# Idle SQS Queue -- No Messages Sent

> An SQS queue bills $0.40 per million requests with no standing charge, so a queue sending zero messages already costs $0, and queue depth of 0 never proved idleness anyway, since a well-drained busy queue reads the same. ZopNight therefore retired this rule in place; it abstains on every queue.

Source: https://zop.dev/integrations/aws/recommendations/idle-sqs-queue-no-messages-sent
Updated: 2026-08-19

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## Queue depth was the wrong idle signal

An earlier version of this rule keyed idleness on `ApproximateNumberOfMessages` reading zero.
That gauge answers "how many messages are sitting here right now", and for a healthy queue the
answer is usually zero: consumers drain it as fast as producers fill it. Depth of zero across
a whole month describes the busiest, best-tuned queues in a fleet just as well as abandoned
ones. The old detection was therefore a false positive on every efficiently-drained queue,
and it recommended deleting them.

## The honest throughput axes for a queue

Whether anything uses a queue is a throughput question, not a depth question. The rule's
declared metrics now name the real axes from [the queue counters SQS reports to CloudWatch](https://docs.aws.amazon.com/AWSSimpleQueueService/latest/SQSDeveloperGuide/sqs-available-cloudwatch-metrics.html): `NumberOfMessagesSent` and
`NumberOfMessagesReceived`, each needing to sit near zero (below a small floor, not exactly
zero) over at least 30 days before "idle" would be a fair claim. One of those axes,
the receive-side counter, is not yet harvested by ZopNight's aggregator; the declaration
keeps the fetch wiring honest so the gap is visible rather than papered over.

## Why an idle queue bills nothing

Even with perfect throughput-based detection, the finding would have no dollar attached. SQS
[charges about $0.40 per million requests](https://aws.amazon.com/sqs/pricing/), the first million per month free, and nothing at
all for a queue that just exists. Zero traffic means zero billable requests means a $0 line
item. ZopNight's cost findings must be concrete or absent, so Evaluate returns nil on every
input. The rule is retired in place. Its category was also corrected from `orphan` (which is
exempt from the low-savings filter, and so had let $0 findings through) to `idle`.

## Checking queue traffic with CloudWatch

```bash
aws cloudwatch get-metric-statistics \
  --namespace AWS/SQS --metric-name NumberOfMessagesSent \
  --dimensions Name=QueueName,Value=my-queue \
  --start-time "$(date -u -v-30d +%Y-%m-%dT%H:%M:%SZ)" \
  --end-time "$(date -u +%Y-%m-%dT%H:%M:%SZ)" \
  --period 86400 --statistics Sum
```

Repeat with `NumberOfMessagesReceived` for the consume side. Flat zeros on both is a queue
nothing talks to.

## If you still want to delete a queue

Do it for clarity, not savings. Before deleting, check for Lambda event source mappings and
SNS subscriptions that target the queue, and whether it serves as a dead-letter queue for
another one; a DLQ is supposed to be silent until something goes wrong, which makes it the
classic false catch of any manual cleanup pass.