Simple Message Queue (SMQ, formerly MNS) enforces the following limits on queues, topics, and API requests. Design your applications within these constraints to avoid request failures or message loss.
Queue limits
| Item | Limit | Adjustable | Description |
|---|---|---|---|
| Queue name length | 120 characters | No | If exceeded, queue creation fails. |
| Number of queues per region | 1,000 | Yes | To request an increase, log on to the Quota Center console and submit an application to increase the Maximum Queue Quantity in a Single Region. See Submit an application to increase a quota. |
| Message size | 64 KB | No | If exceeded, the message is discarded. |
| Messages per batch operation | 16 | No | The maximum number of messages that a single batch request can process. |
| Long polling wait time | 30 seconds | No | The maximum wait time for a single long polling request. |
| Message retention period | 7 days | No | After the retention period expires, the message is deleted. Set a retention period based on your business requirements. |
Topic limits
| Item | Limit | Adjustable | Description |
|---|---|---|---|
| Topic name length | 120 characters | No | If exceeded, topic creation fails. |
| Number of topics per region | 1,000 | Yes | To request an increase, log on to the Quota Center console and submit an application to increase the Maximum Topic Quantity in a Single Region. See Submit an application to increase a quota. |
| Message size | 64 KB | No | If exceeded, the message is discarded. |
| Subscriptions per topic | 100 | No | The maximum number of subscriptions that a single topic supports. |
| Message retention period | 1 day | No | After the retention period expires, the message is deleted. Set a retention period based on your business requirements. |
| Message filtering tags per message | 1 | No | Each tag can be up to 16 characters in length. |
| Topic subscription on queues | Queue size must be equal to or greater than topic size | No | If exceeded, subscription creation fails. |
Throttling
SMQ applies a throttling policy to protect service stability. For details, see Throttling policy.