Add a Dynamodb Global Secondary Index in AWS CDK [GSI]

# Adding a Dynamodb GSI in AWS CDK

To add a Global Secondary Index to a Dynamodb Table in AWS CDK, we have to use the addGlobalSecondaryIndex method on an instance of the Table class.

The code for this article is available on GitHub

Let's look at a simple example where we create a dynamodb table and add a global secondary index to it:

lib/cdk-starter-stack.ts

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import * as dynamodb from 'aws-cdk-lib/aws-dynamodb';
import * as cdk from 'aws-cdk-lib';

export class CdkStarterStack extends cdk.Stack {
  constructor(scope: cdk.App, id: string, props?: cdk.StackProps) {
    super(scope, id, props);

    // 👇 create Dynamodb table
    const table = new dynamodb.Table(this, id, {
      partitionKey: {name: 'todoId', type: dynamodb.AttributeType.STRING},
      sortKey: {name: 'createdAt', type: dynamodb.AttributeType.NUMBER},
      billingMode: dynamodb.BillingMode.PROVISIONED,
      readCapacity: 1,
      writeCapacity: 1,
      removalPolicy: cdk.RemovalPolicy.DESTROY,
    });

    // 👇 add global secondary index
    table.addGlobalSecondaryIndex({
      indexName: 'userIdIndex',
      partitionKey: {name: 'userId', type: dynamodb.AttributeType.STRING},
      sortKey: {name: 'status', type: dynamodb.AttributeType.STRING},
      readCapacity: 1,
      writeCapacity: 1,
      projectionType: dynamodb.ProjectionType.ALL,
    });
  }
}

Let's go over the code snippet.

We created a dynamodb table with provisioned capacity
We created a Global secondary index on the table using the addGlobalSecondaryIndex method. The props we have passed to the method are:

indexName - the name of the global secondary index
partitionKey - the partition key attribute for the global secondary index
sortKey - the sort key attribute for the global secondary index
readCapacity and writeCapacity - the capacity for the global secondary index. These properties can only be provided if the table is configured with PROVISIONED capacity. By default readCapacity and writeCapacity are set to 5.
projectionType - which attributes should be projected into the global secondary index. By default all attributes are projected into the GSI, so we could have omitted this property.

I'll deploy the stack:

shell

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npx aws-cdk deploy

After a deployment, the dynamodb table has been provisioned and the global secondary index has been added to the table:

table with gsi

I've also written a guide on how to provision and configure a Dynamodb table using AWS CDK.

# Additional Resources

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Add a Dynamodb Global Secondary Index in AWS CDK [GSI]

# Adding a Dynamodb GSI in AWS CDK

# Additional Resources

Borislav Hadzhiev