Message Queue for Apache Kafka imposes limits on specific items. To prevent program exceptions when you use Message Queue for Apache Kafka, do not exceed the limits.

The following table describes the limits of relevant items.

Item Limit Description
Total number of topics (partitions) Limited In Message Queue for Apache Kafka, messages are stored and scheduled by partition. If messages are stored in a large number of topics (partitions), storage fragmentation occurs. This reduces cluster performance and stability.
Reduction in the number of partitions of a topic Not supported This is due to the design constraints of Apache Kafka.
Exposed ZooKeeper Not supported ZooKeeper has been masked since Apache Kafka 0.9.0. Therefore, you do not need to access ZooKeeper to use a client. In Message Queue for Apache Kafka, ZooKeeper is partially shared. For security purposes, it is not exposed. You do not need to learn about ZooKeeper.
Logons to the machines on which Message Queue for Apache Kafka is deployed Not supported N/A
Versions 0.10.x to 2.x
  • Version 2.x is compatible with versions 0.10.x and 0.9.0.
  • Version 0.10.x is compatible with version 0.9.0.
  • For more information about how to upgrade an instance from 0.10.x to 2.x, see Upgrade the instance version.
Group specification Twice the number of topics For example, if you can create a maximum of 50 topics on your Message Queue for Apache Kafka instance, you can create a maximum of 100 groups on the instance. To create more groups, you need to purchase more topics. Each time you purchase a topic, a quota of two groups is added. For more information about how to upgrade the instance, see Upgrade instance specifications.
Relationship between the number of topics and partitions 1:16 In addition to the default number of partitions, 16 partitions are added each time you purchase a topic. For example, you have purchased a Standard Edition (High Write) instance that provides 50 topics, 2xlarge traffic, and 400 default partitions. If you purchase another 10 topics for this instance, 160 additional partitions are added to this instance. The total number of partitions becomes 560.
Number of topics of a Professional Edition instance Twice the number of purchased topics For example, if you purchase a Professional Edition instance that provides 50 topics, you can create 100 topics on the instance.
Changes to the region of an instance Not supported After an instance is purchased and deployed, its region is closely associated with its physical resources and cannot be changed. If you need to change the region of an instance, release the instance and purchase a new instance.
Changes to the network properties of an instance Supported Network properties can be modified as needed. For more information, see Upgrade instance specifications.
Message size 10 MB The maximum size of a message is 10 MB. A message larger than 10 MB in size cannot be sent.
Monitoring and alerting Limited The data latency is 1 minute.
Number of client connections to each broker Up to 1,000 Message Queue for Apache Kafka clients need to establish socket connections to brokers to send or consume messages. If the number of client connections to a broker exceeds the limit, the broker spends many resources on maintaining the connections, and the stability of the broker is severely affected. Therefore, we recommend that you establish no more than 1,000 client connections to each broker.