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46 changes: 46 additions & 0 deletions docs/snippets/idempotency/workingWithBatch.ts
Original file line number Diff line number Diff line change
@@ -0,0 +1,46 @@
import {
BatchProcessor,
EventType,
processPartialResponse,
} from '@aws-lambda-powertools/batch';
import type {
Context,
SQSBatchResponse,
SQSEvent,
SQSRecord,
} from 'aws-lambda';
import { DynamoDBPersistenceLayer } from '@aws-lambda-powertools/idempotency/dynamodb';
import {
IdempotencyConfig,
makeIdempotent,
} from '@aws-lambda-powertools/idempotency';

const processor = new BatchProcessor(EventType.SQS);

const dynamoDBPersistence = new DynamoDBPersistenceLayer({
tableName: 'idempotencyTable',
});
const idempotencyConfig = new IdempotencyConfig({
eventKeyJmesPath: 'messageId',
});

const processIdempotently = makeIdempotent(
async (_record: SQSRecord) => {
// process your event
},
{
persistenceStore: dynamoDBPersistence,
config: idempotencyConfig,
}
);

export const handler = async (
event: SQSEvent,
context: Context
): Promise<SQSBatchResponse> => {
idempotencyConfig.registerLambdaContext(context);

return processPartialResponse(event, processIdempotently, processor, {
context,
});
};
56 changes: 52 additions & 4 deletions docs/utilities/idempotency.md
Original file line number Diff line number Diff line change
Expand Up @@ -79,10 +79,10 @@ As of now, Amazon DynamoDB is the only supported persistent storage layer, so yo

If you're not [changing the default configuration for the DynamoDB persistence layer](#dynamodbpersistencelayer), this is the expected default configuration:

| Configuration | Default value | Notes |
| ------------------ |:--------------|-----------------------------------------------------------------------------------------|
| Partition key | `id` | The id of each idempotency record which a combination of `functionName#hashOfPayload`. |
| TTL attribute name | `expiration` | This can only be configured after your table is created if you're using AWS Console. |
| Configuration | Default value | Notes |
| ------------------ | :------------ | -------------------------------------------------------------------------------------- |
| Partition key | `id` | The id of each idempotency record which a combination of `functionName#hashOfPayload`. |
| TTL attribute name | `expiration` | This can only be configured after your table is created if you're using AWS Console. |

???+ tip "Tip: You can share a single state table for all functions"
You can reuse the same DynamoDB table to store idempotency state. We add the Lambda function name in addition to the idempotency key as a hash key.
Expand Down Expand Up @@ -767,6 +767,54 @@ This means that we will raise **`IdempotencyKeyError`** if the evaluation of **`
}
```

### Batch integration

You can easily integrate with [Batch](batch.md) utility by using idempotency wrapper around your processing function.
This ensures that you process each record in an idempotent manner, and guard against a [Lambda timeout](#lambda-timeouts) idempotent situation.

???+ "Choosing a unique batch record attribute"
In this example, we choose `messageId` as our idempotency key since we know it'll be unique.
Depending on your use case, it might be more accurate [to choose another field](#choosing-a-payload-subset-for-idempotency) your producer intentionally set to define uniqueness.



=== "Integration with batch processor"

```typescript hl_lines="27 31-34 41"
--8<-- "docs/snippets/idempotency/workingWithBatch.ts"
```

=== "Sample event"

```json hl_lines="4"
{
"Records": [
{
"messageId": "059f36b4-87a3-44ab-83d2-661975830a7d",
"receiptHandle": "AQEBwJnKyrHigUMZj6rYigCgxlaS3SLy0a...",
"body": "Test message.",
"attributes": {
"ApproximateReceiveCount": "1",
"SentTimestamp": "1545082649183",
"SenderId": "AIDAIENQZJOLO23YVJ4VO",
"ApproximateFirstReceiveTimestamp": "1545082649185"
},
"messageAttributes": {
"testAttr": {
"stringValue": "100",
"binaryValue": "base64Str",
"dataType": "Number"
}
},
"md5OfBody": "e4e68fb7bd0e697a0ae8f1bb342846b3",
"eventSource": "aws:sqs",
"eventSourceARN": "arn:aws:sqs:us-east-2:123456789012:my-queue",
"awsRegion": "us-east-2"
}
]
}
```

### Customizing AWS SDK configuration

The **`clientConfig`** and **`awsSdkV3Client`** parameters enable you to pass in custom configurations or your own [DynamoDBClient](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/dynamodb/){target="_blank"} when constructing the persistence store.
Expand Down