Configure DynamoDB stream trigger with insert only

Question

I currently have an AWS DynamoDB stream triggers a Lambda function.

The Lambda function is triggered by both insert and update events in the DynamoDB. Is there a way to change the configuration so that the Lambda function would only be triggered by 'insert'?

score 22 · Accepted Answer · answered Dec 13 '16 at 11:29

22

To my knowledge this is not possible. AWS Lambda polls the stream and invokes your Lambda function when it detects any type of stream record update. Your Lambda will have to ignore the records that you are not interested in. You can use the eventName property of the stream record (can have values INSERT | MODIFY | REMOVE)

answered Dec 13 '16 at 11:29

Peter Fennema

1,650
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17

Thanks for your reply, but using Lambda functions to ignore the records would cause an unnecessary cost of invoking the Lambda. I really feel AWS should make this configurable. – C.Lee Dec 13 '16 at 17:24
8

Yeah AWS, a little Customer Obsession here please? – Eric Hartford Feb 28 '18 at 22:49
Still this is not supported by AWS? – Abhi Jun 13 '19 at 04:52

score 6 · Answer 2 · edited Apr 29 '22 at 10:28

6

You can use your lambda function to ignore rest other than insert.

 for record in event.get('Records'):
    if record.get('eventName') in ('INSERT'):
       """ code for execution. """

    elif record.get('eventName') == 'REMOVE':
        pass
    elif record.get('eventName') ==  'MODIFY':
        pass

edited Apr 29 '22 at 10:28

Antash

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answered May 14 '19 at 05:53

Pirate

91
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Paying for lambda invocations that we won't use doesn't seem like good architecture – Jorge Freitas May 05 '21 at 16:54
3

There's no such eventName as DELETE, or at least not anymore. Replace with **REMOVE** instead. – Akah Jul 28 '21 at 16:49

score 0 · Answer 3 · answered Jul 22 '22 at 02:44

In general, not only for nodejs but all types, this is supported for non global tables. Good collection of filter snippets can found here.

You basically apply filtering on Lambda service side before function gets triggered.

PS, Also great article explaining how it works

score 0 · Answer 4 · answered Sep 25 '22 at 09:21

While the accepted answer was accurate this is now supported by Lambda Event Filtering leveraging event source mappings.

aws lambda create-event-source-mapping \
    --function-name my-function \
    --event-source-arn arn:aws:sqs:us-east-2:123456789012:my-queue \
    --filter-criteria "{\"Filters\": [{\"Pattern\": \"{ \"a\" : [ 1, 2 ]}\"}]}"

Furthermore, you can include this in your Cloud formation or CDK workflow. See the accepted answer from this for more details.

Sebastian Sippl · Answer 5 · 2023-05-25T13:35:48.340

0

You can use stream filters now and filter for those event types that you need only:

https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Streams.Lambda.Tutorial2.html

edited May 25 '23 at 13:35

answered May 25 '23 at 13:34

Sebastian Sippl

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While this link may answer the question, it is better to include the essential parts of the answer here and provide the link for reference. Link-only answers can become invalid if the linked page changes. - [From Review](/review/late-answers/34446906) – DSDmark May 27 '23 at 15:04

Configure DynamoDB stream trigger with insert only

5 Answers5