Perform DynamoDB CRUD operations with Step Functions - AWS Step Functions
Supported APIsIAM policies

Perform DynamoDB CRUD operations with Step Functions

You can integrate Step Functions with DynamoDB to perform CRUD operations on a DynamoDB table. This page lists the supported DynamoDB APIs and provides an example Task state to retrieve an item from DynamoDB.

To learn about integrating with AWS services in Step Functions, see Integrating services and Passing parameters to a service API in Step Functions.

Key features of optimized DynamoDB integration

The following is a Task state that retrieves a message from DynamoDB.

    "Read Next Message from DynamoDB": {
      "Type": "Task",
      "Resource": "arn:aws:states:::dynamodb:getItem",
      "Parameters": {
        "TableName": "TransferDataRecords-DDBTable-3I41R5L5EAGT",
        "Key": {
          "MessageId": {"S.$": "$.List[0]"}
        }
      },
      "ResultPath": "$.DynamoDB",
      "Next": "Send Message to SQS"
    },

To see this state in a working example, see the Transfer data records with Lambda, DynamoDB, and Amazon SQS sample project.

Note

There is a quota for the maximum input or result data size for a task in Step Functions. This restricts you to 256 KB of data as a UTF-8 encoded string when you send to, or receive data from, another service. See Quotas related to state machine executions.

Supported DynamoDB APIs

Parameters in Step Functions are expressed in PascalCase

Even if the native service API is in camelCase, for example the API action startSyncExecution, you specify parameters in PascalCase, such as: StateMachineArn.

IAM policies for calling DynamoDB

The following example templates show how AWS Step Functions generates IAM policies based on the resources in your state machine definition. For more information, see How Step Functions generates IAM policies for integrated services and Discover service integration patterns in Step Functions.

Static resources

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "dynamodb:GetItem",
                "dynamodb:PutItem",
                "dynamodb:UpdateItem",
                "dynamodb:DeleteItem"
            ],
            "Resource": [
                "arn:aws:dynamodb:[[region]]:[[accountId]]:table/[[tableName]]"
            ]
        }
    ]
}

Dynamic resources

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "dynamodb:GetItem",
                "dynamodb:PutItem",
                "dynamodb:UpdateItem",
                "dynamodb:DeleteItem"
            ],
            "Resource": "*"
        }
    ]
}

For more information about the IAM policies for all DynamoDB API actions, see IAM policies with DynamoDB in the Amazon DynamoDB Developer Guide. Additionally, for information about the IAM policies for PartiQL for DynamoDB, see IAM policies with PartiQL for DynamoDB in the Amazon DynamoDB Developer Guide.