Message Queue for Apache Kafka sets limits for some metrics. 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.
|Total number of topics (partitions)||Supported||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 Message Queue for Apache Kafka.|
|Exposed ZooKeeper||Not supported||ZooKeeper has been masked since Message Queue for Apache Kafka 0.9.0. Therefore, you do not need to access ZooKeeper to use the 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.|
|Log on to the machines on which Message Queue for Apache Kafka is deployed||Not supported||N/A|
|Versions||0.10.x to 2.x||
|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 Group s on the instance. To create more Group s, you need to purchase more topics. Each time you purchase a topic, a quota of two Group s 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 with 50 topics, 2xlarge traffic, and 400 partitions by default. 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 with 50 topics, you can create 100 topics in the instance.|
|Changes to the region or network properties of an instance||Not supported||After an instance is purchased and deployed, its region and network properties are closely associated with its physical resources and cannot be changed. If you need to change the region or network properties of an instance, release the instance and purchase a new instance.|
|Message size||10 MB||The maximum size of a message is 10 MB. A message larger than 10 MB cannot be sent.|
|Monitoring and alerting||Supported||The data latency is one 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 receive messages. If the number of client connections to a broker is too large, 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.|