Message Queue for Apache RocketMQ regulates and sets constraints for some metrics. To avoid program exceptions when you use Message Queue for Apache RocketMQ, do not exceed the maximum limits.

The following table describes the limits of relevant items.

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
Length of a topic name 64 characters If the length of a topic name exceeds this limit, messages under this topic cannot be sent or subscribed to properly.
Message size
  • A normal message or ordered message: 4 MB
  • A transactional message, scheduled message, or delayed message: 64 KB
If the size of a message exceeds the corresponding limit, 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.
Transactions per second (TPS) for sending and receiving messages under a single Message Queue for Apache RocketMQ instance
  • Standard Edition: 5000 messages per second. If you want to increase the TPS, submit a ticket.
  • Enterprise Platinum Edition: See specifications of your purchased instance.
None
Delay time of scheduled or delayed messages 40 days The msg.setStartDeliverTime parameter can be set to any time in milliseconds within 40 days. The message cannot be scheduled to be sent after 40 days.
Note A latency of 1 to 2 seconds may occur to scheduled messages.
Sending messages in batches Not supported Message Queue for Apache RocketMQ does not support sending messages in batches.