AWS - SQS Batch Size and Lambda approach : <p>If I understand correctly, batch size setting on Lambda decides how many messages to take in one sweep from the SQS. Therefore this JSON (taken from the test Lambda SQS);</p>

<pre><code>{
  "Records": [
    {
      "messageId": "19dd0b57-b21e-4ac1-bd88-01bbb068cb78",
      "receiptHandle": "MessageReceiptHandle",
      "body": "FAIL",
      "attributes": {
        "ApproximateReceiveCount": "1",
        "SentTimestamp": "1523232000000",
        "SenderId": "123456789012",
        "ApproximateFirstReceiveTimestamp": "1523232000001"
      },
      "messageAttributes": {
      },
      "md5OfBody": "7b270e59b47ff90a553787216d55d91d",
      "eventSource": "aws:sqs",
      "eventSourceARN": "arn:aws:sqs:eu-west-1:123456789012:MyQueue",
      "awsRegion": "eu-west-1"
    }
  ]
}
</code></pre>

<p>There is Records array. And if I set batch size to 5, then if there are 5 messages in SQS, they will be included in array. If there are 10 messages, then Lambda will be invoked twice, with 5 messages in each Record.</p>

<p>I am now confused a bit, as to what approach to take. My Lambda is fairly simple. It will be Axios POST request to external service. If it errors out, I will throw an error. I could even use axios-retry, and make retries fairly easy.</p>

<p>Should I use batch in my case? Naively lookin, all I need is 1 to 1. In other words, message arrives. Lambda takes it. If it errors, it will be retried automatically a bit later.</p>

<p>Contrary, I would have to iterate via all messages and attempt an Axios request. What if the third of five messages fails, in that case I throw an error and Lambda is stopped. What happens to messages four and five? Are they resent to SQS and then again picked up for another execution?</p>
