RocketMQ constrains and regulates certain metrics. To avoid program exceptions when using RocketMQ, do not exceed the maximum limits. For more information about the maximum limits of relevant items, see the following table.
| Item | Limit | Description |
|---|---|---|
| Maximum number of instances in a single region | Standard Edition: 8 Enterprise Platinum Edition: not limited |
None |
| Topic name length | 64 characters | If the length of the name of a topic exceeds this value, consumers will fail to send or subscribe to messages under this topic. |
| Message size | A normal or ordered message: 4 MB A transactional, scheduled, or delayed message: 64 KB |
If the size of a message exceeds this value, the message will be discarded. |
| Message retention period | 3 days | Messages are retained for at most three days, and the system automatically deletes them after three days. |
| Reset consumption offset | 3 days | Any message consumed within 3 days can be reset. |
| TPS for sending and receiving messages under a single topic | Standard Edition: 5000 messages/s Enterprise Platinum Edition: See the purchased specifications. |
None |
| Delay of scheduled or delayed messages | 40 days | The msg.setStartDeliverTime parameter can be set to any time (unit: milliseconds) within 40 days. The message cannot be scheduled to be sent after 40 days. |