Help Center/ Distributed Message Service for RocketMQ/ Service Overview/ Restrictions
Updated on 2024-12-25 GMT+08:00
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Restrictions

This section describes the restrictions on using DMS for RocketMQ.

Any instability caused by ignorance of the notes and constraints is not covered by the SLA.

Instance

Table 1 Restrictions

Item

Restrictions

Version

Fixed once the instance is created. Use the same version as your client.

Storage space
  • The disk type cannot be changed once the instance is created.
  • Can only be increased.
  • Can be increased for up to 20 times.

Broker quantity

Can only be increased.

Broker flavor

Can be increased.

  • If the broker quantity is 1, a master/standby switchover will be performed during an increase, interrupting services for within 30s.
  • If the broker quantity is greater than 1 and topics are across brokers, intermittent disconnections in seconds will occur during an increase. Ordered messages may not work properly. You are advised to perform an increase during off-peak hours.

VPC/subnet/AZ

Fixed once the instance is created.

Request-Reply

Not supported.

Configuration parameters

Cannot be modified using open-source APIs.

Topic

Table 2 Restrictions

Item

Restrictions

Maximum number of topics

Depends on the instance specifications. This limit cannot be changed.

When this limit is reached, no more topics can be created.

Automatic topic creation

Not supported.

Broker faults

When some brokers of an instance are faulty, topics cannot be created, modified, or deleted, but can be queried.

Consumer Group

Table 3 Restrictions

Item

Restrictions

Maximum number of consumer groups

Depends on the instance specifications. This limit cannot be changed.

When this limit is reached, no more consumer groups can be created.

Creating consumer groups, consumers, and producers

Consumer groups, consumers, and producers are generated automatically when you use the instance.

Consumer offset reset

You can reset the retrieval start position to any time within two days.

Resetting the consumer offset

Messages may be consumed more than once after the offset is reset.

Broker faults

When some brokers of an instance are faulty, consumer groups cannot be created, modified, or deleted, but can be queried.

Message

Table 4 Restrictions

Item

Restrictions

Message retention duration

The default retention period is 48 hours, which can be modified to up to 720 hours. Messages will be automatically deleted after the retention period expires.

Message size

The maximum size of a message is 4 MB. The maximum size of any message attribute (topic name, message type, message ID, or message creation time) is 16 KB. The message size cannot be changed.

When this limit is reached, messages will fail to be sent.

Delay of scheduled messages

The maximum delay is one year. This limit cannot be changed.

You can schedule messages to be delivered at any time within one year.

User

Table 5 Restrictions

Item

Restrictions

Number of users

A maximum of 1000 users can be created for a RocketMQ instance.

Broker faults

When some brokers of an instance are faulty, users cannot be created, modified, or deleted, but can be queried.