in DynamoDB? (Step by Step)

Create DynamoDB Global Tables using AWS Console

1. Create a table as you would do that regularly. You can do that using AWS Console, Dynobase, CloudFormation, Serverless Framework, or whatever you like.
2. Enable DynamoDB Streams on that table. They are required to create Global DynamoDB Table.
3. Go to AWS DynamoDB Console, select your table, and head to the "Global Tables" section. Click "Add Region".

4. Select the region and confirm the selection by clicking "Create Replica".

After a few seconds, your table in another region should be ready.

Create DynamoDB Global Tables using CloudFormation

If you want to create your Global DynamoDB Table using CloudFormation, you have to do that using custom resources and use their createGlobalTable API in your custom resource. This approach allows for more complex and automated deployments, especially in large-scale environments.

Create DynamoDB Global Tables using CDK

Creating DynamoDB Global Tables with CDK is fortunately much easier. The Table construct accepts the replicationRegions property, which is an array of regions where replica tables will be created. In TypeScript, you can use it like this:

const table = new Table(this, 'global-table', {
    partitionKey: { name: 'hashKey', type: AttributeType.STRING },
    replicationRegions: ['us-east-1', 'eu-central-1', 'ap-southeast-2'],
});
const table = new Table(this, 'global-table', {
    partitionKey: { name: 'hashKey', type: AttributeType.STRING },
    replicationRegions: ['us-east-1', 'eu-central-1', 'ap-southeast-2'],
});

Using DynamoDB Global Tables

Using DynamoDB Global Tables is quite similar to using standard DynamoDB tables. The key difference is the region you set when using the DynamoDB/DocumentClient SDK. Make sure you're using the region where your compute resources are deployed. If your Lambda functions or EC2 instances are deployed in a region where you don't have a DynamoDB Global Table replica, you might use a fallback to a base region. In Node.js, it might look like this:

const currentRegion = process.env.AWS_DEFAULT_REGION;
const replicatedRegions = ['us-east-1', 'ap-southeast-2', 'eu-central-1'];

const region = replicatedRegions
    .find((r) => r === currentRegion) || replicatedRegions[0]; // Fallback to the first available

const ddb = new DynamoDB({
    region,
});
const currentRegion = process.env.AWS_DEFAULT_REGION;
const replicatedRegions = ['us-east-1', 'ap-southeast-2', 'eu-central-1'];

const region = replicatedRegions
    .find((r) => r === currentRegion) || replicatedRegions[0]; // Fallback to the first available

const ddb = new DynamoDB({
    region,
});