This topic describes the limits on some metrics in Message Queue for Apache RocketMQ. To avoid program exceptions, you must set these metrics to values within these limits when you use Message Queue for Apache RocketMQ.

The following table describes the limits.

Item Limit Description
Maximum number of Message Queue for Apache RocketMQ instances in a single region
  • Standard Edition: 8
  • Enterprise Platinum Edition: not limited
None
Topic name length 64 characters The length of a topic name cannot exceed 64 characters. Otherwise, messages in the topic cannot be sent or subscribed to.
Message size
  • A normal message or ordered message: 4 MB
  • A transactional message, scheduled message, or delayed message: 64 KB
Note The size of attributes for a message cannot exceed 16 KB for all message types.
The size of a message cannot exceed the corresponding limit. Otherwise, the message cannot be sent.
Message retention period 3 days Messages are retained for up to three days, and the system automatically deletes them after three days.
Consumer offset reset 3 days Consumer offsets can be reset for messages that are sent at a time point within three days before the last message in a specified topic is sent.
Transactions per second (TPS) for messaging on a single Message Queue for Apache RocketMQ instance
  • Standard Edition: 5,000 messages/second
  • Enterprise Platinum Edition: The value varies with purchased specifications.
If you need a higher limit on a Standard Edition instance, create a ticket, add your business expectations and computing logic, and then submit the ticket.

However, not all applications can be approved. This is because Standard Edition instances share physical resources and resources are allocated based on physical limits, such as resource usage of all Standard Edition instances.

We recommend that you upgrade your instance from the Standard Edition to the Enterprise Platinum Edition to meet your business needs.

Delay time of scheduled or delayed messages 40 days You can set the msg.setStartDeliverTime parameter for a message to a value in milliseconds within 40 days after the message is sent. The message cannot be delivered after 40 days.
Note A latency of 1 to 2 seconds may occur to scheduled messages.
Batch message sending Not supported Message Queue for Apache RocketMQ does not allow you to send messages in batches.