# Idle SQS Queue, No Messages

> Explains why ZopNight raises no SQS idle finding: queues have no standing charge and zero depth does not mean zero use.

Source: https://zop.dev/integrations/aws/recommendations/idle-sqs-queue-no-messages

---

## Why depth zero can mean a healthy queue

The tempting test for an unused queue is "no messages waiting". It is wrong. A queue whose
consumers keep up with producers drains almost instantly, so it reads close to zero while
handling millions of messages. The
[SQS CloudWatch metrics reference](https://docs.aws.amazon.com/AWSSimpleQueueService/latest/SQSDeveloperGuide/sqs-available-cloudwatch-metrics.html)
describes `ApproximateNumberOfMessagesVisible` as the current backlog, while
`NumberOfMessagesSent` counts messages successfully added. Only the second tells you whether
anyone is using the queue.

## Measuring sends instead of backlog

```bash
aws cloudwatch get-metric-statistics \
  --namespace AWS/SQS --metric-name NumberOfMessagesSent \
  --dimensions Name=QueueName,Value=my-queue \
  --start-time 2026-08-26T00:00:00Z --end-time 2026-09-25T00:00:00Z \
  --period 86400 --statistics Sum

aws sqs get-queue-attributes \
  --queue-url https://sqs.us-east-1.amazonaws.com/111122223333/my-queue \
  --attribute-names ApproximateNumberOfMessages RedrivePolicy
```

AWS notes that SQS metrics are emitted only while a queue is active, so a series with no
datapoints at all over a month is itself a signal. Check `NumberOfMessagesReceived` too, and
remember that messages moved to a dead-letter queue by a redrive policy are not counted as sends
to that queue.

## Where the check stands today

ZopNight gathers the send and depth metrics for every queue, but the check does not raise
a recommendation. The earlier version treated an empty queue as idle, which would have flagged
efficient, busy queues for deletion. Even with the throughput metrics in hand, the next problem
remains: there is no money to recover.

## Why no saving is possible

[Amazon SQS pricing](https://aws.amazon.com/sqs/pricing/) says you pay only for what you use and
there is no minimum fee; every customer gets 1 million requests free each month. A queue that
receives no messages makes no billable requests, so its monthly cost is zero. ZopNight reports cost
recommendations only when the saving is a real figure, and zero is not one.

## What stays out of scope

Dead-letter queues, FIFO queues and standard queues are all treated the same: none produces a
finding from this check. If you want a hygiene list, build it from the send metric above.

## Deleting a queue that is truly abandoned

1. Confirm no producer is expected to send: search code, infrastructure templates and SNS
   subscriptions for the queue URL or ARN.
2. Check whether it is the dead-letter target of another queue's `RedrivePolicy`.
3. List Lambda triggers with `aws lambda list-event-source-mappings --event-source-arn` and the
   queue ARN, and remove them.
4. Delete it with `aws sqs delete-queue --queue-url` and the URL.

**Warning**
Deleting a queue discards any messages still in it, and you must wait at least 60 seconds
before creating a queue with the same name. Drain or archive anything you need first.