# Perform DynamoDB CRUD operations with Step Functions
<a name="connect-ddb"></a>

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](integrate-services.md) and [Passing parameters to a service API in Step Functions](connect-parameters.md).

**Key features of optimized DynamoDB integration**  
There is no specific optimization for the [Request Response](connect-to-resource.md#connect-default) integration pattern.
[Wait for a Callback with Task Token](connect-to-resource.md#connect-wait-token) integration pattern is not supported.
Only [https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_GetItem.html](https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_GetItem.html), [https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_PutItem.html](https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_PutItem.html), [https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_UpdateItem.html](https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_UpdateItem.html), and [https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_DeleteItem.html](https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_DeleteItem.html) API actions are available through optimized integration. Other API actions, such as [https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_CreateTable.html](https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_CreateTable.html) are available using the DynamoDB AWS SDK integration. 

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

```
"Read next Message from DynamoDB": {
    "Type": "Task",
    "Resource": "arn:aws:states:::dynamodb:getItem",
    "Arguments": {
        "TableName": "DYNAMO_DB_TABLE_NAME",
        "Key": {
            "MessageId": {"S": "{% $List[0] %}"}
        }
    }
```

To see this state in a working example, see the [Transfer data records with Lambda, DynamoDB, and Amazon SQS](sample-project-transfer-data-sqs.md) starter template.

**Exception prefix differences**  
When standard DynamoDB connections experience an error, the exception prefix will be `DynamoDb` (mixed case).  
For optimized integrations, the exception prefix will be `DynamoDB` (uppercase `DB`). 

**Quota for input or result data**  
When sending or receiving data between services, the maximum input or result for a task is 256 KiB of data as a UTF-8 encoded string. See [Quotas related to state machine executions](service-quotas.md#service-limits-state-machine-executions).

## Optimized DynamoDB APIs
<a name="connect-dynamodb-api"></a>
+ [https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_GetItem.html](https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_GetItem.html)
+ [https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_PutItem.html](https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_PutItem.html)
+ [https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_DeleteItem.html](https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_DeleteItem.html)
+ [https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_UpdateItem.html](https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_UpdateItem.html)

**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
<a name="dynamo-iam"></a>

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](service-integration-iam-templates.md) and [Discover service integration patterns in Step Functions](connect-to-resource.md).

*Static resources*

****  

```
{
    "Version":"2012-10-17",		 	 	 
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "dynamodb:GetItem",
                "dynamodb:PutItem",
                "dynamodb:UpdateItem",
                "dynamodb:DeleteItem"
            ],
            "Resource": [
                "arn:aws:dynamodb:us-east-1:123456789012:table/myTableName"
            ]
        }
    ]
}
```

*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](https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/using-identity-based-policies.html) in the *Amazon DynamoDB Developer Guide*. Additionally, for information about the IAM policies for PartiQL for DynamoDB, see [IAM policies with PartiQL for DynamoDB](https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/ql-iam.html) in the *Amazon DynamoDB Developer Guide*.